Mechanics-perspective evaluation of self-sensing geopolymer coatings in structural health monitoring

Abstract

Self-sensing cementitious coatings are a promising alternative in structural health monitoring due to their high sensing performance and simple production and deployment. The sensing behavior of coatings though differs compared to conventional self-sensing materials due to the interface between the coating and substrate. In this study, the bonding and sensing performance of geopolymer coatings under cyclic compression was investigated by employing four surface treatments – untreated, chipping, brooming, and chemical treatment. The coatings' splitting tensile bond strength ranged between 3.52 MPa and 6.54 MPa. The strain ratio between the coatings and substrates was between 0.62 and 0.67 and the gauge factor was found between 29 and 34. A numerical analysis involving finite element models on the strain behavior of coatings and parametric studies on the coatings' elastic modulus and thickness was carried out. A bonding coefficient, that accounts for the coatings’ mechanical and geometric properties, was proposed to accurately determine the gauge factor.