Cover Meter

CE 308 PLAIN AND REINFORCED CONCRETE -II   Determination of size, spacing and cover in reinforced concrete slab by cover meter

MILITARY COLLEGE OF ENGINEERING RISALPUR

Objective: To determine the position of reinforcement, cover space and size of bar in R.C.C Fieldslab. relation of the test: 1. Engineers and Contractors need to locate reinforcement in concrete primarily for four (4) different reasons. These are: a. To locate safe areas where they can drill or core without hitting reinforcements (reinforcement avoidance). b. To determine if the reinforcement had been installed. c. To determine if the reinforcement had been installed in accordance with the contract drawing and industry accepted tolerances. d. To determine the approximate location of the reinforcement when plans and specifications are not available.

Learning about the reinforcement position in concrete components is essential as they are a very important component of concrete structures provided to offer ductility and tensile strength to the concrete. In many field applications, it becomes essential to know the depth of cover, identify location of re-bars and their diameter. This information becomes essential directly or indirectly in the field. Ascertaining the cover depth is important to implement durability standards to the structure under construction.

Knowing the diameter of the bar and their location is essential to understand the bar spacing and their placement, in existing structures where drawing may not be available. Also, in cases where concrete core extracts are to be taken the identification of the rebar locations becomes essential to avoid cutting of the reinforcement bars.

Apparatus 1. cover meter, 2. concrete with reinforcement

Procedure:  

 The cover meter is switched on and the meter is adjusted on test specimen.  The search head is then scanned over the surface of the concrete to be examined for the presence of reinforcement. If reinforcement exists below the surface and within the working range of the cover meter, this will be indicated by the meter by producing a pitch of sound.  During scanning the signals are analyzed by the instrument and corresponding information is indicated on the display.

Procedure:  On the display three readings are shown (left corner, center and right corner)  Left corner reading indicate cover reading, center reading indicate bar size and right corner reading indicate bar type.  Move the search head of meter on flat surface of concrete until a minimum cover reading is obtained, which indicate the direction of reinforcement and also shows that the bar is parallel to the axis of the search head.  Note the cover and mark the position of the bar.  And also note the bar size at the same point which will be shown at the center of display.

Procedure: For spacing move the search head beyond the bar and locate the 2nd bar by the same process as discussed above. Then find the spacing between bars manually.