Evaluation of Bored Pile Defects According to Ultrasonic Wave Velocity

Abstract

The ultrasonic testing method for concrete, based on measuring the velocity of sound waves transmitted through the material, is a widely used approach globally and in Vietnam for assessing the quality of concrete after construction. The principle of this method relies primarily on the sound velocity in concrete, resulting in relatively high accuracy and reasonable costs. The testing procedure and equipment operation are straightforward, and the method is explicitly outlined in current standards. However, for bored piles, identifying and evaluating concrete defects based on ultrasonic testing results can vary, depending heavily on calculation approaches and the experience of the operator. In this paper, the author provides an overview of the theoretical basis, requirements, and technical guidelines for the ultrasonic testing method using the cross-hole technique. Additionally, based on the actual ultrasonic testing results of piles from two projects, one in Cau Giay and another in Long Bien, Hanoi, the study highlights differing outcomes regarding the concrete's uniformity. From these experimental results, recommendations are made regarding defect evaluation and the prediction of concrete pile strength based on the obtained ultrasonic wave velocity.

Keywords: Ultrasonic waves; wave velocity; bored concrete piles; defects; concrete strength.