Effects of waste liquid–crystal display glass powder and fiber geometry on the mechanical properties of ultra-high-performance concrete

Mechanically more performant ultra-high-performance concrete (UHPC) was developed by incorporating waste liquid–crystal display (LCD) glass powder and modifying steel fiber geometry. For this purpose, 50% of inert silica flour was replaced by LCD glass powder, and five steel fiber types with various cross-sectional shapes (circular or triangular) and twisting rates were considered. Results suggest that the glass powder was effective in enhancing the tensile and flexural performance of UHPC with straight steel fibers due to the increased frictional shear resistance at the fiber/matrix interface. However, its effectiveness was diminished when the fibers were twisted. Better tensile and flexural performances were reported for the circular fibers than that reported for triangular fibers due to the minor matrix damage and higher pullout energy. Such performance and cracking behavior of the latter could also be improved by twisting the fibers through the torsional action. The single twisting of triangular fiber improved the performance of UHPC, and no further improvement was observed by increasing the number of twisting. Synthetically, the circular fiber or singly twisted triangular fiber was considered as the most appropriate reinforcing type of UHPC.