Comprehensive investigation of recycled waste glass in concrete using silane treatment for performance improvement

An in-depth investigation of the incorporation of silane-treated and untreated glass waste in concrete is presented in this research. Coarse and fine aggregates were replaced with glass waste in 30 wt.-% and 50 wt.-% ratios, while glass powder was employed as an additive to concrete with 2 wt.-% and 5 wt.-% ratios. Physical, mechanical, microstructural and surface chemical properties of the produced concrete samples were studied by conducting water absorption test, compressive and splitting tensile strength tests, Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) analyses, respectively. The results showed that the combined influence of glass waste and silane coupling agent enhanced the impermeability of concrete by 87% when replacing sand with 50 wt.-% glass. In addition, all modified mixtures showed a reduction in their 28 days’ compressive strength compared to the control, except mixtures where untreated glass powder was used as an additive, which led to an increase in their compressive strength by 1%. Moreover, replacing sand with 50 wt.-% glass enhanced the splitting tensile strength of concrete by 25%. Microstructural analysis revealed a delaminated interface between glass and cement paste when using silane-treated coarse glass and the formation of Ettringite at later ages.