Concrete-concrete pressure contacts under dynamic loading, studied by contact electrical resistance measurement

A mortar-mortar contact was studied under dynamic loading at different compressive stress amplitudes by measuring the contact electrical resistance. Irreversible decrease in the contact resistance upon unloading was observed at a low stress amplitude (5 MPa) due to local plastic deformation at the asperities at the interface. Irreversible increase in the contact resistance at the maximum stress was observed, probably due to debris generation; it was more significant at a higher stress amplitude (15 MPa). At a stress amplitude of 15 MPa, irreversible increase in the contact resistance upon unloading was observed in the first four loading cycles, probably due to severe debris generation.