Experimental investigation on fiexural properties of directional steel fiber reinforced rubberized concrete

Incorporating rubber and steel fiber into concrete can avoid brittle failure of the concrete under complex stress condition and improve its fiexural performance. The present study aims to investigate the synergistic effect of the rubber and steel fiber on the mechanical strengths, fiexural toughness and strain field characteristics of the steel fiber reinforced rubberized concrete (SFRRC). Accordingly, a series of mechanical tests in terms of compressive, tensile splitting and fiexural tests were conducted on 13 groups concrete specimens proportioned with different rubber volume content, steel fiber volume fraction and orientation of steel fiber. In addition, digital image correlation (DIC) technology was applied to analyze the process of crack propagation and strain field distribution of cracks of the concrete in the fiexural tests. Experimental results suggested that rubber could enhance the residual strength f(150) (maximum increase of 128.8%) of steel fiber reinforced concrete (SFRC) in the fiexural tests, but caused a negative effect on its fiexural strength. Furthermore, steel fiber and the orientation of steel fiber promoted the fiexural strength, crack resistance and fiexural toughness while decreased the strain value of cracks of the SFRRC. The maximum toughness indexes T-150 of the directional SFRRC was 11.14 times of that of the rubberized concrete. Consequently, the coexistence of the rubber and steel fiber is conducive to improving the fiexural performance of the SFRRC.