An investigation into the hydration and microstructure of cement pastes modified with glass powders

This paper examines the hydration and microstructure evaluation of cement pastes modified with two types of glass powders with a fine size distribution and a class F fly ash. Hydration was investigated by measuring the heat of hydration, chemical shrinkage and setting time at early age and non-evaporable water content at late ages. Pozzolanic behavior was studied using thermogravimetric analysis and X-ray diffraction. The microstructure was evaluated by the electrical resistivity measurement and image analysis. Based on the findings of this study for the glass powders and fly ash used, glass powders were shown to enhance the early hydration of cement and fly ash demonstrated a small delaying effect. Glass powders were found to possess pozzolanic behavior and to improve the hydration of cement paste at later ages. Microstructure evaluation indicated pore refinement in the microstructure of cement pastes modified with glass powders. It was concluded that glass powders with a microscale size distribution can be used as a pozzolan in cement-based materials.