Mechanical strength and microstructure of ultra-high-performance cementitious composite with glass powder substituted cement/silica fume

Ultra-high-performance cementitious composite (UHPCC) incurs higher economic costs and resource wastage due to its high cement/silica fume (SF) content. The paper aims to achieve sustainability and environmental friendliness of UHPCC by substituting cement/SF with glass powder (GP). The influence of various GP particle sizes and substitution levels on the mechanical properties of UHPCC was investigated. X-ray diffraction and scanning electron microscopy were employed to analyze the impact of GP on the hydration process of UHPCC from a microscopic perspective. In addition, the internal damage pattern of GP-UHPCC was simulated by the RFPA(3D) program. The results show that the addition of GP could achieve superior fluidity than GP-0. Compared to conventional UHPCC, GP-20 exhibits improved strength, initial flexural toughness, and residual flexural toughness. Furthermore, finer GP particle sizes contribute to enhanced matrix strength and flexural energy absorption capacity to some extent. Additionally, the incorporation of 5%-20% GP leads to an increase in the characteristic peaks of hydrated lime and C-S-H gel, which are beneficial to improving the internal microstructure of the matrix. Based on the RFPA(3D) program, the crack area, principal stress distribution, and acoustic emission energy of specimens with 15%-25% GP substitution levels were significantly higher than those of specimens with low substitution levels (0%-10%). Generally speaking, a GP substitution level of 15%-25% is found the most effective range for improving strength, and toughness behavior in this study.