Strength And Durability Properties Of Geopolymer Concrete With Fa And Ggbs As Source Materials

Strength and durability properties of geopolymer concrete with FA and GGBS as source materials CHAPTER 1 INTRODUCTION 1.

Introduction The geopolymer technology is proposed by Davidovits (1978)

gives considerable promise for application in concrete industry as an alternative binder to the Portland cement .In terms of reducing global warming, the geopolymer technology could reduce the co 2 emission into the atmosphere, caused by cement and aggregate industries about 80%.In this technology ,the source material that is FA and GGBS [Fly Ash and Ground Granulated Blast Furnace slag] in silicon (si) and aluminum (Al) is reacts with a highly alkaline solution

through the process of geopolymerisation to

produce the binding material . Geopolymer concrete is a new material which does not need presence of Portland cement as a binder. The major problem the world is facing today is the environmental pollution. The production of cement causes emission of CO 2 .There is two different sources of CO 2 during cement production. Combustion of fossil fuels to operate the rotating kiln is the largest source and other one is the chemical process of calcimining limestone into lime in the cement kiln also production CO2 Hendricks et al (2004) carried out emission reduction of green house gases from the cement industry. Ernest woverell and Lynn price et al (2002), have reported that CO2 emission from the global cement industry. In India about 2069738 thousands of metric tons of CO2 is emitted in the year 2010, and also the cement is manufactured by using the raw materials such as lime stone, clay and other minerals. Quarrying of these raw materials is also caused environmental degradation. 1.6 tons of raw materials are required to produce 1 ton of cement. Formation of lime stone takes much longer time than the rate at which human beings use it. 1.1.

General The cement industry is extremely energy intensive. After

aluminum and steel, the manufacturing of Portland cement is the most Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials energy intensive process as it consumes 4GJ per tons of energy. After thermal power plants and the iron and steel sector, the India cement industry is the third largest user of coal in the country. As a consequence, a huge amount of fly ash (FA) is generated in thermal power plants, causing several disposals –related problems. Insplit of initiatives taken by the government ,several non-government organization and research and development organization , the total utilization of FA is only about 50%.India produce 130million ton of FA annually which is expected to reach 175 million ton by 2012 .FA has been successfully used as a mineral admixture component of Portland pozzolan blended cement for nearly 60years .These is effective utilization of FA in making cement concrete as it extends technical advantages as well as controls the environmental pollution. In this investigation, in order to produce concrete low-calcium fly ashbased geopolymer is utilized as binder instead Portland cement. The fly ashbased geopolymer paste binds the loose coarse aggregates, fine aggregate sand other un-reacted materials together to form the geopolymer concrete, with or without the presence of admixtures. The manufacture of geopolymer concrete is carried out using the usual concrete technology methods.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

As in the case of OPC concrete, the aggregates occupy about 75-80 % by mass, in geopolymer concrete. The silicon and the aluminum in the low-calcium (ASTM Class F) fly ash react with an alkaline liquid that is a combination of sodium silicate and sodium hydroxide solutions to form the geopolymer paste which binds the aggregate as well as other un-reacted material. Ground granulated blast furnace slag (GGBS) is a by-product from the blast –furnaces used to make iron. GGBS is a glassy, granular, nonmetallic consistency essentially of silicate and aluminate of calcium and other bases. GGBS has almost the same particle size as cement. GGBS, often blended with Portland cement as low cast filler, enhance concrete workability, density, durability and resistance to alkali –silica reaction. 1.1.2. Geopolymer concrete It is known factor that the production of Portland cement consumes significant amount of energy and at the same time it releases abundant quantity of carbon dioxide in to the atmosphere. The climate change due to global warming has become a major concern. The global warming is caused by the emission of greenhouse gases, such as carbon dioxide (CO2), to the atmosphere by human activities. The cement industry is held responsible for some of the CO2 emissions, because the production of one ton of Portland cement emits approximately one ton of CO2 into the atmosphere (Davidovits, 1994; McCaffery, 2002). However, Portland cement is still the main binder in concrete construction prompting a search for more environmentally friendly materials. Several efforts are in progress to Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials supplement the use of Portland cement in concrete in order to address the global warming issues. These include the utilization of supplementary cementing materials such as fly ash, silica fume, granulated blast furnace slag, rice-husk ash and metakaolin, and the development of alternative binders to Portland cement. One possible alternative is the use of alkali-activated binder using industrial by-products containing silicate materials. In 1978, Davidovits (1999) proposed that binders could be produced by a polymeric reaction of alkaline liquids with the silicon and the aluminium in source materials of geological origin or by-product materials such as fly ash, GGBS and rice husk ash. He termed these binders as geopolymer. The most common industrial by-products used as binder materials are fly ash (FA) and ground granulated blast furnace slag (GGBS). In 2001, when this research began, several publications were available describing geopolymer pastes and geopolymer coating materials (Davidovits 1991; Davidovits et al. 1994; Balaguru, et al. 1997; Davidovits 1999; Palomo et al. 1999). However, very little was available in the published literature regarding the use of geopolymer technology to make low-calcium (ASTM Class F) fly ash and GGBS based geopolymer concrete. The research reported in this thesis was dedicated to investigate the process of making fly ash and GGBS based geopolymer concrete and the short-term engineering properties of the hardened concrete. 1.2. Objectives and scope of investigation In this investigation “strength and durability properties of geopolymer concrete with FA and GGBS as source material” have been studied. The objectives comprises:1. To develop a mixture proportioning process to manufacture low-calcium fly ash and GGBS based geopolymer concrete. 2. To study the influence of ground granulated blast furnaces slag on geopolymer concrete. The type of geopolymer concrete mixes are(i)0%FA and 100%GGBS (ii)25% FA and 75% GGBS.(iii) 50% FA and 50% GGBS (iv) 75% FA and 25% GGBS (v)100%FA and 0% GGBS

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials 3.

To study the short-term engineering properties of hardened low

calcium fly ash and GGBS based geopolymer concrete such as compressive strength and split tensile strength. 4. To study the durability properties of geopolymer concrete by conducting RCPT and Water absorption. 6. To study the effect of concentration of alkaline activators solution in geopolymer concrete. The molar ratio of hydroxide solution considered in the investigation is 10M. Based on the experimental results, an attempt is made to establish an empirical relationship between compressive strength and split tensile strength of geopolymer concrete prepared with various proportions of FA: GGBS at different curing periods. An attempt is also made to compare the cost of one cubic meter of CC (M45) at 28 days compressive strength.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

CHAPTER 2 LITERATURE REVIEW This Chapter presents the background to the needs for the development of alternative binders to manufacture concrete. The available published literature on geopolymer technology is also briefly reviewed. 2.1 Concrete and environment The emission of CO 2 is a critical factor in general for the industries, particularly to the cement industries the emission of CO 2 causes green house effect which increases the global temperature that may result in climate changes. The production of cement is increasing about 3% annually (McCaffrey, 2002). The production of one ton of cement liberates about one ton of CO2 to the atmosphere which causes global warming. The contribution of Portland cement production worldwide to the greenhouse gas emission is estimated to be about 1.35 billion tons annually or about 7% of the total greenhouse gas emissions to the earth’s atmosphere (Malhotra, 2002). Cement is also among the most energy-intensive construction materials, after aluminium and steel. The durability of ordinary Portland cement is still under examination as many concrete structures built-in corrosive environmental deteriorate after 20 to 30 years, even though they have been designed for more than 50 years of service life (Mehta, 2002). In order to produce environmentally friendly concrete, Mehta (2002) suggested the use of fewer natural resources, less energy and minimise carbon dioxide emissions. Several efforts are in progress to supplement the use of Portland cement in concrete in order to address the global warming issues. These include the utilization of supplementary cementing materials such as fly ash, silica fume, ground granulated blast furnace Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials slag, rice-husk ash and metakaolin, and the development of alternative binders to Portland cement. In this respect, the geopolymer technology shows considerable promise for application in concrete industry as an alternative binder to the Portland cement (Duxson et al, 2007). In terms of global warming, the geopolymer technology could significantly reduce the CO2 emission to the atmosphere caused by the cement industries as shown by the detailed analyses of (Gartner, 2004).

2.2 Geopolymers In 1978, Davidovits proposed that an alkaline liquid could be used to react with the silicon (Si) and the aluminium (Al) in a source material of geological origin or in by-product materials such as fly ash and rice husk ash to produce binders. Because the chemical reaction that takes place in this case is a polymerisation process, Davidovits (1994, 1999) coined the term ‘Geopolymer’ to represent these binders. Geopolymers are members of the family of inorganic polymers. The chemical composition of natural zeolitic material, whereas the microstructure is amorphous instead of crystalline (Palomo et al. 1999; Xu and van Deventer, 2000). The polymerisation process involves a substantially fast chemical reaction under alkaline condition on Si-Al minerals that results in a three dimensional polymeric chain and ring structure consisting of Si-O-Al-O bonds. Geopolymerization involves the chemical reaction of alumino-silicate oxides (Si2O5, Al2O2) with alkali polysilicates yielding polymeric Si – O – Al bonds. Polysilicates are generally sodium or potassium silicate supplied by chemical industry or manufactured fine silica powder as a by-product of ferro-silicon metallurgy.

Unlike

ordinary

Portland/pozzolanic

cements,

geopolymers do not form calciumsilicate-hydrates (CSHs) for matrix Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials formation and strength, but utilise the polycondensation of silica and alumina precursors and a high alkali content to attain structural strength. Hence, geopolymers are sometimes referred to as alkali activated alumino silicate binders (Davidovits, 1994a; Palomo et. al., 1999; Roy, 1999; van Jaarsveld et. al., 2002a). 2.3 Constituents of geopolymer 2.3.1 Source materials There are two main constituents of geopolymers, namely the source materials and the alkaline liquids. The source materials for geopolymers based on alumina-silicate should be rich in silicon (Si) and aluminium (Al). These could be natural minerals such as kaolinite, clays, micas, andalousite, spinel, etc whose empirical formula contains Si, Al, and oxygen (O) (Davidovits, 1988c). Alternatively, by-product materials such as fly ash, silica fume, slag, rice-husk ash, red mud, etc could be used as source materials. The choice of the source materials for making geopolymers depends on factors such as availability, cost, and type of application and specific demand of the end users. Among the waste or by-product materials, fly ash and GGBS are the most potential source of geopolymers. Low calcium (ASTM Class F) fly ash is preferred as a source material instand of high calcium (ASTM Class C) fly ash. The presence of calcium in high amount may interfere with the polymerisation process and alter the microstructure (Gourley 2003). 2.3.2 Alkali activators The most common alkaline activator used in geopolymerisation is a combination of sodium hydroxide (NaOH) or potassium hydroxide (KOH) and sodium silicate or potassium silicate (Davidovits 1999). Palomo et al (1999) concluded that the type of activator plays an important role in the polymerisation process. Reactions occur at a high rate when the alkaline activator contains soluble silicate, either sodium or potassium silicate, Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials compared to the use of only alkaline hydroxides. Xu and van Deventer (2000) confirmed that the addition of sodium silicate solution to the sodium hydroxide solution as the alkaline activator enhanced the reaction between the source material and the solution. Furthermore, after a study of the geopolymerisation of sixteen natural Al-Si minerals, they found that generally the NaOH solution caused a higher extent of dissolution of minerals than the KOH solution. A combination of sodium silicate solution and sodium hydroxide (NaOH) solution can be used as the alkaline liquid. It is recommended that the alkaline liquid is prepared by mixing both the solutions together at least 24 hours prior to use. The sodium silicate solution is commercially available in different grades. The sodium silicate solution A53 with SiO2-to-Na2O ratio by mass of approximately 2, i.e., SiO2 = 29.4%, Na2O = 14.7%, and water = 55.9% by mass, is generally used. The sodium hydroxide with 9798% purity, in flake or pellet form, is commercially available. The solids must be dissolved in water to make a solution with the required concentration. The concentration of sodium hydroxide solution can vary in the range between 8 Molar and 16 Molar; however, 8 Molar solution is adequate for most applications. The mass of NaOH solids in a solution varies depending on the concentration of the solution. For instance, NaOH solution with a concentration of 8 Molar consists of 8x40 = 320 grams of NaOH solids per litre of the solution, where 40 is the molecular weight of NaOH. Note that the mass of water is the major component in both the alkaline solutions. In order to improve the workability, a high range water reducer super plasticizer and extra water may be added to the mixture. The aggregate both coarse and fine employed by the concrete industry are also suitable to produce geopolymer concrete. The aggregate grading curves currently used in concrete practice are applicable in the case of Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials geopolymer concrete (Hardjito and Rangan, 2005; Wallah and Rangan, 2006; Sumajouw and Rangan, 2006; Gourey, 2003; Siddiqui, 2007).

