Flexural behavior analysis and strength prediction of steel fiber-and-nanosilica reinforced rubber concrete

In this study, a series of experiments were conducted to investigate the effects of the hook-shaped steel fiber (SF) and nanosilica (NS) on the flexural properties of the rubber concrete (RC), and the modification mechanisms of the NS on the flexural properties of steel fiber-and-nanosilica reinforced rubber concrete (SFNS-RC) were also revealed by using the X-ray diffraction (XRD) and scanning electron microscope. Based on the RC specimen with a rubber content of 5%, the experimental variables included the SF volume fractions (0%, 0.5%, 1.0%, and 1.5%) and NS replacement ratios (0%, 1%, and 2%). The results indicated that the NS could improve the microstructure of the RC, the peaks of Ca(OH)(2), C3S, and C2S steadily reduced as the NS replacement ratio increased, respectively, and the microstructure of SFNS-RC became more compact and uniform because the NS could produce pozzolanic activity to fill the pores of the matrix and strengthen the bond behavior between the SF and matrix. In addition, the RC specimens containing the SF and NS displayed the excellent flexural behaviors, including the ductility and energy dissipation characteristics. Finally, the empirical formulae for predicting the first-peak flexural strength and peak flexural strength of SFNS-RC were proposed through the analysis of experimental data, respectively.