Adhesion at interface of geopolymer and cement mortar under compression: An experimental study

Based on a simple mechanical model that elucidates the effects of distinct components of a cement mortar specimen that contains a geopolymer interlayer, this study undertakes a series of laboratory tests to determine corresponding representative parameters for each component in the model. Failure modes, deformational moduli and strength parameters of cement mortar, geopolymer, their interface, and the composite specimen, are thus obtained. The apparent angle of friction of the interface is close to that of the geopolymer and markedly exceeds that of the cement mortar. The interface adhesion is 34–43% as strong as the cohesions of the two compositional components. The comprehensive failure envelope for the composite specimen can be used to predict the possible failure mode and strength under various stresses when geopolymer is used as an adhesive material to repair defects in concrete.