2.4

Mixture proportion of geopolymer concrete The primary depends between Portland cement concrete

and geopolymer concrete is the binder. The silicon and aluminum oxides in the low-calcium fly ash and GGBS reacts with the alkaline liquid to form the geopolymer paste that binds the loose coarse aggregates, fine aggregates, and other un-reacted materials together to form the geopolymer concrete. As in the case of Portland cement concrete, the coarse and fine aggregates occupy about 75 to 80% of the mass of geopolymer concrete. The tools currently available for the design of Portland cement concrete can be made use of to prepare geopolymer concrete mixes. The compressive strength and the workability of geopolymer concrete are influenced by the proportions and properties of the constituent materials that make the geopolymer paste. Experimental results of Hardjito and Rangan (2005) on geopolymer concrete have shown the following:  Higher concentration (in terms of molar) of sodium hydroxide solution results in

higher compressive strength of geopolymer

concrete.  Higher the ratio of sodium silicate solution-to-sodium hydroxide solution by mass,

higher is the compressive strength of

geopolymer material.  The addition of naphthalene sulphonate-based super plasticizer, up to

approximately 4% of fly ash by mass, improves the

workability of the fresh geopolymer concrete; however, there is a slight degradation in the compressive strength of hardened concrete when the super plasticizer dosage is greater than 2%. Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials 

The slump value of the fresh geopolymer concrete increases when the water content of the mixture increases.

 As the H2O-to-Na2O molar ratio increases, the compressive strength of geopolymer concrete decreases. As can be seen from the above, the interaction of various parameters on the compressive strength and the workability of geopolymer concrete is complex. In order to assist the design of lowcalcium fly ash-based geopolymer concrete mixtures, a single parameter called ‘water-to-geopolymer solids ratio’ by mass was devised. In this parameter, the total mass of water is the sum of the mass of water contained in the sodium silicate solution, the mass of water used in the making of the sodium hydroxide solution, and the mass of extra water, if any, present in the mixture. The mass of geopolymer solids is the sum of the mass of fly ash, the mass of sodium hydroxide solids used to make the sodium hydroxide solution, and the mass of solids in the sodium silicate solution (i.e. the mass of Na2O and SiO2). Test were carried out to establish effect of water-togeopolymer solids ratio by mass on the workability and compressive strength and geopolymer concrete. Obviously, as the water-togeopolymer solids ratio increased, the workability increased as the mixtures contained more water (Hardjito and Rangan, 2005). Rajmane (2006) studied the effect of geopolymeric binders such as GGBS and FA by activating silicon dioxide and aluminium oxide present in the binders, to form inorganic polymer binder system. This binder system can be used to produce concretes containing river sand as fine aggregate and coarse aggregate in the form of either sintered FA aggregates (SFFA) or crushed granite aggregates (CGA). It was concluded that the lightweight aggregate based geopolymer concrete have one day compressive strength of about 35 MPa and a 28 days strength of more than 50 MPa. CGA based geopolymer concretes produced marginally higher compressive strength of about 45 MPa at one day and 65 MPa at 28 days. Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

2.5 GPC mix design Rangan and Hardjito (2005) have noted that unlike conventional cement concretes GPCs are a new class of construction materials and therefore no standard mix design approaches are yet available for GPCs. While GPC involves more constituents in its binder (viz., FA, GGBS, sodium silicate, sodium hydroxide and water), whose interactions and final structure and chemical composition are under intense research whereas the chemistry of Portland cement and its structure and chemical composition (before and after hydration) are well established due to extensive research carried out over more than century. While the strength of cement concrete is known to be well related to its water-cement ratio, such a simplistic formulation may not hold good for GPCs. Hence, the formulation of GPC has to be made by trial and error basis. The role and the influence of aggregates are considered to be the same as in the case of Portland cement concrete. The mass of combined aggregates may be taken to be between 75% and 80% of the mass of geopolymer concrete. The performance criteria of a geopolymer concrete mixture depend on the application. For simplicity, the compressive strength of hardened concrete and the workability of fresh concrete are selected as the performance criteria. In order to meet these performance criteria, the alkaline liquid-to-fly ash ratio by mass, water-to-geopolymer solids ratio by mass, the wet-mixing time, the heat-curing temperature, and the heat-curing time are selected as parameters. The alkaline liquid-to-fly ash ratio values by mass in the range of 0.30 and 0.45 are recommended. Sodium silicate solution is cheaper than sodium hydroxide solids. Commercially available sodium silicate solution A53 with SiO2-to-Na2O ratio by mass of approximately 2, i.e., Na 2O = 14.7%, SiO2 = 29.4%, and water = 55.9% by mass, and sodium hydroxide solids (NaOH) with 97-98% purity are recommended. Laboratory experience suggests that the ratio of sodium silicate solutionDepartment of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials to-sodium hydroxide solution by mass may be taken approximately as 2.5 (Hardjito and Rangan, 2005). Mixture proportion of heat-cured low-calcium fly ashbased geopolymer concrete with design compressive strength of 45 MPa is needed for precast concrete products as follows:Assume that normaldensity aggregates in SSD condition are to be used and the unit-weight of concrete is 2400 kg/m3. Take the mass of combined aggregates as 77% of the mass of concrete, i.e. 0.77x2400 = 1848 kg/m3. The combined aggregates may be selected to match the standard grading curves used in the design of Portland cement concrete mixtures. For instance, the aggregates may comprise 277 kg/m3 (15%) of 20 mm aggregates, 370 kg/m3 (20%) of 14 mm aggregates, 647 kg/m3 (35%) of 7 mm aggregates, and 554 kg/m3 (30%) of fine sand are required to meet the reauirements of standard grading curves. The fineness modulus of the combined aggregates is approximately 5.0. The mass of low-calcium fly ash and the alkaline liquid = 2400 – 1848 = 552 kg/m3. Take the alkaline liquid-to-fly ash ratio by mass as 0.35; the mass of fly ash = 552/ (1+0.35) = 408 kg/m 3 and the mass of alkaline liquid = 552 – 408 = 144 kg/m 3. Take the ratio of sodium silicate solution-to-sodium hydroxide solution by mass as 2.5; the mass of sodium hydroxide solution = 144/ (1+2.5) = 41 kg/m 3; the mass of sodium silicate solution = 144 – 41 =103 kg/m3. Therefore, the trial mixture proportion is as follow: combined aggregates = 1848 kg/m3, low-calcium fly ash = 408 kg/m3, sodium silicate solution = 103 kg /m 3, and sodium hydroxide solution = 41 kg/m3. The sodium hydroxide solids (NaOH) with 97-98% purity is purchased from commercial sources, and mixed with water to make a solution with a concentration of 8 Molar. This solution comprises 26.2% of NaOH solids and 73.8% water, by mass. For the trial mixture, water-to-geopolymer solids ratio by mass is calculated as follows: In sodium silicate solution, water = 0.559x103 = 58 kg, and solids = 103 – Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials 58 = 45 kg. In sodium hydroxide solution, solids = 0.262x41 = 11 kg, and water = 41 – 11 = 30 kg. Therefore, total mass of water =58+30 = 88 kg, and the mass of geopolymer solids = 408 (i.e. mass of fly ash) +45+11 = 464 kg. Hence, the water-to-geopolymer solids ratio by mass = 88/464 = 0.19. For water-to-geopolymer solids ratio by mass of 0.19, the design compressive strength is approximately 45 MPa, as needed. The geopolymer concrete mixture proportion is therefore as follows: 20 mm aggregates = 277 kg/m3, 14 mm aggregates = 370 kg/m3, 7 mm aggregates = 647 kg/m3, fine sand = 554 kg/m3, low-calcium fly ash (ASTM Class F) =

408 kg/m3, sodium silicate solution (Na2O =

14.7%, SiO2 = 29.4%, and water = 55.9% by mass) = 103 kg/m 3, and sodium hydroxide solution (8 Molar) = 41 kg/m 3 ( Note so as to the 8 Molar sodium hydroxide solution is complete by mixing 11 kg of sodium hydroxide solids with 97-98% cleanliness in 30 kg of water). Geopolymer concrete can be manufactured by adopting the conventional techniques used in the manufacture of Portland cement concrete. It is recommended that the alkaline liquid is prepared by mixing both the solutions together at least 24 hours prior to use. In the laboratory, the fly ash and the aggregates were first mixed together dry in 80-litre capacity pan mixer for about three minutes. The aggregates were prepared in saturated-surface-dry (SSD) condition. The alkaline liquid was mixed with the superplasticiser (SP) and the extra water, if any. The liquid component of the mixture was then added to the dry materials and the mixing continued usually for another four minutes. The fresh concrete could be handled up to 120 minutes without any sign of setting and without any degradation in the compressive strength. The fresh concrete was cast and compacted by the usual methods used in the case of Portland cement concrete (Hardjito and Rangan, 2005). Fresh fly ashbased geopolymer concrete was usually cohesive. The conventional slump test is used for measuring the workability of concrete. 2.6 Properties of GPC Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials Several factors have been identified as important parameters affecting the properties of geopolymers. Palomo et al (1999) concluded that the curing temperature was a reaction accelerator in fly ash-based geopolymers, and significantly affected the mechanical strength, together with the curing time and the type of alkaline activator. Previous studies have reported that heat-cured geopolymer concrete possesses the properties of high compressive strength, low drying shrinkage and creep, and good resistance to sulfate and acid (Rangan BV, 2004). Sarker et al (2004) studied the fracture mechanics of heat cured fly ash based geopolymer concrete and they concluded that the denser interfacial transition zone of GPC resulted in higher critical stress intensity factor and more brittle type of failure with smoother fracture plane as compared to OPC concrete. Van Jaarsveld et al (2002) concluded that the water content, and the curing and calcining condition of kaolin clay affected the properties of geopolymers. However, they also stated that curing at too high temperature caused cracking and a negative effect on the properties of the material. Finally, they suggested the use of mild curing to improve the physical properties of the material. In another report, van Jaarsveld et al (2003) stated that the source materials determine the properties of geopolymers, especially the CaO content, and the water-to-fly ash ratio. Based on the study of geopolymerisation of sixteen natural Si-Al minerals, Xu and van Deventer (2000) reported that factors such as the percentage of CaO, K2O, and the molar Si-to-Al ratio in the source material, the type of alkali activator, the extent of dissolution of Si, and the molar Si-to-Al ratio in solution significantly influenced the compressive strength of geopolymers. Alkaline activator that contained soluble silicates was proved to increase the rate of reaction compared to alkaline solutions that contained only hydroxide (Xu and van Deventer, 2000). Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials The results of recent studies have shown the potential use of heat-cured fly ash based geopolymer concrete as a construction material (Rangan BV, 2004). Fly ash blended with blast furnace slag (Nath and Sarker, 2012) and rice husk ash (Wongpa et al., 2010) has also been used as the base material for geopolymer. Adding slag up to 30% of the total binder achieved compressive strength of concrete up to 55 MPa and that of mortar up to 63 MPa at 28 days (Nath and Sarker, 2012). Based on laboratory tests, Davidovits (1988b) reported that geopolymer cement can harden rapidly at room temperature and gain the compressive strength in the range of 20 MPa after only 4 hours at 20oC and 70-100 MPa after 28 days. Comrie et. al. (1988) conducted tests on geopolymer mortars and reported that most of the 28- day strength was gained during the first 2 days of curing. The presence of alkalis in the normal Portland cement or concrete could generate dangerous Alkali-AggregateReaction. However the geopolymeric system is safe from that phenomenon even with higher alkali content. As demonstrated by Davidovits (1994a; 1994b), based on ASTM C227 bar expansion test, geopolymer cements with much higher alkali content compared to Portland cement did not generate any dangerous alkali-aggregate reaction . Geopolymer cement is also acid-resistant. Geopolymer cements do not rely on lime. They

are not dissolved by acidic

solutions. As shown by the tests of exposing the specimens in 5% of sulfuric acid and chloric acid, geopolymer cements were relatively stable with the weight lose in the range of 5-8% while the Portland based cements were destroyed and the calcium alumina cement lost weight about 30-60% (Davidovits, 1994b). Some recently published papers (Bakharev, 2005c; Gourley & Johnson, 2005; Song et. al., 2005a) also reported the result of the tests on acid confrontation of Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials geopolymers and geopolymer concrete. By observing the weight loss after acid exposure, these researchers concluded that geopolymers or geopolymer concrete is superior to Portland cement concrete in terms of acid resistance as the weight loss is much lower. 2.7 Fields of application According to Davidovits (1988b), geopolymeric materials have a wide range of applications in the field of industries such as in the automobile and aerospace, nonferrous foundries and metallurgy, civil engineering and plastic industries. The type of application of geopolymeric materials is determined by the chemical structure in terms of the atomic ratio Si:Al in the polysialate. Davidovits (1999) classified the type of application according to the Si:Al ratio as presented in Table 2.1. A low ratio of Si:Al of 1, 2, or 3 initiates a 3DNetwork that is very rigid, while Si:Al ratio higher than 15 provides a polymeric character to the geopolymeric material. It can be seen from Table 2.1 that for many applications in the civil engineering field a low Si:Al ratio is suitable. Table 2.1 Applications of geopolymeric materials based on Si:Al atomic ratio Si:Al ratio 1

