Reactivity of cement mixtures containing waste glass using thermal analysis

A laboratory study was undertaken to compare the performance of waste glass as a supplementary cementitious material (SCM) to traditional SCMs at the same particle size and level of replacement in both high and low alkali cement paste. The consumption of Ca(OH)2 as measured by differential thermal analysis (DTA) is used as an indicator of reactivity. The DTA results of the pastes aged to 150 days are presented, and indicate that glass reactivity is similar to ground-granulated blast furnace slag (GGBFS) and lower than silica fume (SF) at comparable particle sizes. Alkali–silica reaction (ASR) is not present for particle sizes below 100 μm, but is induced by agglomeration of the glass particles and is observed by fluorescence in optical microscopy images. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) are used to compare the microstructural properties of the SCMs and measure the chemical composition of the reaction products. The alkalinity of the cement was found to influence the nature of composition as observed by thermal analysis, and the temperatures at which their reactions occurred.