Use of recycled glass as a raw material in the manufacture of Portland cement

Scrap glass is a solid waste from daily recycling. Most of the waste glass is sodium-lime-silicate glass which has, more or less, similar chemical compositions to clay, a raw material in cement manufacturing. Therefore, we utilize the solid waste in cement raw mix by replacing part of the clayey component. In this study, the effects of the glass in cement raw mix on clinker burning were investigated. The experimental results show that the addition of the glass into cement raw mix (1) results in the formation of more liquid phase between 950°C to 1250°C compared with conventional raw meals; (2) decreases C3S content in the clinker; and (3) increases NC8A3 content, which leads to flash setting and poor strength development of the cement. Therefore, it is necessary to increase the SG value [SG=SO3•100%/(1.292 K2O+0.85 Na2O)] of the clinker when the glass is present in the raw mix.