2

3

Applications -

Bricks

-

Ceramics

-

Fire protection

-

Concretes and low CO2 cements

-

Toxic waste encapsulation and radioactive

-

Fire protection

-

Foundry equipments

-

Heat resistant composites, 2000C to 10000C

-

Tooling for aeronautics titanium process

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials >3

-

Sealants for industry, 2000C to 6000C

- Tooling for aeronautics SPF aluminium 20-35

-

Fire resistant and heat resistant fibre composites One of the potential fields of application of

geopolymeric materials is in toxic waste management because geopolymers behave similar to zeolitic materials that have been known for their ability to absorb the toxic chemical wastes (Davidovits, 1988b). Another application of geopolymer is in the strengthening of concrete structural elements. Balaguru et. al. (1997) reported the results of the investigation on using geopolymers, instead of organic polymers, for fastening carbon fabrics to surfaces of reinforced concrete beams. It was found that geopolymer provided excellent adhesion to both concrete surface and in the interlaminar of fabrics. In addition, the researchers observed that geopolymer was fire resistant, did not degrade under UV light, and was chemically compatible with concrete. In Australia, the geopolymer technology has been used to develop sewer pipeline products, railway sleepers, building products including fire and chemically resistant wall panels, masonry units, protective coatings and repairs materials, shotcrete and high performance fibre reinforced laminates (Gourley, 2003; Gourley and Johnson, 2005). 2.8 Fly ash 2.8.1 Introduction Fly ash (FA) is a by-product of the combustion of pulverized coal in thermal power plants. It is a fine grained, powdery and glassy particulate material that is collected from the exhaust gases by electrostatic precipitators or bag filters. When pulverised coal is burnt to generate heat, the residue contains 80 per cent fly ash and 20 per cent bottom ash. The size of particles is largely dependent on the type of dust Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials collection equipment. Diameter of fly ash particles ranges from less than 1 μm–150 μm. It is generally finer than Portland cement. Their surface area is typically 300 to 500 m 2/kg, although some fly ashes can have surface areas as low as 200 m2/kg and as high as 700 m2/kg. However, the effect of increase in specific surface area beyond 600 m2/kg is reported to be insignificant. Fly ash is primarily silicate glass containing silica, alumina, iron, and calcium. The relative density or specific gravity of fly ash generally ranges between 1.9 and 2.8 and the colour is generally gray or tans (Halstead, 1986). The types and relative amounts of incombustible material in the coal used help in the determination of chemical composition of fly ash. Depending upon the source and makeup of the coal being burnt, the components of fly ash vary considerably, but all fly ash includes substantial amounts of silicon dioxide (SiO2) (both amorphous and crystalline), aluminium oxide (Al2O3) and calcium oxide (CaO). Based on the chemical composition, fly ash is pozzolanic and some times self-cementitious in nature and it undergoes a “pozzolanic reaction” with the lime (calcium hydroxide) created by the hydration of cement and water, to create the same binder (calcium silicate hydrate ) as cement (Siddique et al., 2011). 2.8.2 Fly ash in concrete One of the efforts to produce more environmentally friendly concrete is to reduce the use of OPC by partially replacing the amount of cement in concrete with by-products materials such as fly ash. As a cement replacement, fly ash plays the role of an artificial pozzolan, where its silicon dioxide content reacts with the calcium hydroxide from the cement hydration process to form the calcium silicate hydrate (C-SH) gel. The spherical shape of fly ash often helps to improve the workability of the fresh concrete, while its small particle size also plays as filler of voids in the concrete, hence to produce dense and durable

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials concrete. Generally, the effective amount of cement that can be replaced by fly ash is not more than 30% (Neville 2000). An important achievement in the use of fly ash in concrete is the development of high volume fly ash (HVFA) concrete that successfully replaces the use of OPC in concrete up to 60% and yet possesses excellent mechanical properties with enhanced durability performance. HVFA concrete has been proved to be more durable and resource-efficient than the OPC concrete (Malhotra, 2002). The HVFA technology has been put into practice, for example the construction of roads in India, which implemented 50% OPC replacement by the fly ash (Desai, 2004). Activation of fly ash with alkaline solutions enables this byproduct material to be a cement-like construction material. In this case, concrete binder can be produced without using any OPC; in other words, the role of OPC can be totally replaced by the activated fly ash. Palomo et al (1999) described two different models of the activation of fly ash or other by-product materials. For the first model, the silicon and the calcium in the material is activated by a low to mild concentration of alkaline solution. The main product of the reaction is believed to be a calcium silicate hydrate (C-S-H) that results from the hydration process. On the contrary, the material used in the second model contains mostly silicon and aluminium, and is activated by a highly alkaline solution. The chemical process in this case is polymerisation. 2.9 Ground granulated blast furnace slag Ground granulated blast furnace slag (GGBS) is a byproduct from the blast-furnaces used to make iron. These operate at a temperature of about 1,500 degrees centigrade and are fed with a carefully controlled mixture of iron-ore, coke and limestone. The iron ore is reduced to iron and the remaining materials form a slag that floats on top of the iron. This slag is periodically tapped off as a molten liquid and if it is to be used for the manufacture of GGBS it has to be rapidly quenched in large volumes of water. The quenching, optimizes the cementations properties Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials and produces granules similar to a coarse sand. The dried ‘granulated slag’ is ground to a fine powder. GGBS is the one of the ‘greenest’ materials used in construction industry. As well as the environmental benefit of utilizing a byproduct, GGBS replaces something that is produced by a highly energyintensive process. By comparison with Portland cement, manufacture of GGBS requires less than a fifth the energy and produces less than a fifteenth of the carbon dioxide emissions. Further 'green' benefits are that manufacture of GGBS does not require the quarrying of virgin materials, and if the slag was not used as cement it might have to be disposed of to tip. The major uses of GGBS is in concrete include:better workability, making placing and compaction easier, lower early-age temperature rise, reducing the risk of thermal cracking, high resistance to chloride ingress, reducing the risk of reinforcement corrosion, high resistance to attack by sulphate and other chemicals, considerable sustainability benefits.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

CHAPTER 3 MATERIALS AND MIX DESIGN 3.1. MATERIALS Although geopolymer concrete can be made using various source materials, the present study used Class F fly ash and GGBS. Also, as in the case of OPC, the aggregates occupied 75-80 % of the total mass of concrete. The following sections discuss constituent materials used for manufacturing GPC. Chemical and physical properties of the constituent materials are presented in this section. 3.1.1. FLY ASH According to ASTM C 618 (2003), Class F fly ash produced from Rayalaseema Thermal Power Plant (RTPP), Muddanur, A.P. was used. The chemical and physical properties are presented in the Table 3.1. Fly ash (FA) is a by-product of the combustion of pulverized coal in thermal power plants. It is a fine grained, powdery and glassy particulate material that is collected from the exhaust gases by electrostatic precipitators or bag filters. When pulverised coal is burnt to generate heat, the residue contains 80 per cent fly ash and 20 per cent bottom ash. The size of particles is largely dependent on the type of dust collection equipment. Diameter of fly ash particles ranges from less than 1 μm–150 μm. It is generally finer than Portland cement. Their surface area is typically 300 to 500 m2/kg, although some fly ashes can have surface areas as low as 200 m2/kg and as high as 700 m2/kg. However, the effect of increase in specific surface area beyond 600 m 2/kg is reported to be insignificant. Fly ash is primarily silicate glass containing silica, alumina, iron, and calcium. The relative density or specific gravity of fly ash generally ranges between 1.9 and 2.8 and the colour is generally gray or tans (Halstead, 1986). The types and relative amounts of incombustible material in the coal help in the determination of chemical composition of Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials fly ash. Depending upon the source and makeup of the coal being burnt, the components of fly ash vary considerably, but all fly ash includes substantial amounts of silicon dioxide (SiO 2) (both amorphous and crystalline), aluminium oxide (Al2O3) and calcium oxide (CaO). Based on the chemical composition, fly ash is pozzolanic and sometimes self-cementitious in nature and it undergoes a “pozzolanic reaction” with the lime (calcium hydroxide) created by the hydration of cement and water, to create the same binder (calcium silicate hydrate ) as cement (Siddique et al., 2011). One of the efforts to produce more environmentally friendly concrete is to reduce the use of OPC by partially replacing the amount of cement in concrete with by-products materials . As a cement replacement, fly ash plays the role of an artificial pozzolan, where its silicon dioxide content reacts with the calcium hydroxide from the cement hydration process to form the calcium silicate hydrate (C-S-H) gel. The spherical shape of fly ash often helps to improve the workability of the fresh concrete, while its small particle size also plays as filler of voids in the concrete, hence to produce dense and durable concrete. Generally, the effective amount of cement that can be replaced by fly ash is not more than 30% (Neville, 2000). An important achievement in the use of fly ash in concrete is the development of high volume fly ash (HVFA) concrete that successfully replaces the use of OPC in concrete up to 60% and yet possesses excellent mechanical properties with enhanced durability performance. HVFA concrete has been proved to be more durable and resource-efficient than the OPC concrete (Malhotra 2002). The HVFA technology has been put into practice, for example the construction of roads in India, which implemented 50% OPC replacement by the fly ash (Desai 2004). Activation of fly ash with alkaline solutions enables this byproduct material to be a cement-like construction material. In this case, concrete binder can be produced without using any OPC; in other words, the role of OPC can be totally replaced by the activated fly ash. Palomo et al (1999) described two different models of the activation of fly ash or other byDepartment of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials product materials. For the first model, the silicon and the calcium in the material is activated by a low to mild concentration of alkaline solution. The main product of the reaction is believed to be a calcium silicate hydrate (C-SH) that results from the hydration process. On the contrary, the material used in the second model contains mostly silicon and aluminium, and is activated by a highly alkaline solution. The chemical process in this case is polymerisation. 3.1.2. GROUND GRANULATED BLAST FURNACE SLAG In the present investigation, GGBS produced from the Vizag steel plant was used in the manufacturing of GPC. The chemical and physical properties are presented in the Table 3.1. Table 3.1. Chemical and physical properties of Class F fly ash and GGBS Particulars

Class F fly

ASTM C 618 Class F

ash

fly ash

GGBS

Chemical composition % Silica(SiO2)

65.6

30.61

% Alumina(Al2O3)

28.0

16.24

% Iron Oxide(Fe2O3)

3.0

% Lime(CaO)

1.0

34.48

% Magnesia(MgO)

1.0

6.79

% Titanium Oxide (TiO2)

0.5

% Sulphur Trioxide (SO3)

0.2

Max. 5.0

Loss on Ignition

0.29

Max. 6.0

SiO2+

Al2O3+

0.584

Fe2O3>70

1.85 2.1

Physical properties Specific gravity

2.12

Fineness (m2/Kg)

