Liquid crystal display glass powder as a filler for enhancing steel fiber pullout resistance in ultra-high-performance concrete

This study investigated the feasibility of using waste liquid crystal display (LCD) glass powder as a partial replacement for the silica flour that is typically used as a filler in ultra-high-performance concrete (UHPC). In this study, 50% of the silica flour was replaced with LCD glass powder, and its effects on the interfacial bond properties of two steel fiber shapes—circular and triangular—were evaluated. The test results indicated that the LCD glass powder effectively enhanced the bond between the steel fibers and the UHPC, which created a denser interfacial zone; this could be attributed to the filling effects of the LCD glass powder and secondary hydrates. The use of the LCD glass powder increased the pullout energy by 15–40% and the average bond strength by 16%, along with formation of additional scratches on the fiber surfaces. For the same matrix, as compared to the circular steel fibers, the triangular steel fibers yielded superior pullout resistance owing to their higher intrinsic fiber efficiency ratio. Thus, the highest average bond strength and pullout energy of 11.2 MPa and 744 mJ could be obtained from the UHPC mixture containing the LCD glass powder and triangular steel fibers.