Hydration of Portland Cement Pastes Containing Untreated and Treated Hemp Powders

In this study, the residual of hemp products as biomass wastes has been ground into powders to be used in cement-based materials. The effect of untreated and alkaline-treated hemp powders on the hydration of portland cement paste was studied by isothermal calorimetry analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy analysis, and scanning electron microscopy analysis. The results show that partially replacing cement with untreated and alkaline-treated hemp powders can delay cement hydration and reduce the degree of hydration. Compared with untreated hemp powders, alkaline-treated (washed or nonwashed) hemp powders show a lower set delay effect on cement hydration; moreover, distilled-water-washed treated hemp powders delay less than nonwashed treated hemp powders. The study also shows that coarse hemp powders exert a lower set delay effect on cement hydration than fine hemp powders. Generally, the distilled-water-washed treated coarse hemp powders exert the minimum delay effect on cement hydration.