360

2.9 Min.225 m2/kg

400

Ground granulated blast furnace slag (GGBS) is a by-product from the blast-furnaces used to make iron. These operate at a temperature of Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials about 1,500 degrees centigrade and are fed with a carefully controlled mixture of iron-ore, coke and limestone. The iron ore is reduced to iron and the remaining materials form a slag that floats on top of the iron. This slag is periodically tapped off as a molten liquid and if it is to be used for the manufacture of GGBS, it has to be rapidly quenched in large volumes of water. The quenching, optimises the cementitious properties and produces granules similar to a coarse sand. This ‘granulated slag’ is then dried out and ground to a fine powder. GGBS is one of the ‘greenest’ of construction materials as well as the environmental benefit of utilizing a by-product, GGBS replaces something that is produced by a highly energy-intensive process. By comparison with Portland cement, manufacture of GGBS requires less than a one fifth of the energy and produces less than a fifteenth of the carbon dioxide emissions. Further 'green' benefits are that manufacture of GGBS does not require the quarrying of virgin materials, and if the slag was not used as cement it might have to be disposed of to tip. The major uses of GGBS is in concrete include: better workability, making, placing and compaction easier, lower early-age temperature rise, reducing the risk of thermal cracking, high resistance to chloride ingress, reducing the risk of reinforcement corrosion, high resistance to attack by sulphate and other chemicals, considerable sustainability benefits. 3.1.3. COURSE AGGREGATE Crushed granite stones of size 20 mm and 10 mm were used as coarse aggregate. The bulk specific gravity in oven dry condition and water absorption of the coarse aggregate 20 mm and 10mm as per IS 2386 (Part III, 1963) were 2.58 and 0.30% respectively. The gradation of the coarse aggregate of size 20mm and 10mm was determined by sieve analysis as per IS 383 (1970) and presented in the Tables 3.2 and 3.3 respectively. The grading curves of the coarse aggregates as per IS 383 (1970) are shown in Figs. 3.1 and 3.2 respectively. Table 3.2. Sieve analysis of 20 mm coarse aggregate Sieve size

Cumulative percent passing 20 mm

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials 20 mm

100

85-100

16 mm

56.17

N/A

12.5 mm

22.32

N/A

10 mm

5.29

0-20

4.75 mm

0

Table 3.3. Sieve analysis of 10 mm coarse aggregate

Sieve size

Cumulative Percentage passing 10 mm

IS 383 (1970) limits

10 mm

99.68

85-100

4.75 mm

8.76

0-20

2.36 mm

2.4

0-5

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig. 3.1 Grading curve of coarse aggregate of size 20mm

Fig. 3.2 Grading curve of coarse aggregate of size 10mm 3.1.4. FINE AGGREGATE Natural river sand was used as fine aggregate. The bulk specific gravity in oven dry condition and water absorption of the sand as per IS 2386 (Part III, 1963) were 2.62 and 1% respectively. The gradation of the Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials sand was determined by sieve analysis as per IS 383 (1970) and presented in the Table 3.4. The grading curve of the fine aggregate as per IS 383 (1970) is shown in Fig. 3.3. Fineness modulus of sand was found to be 2.69. Table 3.4. Sieve analysis of fine aggregate Sieve No.

Cumulative percent passing Fine aggregate

IS: 383-1970 – Zone II requirement

3/8” (10mm)

100

100

No.4 (4.75mm)

98.8

90-100

No.8 (2.36mm)

96.8

75-100

No.16 (1.18mm)

70.8

55-90

No.30 (600μm)

48.2

No.50 (300μm)

14.4

8-30

No.100 (150μm)

2.0

0-10

35-59

Fig. 3.3 Grading curve of fine aggregate 3.1.5. ALKALINE LIQUIDE The alkaline liquid used was a combination of sodium silicate solution and sodium hydroxide solution. The sodium silicate solution (Na2O= 13.7%, SiO2=29.4%, and water=55.9% by mass) was purchased from a local Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials supplier. The sodium hydroxide (NaOH) in flakes or pellets from with 97%98% purity was also purchased from a local supplier. The sodium hydroxide (NaOH) solution was prepared by dissolving either the flakes or the pellets in water. The mass of NaOH solids in a solution diverse depending on the concentration of the solution which is expressed in terms of molar, M. For instance, NaOH solution with a concentration of 10M consisted of 10x40 = 400 grams of NaOH solids (in flake or pellet form) per litre of the solution, where 40 is the molecular weight of NaOH. 3.2. Test conducted on fly ash  The following test is conducted on fly ash (i) Specific gravity Result:The specific gravity of fly ash=2.133 3.3. Test conducted on ground granulated blast furnace slag (GGBS)  The following test is conducted on GGBS (i) Specific gravity Result:The specific gravity of GGBS=2.92 3.4. Tests conducted on fine aggregate  The following tests are conducted on fine aggregate (i) Specific gravity (ii) Water absorption (iii) Finesse modulus Result:The specific gravity of fine aggregate=2.415 Water absorption for fine aggregate=1% Finesse modulus of fine aggregate=2.47 3.5. Tests conducted on coarse aggregate  The following tests are conducted on coarse aggregate of size 10mm and 20mm (i) Specific gravity (ii) Water absorption (iii) Finesse modulus Result:The specific gravity of coarse aggregate =2.16 Water absorption for 10mm coarse aggregate=0.3% Water absorption for 20mm coarse aggregate=0.3% Finesse modulus for 10mm coarse aggregate=5.89 Finesse modulus for 20mm coarse aggregate=6.95 3.6. Mix design

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials Based on the limited past research on GPC (Hardjito & Rangan, 2005), the following proportions were selected for the constituents of the mixtures.  The combined mass of coarse and fine aggregates has taken as 77% of the mass of concrete.  Ratio of activator solution-to-fly ash and GGBS, by mass, in the range of 0.3 and 0.4. This ratio was fixed at 0.35.  Class F fly ash and GGBS (FA100-GGBS0; FA25-GGBS75; FA50-GGBS50; FA75-GGBS25; FA0-GGBS100).  Ratio of sodium silicate solution-to-sodium hydroxide solution, by mass, of 0.4 to 2.5. This ratio was fixed at 2.5 for most of the mixtures, because the sodium silicate solution is considerably cheaper than the sodium hydroxide solution.  Molarity of sodium hydroxide (NaOH) solution was kept at 10M.  Calculate water-to-geopolymer solids.  Extra water, when added, in mass. The following scenario describes the GPC mix design of the present study: Assume that normal-density aggregates in SSD condition are to be used and the unit-weight of concrete is 2400 kg/m 3. Take the mass of combined aggregates as 77% of the mass of concrete, i.e. 0.77x2400=1848 kg/m3. The combined aggregates may be selected to match the standard grading curves used in the design of Portland cement concrete mixtures. For instance, the coarse aggregates (70%) may comprise 776 kg/m3 (60%) of 20 mm aggregates, 517 kg/m3 (40%) of 10 mm aggregates, and 554 kg/m3 (30%) of fine aggregate to meet the requirements of standard grading curves. After considering the water absorption values of coarse and fine aggregates, the adjusted values of coarse and fine aggregates are 774 kg/m3 of 20 mm aggregates, 516 kg/m3 of 10 mm aggregates and 549 kg/m3 (30%) of fine aggregate. The mass of geopolymer binders (fly ash and GGBS) and the alkaline liquid = 2400 – 1848 = 552 kg/m 3. Take the alkaline liquid-to-fly ash ratio by mass as 0.35; the mass of fly ash = 552/ (1+0.35) = 409 kg/m 3 and Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials the mass of alkaline liquid = 552 – 409 = 143 kg/m 3. Take the ratio of sodium silicate solution-to-sodium hydroxide solution by mass as 2.5; the mass of sodium hydroxide solution = 144/ (1+2.5) = 41 kg/m3; the mass of sodium silicate solution = 143 – 41 =102 kg/m3. The sodium hydroxide solid (NaOH) is mixed with water to make a solution with a concentration of 10 Molar. This solution comprises 40% of NaOH solids and 60% water, by mass. For the trial mixture, water-to-geopolymer solids ratio by mass is calculated as follows: In sodium silicate solution, water = 0.559x102 = 57 kg, and solids = 102 – 57 = 45 kg. In sodium hydroxide solution, solids = 0.40x41 = 16 kg, and water = 41 – 16 = 25 kg. Therefore, total mass of water = 57+25 = 82 kg, and the mass of geopolymer solids = 409 (i.e. mass of fly ash and GGBS) + 45 + 16 = 470 kg. Hence, the water-to-geopolymer solids ratio by mass = 82/470 = 0.17. Extra water of 55 litres is calculated on trial basis to get adequate workability. M45 grade of conventional concrete (CC) has been designed (refer Appendix (B) as per IS 10262 (2009) and IS 456 (2000) for comparative study.

The CC and geopolymer concrete mixture proportions are given as follows: Table 3.5. GPC mix proportions M4

Materials

FA0-

Mass (kg/m3) FA25FA50-

FA75-

FA100-

20mm

606

GGBS100 776

GGBS75 776

GGBS50 776

GGBS25 776

GGBS0 776

10mm aggregate Fine aggregate Cement Fly ash (Class F)

404 625 533 0

517 554 0 0

517 554 0 102.2

517 554 0 204.5

517 554 0 306.7

517 554 0 409

5

Coarse

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials GGBS

0

409

306.7

204.5

102.2

0

0

102

102

102

102

102

0

41 (10M)

41(10M)

41 (10M)

41 (10M)

41(10M)

solution Extra water

0

55

55

55

55

55

Alkaline solution/

0

0.35

0.35

0.35

0.35

0.35

(FA+GGBS) (by weight) Water/ geopolymer

0

0.29

0.29

0.29

0.29

0.29

Sodiu silicate solution Sodium

hydroxide

solids (by weight)

3.6.1. Factors affecting the properties of GPC Several factors have been identified as important parameters affecting the properties of geopolymers. Palomo et al (1999) concluded that the curing temperature was a reaction accelerator in fly ash-based geopolymers, and significantly affected the mechanical strength, together with the curing time and the type of alkaline activator. Higher curing temperature and longer curing time were proved to result in higher compressive strength. Alkaline activator that contained soluble silicates was proved to increase the rate of reaction compared to alkaline solutions that contained only hydroxide. Van Jaarsveld et al (2002) concluded that the water content, and the curing and calcining condition of kaolin clay affected the properties of geopolymers. However, they also stated that curing at too high temperature caused cracking and a negative effect on the properties of the material. Finally, they suggested the use of mild curing to improve the physical properties of the material. In another report, van Jaarsveld et al (2003) stated that the source materials determine the properties of geopolymers, especially the CaO content, and the water-to-fly ash ratio. Based on the study of geopolymerisation of sixteen natural Si-Al minerals, Xu and van Deventer (2000) reported that factors such as the percentage of CaO, K2O, and the molar Si-to-Al ratio in the source material, the type of alkali activator, the extent of dissolution of Si, and the molar Si-to-Al ratio in solution significantly influenced the compressive strength of geopolymers. 3.6.2. Properties of GPC Previous studies have reported that geopolymers possess high early strength, low shrinkage, freeze-thaw resistance, sulfate resistance, corrosion resistance, acid resistance, fire resistance, and no dangerous alkali-aggregate Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials reaction. Based on laboratory tests, Davidovits (1988b) reported that geopolymer cement can harden rapidly at room temperature and gain the compressive strength in the range of 20 MPa after only 4 hours at 20 0C and about 70-100 MPa after 28 days. Comrie et. al., (1988) conducted tests on geopolymer mortars and reported that most of the 28- day strength was gained during the first 2 days of curing. Geopolymeric cement was superior to Portland cement in terms of heat and fire resistance, as the Portland cement experienced a rapid deterioration in compressive strength at3000C, whereas the geopolymeric cements were stable up to 600oC (Davidovits, 1988b; 1994b). It has also been shown that compared to Portland cement, geopolymeric cement has extremely low shrinkage. The presence of alkalis in the normal Portland cement or concrete could generate dangerous Alkali-Aggregate-Reaction. However the geopolymeric system is safe from that phenomenon even with higher alkali content. As demonstrated by Davidovits (1994a; 1994b), based on ASTM C227 bar expansion test, geopolymer cements with much higher alkali content compared to Portland cement did not generate any dangerous alkali-aggregate reaction where the Portland cement did. Geopolymer cement is also acid-resistant, because unlike the Portland cement, geopolymer cements do not rely on lime and are not dissolved by acidic solutions. As shown by the tests of exposing the specimens in 5% of sulphuric acid and caloric acid, geopolymer cements were relatively stable with the weight loss in the range of 5-8% while the Portland based cements were destroyed and the calcium alumina cement lost weight about 30-60% (Davidovits, 1994b). Some recently published papers (Bakharev, 2005c; Gourley & Johnson, 2005; Song et. al., 2005a) also reported the results of the tests on acid resistance of geopolymer concrete and geopolymers. By observing the weight loss after acid exposure, these researchers concluded that geopolymers or geopolymer concrete is superior to Portland cement concrete in terms of acid resistance as the weight loss is much lower. However, Bakharev and Song et al has also observed that there is degradation in the compressive strength of test specimens after acid exposure and the rate of degradation depends on the period of exposure. Tests conducted by U.S. Army Corps of Engineers also revealed that geopolymers have Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials superior resistance to chemical attack and freeze/thaw, and very low shrinkage coefficients (Comrie et. al., 1988; Malone et. al., 1985).

