Testing
Rebound hammer test method is based on the principle that the rebound of an elastic mass depends on the hardness of the concrete surface against which the mass strikes.” In other words, the amount of rebound recorded using the hammer will depend on the hardness of the concrete surface, which will then correlate to the compressive strength of the concrete.
An ultrasonic pulse velocity (UPV) test is an In-situ, non- destructive test to check the Quality of concrete. In this test, the strength and quality of concrete is assessed by measuring the velocity of an ultrasonic pulse passing through a concrete structure. The high UPV Test and lower time of travel indicate good quality of concrete in terms of density, uniformity, homogeneity, etc.
The half-cell potential is the potential developed at the electrode of a half cell due to the process of oxidation or reduction. This potential is used to indicate corrosion activity, and measures the tendency of one relation, like oxidation, to proceed at its one half-cell electrode and similarly measures the corresponding tendency for reduction to proceed at the other half-cell electrode. he corrosion activity of the reinforcing steel.
Carbonation of concrete is a process by which Carbon di Oxide from the air penetrates into the concrete and reacts with calcium hydro-oxide to form calcium carbonates. Conversion of Ca(OH)2 into CaCO3 by action of CO2 by itself is not reactive. In the presence of moisture, CO2 changes into dilute carbonic acid which attacks the reinforcement and also reduces alkalinity of concrete. In this test Phenolphthalein solution is used as indicator.
Rebar mapping surveys can determine rebar distribution (spacing and depth of the different rebar layers), rebar cover thickness, overall concrete slab thickness, and detect any other features within concrete including post tension cables, conduits, ducts, andvoids.
Core tests involve taking the actual core Samples from the structure using the diamond core cutting bits and subjecting the cores to compressive loading in the compression testing machines, followed by the visual inspection. Core tests are conducted in conformance with the guidelines laid out in IS: 456.
The test measures the force required to pull out a previously cast in steel insert with an embedded enlarged end in the concrete. In this operation, a cone of concrete is pulled out and the force required is related to the compressive strength of concrete. This test method is used to determine. 1) Bond strength of a repair or an overlay Material to the substrate. 2) The tensile Strength of a repair or overlay material, or an adhesive used in repairs, after the material has been applied to a surface.
The strength evaluation of structural member of RC structure is of prime Importance. One such method for strength evaluation of flexural member (beam and slab) of RC structure is physical load test. Linear potentiometers are placed below the slab and beams and the graphs for deflection are recorded as per the gradual Increase in the loading.
The Cut and Pull out (CAPO) is a reliable test method to determine the in-situ compressive strength of concrete. The groove is recessed through the centre hole by a diamond tool with a similar shape as a dentist's drill, larger at the tip than at the base. The CAPO test results are found to be within 8-10% of the results obtained from conventional methods. The CAPO tests determines the compressive strength of in-situ concrete in various structures like concrete roads, bridges, buildings etc.
