Non Destructive Testing


Non Destructive Testing

Non-Destructive Tests are used for structural health monitoring of existing structures. These tests are extremely useful in establishing the condition of structures and hence form the basis for repair & retrofitting of structures.

Capstone has one of the most experienced and fastest-growing Non-Destructive Testing teams in India. We have performed tests in all corners of India; our team has also been appointed for testing projects overseas. We have a fully equipped testing lab in Mumbai.

We have been repeatedly engaged by reputed institutions like IIT Bombay, VJTI, and BARC which itself speaks volumes about the quality of services we provide.

We Are Equipped To Perform The Following Tests

These tests are primarily done to establish:

  • The homogeneity of concrete
  • Presence of cracks, voids and other imperfections

UPV Tests are done in accordance with Indian standards IS: 13311 (Part 1)

The velocity of the Ultrasonic Pulse in concrete is obtained through this test which helps in grading the concrete quality.

These tests are primarily done to assess:

  • the likely compressive strength of concrete
  • the uniformity of concrete

Rebound Hammer tests are done in accordance with Indian standards IS: 13311 (Part 2)

The hammer is pressed against cleaned concrete surface and released. This gives the Rebound hammer reading which is correlated to the compressive strength of concrete.

These tests are primarily done to obtain the compressive strength of the concrete sample. In addition, the density of the concrete sample is also obtained. Concrete Core tests are done in accordance with Indian standards IS: 1199 and IS: 516 Concrete core sample is extracted from the member to be tested using a core cutting machine. The core surface is prepared in the laboratory; the core is then cured and tested in a Compressive Testing Machine. The obtained compressive strength is converted to equivalent cube strength using suitable correction factors in accordance with the Indian standards.

The half-cell potential test is an electrochemical testing method to determine if active corrosion may be occurring in reinforcing steel within concrete structures.

HCP Tests are done in accordance with ASTM C876 standard.

This test uses a voltmeter to measure the potential difference between the reinforcing steel and a copper-copper sulfate reference electrode in contact with the concrete surface. The potential difference provides an indication of the presence or absence of active corrosion in the reinforcing steel.

This test is carried out to determine the depth of concrete affected due to combined effect of atmospheric carbon dioxide and moisture causing a reduction in level of alkalinity of concrete.

Carbonation depth is measured using a solution of phenolphthalein indicator. When sprayed on test specimen, the color of concrete changes to pink if value of pH is greater than 9. For pH value lower than 9, concrete remains colorless.

These tests are used to assess the pH level, Chloride (Cl) content and SO3 content of concrete. A higher pH value or a higher content of chloride or SO3 than permitted by Indian standard codes shows the presence of an environment where corrosion of reinforcement has much higher probability than normal.

The obtained results are correlated with the permissible limits given by IS 456: 2000 code.

Permissible Limits:
Ph Not less than 8
Cl (kg/m3) For PCC, maximum 3.0 kg of Chloride per m3 of concrete.
For RCC, maximum 0.6 kg of Chloride per m3 of concrete.
SO3 (%) Less than 4% by mass of cement in the concrete mix.

Rebar mapping is a mechanism to obtain information related to reinforcement in existing concrete buildings where drawings are missing or reinforcing data needs to be verified.

These tests are used to:

  • check the size and numbers of reinforcing bars present in concrete members
  • determine the concrete cover provided to reinforcement
  • prepare structural drawings for RCC structures where original drawings are not available

This test is used for qualitative evaluation of the continuity of the pile and the presence of any necking or bulging along the pile length.

These tests are done in accordance with Indian Standard IS:14893. The pile head is hit with a hammer which generates sonic waves that are recorded by a sensor. The recorded waves are then analyzed using computer software to determine any imperfections in the pile.

Pile dynamic tests are used to determine the load carrying capacity of piles. These are an alternate to static load tests and offer a considerable saving of time and cost compared to static pile test.

The pile capacity is calculated in accordance with IS: 2911 based on the settlement of the pile on application of vertical force by dropping a free falling ram.

Magnetic particle inspection is a method of locating and defining discontinuities in magnetic materials. It is excellent for detecting surface & sub-surface defects in all magnetic materials and in welds, including discontinuities that are too small to be seen with the naked eye.

Probes are placed on each side of the area to be inspected, and an electric current is passed between them.

A magnetic flux is produced at right angles to the flow of current.

When a discontinuity such as a crack is detected, the magnetic flux leaks, creating points of attraction.

A magnetic powder is then applied to the surface and clings to the leakage area more tenaciously than elsewhere, forming an indication of the discontinuity.

This test is used to detect any surface discontinuities such as cracks from fatigue, improper welding, porosity, and incomplete fusion in welds.

Penetrant is applied on the surface and some time is allowed for the penetrant to soak in into the discontinuities

Excess penetrant is then removed from the surface

A developer powder is then applied on the surface which shows any defects clearly

An ultrasonic thickness gauge is used to measure the thickness of steel or any other metallic members. This technique is especially useful because access is required only from one side of the member/plate whose thickness is to be measured.

Thickness measurements are required to:

  • Check if the fabricated items conform with the drawings & Indian Standards
  • To estimate the loss in thickness of steel members due to corrosion
  • Can be used to check thickness of pressure vessels, boilers, storage tanks, tubes & pipes and steel sections (I beams, Channels etc).

Some structures are subjected to routine dynamic loads such as blast loads or dynamic loads due to movement of trains, heavy vehicles or equipments. Many of these structures may not been designed for these vibration loads, especially where these loads were not present during planning. In these cases it is important to quantify the vibration loads and check the adequacy of the structure in terms of strength and serviceability.

Slab Load tests are used to determine the load carrying capacity of slabs. This test is performed in accordance with Indian Standard IS:456.

The slab to be tested is loaded using sand bags and deflection is measured. The recovery in deflection after removal of super imposed loads helps in determining the load carrying capacity of the slab.

Moisture meter tests are used to determine the moisture content in wood, concrete and gypsum materials. These tests are particularly useful when there are dampness problems in old buildings due to water leakage.

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