Fig 3.4 Fly Ash

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig 3.5

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials Fig 3.6 10mm coarse aggregate

Fig 3.7 20mm coarse aggregate

Fig 3.8 Fine aggregate

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig 3.9 Sodium hydroxide

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig 3.10 Sodium silicate

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig 3.11 Geopolymer concrete in cube moulds

Fig 3.12 Geopolymer concrete in cylindrical moulds

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig 3.13 Cubes and cylinders kept for ambient curing

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig 3.14 Compression test of concrete cubes in progress

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig3.15 Concrete cube after crushing

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials Fig 3.16 Split tensile test of concrete cylinder in progress

Fig3.15 Concrete cylinder after crushing

CHAPTER 4 EXPERIMENTAL INVESTIGATIONS 4.1. INTRODUCTION This Chapter presents the details of development of the process of making low calcium (ASTM Class F) fly ash and GGBS based geopolymer

concrete.

First,

the

materials,

mixture

proportions,

manufacturing and curing of the test specimens are explained. This is then followed by the test procedures. As far as possible, the current practice used in the manufacture and testing of Ordinary Portland Cement (OPC) concrete was followed. The aim of this action was to ease the promotion of this ‘new’ material to the concrete construction industry. The compressive strength was chosen as the benchmark to simplify the development process. This is not unusual because compressive strength has an intrinsic importance in the structural design of concrete structures (Neville, 2000). 4.2 Mechanical properties 4.2.1 Compressive strength on geopolymer concrete Compressive strength test was conducted on the cubical specimens for all the mixes after 7, 28, 56 and 90 days of curing as per IS 516 (1991). Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials Three cubical specimens of size 150 mm x 150 mm x 150 mm were cast and tested for each age and each mix. The compressive strength (f’c) of the specimen was calculated by dividing the maximum load applied to the specimen by the cross-sectional area of the specimen. 4.2.2. Split tensile strength on geopolymer concrete Splitting tensile strength (STS) test was conducted on the specimens for all the mixes after 90 days of curing as per IS 5816 (1999). Three cylindrical specimens of size 150 mm x 300 mm were cast and tested for each age and each mix. The load was applied gradually till the failure of the specimen occurs. The maximum load applied was then noted. Length and cross-section of the specimen were measured. The splitting tensile strength (fct) was calculated as follows: fct (N/mm2) = 2P/ (Π l d) Where, P = Maximum load applied to the specimen ( Newton); l = Length of the specimen (mm); d = cross-sectional diameter of the specimen (mm). 4.3. Durability properties 4.3.1. Water absorption on geopolymer concrete Water absorption test was conducted on cylindrical specimens of size 100 mm x 50 mm after 28, 56 and 90 days of curing as per ASTM C 64297.Three test specimens were cast and tested for each age and each mix. After each curing period, these specimens were oven dried for 24 hours at the temperature of 1100c and oven dry weight of specimens were measured (W1). After oven drying, these test specimens were immersed in water and measured the weight of the saturated surface dry specimens at an interval of 12 hours (W2). This procedure was repeated for not less than 48 hours until the two successive readings were same. Water absorption of the tested specimen were calculated as follows: Water absorption (%) = [(W2 – W1) / W1] x 100. 4.3.2. Rapid chloride permeability test This test covers the laboratory evaluation of the electrical conductance of concrete samples to provide a rapid indication of their resistance to chloride ion penetration. It is widely accepted that the ability of concrete to resist ingress of chloride ions can result in a significantly more Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials durable concrete. The ASTM C 1202-07 Standard Test Method for the Electrical Indication of Concrete’s Ability to Resist Chloride Ion Penetration was conducted on specimens. This apparatus consists of a regulated D.C. power supply of 60 Volt which can be adjustable to ±10 % by an adjustable potentiometer. The digital LED display indicates the voltage available across the concrete specimen under test. The power can be fed into the eight sets of diffusion cells. The current flowing through each diffuser cell can be monitored by micro-controller with LCD display. The current readings were noted down. The diffuser cells are made up of non-corrosive acrylic chamber as per the standards. The outer groove was machined for 103mm diameter for a depth of 6mm to keep the sample specimen in its place. The inner groove diameter is 90mm and machined for depth of 25mm. The inner groove was fixed with a mesh brass sheet and a brass mesh which will be terminated through a copper lead to the external terminal for easier power connections. Rapid Chloride Permeability test (RCPT) was conducted on cylindrical specimens of size 100 mm x 50 mm after 28, 56 and 90 days of curing. Three test specimens were cast and tested for each age and each mix. RCPT is a two component cell assembly checked for air and watertight. The cathode compartment is filled with 3% NaCl solution and anode compartment is filled with 0.3 NaOH solutions. Then the concrete specimens were subjected to RCPT by impressing a 60V from a DC power source between the anode and cathode as shown in Figs. 4.1 and 4.2. Current is monitored up to 6 hours at an interval of 30 minutes.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig. 4.1. Rapid chloride permeability Test procedure

Fig. 4.2. Rapid chloride permeability test setup From the current values, the chloride permeability is calculated in terms of coulombs at the end of 6 hours by using the formula. Q= 900 (I0 + 2 I30 + 2 I60 + 2 I90 + …………. + 2 I300 + 2 I330 + 2 I360) Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials The relationship between chloride penetrating rate and the charge passed by coulombs is given in below Table 4.1. Table 4.1 Chloride penetrability characteristics as per ASTM C1202 Charge

Passed

(Coulomb)

Chloride Penetrability

> 4000

High

2000 to 4000

Moderate

1000 to 2000

Low

100 to 1000

Very Low

<100

Negligible

CHAPTER-5 RESULTS AND DISCUSSION 5.1

INTRODUCTION In this Chapter, the test results are presented and

discussed. The test results cover the effect of FA and GGBS on the mechanical properties viz. compressive and split tensile strength and durability properties of GPC at ambient room temperature curing. The compressive strength values of GPC mixes were measured after 7, 28, 56 and 90 days of curing. The durability properties values of GPC mixes were measured after 28, 56 and 90 days of curing. These short-term mechanical and durability properties were then compared to that of M45 grade of conventional concrete (CC). 5.2

MECHANICAL PROPERTIES OF CC AND GPC 5.2.1 Compressive strength

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials Table 5.1 shows the compressive strength of CC (M 45) and GPC mixes (FA100-GGBS0; FA25-GGBS75; FA50-GGBS50; FA75-GGBS25; FA0-GGBS100) at different curing periods. Table 5.1 Compressive strength of CC and GPC Mix type Mechanical property

FA0Age

FA25-

FA50-

FA75-

FA100-

7

M45 26.12

GGBS100 GGBS75 GGBS50 GGBS25 GGBS0 54.29 51.11 35.30 13.30 10.51

Compressive

28

51.39

60.23

58.12

46.32

15.55

12.11

strength pc

56

54.23

63.11

59.02

48.33

28.22

18.68

(MPA)

90

56.34

65.23

62.32

51.78

33.02

22.03

For conventional concrete the compressive strength at 7 days curing period is 26.12Mpa. For geopolymer concrete for mix proportion FA:GGBS:0:100, FA:GGBS:25:75 and FA:GGBS:50:50, the compressive strength values at 7 days curing period are higher than that of the conventional concrete, whereas for mix proportions FA:GGBS:75:25 and FA:GGBS:100:0,the compressive strength values are lower than that of the conventional concrete. For conventional concrete the compressive strength at 28 days curing period is 51.39Mpa. For geopolymer concrete for the mix proportion FA: GGBS: 0:100 and FA: GGBS: 25:75, the compressive strength values at 28 days curing period are higher than that of the conventional concrete, whereas for mix proportions FA: GGBS: 50:50, FA: GGBS: 75:25 and FA: GGBS: 100:0,the compressive strength values are lower than that of the conventional concrete. Similar trend is observed at 56 and 90 days curing periods.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig. 5.1 Compressive strength versus Age The variation of the compressive strength of geopolymer concrete for the various mix proportions of FA: GGBS and for different curing period is shown as bar diagram in Fig 5.1. From the bar diagram, it is clear that the geopolymer concrete blended with 100% GGBS shows maximum compressive strength value at all curing periods and the values are greater than that of the conventional concrete (M45 grade). In case of geopolymer concrete blended with 100% FA, the compressive strength values are minimum at all curing periods and the values are lower than that of conventional concrete (M45 grade).

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

7days 28days 56days 90days

70

Compressive strength pc(Mpa)

60

50

40

30

20

10 0:100

25:75

50:50

75:25

100:0

fig 5.2:variation compressive strength with the various proportions of FA:GGBS

The variation of compressive strength of geopolymer concrete with various proportions of FA: GGBS and for different curing period is shown in Fig 5.2. From Fig 5.2, it is observed that compressive strength of geopolymer concrete decreases with increasing FA content in the mix irrespective of curing period. It is also observed for a given proportion of the mix, the compressive strength increases with age. The compressive strength of CC of M 45 grade at 7 days curing period is 26.12Mpa. In order to achieve the same value of compressive strength in case of geopolymer concrete the mix proportion FA: GGBS obtained from the graph (Fig 5.2) is FA: GGBS: 60:40 Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials The compressive strength of CC of M 45 grade at 28 days curing period is 51.39Mpa.In order to achieve the same value of compressive strength in case of geopolymer concrete the mix proportion FA: GGBS obtained from the graph (Fig 5.2) is FA: GGBS: 39:61 The compressive strength of CC of M 45 grade at 56 days curing period is 54.23Mpa. In order to achieve the same value of compressive strength in case of geopolymer concrete the mix proportion FA: GGBS obtained from the graph (Fig 5.2) is FA: GGBS: 35:65 The compressive strength of CC of M 45 grade at 90 days curing period is 56.34Mpa.In order to achieve the same value of compressive strength in case of geopolymer concrete the mix proportion FA: GGBS obtained from the graph (Fig 5.2) is FA: GGBS :38:62 The compressive strength of geopolymer concrete is maximum. When the proportion FA: GGBS: 0:100 irrespective of curing period. The compressive strength of geopolymer concrete is compared with the compressive strength of conventional concrete at same age. That is, conventional concrete is considered as the reference mix. The percentage increase in compressive strength values of geopolymer concrete at 7, 28, 56 and 90 days are 107.8%, 17.2%, 16.3% and 15.7% respectively. It is seen that rate of gain in compressive strength of geopolymer concrete is very faster at 7 days curing period and the rate gets reduced with age. It is also observed that compressive strength of GPC decreases with increasing FA content in the mix irrespective of curing period. It is also observed for given proportion of the mix , the compressive strength increasing with age. While comparing M 45 CC and FA0-GGBS100, the mix FA0GGBS100 has attained higher values of compressive strength at all ages. Hence, it is recommended to use the mix proportion of FA0-GGBS100 for the development M45 grade of sustainable concrete. So, it is clearly seen that the gain of compressive strength was very significant in GPC mixes with the increased level of GGBS at all ages as compared to those of only FA based GPC. Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

