Cracking Diagnosis in Fibre Reinforced Concrete Cubes and Cylinders with Synthetic Fibres using a PZT-based Health Monitoring System

This paper carried out experimental research of concrete specimens with synthetic fibres under repeated splitting tension and uniaxial compression to investigate the efficiency of a proposed health monitoring methodology that implements surface-bonded piezoelectric transducers. The developed technique uses small-sized custom-made devices for diagnosing damage due to concrete cracking caused by the imposed repeated loading at various load levels. A test program of standard 150/300 mm cylinders and 150 mm cubes made of plain and fibre reinforced concrete subjected to splitting tensile and compressive repeated loading is presented and discussed. The proposed method utilises the frequency response measurements of a network of small-sized piezoelectric patches mounted to the surface of the tested specimens in order to detect the onset of damage since cracking has probably been developed in the inner concrete, whereas no visible cracks appeared on their surface. The objectives of this study also include development of a quantitative assessment procedure of damage using the statistical index values distribution at various points of measurements. The influence of distance, type of material (plain or fibrous concrete) and damage level triggers changes in the measurements of the piezoelectric transducers and the adopted statistical index seems to be a reliable assessment tool for damage quantification. Further, for the first time, a wireless and portable structural health monitoring system display feasible detection of premature cracks for damage prognosis in fibre reinforced concrete structural members.