Experimental evaluation on fiber distribution characteristics and mechanical properties of calcium carbonate whisker modified hybrid fibers reinforced cementitious composites

Abstract

Calcium carbonate whisker (CW) is used to modify the steel-PVA hybrid fibers reinforced cementitious composites (SPFRCC). The addition of CW result in excellent mechanical properties and considerable economic benefit owing to its microscopic reinforcement effect and low cost. In this study, the flexural behavior, fiber distribution characteristics and compression response of CW modified steel-PVA hybrid fibers reinforced cementitious composites (CW-SPFRCC) are investigated by three-point bending test, image processing technique and uniaxial compression test, respectively. The results indicate that the addition of CW can effectively improve the flexural properties of SPFRCC because of the crack resistance and filling effect at microscale. The best fiber distribution characteristics are observed in CW10-S15P05 due to the presence of CW that modify the adhesion and flowability of cement matrix. The uniaxial compression strength, peak strain, elastic modulus and Poisson's ratio of CW-SPFRCC are increased by 37.1%, 40.2%, 3.7% and 30.7%, respectively. Meanwhile, the uniaxial compression constitutive model is proposed to describe the compression stress–strain relationship of CW-SPFRCC based on the experimental results. Moreover, the microstructure analysis demonstrates that the modification mechanism of CW in SPFRCC is attributed to the interface improvement, CW pull-out, CW slippage, and CW rupture.