5.2.2 Split tensile strength Table 5.2 shows the split tensile strength of CC (M 45) and GPC mixes (FA100-GGBS0; FA25-GGBS75; FA50-GGBS50; FA75-GGBS25; FA0-GGBS100) at different curing periods. Table 5.2 Split tensile strength of CC and GPC Mix type Mechanical property

Split tensile

FA0-

FA25-

FA50-

FA75-

FA100-

GGBS100

GGBS75

GGBS50

GGBS25

GGBS0

M45 2.23

2.46

2.54

1.84

1.273

1.132

Age

7

strength

28

3.44

3.56

3.23

2.06

1.362

1.160

strength pt

56

3.51

3.82

3.32

2.47

1.485

1.182

(MPA)

90

3.59

4.06

3.54

2.68

1.67

1.32

For conventional concrete the split tensile strength at 7 days curing period is 2.23Mpa. For geopolymer concrete for mix proportion FA:GGBS:0:100 and FA:GGBS:25:75 the split tensile strength values at 7 days curing period are higher than that of the conventional concrete, whereas for

mix

proportions

FA:GGBS:50:50,

FA:GGBS:75:25

and

FA:GGBS:100:0,the split tensile strength values are lower than that of the conventional concrete. For conventional concrete the split tensile strength at 28 days curing period is 3.44Mpa. For geopolymer concrete for the mix proportion FA: GGBS: 0:100, the split tensile strength values at 28 days curing period are higher than that of the conventional concrete, whereas for mix proportions FA:GGBS:25:75,FA: GGBS: 50:50, FA: GGBS: 75:25 and FA: GGBS: 100:0,the split tensile strength values are lower than that of the conventional concrete. Similar trend is observed at 56 and 90 days curing periods.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig. 5.2 Split tensile strength versus Age The variation of the split tensile strength of geopolymer concrete for the various mix proportions of FA: GGBS and for different curing period is shown as bar diagram in Fig 5.2. From the bar diagram, it is clear that the geopolymer concrete blended with 100% GGBS shows maximum split tensile strength values at all curing periods and the values are greater than that of the conventional concrete (M45 grade). In case of geopolymer concrete blended with 100% FA, the split tensile strength values are minimum at all curing periods and the values are lower than that of conventional concrete (M45 grade).

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

7days 28days 56days 90days

4.2 4.0

Split tensile strength pt (Mpa)

3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0:100

25:75

50:50

75:25

100:0

fig 5.4:variation split tensile strength with the various prapotions of FA:GGBS

The variation of split tensile strength of geopolymer concrete with various proportions of FA: GGBS and for different curing periods is shown in Fig 5.4. From Fig 5.4, it is observed that split tensile strength of geopolymer concrete decreases with increasing FA content in the mix irrespective of curing period. It is also observed for a given proportion of the mix, the split tensile strength increases with age. The split tensile strength of CC of M 45 grade at 7 days curing periods 2.23Mpa. In order to achieve the same value of split tensile strength in case of geopolymer concrete the mix proportion FA: GGBS obtained from the graph (Fig 5.4) is FA: GGBS:36:64 The split tensile strength of CC of M45 grade at 28 days curing periods 3.44Mpa.In order to achieve the same value of split tensile strength in case of geopolymer concrete the mix proportion FA: GGBS obtained from the graph (Fig 5.4) is FA: GGBS:11:89 Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials The split tensile strength of CC of M45 grade at 56 days curing periods 3.51Mpa. In order to achieve the same value of split tensile strength in case of geopolymer concrete the mix proportion FA: GGBS obtained from the graph (Fig 5.4) is FA: GGBS :16:84 The split tensile strength of CC of M45 grade at 90 days curing periods 3.59Mpa.In order to achieve the same value of split tensile strength in case of geopolymer concrete the mix proportion FA: GGBS obtained from the graph (Fig 5.4) is FA: GGBS :21:79 The split tensile strength of geopolymer concrete is maximum. When the proportion FA: GGBS: 0:100 irrespective of curing period. The split tensile strength of geopolymer concrete is compared with the split tensile strength of conventional concrete at same age. That is, conventional concrete is considered as the reference mix. The percentage increase in split tensile strength values of geopolymer concrete at 7, 28, 56 and 90 days are 23.76%, 3.48%, 8.83% and 13.09% respectively. It is seen that rate of gain in split tensile strength of geopolymer concrete is very faster at 7 days curing period and the rate gets reduced with age. It is also observed that split strength of GPC decreases with increasing FA content in the mix irrespective of curing period. It is also observed for given proportion of the mix , the split strength increasing with age. While comparing M45 CC and FA0-GGBS100, the mix FA0GGBS100 has attained higher values of split tensile strength at all ages. Hence, it is recommended to use the mix proportion of FA0-GGBS100 for the development M 45 grade of sustainable concrete. So, it is clearly seen that the gain of split tensile strength was very significant in GPC mixes with the increased level of GGBS at all ages as compared to those of only FA based GPC. 5.3

DURABILITY PROPERTIES OF CC AND GPC Concrete is an important versatile construction material used

wide verity of situation. It is very important to consider the durability of building material as indirect effect on economy severability and maintenance concrete should with stand the conditions for which it has been designed. Such Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials concrete is said to be durable. The useful life of concrete may be reduced by the environment to which the concrete is exposed or by internal causes within the concrete itself. The external causes may be physical, chemical or mechanical the extent of damage produced by these depends largely on the quality of concrete. The internal causes may be ‘alkali’ aggregate reaction, volume changes due to the difference in thermal properties of the aggregate and cement paste and the permeability of concrete. A durable concrete must be relatively impervious. 5.3.1 Water absorption Table 5.3 shows the water absorption of CC (M 45) and GPC mixes (FA100-GGBS0; FA25-GGBS75; FA50-GGBS50; FA75-GGBS25; FA0GGBS100) at different curing periods. Table5.3 Water absorption values of GPC and CC Mix type

FA0-GGBS100

FA25-GGBS75

FA50-GGBS50 FA75-GGBS25 FA100-GGBS0 M 45

Age

Water absorption

(days)

(%)

28

1.23

56 90

0.78 0.56

28

1.52

56 90 28 56 90 28 56 90 28 56 90 28 56 90

1.13 0.94 2.03 1.69 1.47 2.90 2.60 2.48 3.72 3.48 3.38 3.13 2.83 2.69

From the Table 5.3, it is observed that the percentage of water absorption decreases as the quantity of GGBS increases in the mix of geopolymer concrete irrespective of curing period.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials From the same table, it is also observed that the percentage of water absorption decreases with curing period irrespective quantity of GGBS in the mix. The variation of percentage of water absorption with the age for geopolymer concrete for different proportions of FA: GGBS in the form of bar chart is shown in Fig 5.5. The variation of percentage of water absorption with age in the form of bar chart for conventional concrete is also shown in Fig 5.5. From figure, it is observed that the percentage of water absorption for geopolymer concrete with proportions FA:GGBS:0:100,FA:GGBS:25:75,FA:GGBS:50:50,FA:GGBS:75:25 is less than that of conventional concrete irrespective of age of concrete. Out of four proportions mentioned above, the water absorption of geopolymer concrete with mix proportion FA: GGBS: 0: 100 gives least values when compared to conventional concrete. From the figure, it is also observed that the percentage of water absorption for geopolymer concrete with mix proportion FA: GGBS: 100: 0 is more than that of conventional concrete irrespective of age of concrete. The percentage water absorption for geopolymer concrete with mix proportion FA: GGBS: 0: 100 at 90 days is small when compared to other mixes and conventional concrete. Hence, it is preferred for preparing geopolymer concrete.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig 5.5 water absorption of mixes

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials 5.3.2 Rapid chloride permeability test (RCPT) Table 5.4 shows the rapid chloride permeability test of CC (M 45) and GPC mixes (FA100-GGBS0; FA25-GGBS75; FA50-GGBS50; FA75GGBS25; FA0-GGBS100) at different curing periods.

Table 5.4 RCPT values of GPC and CC

Mix type

FA0-GGBS100

FA25-GGBS75

FA50-GGBS50 FA75-GGBS25 FA100-GGBS0 M 45

Age

Charge passed

Chloride

(days)

(Coulombs)

penetrating rate

28

1302.6

Low

56 90

1081.5 973.8

Low Very low

28

1448.1

Low

56 90 28 56 90 28 56 90 28 56 90 28 56 90

1225.8 1130.4 1665.3 1455.3 1379.4 2069.4 1871.1 1778.7 2946.0 2765.7 2675.7 2424.6 2169.0 1924.5

Low Low Low Low Low Moderate Low Low Moderate Moderate Moderate Moderate Moderate Low

Farm the Table 5.4, it is found that the Chloride penetrating rate of the geopolymer concrete prepaid with FA: GGBS: 0: 100 mix cured at 90 days is very low when compared to other mixes and conventional concrete. It indicates that the geopolymer concrete prepared with the above mix proportion produced dense concrete with less porous structure. Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials The variation of RCPT charge passing with the age for geopolymer concrete for different proportions of FA: GGBS in the form of bar chart is shown in Fig 5.6.The variation of RCPT charge passing with age in the form of bar chart for conventional concrete is also shown in Fig 5.6. From the figure, it is observed that the percentage of RCPT for geopolymer concrete with mix

proportions

FA:GGBS:0:100, FA:GGBS:25:75, FA:GGBS:50:50,

FA:GGBS:75:25 is less than that of conventional concrete irrespective of age of concrete. Out of four proportions mentioned above, the RCPT of geopolymer concrete with mix proportion FA: GGBS: 0: 100 gives least values when compared to conventional concrete. From the figure, it is also observed that the RCPT charge passing for geopolymer concrete with mix proportion FA: GGBS: 100: 0 is more than that of conventional concrete irrespective of age of concrete.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig. 5.6 RCPT of mixes Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

CHAPTER-6 ANLATICAL WORK The results and discussion on compressive strength and split tensile strength are discussed in the sections 5.1 and 5.2 respectively. There is an established relationship for controlled concrete between tensile strength and compressive strength. 6.1 Relationship between tensile strength and compressive strength The compression strength test is relatively simple to be conducted. The compressive strength of concrete is one of the most important and useful properties of concrete. Attempts have been made to co-relate the various other strengths such as modulus of rupture or direct tensile strength and some other properties like modulus of elasticity to the compressive strength of concrete. There are number of empirical relationship connecting tensile strength and compressive strength of concrete. One of the most common relationship is given below. Tensile strength =k (compressive strength)n Pt=k (Pck)n --------------------(6.1) Where, value of k various from 6.2 for gravels to 10.4 for crushed rock (average value 8.3) and value of ‘n’ may vary from ½ to 3/4.

Table 6.1 shows relationship between compressive strength and tensile strength of concrete (PCA).

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials 

Table 6.1: Relationship between compressive strength and split tensile strength of concrete

Compressive strength of concrete (MPA)

Ratio of direct tensile strength to compressive strength

7

0.11

14

0.19

21

0.16

28

0.15

35

0.14

42

0.13

49

0.12

56

0.12

63

0.11

The tensile strength of concrete ranges from 8 to 12 per cent of its compressive strength .An average valve of 10% is generally adopted (Gambhir and Neha Jamwal(2014)) The relation between compressive strength and split tensile strength of concrete is presented in Figure 6.1.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig:6.1 Relation between compressive strength and split tensile strength of concrete (Gambhir and Neha Jamwal (2014)) Here, an attempt is made to establish empirical relationship between the tensile strength of geopolymer concrete based on the experimental results obtained for concrete prepared with different combinations of admixtures FA and GGBS. Tables 6.2, 6.3, 6.4, 6.5 and 6.6 represent split tensile strength Vs compressive strength of geopolymer concrete prepared with different combinations of admixtures FA and GGBS and cured for various curing periods. Table 6.2: Split tensile strength Vs Compressive strength FA: GGBS: 0:100

Curing period days 7

28

56

90

Period Compressive strength

54.29

60.23

63.11

65.23

(Mpa) Split tensile strength

2.76

3.56

3.82

4.06

(Mpa) Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Table 6.3: Split tensile strength Vs Compressive strength FA: GGBS: 25:75

Curing period days 7

28

56

90

Period Compressive strength

51.11

58.12

59.02

62.32

2.54

3.23

3.32

3.54

(Mpa) Split tensile strength (Mpa)

Table 6.4: Split tensile strength Vs Compressive strength FA: GGBS: 50:50

Curing period days 7

28

56

90

Period Compressive strength

35.30

46.32

48.33

51.78

1.84

2.06

2.47

2.68

(Mpa) Split tensile strength (Mpa)

Table 6.5: Split tensile strength Vs Compressive strength FA: GGBS: 75:25

Curing period days 7

28

56

90

Period Compressive strength

13.30

15.55

28.22

33.02

1.27

1.362

1.148

1.67

(Mpa) Split tensile strength (Mpa)

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials Table 6.6: Split tensile strength Vs Compressive strength FA: GGBS: 100:0

Curing period days 7

28

56

90

Period Compressive strength

10.51

12.11

18.68

22.03

(Mpa) Split tensile strength

1.132

1.16

1.182

1.32

(Mpa) The variation of split tensile strength with respect to compressive strength of geopolymer concrete prepared with FA: GGBS: with different combinations of admixtures for different curing periods is shown in Figs 6.2, 6.3, 6.4, 6.5, and 6.6.

