Non-Destructive Testing (NDT)
Non-destructive testing is a descriptive term used for the examination of materials and components in such a way that allows materials to be examined without changing or destroying their usefulness. NDT can be used to find size and locate surface and subsurface flaws and defects. When the structure is constructed then the next step is to determine the stability of the building, Bridges, Dams, Power Plant, Commercial and Residential Buildings, etc constructed that can be determined by the Non-destructive testing
Structural Audit
Visual Inspection- to check symptoms of reasons/causes of health deficiencies of a building’s structure like leakages/seepage, cracks, delimitation, distress, separation etc.
Nondestructive testing- Rebound hammer test for surface hardness, Ultrasonic Pulse velocity for concrete compressive strength & general quality, Half-cell potential meter for corrosion testing of steel, etc.
Rebar locator test for rebar location, its diameter & concrete cover depth checking
Some of the Non-Destructive Testing Methods are as follows:
| Sr no. | Tests & Parameters | Test Method |
|---|---|---|
| 1 | Rebound Hammer Tests | IS 516 (Part 5/ Sec 4) |
| 2 | Ultrasonic Pulse velocity (UPV) Testing | IS 516 (Part 5/ Sec 1) |
| 3 | Measurement of Depth of Crack by Ultrasonic Pulse Velocity | IS 516 (Part 5/ Sec 1) |
| 4 | Path length measurement by Ultrasonic Pulse Velocity | IS 13311 (Part 1) |
| 5 | Carbonation test & Concrete Resistivity Test | BS EN 14630 |
| 6 | Half Cell potential | ASTM C876 |
| 7 | Core Extraction and Testing | IS 516 |
| 8 | Re Bar Locator & Concrete depth Measurement | |
| 9 | CAPO Test |
Rebound Hammer Test
Rebound hammer test is conducted to find out the compressive strength of concrete by using rebound hammer. The rebound of an elastic mass depends upon the hardness of the surface when it strikes.
When the plunger of rebound hammer test is pressed against the surface of the concrete, the mass rebounds and the extent of such a rebound depends upon the surface hardness of the concrete.
The spring-loaded hammer must travel with a consistent and reproducible velocity. The rebound distance of the steel hammer from the steel plunger is measured on a linear scale attached to the frame of the instrument.
The tests can be performed in horizontal, vertically upward, vertically downward or any intermediate angled positions in relation to the surface. The devices are furnished with correlation curves by the manufacturer.
IS 516 (Part 5/Sec 4) : 2020 now states that these references to the relationship between the rebound hammer and compressive strength provided by the manufacturer shall be used only to provide indications of relative concrete strength at different locations in a structure.
To obtain greater accuracy of test results, it is recommended that the user develops a correlation for the device on each concrete mixture design to be tested and at the intended test angle.
Ultrasonic Testing
We offer services for testing concrete, where the velocity of ultrasonic pulses is measured and identification of cracks, voids, strength, and elasticity are checked to determine the areas which can provide the basis for recognizing the defects. The pulse velocity in a material depends on its density and its elastic properties, which in turn are related to the quality and the compressive strength of the concrete.
Ultrasonic pulse velocity (UPV)
The ultrasonic pulse velocity test is an in-situ, non destructive test to check the quality of concrete and natural rocks. In this test, the strength and quality of concrete or rock is assessed by measuring the velocity of an ultrasonic pulse passing through a concrete structure or natural rock formation.
Crack depth measurement by ultrasonic pulse velocity
The probable depth of propagation of any cracks in concrete surface are measured using UPV instruments.
Carbonation test & Concrete Resistivity Test
Measurement of carbonation depth by phenolphthalein spray test at the selected location on RCC members of the structures covered under the study is used to see the depth of carbonation.
Half–Cell / Surface Potential Test
Measuring the half-cell /surface potential at the selected location on RCC members of the structures covered under the study will help in understanding the extent of reinforcement corrosion as per ASTM C 876.
CAPO Test
Cut and Pull Out (CAPO) is an effective test method for determining RCC constructions’ in-situ compressive strength.
The results of the CAPO test are found to be within 8% of those obtained using traditional or conventional procedures.
A diamond tool, shaped like a dentist’s drill and larger at the tip than at the base, is used to recess the groove into the central hole.
The CAPO tests are used to assess the compressive strength of in-situ concrete in structures such as concrete roads, bridges, and buildings.
The CAPO test is performed in compliance with ASTM C900, BS-1881: Part 207, and EN-12504-3 requirements and is accredited by the Indian Road Congress (IRC).
