Effect of microwave curing on the hydration properties of cement-based material containing glass powder

- Microwave curing accelerates the cement hydration by Na dissolved from glass powder.
- Microwave curing increases the porosity slightly at early age by the increase of pores smaller than 50 nm.
- Microwave curing increases the compactness of interfacial transition zone.
- Microwave curing increases the adsorption of Na by alkali-silica reaction gel.

The effects of microwave curing on the hydration of cement-based materials containing coarse glass powder were studied by performing compressive strength, XRD, TG-DSC, SEM-EDS and MIP analysis. The results showed that microwave curing could effectively improve the early-age compressive strength of mortar prepared with composite binder containing coarse glass powder. Microwave curing accelerated the hydration of cement particles by dissolution of Na+ from glass powder and thermal effect. Although microwave curing increased the porosity slightly at the early age, the porosity of pores larger than 50 nm did not increase, which has little effect on the decrease of compressive strength. Additionally, microwave curing increased the connection of aggregate, CH, hydrated glass powder and cement particles by reticular C-S-H, leading to a denser microstructure of the interfacial transition zone of mortar. The adsorption of Na+ by alkali-silica reaction gel under microwave curing reduced the adverse effect of Na+ on the late hydration of cement and the compressive strength. But the total porosity of mortar under microwave curing was increased by the increase of pores in the range of 50-100 nm, which goes against the improvement of compressive strength.