Fig 6.2: Split tensile strength Vs Compressive strength of geopolymer concrete ( FA: GGBS :0:100)

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials By subjecting all the data to statistical, the treatment by equation obtained between split tensile strength and compressive strength of concrete for (FA: GGBS: 0:100) is Pt=0.0008pc3-0.1494pc2+9.1973pc-186.89

--------------------- (6.2)

Fig 6.3: Split tensile strength Vs Compressive strength of geopolymer concrete ( FA: GGBS :25:75) By subjecting all the data to statistical treatment the equation obtained between split tensile strength and compressive strength of concrete for (FA: GGBS: 25:75) is Pt=-0.0007pc3+0.1223pc2-6.7572pc+125.32 ----------------- (6.3)

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig 6.3: Split tensile strength Vs Compressive strength of geopolymer concrete ( FA: GGBS :50:50) By subjecting all the data to statistical treatment the equation obtained between split tensile strength and compressive strength of concrete for (FA: GGBS: 50:50) is Pt=-0.0025pc3+0.3395pc2-15.113pc+222.32--------------------------- (6.4)

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig 6.4: Split tensile strength Vs Compressive strength of geopolymer concrete ( FA: GGBS :75:25) By subjecting all the data to statistical treatment the equation obtained between split tensile strength and compressive strength of concrete for (FA: GGBS: 75:25) is Pt=0.0002pc3-0.0126pc2+0.2863pc-0.7474

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-------------------- (6.5)

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Figure 6.5: Split tensile strength Vs Compressive strength of geopolymer concrete ( FA: GGBS :100:0) By subjecting all the data to stastical treatment the equation obtained between split tensile strength and compressive strength of concrete for (FA: GGBS: 100:0) is Pt=0.0005pc3-0.0216pc2+0.3214pc-0.4172 ------------------------ (6.6)

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials



Table 6.7:Relationship between compressive strength and split tensile strength of geopolymer concrete for various proportions of FA and GGBS and for different curing periods ` Geopolymer concrete on cubes S.NO

FA:GGBS

Curing

1

periods 7

2 3

0:100

4 5 6 7 8 9 10 11 12

25:75

50:50

13 14 15 16 17 18 19 20

75:25

100:0

Compressive

Ratio of split tensile strength to

strength(Mpa)

compressive strength

54.29

0.05

28

60.23

0.05

56

63.11

0.06

90 7 28 56

65.23 51.11 58.12 59.02

0.06 0.04 0.05 0.05

90

62.23

0.05

7 28 56

35.30 46.32 48.33

0.05 0.04 0.05

90

51.78

0.05

7 28 56

13.30 15.55 28.22

0.09 0.08 0.05

90

33.02

0.05

7 28 56 90

10.51 12.11 18.68 22.03

0.10 0.09 0.06 0.05

The variation of split tensile strength with respect to compressive strength of geopolymer concrete prepared with FA: GGBS: geopolymer concrete for different curing periods for all proportion is shown in Fig 6.6.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Fig 6.6: Split tensile strength Vs Compressive strength of geopolymer concrete By subjecting all the data to stastical treatment are unique relation obtained between split tensile strength and compressive strength of concrete is Pt=2E-05pc3-0.0008pc2-0.0308pc+0.9022---------------------- (6.7) Split tensile strength of geopolymer concrete prepared with different combinations of FA and GGBS for various curing periods can be predicted knowing the compressive strength using the co-relations presented herein without conducting elaborate, tedious and cumbersome tests.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

CHAPTER-7 COST ANALYSIS 7.1 COST ANALYSIS OF GPC OVER CC This section mainly focused on the cost analysis of GPC (FA39-GGBS69) and M45 grade of CC. Time, cost and quality are the three important factors which assume significance in construction due to their impact on the industry as a whole. Any development which has positive impact on these factors is always in the interest of civil engineering. The compressive strength test can be relatively easily conducted. Hence, the most frequently conducted test on concrete is the compressive strength test. The compressive strength at 28 days after casting is taken as a criterion for specifying the quality of concrete which is called grade of concrete. The concrete develops strength with continued hydration. The rate of gain of strength is earlier to start with and the rate gets reduced with age. It is customary to assume the 28 days strength as the full strength of concrete. The 28 days compressive strength of M 45 grade CC is 51.39Mpa. In order to achieve the same strength in case of GPC, the proportion of FA: GGBS is 39: 61. Hence, in this chapter the cost of one cubic meter of GPC for the above proportion is worked out and is compared with the cost of one cubic meter of M45 grade of CC. Calculations of quantities of dry ingredients of CC and GPC for the cost analysis are presented in Table 1 and 2 respectively.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Table 1: Calculation of quantities of dry ingredients of CC Quantity calculation of M45 grade of CC Dry co-efficient of concrete : 1.52 (a)

Material

Weight

Specific

Volume

(Kg/m3)

gravity

(m3)

(b)

(c)

(d)=(b)/(c)

Volume Proportio ns (e)=(d)/(f)

Quantity per cubic meter of concrete (m3)

Remar ks

Cement

533

3.06

174.18 (f)

1.00

(h)=(e)*(a)/(g) 0.33

Sand

625

2.62

238.55

1.37

0.45

cement

CA 20

606.4

2.58

235.04

1.35

0.44

bag of

CA 10

404.3

2.658

156.71

0.90

0.30

50 kg =

Let 1

0.0347 Total volume of proportions

4.62 (g)

Total: 1.52

m3 volume

Table 2: Calculation of quantities of dry ingredients of GPC Quantity calculation of M45 grade of GPC

Material

Volume

Quantity per

Weight

Specific

Volume

Proporti

cubic meter

(Kg/m3)

gravity

(m3)

ons

of concrete

(b)

(c)

(d)=(b)/(c)

(e)=(d)/

(m3) (h)=(e)*(a)/(g) 0.14

GGBS

249.49

2.9

86.03 (f)

(f) 1.00

Fly ash

159.51

2.12

72.17

0.87

0.12

Sand CA 20

554 776

2.62 2.58

211.45 300.78

2.50 3.49

0.37 0.52

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Remar ks

Strength and durability properties of geopolymer concrete with FA and GGBS as source materials CA 10

517

2.58

200.39

Total volume of proportions

2.32

0.34

10.18 (g)

Total: 1.49

Table 3: Cost analysis of M45 grade of CC and GPC

Control concrete (M45) Material

Unit

GPC (FA39-GGBS61)

Rate (Rs) Quantity

Amount

Quantity

(Rs)

Amount (Rs)

Cement GGBS

Bags m3

250 70

9.51 0

2377.50 0

0 0.14

0.00 9.8

Fly ash CA 20

m3 m3

65 1076

0 0.44

0 473.44

0.12 0.54

7.8 559.52

CA 10 Sand Sodium silicate

m3 m3

788 375

0.30 0.45

236.40 168.75

0.34 0.37

267.92 138.75

24

0

0

102

2448.00

55

0

0 3256.09

16

880.00 4311.79

solution NaOH pellets Total

Litre Kg

Cost over CC(%)

32.42

Cost analysis of M45 grade of CC and GPC is made as per standard schedule of rates (SSR(2013)) and is presented in Table 3. From the Table 3, it is found that the initial material cost of GPC (FA0-GGBS100) was about 32% higher than that of CC (M45). Obviously, the higher material cost of GPC over CC gives a feeling that GPC is much costlier than CC for the same strength.

But having realized the other components of GPC such as savings in natural resources, sustainability, environment, production cost, maintenance cost and all other GPC properties (mechanical and durable), it is inferred that these Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials components would offset the initial material cost of GPC. Though lot of research work needs to be done on cost-effective GPC, it can be recommended as an innovative construction material for the use of constructions.

CHAPTER-8 SUMMARY AND CONCLUSIONS 8.1 Summary This chapter summarizes the overall conclusions drawn from the investigation of FA and GGBS based GPC mixes. The GPC mixture proportions used in this study were developed based on the previous study on GPC (Hardjito and Rangan, 2005). In this study, short-term mechanical and durability properties of FA and GGBS based GPC mixes were studied. This study also compared the short-term mechanical and durability properties of GPC with that of M45 grade of CC. Now a days concrete is one of the most widely used construction materials in construction industry. Portland cement is the main constituent for making concrete. Geopolymer can be considered as the key factor which does not utilize Portland cement, nor releases greenhouse gases. The geopolymer technology proposed by Davidovits (1978) shows considerable promise for application in concrete industry as an alternative binder to the Portland cement. He proposed that binders could be produced by a polymeric reaction of alkaline liquids with the silicon and the aluminum in source materials of geological origin or by-product materials such as Fly Ash, Slag and Rice-Husk Ash. He termed these binders as geopolymers. Among the waste or by-product materials, Fly Ash and Slag are the most potential source of geopolymers. Ganapathi Naidu (2011), Parthiban et al (1988), Kishna Rao (2013), Hardjito et al (2005), Supraja and Kantha Rao (2008), Madheswara and Ganasundhar (2013) etc have worked in the area of geopolymer concrete.Most of the researchers have replaced cement by the by-product materials such as Fly Ash and Ground Granulated Blast furnace Slag (GGBS) and have concentrated on the compressive strength of geopolymer concrete at different levels. Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials The objective of this project is to study the effect of class Fly Ash (FA) and Ground Granulated Blast furnace Slag (GGBS) on the mechanical and durability properties of geopolymer concrete (GPC) at different replacement levels (FA0-GGBS100; FA25-GGBS75; FA50-GGBS50; FA75GGBS25 ; FA100-GGBS0). Sodium silicate (Na 2SiO3) and sodium hydroxide (NaOH) solution will be used as alkaline activators. In the present investigation, it is proposed to study the mechanical properties viz. compressive strength, split tensile strength and durability properties viz. water absorption and Rapid Chloride Permeability of low-calcium Fly Ash and Slag based geopolymer concrete. These properties will be determined at different curing periods like 7, 28,56 and 90 days at ambient room temperature. Hence, in this investigation the strength and durability properties on Geopolymer concrete have been studied. Chapter 1 deals with the general introduction including the scope and objectives of the investigation. Chapter 2 gives a review of literature pertaining to alkaline activators like Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solution, the development of alternative binders to manufacture concrete such as FA and GGBS and their constituents and their phase relationship and properties. Chapter 3 deals with materials used in mix design, and the physical and chemical properties of FA and GGBS sand, aggregate, alkaline activators , water used in this investigation and also the experimental procedure in mix design. The determination of specific gravity of both FA and GGBS , specific gravity , water absorption and fineness modulus of both fine aggregate and course aggregate are also presented. The mix designs used for the preparation of specimen are also dealt herein.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials Chapter 4 deals with different experimental investigations pertaining to compressive strength, split tensile strength, water absorption and Rapid Chloride Permeability. Cubes were prepared for testing of compressive strength; cylinders were prepared for testing of tensile strength, cylindrical specimens of size 100 mm x 50 mm were prepared for testing water absorption and rapid chloride permeability test. The results and discussion are presented in chapter 5. The results of the present investigation are presented both in tabular, bar chart and graphical forms. In order to facilitate the analysis, interpretation of the results are carried out at each phase of the experimental work. This interpretation of the results obtained is based on the current knowledge available in the literature as well as on the nature of results obtained. The significance of the results is assessed with reference to the standards specified by the relevant previous mix code. The results and discussion chapter is divided into four sections. (i) Results and discussion on compressive strength (ii) Results and discussion on split tensile strength (iii) Results and discussion on water absorption (iv)Results and discussion rapid chloride permeability test Chapter 6 deals with analytical work. The co-relations between compressive strength and split tensile strength for geopolymer concrete prepared with FA and GGBS for various proportions are reported herein. Pt=0.0008pc3-0.1494pc2+9.1973pc-186.89

