Effect of variation of steel reinforcement on ultrasonic pulse velocity prediction in concrete beam

Abstract

Ultrasonic pulse velocity [UPV] method is one of the sensitive methods for determining the quality of the concrete. The quality of the concrete is determined based on the velocity of ultrasonic pulse [UP] in the interrogated component of the concrete structure. The velocity of the UP is altered due to presence of reinforcement in the concrete, which results in the incorrect measurement of the ultrasonic pulse velocity. The velocity of ultrasonic pulse (UP) in the reinforcement bar is more than UP in plain concrete. The UP waves travel partial path through the reinforcement bar which results in an overall more velocity in comparison to plain concrete. Hence, the prediction of the quality of the concrete based on the calculated velocity is not accurate. In the presented work, effects of presence of reinforcement bars on the velocity of UPV in the concrete structure were investigated on lab size samples and a correction factor was suggested to modify the velocity of UP for RCC structure. The experiment was performed on the lab size samples. Cubes of 150x150x150 mm and beam of dimension 800x300x150 mm were casted and reinforcement of 0.8%, 1.0%, 1.2%, and 1.4%, were inserted. These samples were tested using ultrasonic pulse velocity instrument and a correlation was developed between number of bars in the concrete sample, cross-sectional area of the steel bars and UPV. It was observed that in the reinforced sample, measured UPV values are 06 to 14 % more than the UPV values in the plane concrete sample. The investigated research work can be used to assess the quality of the reinforced cement concrete accurately.