Flexural fatigue properties of a polyvinyi alcohol-engineered cementitious composite

摘要

The flexural fatigue properties of a recently developed polyvinyl alcohol-engineered cementitious composite (PVA-ECC) using local dune sand were investigated. Fatigue flexural tests were conducted under a four-point bending setup. Normal concrete beams were also tested as a benchmark. To determine the stress range versus fatigue life relationship, five and four stress ranges were applied to the PVA-ECC and the normal concrete specimens, respectively. It was found that, compared with normal concrete specimens, the PVA-ECC specimens showed much superior flexural fatigue performance in terms of fatigue strength and deformation capacity, with a more ductile failure mode. Furthermore, typical fatigue performance indicators of the PVA-ECC specimens, including evolution of the midspan deflection, total crack mouth opening displacement, crack width and crack depth of the critical crack that led to final failure, with number of cycles as well as total dissipated energy, were recorded and compared with those of normal concrete specimens. It was observed that the PVA-ECC specimens tested under a stress range of 3 MPa (32% of the flexural strength) did not fail by fatigue after 5.6 million cycles; subsequent static tests demonstrated that they still had good residual flexural properties, including residual flexural strength, deformation capacity, stiffness and energy absorption capacity.