(FA: GGBS: 0: 100)

Pt=-0.0007pc3+0.1223pc2-6.7572pc+125.32 (FA: GGBS: 25: 75) Pt=-0.0025pc3+0.3395pc2-15.113pc+222.32 (FA: GGBS: 50: 50) Pt=0.0002pc3-0.0126pc2+0.2863pc-0.7474

(FA: GGBS: 75: 25)

Pt=0.0005pc3-0.0216pc2+0.3214pc-0.4172

(FA: GGBS: 100: 0)

By subjecting all the data to stastical treatment an unique relation obtained between split tensile strength and compressive strength of geopolymer concrete is Pt=2E-05pc3-0.0008pc2-0.0308pc+0.9022 Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

Chapter 7 deals with cost analysis. The 28 days compressive strength of M 45 grade CC is 51.39Mpa. In order to achieve the same strength of in case of GPC the proportion of FA: GGBS: 39: 61. Hence, in this chapter the cost of one cubic metre of GPC for above proportion is worked out and is compared with the cost of one cubic meter of M45 grade of CC. A brief summary of the work and the conclusions drawn are reported in chapter 8. 8.2 Conclusions Based on the results reported in this investigation, the following conclusions are drawn 1. The compressive strength and split tensile strength of geopolymer concrete decrease with increase in FA content in the mix irrespective of curing period. 2. For a given proportion of mix, the compressive strength and split tensile strength increase with age. 3. The compressive strength and split tensile strength of geopolymer concrete is maximum, when the mix proportion FA: GGBS: 0:100 irrespective of curing period. 4.

The rate of gain in compressive strength and split tensile strength of

geopolymer concrete is very faster at 7 days curing period and the rate gets reduced with age. 5. The initial material cost of GPC (FA39-GGBS61) is about 32% higher than that of CC (M45) at 28 days compressive strength. 6. The percentage of water absorption decreases as the quantity of GGBS increases in the mix of geopolymer concrete irrespective of curing period. 7.

The percentage of water absorption decreases with curing period

irrespective quantity of GGBS in the mix. 8. RCPT indicates that the geopolymer concrete mixture prepared with FA: GGBS: 0:100 proportions produces a dense concrete with less porousstructure. 9. Geopolymer concrete can be recommended as an innovative construction material for the use of the constructions. Department of civil engineering

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

8.3 Scope for further work In this investigation strength and durability properties of geopolymer concrete with FA and GGBS as source material are studied. The studies are concentrated on compressive and split tensile strengths only. All the mixes are prepared with 10M. The work can be extended to study the remaining mechanical properties such as Young’s modulus and flexure of geopolymer concrete. The effect of molarity on strength and durability properties of geopolymer concrete can also be studied. In this investigation the durability of geopolymer concrete is studied by conducting RCPT and water absorption tests. The durability properties of geopolymer concrete can also be studied by conducting acid and drying shrinkage tests. By studying mechanical properties such as compressive strength, split tensile strength, Young’s modulus and flexural characteristics, and durability like RCPT , water absorption test, acid test and drying shrinkage, a comprehensive knowledge regarding geopolymer concrete can be obtained.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials

REFERENCES 1. ASTM C 1202-07 (1997) Standard Test Method for the Electrical Indication of Concrete’s Ability to Resist Chloride Ion Penetration was conducted on specimens. Annual book of ASTM standards, vol.4.02, American Society for Testing and Materials, West conshohcken. 2. ASTM C 618 (1978): specification for pozzuolana, Philadelphia. 3. Bakharev, T. (2005c). Resistance of geopolymer materials to acid attack. Cement And Concrete Research, 35(4), 658-670. 4. Balaguru, P., Kurtz, S., & Rudolph, J. (1997). Geopolymer for Repair and Rehabilitation of Reinforced Concrete Beams. The Geopolymer Institute. Retrieved 3 April, 2002, from the World Wide Web: www.geopolymer.org 5. Comrie, D. C., Paterson, J. H., & Ritchey, D. J. (1988). Geopolymer Technologies in Toxic Waste Management. Paper presented at the Geopolymer ’88, First European Conference on Soft Mineralurgy, Compiegne, France. 6. Davidovits, J. (1984). Synthetic Mineral Polymer Compound of The Silicoaluminates Family and Preparation Process, United States Patent 4,472,199 (pp. 1-12). USA.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials 7. Davidovits, J. (1988a). Soft Mineralurgy and Geopolymers. Paper presented at the Geopolymer ’88, First European Conference on Soft Mineralurgy, Compiegne, France. 8. Davidovits, J. (1988b). Geopolymer Chemistry and Properties. Paper presented at the Geopolymer ’88, First European Conference on Soft Mineralurgy, Compiegne, France. 9. Davidovits, J. (1988c). Geopolymers of the First Generation: SILIFACEProcess. Paper presented at the Geopolymer ’88, First European Conference on Soft Mineralurgy, Compiegne, France. 82 10. Davidovits, J. (1988d). Geopolymeric Reactions in Archaeological Cements and in Modern Blended Cements. Paper presented at the Geopolymer ’88, First European Conference on Soft Mineralurgy, Compiegne, France. 11. Davidovits, J. (1999, 30 June - 2 July 1999). Chemistry of Geopolymeric Systems, Terminology. Paper presented at the Geopolymere ’99 International Conference, Saint-Quentin, France. 12. Duxson, P., Lukey, G., & van Deventer, J. (2007). Physical evolution of Nageopolymer derived from metakaolin up to 1000 °C. Journal of Materials Science, 42(9), 3044-3054. 13. Desai, J. P. (2004). Construction and Performance of High-Volume Fly Ash Concrete Roads in India. Eighth CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete, Las Vegas,USA, American Concrete Institute. 14. Gartner E (2004), “Industrially Interesting Approaches to ‘Low-CO2’ Cements”, Cement and Concrete Research, 34(9), 1489-1498.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials 15. Gourley, J. T. (2003). Geopolymers; Opportunities for Environmentally Friendly Construction Materials. Paper presented at the Materials 2003 Conference: Adaptive Materials for a Modern Society, Sydney. 16. Gourley, J. T., & Johnson, G. B. (2005). Developments in Geopolymer Precast Concrete. Paper presented at the International Workshop on Geopolymers and Geopolymer Concrete, Perth, Australia. 17. Hardjito, D., & Rangan, B. V. (2005). Development and Properties of LowCalcium Fly Ash-Based Geopolymer Concrete. Research Report GC1, Perth, Australia: Faculty of Engineering, Curtin University of Technology. 18. Hardjito, S.E. Wallah, D.M.J. Sumajouw and B.V.Rangan (2005), “On the development of Fly ash-Based Geopolymer Concrete”, ACI Materials Journal, pp 467-472. 19. IS 383 (1970). Specification for coarse and fine aggregates from natural sources for concrete. Bureau of Indian Standards, New Delhi. 20. IS 456 (2000). Plain and reinforced concrete code for practice. Bureau of Indian Standards, New Delhi. 21. IS 516 (1991). Methods of tests for strength of concrete. Bureau of Indian Standards, New Delhi. 22. IS 5816 (1999). Splitting tensile strength of concrete method of test. Bureau of Indian Standards, New Delhi. 23. IS 10262 (2009). Concrete Mix Proportioning-Guidelines. Bureau of Indian Standards, New Delhi.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials 24. IS 2386 (1963). Methods of test for aggregates for concrete. Part III Specific gravity, Density, Voids, Absorption and Bulking. Bureau of Indian Standards, New Delhi.

25. Malhotra, V. M., & Mehta, P. K. (2002). High-Performance, High-Volume Fly

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Construction Practice, and Case Histories. Ottawa: Supplementary Cementing Materials for Sustainable Development Inc. 26. Malone, P. G., Charlie A. Randall, J., & Kirkpatrick, T. (1985). Potential Applications of Alkali-Activated Alumino-Silicate Binders in Military Operations. Washington, DC: Department of The Army, Assistant Secretary of the Army (R&D). 27. McCaffrey, R. (2002). Climate Change and the Cement Industry. Global Cement and Lime Magazine (Environmental Special Issue), 15-19. 28. Mehta, P. K. (2002), Greening of the Concrete Industry for Sustainable Development, ACI Concrete International ;24(7): 23-28 29. Neville, A. M. (2000). Properties of Concrete (Fourth and Final ed.). Essex, England: Pearson Education, Longman Group.

30. Nath and P.K. Sarker (2012), “ Effect of GGBS on setting, workability and early strength properties of fly ash geopolymer concrete cured in ambient condition”, Construction Building Materials Vol. 66 , pp. 163-171.

31. Palomo, A., M.W.Grutzeck, & M.T.Blanco. (1999). Alkali-activated fly ashes A cement for the future. Cement And Concrete Research, 29(8), 13231329.

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Strength and durability properties of geopolymer concrete with FA and GGBS as source materials 32. Roy, D. M. (1999). Alkali-activated cements Opportunities and Challenges. Cement & Concrete Research, 29(2), 249-254. 33. Rangan, B.V. (2004) “Low-Calcium Fly Ash-based Geopolymer Concrete”, Chapter 26 in ConcreteConstruction Engineering Handbook, Editor-in Chief: E.G. Nawy, Second Edition, CRCPress, New York. 34. Siddiqui, K.S. (2007),”Strength and Durability of Low-Calcium Fly Ashbased Geopolymer Concrete”, Final Year Honours Dissertation, The University of Western Australia, Perth. 35. Siddique R, Iqbal Khan M. 2011. Supplementary Cementing Materials. Springer-Verlag Berlin Heidelberg. 36. Song, X. J., Marosszeky, Brungs, M. M., & Munn, R. (2005a, 17-20 April). Durability of fly ash-based Geopolymer concrete against sulphuric acid attack. Paper presented at the 10DBMC International Conference on Durability of Building Materials and Components, Lyon, France. 37. Sumajouw, M.D.J. and Rangan, B.V. (2006), Low-Calcium Fly Ash-Based Geopolymer Concrete: Reinforced Beams and Columns, Research Report GC3, Faculty of Engineering, Curtin University of Technology, Perth, available at espace@curtin or www.geopolymer.org. 38. Sarker P.K., and deMeillon T (2004), “Residual Strength of Geopolymer Concrete After Exposure toHigh Temperature”, Proceedings of Recent Developments in Structural Engineering, Mechanics and Computation, CD ROM, Editor: A. Zingoni, Millpress, the Netherlands, 1566-1571. 39. van Jaarsveld, J. G. S., van Deventer, J. S. J., & Lukey, G. C. (2003). The characterisation of source materials in fly ash-based geopolymers. Materials Letters, 57(7), 1272-1280. Department of civil engineering

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40. Van Jaarsveld J.G.S, J. S. J. van Devener, and G. C. Lukey(2002), “The effect of composition and Temperature on the Properties of Fly ash and Kaolinite-based Geopolymers”, Chemical Engineering Journal, 89 (1-3), pp. 63-73. 41. Van Jaarsveld, J.G.S., Van Deventer, J.S.J., Lorenzon (2008), The Potential Use of Geopolymeric Materials to Immobilise Toxic Metal: Part 1 Theory and Application, Minerals Engineering 10(7), 659-669. 42. Wallah, S. E., & Rangan, B. V. (2006). Low-Calcium Fly Ash-Based Geopolymer 43. Concrete: Long-Term Properties (Research Report GC 2). Perth: Faculty of Engineering Curtin University of Technology. 44. Xu, H., & Van Deventer, J. S. J. (2000). The geopolymerisation of aluminosilicate. 45. Xu, H.; Van Deventer, J.S.J. (2000). The geopolymerisation of aluminosilicate minerals. International Journal of Mineral Processing, 59(3), 247-266. 46. Minerals. International Journal of Mineral Processing, 59(3), 247- 266.

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