Crack propagation analysis and mechanical properties of basalt fiber reinforced cement composites with changing fiber surface characteristics

Abstract

The large-scale application of basalt fiber reinforced cement composites (BFRCC) is due to the relatively high performance and decreased CO2 footprint of basalt fiber. Still, the ultimate tensile strain of BFRCC is always difficult to exceed 1%, hindering its popularity. Chemical grafting on the basalt fiber surface is a promising way to deal with the such drawback. The crack propagation mechanism of BFRCC is also unclear. Thus, the influence of fiber interface characteristics on the tensile failure mechanism of BFRCC is analyzed. The main work of this study is to achieve ultra-high toughness BFRCC with ultimate tensile strain exceeding 2% through chemical modification of fiber surface. The decrease in bonding strength has little effect on the water absorption of BFRCC but can improve its compressive and tensile properties to 1.88 times and 1.95 times. The crack resistance mechanism of modified BFRCC was revealed. The results showed that the average crack propagation speed of modified BFRCC was one order of magnitude lower, and the initiation energy threshold and crack propagation energy were higher. Proper interfacial bonding strength and high sliding friction coefficient can suppress the cracking width and fiber breaking rate.