The integrity of concrete piles and / or prefabricated concrete piles can be controlled by means of a acoustic (sonic) test method. Piles formed in the ground are checked for cracking, diameter changes and other unwanted discontinuities using this technique. In prefabricated piles, the check remains limited to cracks and fractures.
The acoustic measurement method consists of placing a sensitive motion sensor on the pile head, then a tap with a plastic hammer is given on the pile head. This creates a wave in the pile that propagates in the concrete towards the pile tip. The Piletip reflects the wave, after which he goes back to the head of the pile. Upon arrival, the “point reflection” is registered by the sensor. By recording the movements of the pole head in time, a judgment can be made regarding the integrity of the pile.
Important condition for successful measurement is that the concrete quality of the pile head is in order. Piles that are created in the ground should be at least five days old. A flat pile head is not necessarily necessary. Sonic measurements of piles can be performed both on land and underwater.
It is noted that the measurement technique does not determine the concrete strength and / or concrete quality. Nor is information available about the bearing capacity of the piles.
In the first quarter of 2007, CUR Recommendation 109 was released “Acoustic Survey of Concrete Foundation Piles”. This recommendation was revised in 2013. This document provides a complete description of the sonic test method on concrete foundation piles. This describes requirements for measuring equipment, measurement measurements, assessment and reporting of measurement results, as well as system limitations. In addition, advice is given for any necessary additional measurements.