In the construction industry, non-destructive testing (NDT) has established itself as an indispensable tool for assessing the strength of concrete. Unlike traditional methods, which involve the creation of cores and destructive testing, NDT offers a fast, economical and safe alternative for determining the compressive strength of concrete in situ, without compromising the integrity of the structure.
The following are the most common NDT techniques:
–Schmidt rebound method (using a sclerometer): this method establishes the surface hardness of concrete by measuring the rebound of a hammer. The reading obtained is correlated, using empirical equations, with the compressive strength. It is a fast and simple technique for preliminary assessments.
–Ultrasound: this technique measures the speed of propagation of ultrasonic waves through concrete. A higher propagation speed usually indicates a higher compressive strength. In addition, it allows the detection of internal defects, such as cracks or voids.
–Penetration methods: These methods use a penetrometer to measure the resistance of the concrete to the penetration of a point into it. This is a useful technique to evaluate the consistency and uniformity of the material.
–Dynamic loading method: This method applies a controlled impact to the concrete to generate stress waves and measure its response. It is especially useful to evaluate structural integrity and detect anomalies.
To obtain accurate and reliable results in any of the techniques, correct calibration of the NDT equipment and the application of specific correlation equations in each type and condition of concrete are essential.
Non-destructive testing for the evaluation of concrete strength contributes to better management of quality and safety in constructions, without altering their structure. At the same time, they serve for preventive maintenance.
By Raúl Soriano, Senior Modeler in the Architecture Department of Amusement Logic
