Exploration of Waste Glass Powder as Partial Replacement of Cement in Concrete

This paper shows that combining the knowledge of relevant chemical compounds and chemical reactions associated with cement hydration together with the chemical compounds in glass can be used to establish the right use of waste glass powder as a partial cement replacement in concrete. The results show that Calcium Hydroxide (Ca(OH)2), which is a by-product of the hydration of Portland cement, reacts with Silicon Oxides (SiO2) in glass powder ensuring the formation of strength imparting compounds Calcium–Silicate-Hydrate (C-S-H), in addition to the C-S-H formed due to the hydration of regular calcium silicate compounds (C2S - Di-Calcium Silicate and C3S- Tri-Calcium Silicate) in cement. A method to establish the optimal cement replacement percentage based on the amount of total C-S-H formed in the mix is presented in the paper. For example, with C3S and C2S compositions of 54% and 20.7%, respectively, of the cement used in the present study and 70% silica in the glass, the optimal cement replacement percentage by glass powder is determined to be 19%.