Monitoring early age property of cement and concrete using piezoceramic benderelements

Abstract

Ultrasonic waves are commonly used for non-destructive evaluation of concretestructures. For fresh concrete, ultrasonic waves have also been used to monitorconcrete setting and strength development at early ages. However, the conventionalultrasonic test set-up typically needs access to the two opposite sides of concretestructures, which is not always possible for in situ field testing. In this paper,embedded piezoceramic bender elements are proposed to measure ultrasonic shear(S) waves in fresh cement paste, mortar and concrete. The shear wave velocitiesare obtained from B-scan images of a collection of recorded signals over time.Experimental results indicate that the shear wave velocity is closely related tothe setting time, and this relationship is independent of air void content andw/c of cement pastes. The low cost bender elements can also be of use to monitorthe setting of fresh concrete and the long term evaluation of hardened concrete.