PULSE VELOCITY
In this method, a pair of piezoelectric sensors are placed at opposite ends of the test member. In one of the sensors, electronic pulses are generated and the time it takes for the pulse to propagate through the concrete is measured by the other sensor. Knowing the distance traveled, propagation velocity is calculated and based on the velocity, condition of the concrete is determined. Depending on the locations of the sensors, the procedure is divided in to three categories: direct (sensors at opposite ends), indirect (sensors on the same sides), and semi-direct (sensors at right angles) transmission. The method is useful in determining presence of cracks or voids and overall quality of the concrete.