NDT plays a very important role in the conditional assessment of RCC structures. NDT not only allows the evaluation of aged and deteriorated structures, but it can also be used in the quality control of new structures. Once the structure is monitored, the lifetime can be predicted, and consequently, treatment and recovery become easier and more economical.

The need to test hardened concrete has been felt for a few decades. The present methods of testing fresh concrete, such as the cube test and slump test, are now supported by various non-destructive testing methods. To assess the integrity of old or new concrete and reinforcement, non-destructive testing is one of the most powerful and reliable tools. The need to conduct non-destructive testing for condition assessment of the RCC structures has grown considerably in recent times, due to the increase in the number of structures showing signs of distress.

In order to diagnose the integrity of the existing structure, different sets of Non-Destructive techniques are adopted. A few of the non-destructive techniques are as follows:

• Ultra-sonic Pulse Velocity Test – To determine the quality of in-situ concrete
• Rebound Hammer Test – To determine the estimated compressive strength of concrete
• Carbonation Test – To determine the extent of corrosion by pH level
• Chemical Analysis of concrete – To determine the chloride & sulphate content in concrete
• Half-cell Potential Measurement test – To determine the level of corrosion in concrete
• Core extraction from RC members – To determine the compressive strength with high precision
• Cover meter test – To evaluate the internal design adopted for an existing structure
• Pile Integrity Test – For assessing the integrity, continuity & depth of pile
• Carbonation , Sulphate, pH / Chloride Content tests – On concrete samples