Influence mechanism of basalt fibre on the toughness and microstructure of spray concrete

The effect of basalt fiber (BF) on the mechanical properties and toughness of basalt fiber reinforced spray concrete (BF/SC) was studied through the experiment. The microstructure of BF/SC was studied by SEM and nuclear magnetic resonance (NMR).The results show that the compressive strength, splitting tensile strength and flexural strength of BF/SC are significantly increased by adding BF. Compared to the plain SC, the flexural strength of BF/SC with 3 kg/m³ and 7.5 kg/m³ are better, and are energy absorption capacity are 2.42 times and 2.69 times as high as the plain SC, respectively. BF has a good dispersion rate in the SC, and displays reasonable bonding within the SC substrate. A proper amount of BF effectively inhibits the formation of large volume pores, in which the proportion of the large pore size of 3 kg/m³ BF/SC is only 0.25%, and the addition of excessive BF leads to an increase of fiber agglomeration and porosity. At the same time, the optimum content of fiber is found to be 3 kg/m³.