Experimental study on the direct shear behavior of three-dimensional basalt fiber network reinforced concrete slabs

Direct shear behavior is one of the fundamental mechanical properties required for the application of three-dimensional (3D) basalt fiber network reinforced concrete (3DBFRC) slabs in construction engineering. The lack of research on the direct shear behavior and design methods of 3DBFRC slabs has hindered its engineering application and popularization. In this study, direct shear tests were performed on 3DBFRC slabs, the effects of key parameters were investigated, and prediction models for the shear strength of 3DBFRC slabs were established. The results indicated that during failure, the concrete on the shear plane was fractured in both 3DBFRC and chopped basalt fiber reinforced concrete (CBFRC) slabs. The 3D basalt fiber networks in 3DBFRC slabs were ruptured, whereas the chopped basalt fibers in CBFRC slabs exhibited two failure modes: fiber rupture and pull-out. The shear strength and shear toughness index of warp-oriented 3DBFRC slabs were 1.64 and 2.08 times those of CBFRC slabs, respectively. The shear strength and shear toughness index of warp-oriented 3DBFRC slabs were 1.48 and 1.94 times those of weft-oriented counterparts, respectively. Increasing the network quantity improved the direct shear behavior of 3DBFRC slabs, while the network height had a negligible influence. A linear prediction model with the fiber cross-sectional fraction as the independent variable is recommended for predicting the shear strength of 3DBFRC slabs. The calculation mode uncertainty of the linear prediction model follows a normal distribution with a mean value of 0.99 and a standard deviation of 0.16.