Carryout compressive strength test

This test is useful for the determination of concrete cover, location of embedded rebars & estimation of size of embedded rebars. The instrument is based on the magnetic technique & is calibrated for different purposes. The cover thickness is important from the point of view of estimation of initiation of corrosion. The location & estimation of bar diameter becomes useful in structures where there are no structural drawings available.

This test can give the probability of corrosion activity taking place at the point where the measurement of potentials are taken from a half-cell, typically a copper-copper sulphate half-cell. An electrical contact is established with the exposed steel & the half-cell is moved across the surface of concrete for measuring the potentials.

Nondestructive testing or Non-destructive testing (NDT) is a wide group of analysis techniques used in science and industry to evaluate the properties of a material, component or system without causing damage.

Cutting and coring experts and construction professionals require a reliable, non-destructive means to locate targets within concrete structures prior to drilling, cutting or coring.

This is basically a surface hardness test & should be used only on concrete where the surface has not carbonated as the results tend to be very high & unrealistic on a carbonated surface. Hence it should be used for younger concrete than for older one. In case of old concrete the carbonated layer should be chipped off or grounded to expose the core concrete & then the hammer test should be conducted. The rebound is affected if the surface is moist.

This test is conducted for assessing the quality & integrity of concrete by passing ultrasound waves through the specimen/RCC member under test. This test can also be used to determine the presence of honeycombs, voids, cracks etc. The instrument consists of a transmitter & a receiver (two probes). The time of travel for the wave to pass from the transmitter to the receiver when kept opposite to each other is recorded in the ultrasonic instrument. The distance between the two probes (path length) can be physically measured.

This test is carried out to assess the quality / uniformity of concrete at various depths. The instrument consists of a four probe device. Electrical current is passed through the outer probes & the potential drop is measured by the inner probes. From the current & voltage drop measurements, the resistivity of concrete can be measured. This resistivity can be related to quality of concrete.