Experimental study of crack propagation in plain and reinforced ECC beams containing PVA fibers

Engineered cementitious composites with polyvinyl alcohol fibers (ECC-PVA) are a group of cementitious composites, which not only provide high ductility and tensile strength but also control the crack width. The strain-hardening behavior under tensile and flexural loads and the formation of multiple shallow cracks instead of deep and concentrated cracks are among the main advantages of these composites, leading to their widespread application. In this paper, eight ECC concrete beam specimens, including four specimens containing 2% and the other four containing 1.5% PVA fibers, were tested and their load-displacement and load-crack mouse opening displacement curves were obtained. To determine the crack mouth opening displacement, four LVDTs were mounted around initial crack formed in the beam. As the displacement applied using the standard testing machine with a 500kN capacity increased, which were recorded using the LVDTs. Afterward, by averaging the recorded opening displacement recorded using LVDTs, the final crack mouth opening displacement was obtained. The results indicated that the ECC specimens with 2% PVA fibers had lower load-carrying capacity, and greater displacement, crack mouth opening displacement, and ductility values compared with the ECC specimens with 1.5% PVA fibers. Moreover, increasing the PVA fiber percentage elevated the flexural capacity of the beams by 10%.