Reusing waste glass fines to substitute cement and sand for recycled ultra-high performance strain-hardening cementitious composites (UHP-SHCC)

Using waste glass fines (WGF) as cement and silica sand replacement for recycled ultra-high performance strain-hardening cementitious composites (UHP-SHCC) provides an effective method for the high-value utilization of waste glass while reducing its carbon emissions and preparation cost. This study investigated the feasibility of preparing recycled UHP-SHCC by simultaneously substituting both cement and silica sand with WGF. WGF, abundant in amorphous components, exhibited favorable pozzolanic activity and filling effect. Substituting high-volume cement with WGF negatively impacted the hydration reaction and micro-properties of UHP-SHCC matrix, while replacing silica sand with WGF improved hydration reaction and micro-structure. Generally, substituting WGF for both silica sand and cement decreased the maximum cumulative hydration heat of UHP-SHCC. The drying shrinkage resistance of UHP-SHCC is improved with WGF replacing an appropriate dosage of cement and silica sand. The compressive and flexural strengths of UHP-SHCC declined as the high-volume replacement of cement with WGF, but improved with an increase in the proportion of silica sand substituted. Simultaneously substituting cement and silica sand with WGF can yield recycled UHP-SHCC with mechanical strengths comparable to those of reference UHP-SHCC. The ductility of UHP-SHCC exhibits a trend of first increasing and then decreasing as the proportion of cement substituted by WGF increases, while it decreases with the addition of WGF as silica sand replacement. Simultaneously substituting both cement and silica sand with WGF can obtain more sustainable UHP-SHCC with high strength and ductility. The tensile strength and tensile strain capacity of recycled UHP-SHCC containing WGF substituting 100 % silica sand and 75 % cement are 10.3 MPa and 7.2 %, respectively.