Hydration characteristics of cementitious materials with manufactured sand from various lithologies and differential effect of CaO-MgO blend expansion agent

Manufactured sand (MS) is increasingly used in massive concrete structures, but research on hydration of cementitious materials containing MS from diverse lithologies remains limited. In this paper, the hydration process of cementitious materials incorporating diverse lithologic MS powder and particles is examined, and the coupled effect of sand particles and stone powder as well as the differential effect of CaO-MgO blind expansion agent (CMEA) on diverse lithologic MS mortar hydration is analyzed. Results show that limestone and tuff stone powders similarly promote cement paste hydration, whereas only tuff MS significantly promotes mortar hydration. Compared to limestone MS, tuff MS has a greater effect on the initial Transverse relaxation time ( T 2 ) distribution of cement paste and mortar. However, the main peak position remains unaffected by stone powder or sand particles once hydration stabilized. Natural sand (NS) particles also influence cement hydration, and the coupled effect of tuff MS particles and stone powder on hydration is the most significant. This influence is most evident in early -age hydration, gradually attenuating with reaction progression. Furthermore, low -field nuclear magnetic resonance investigations suggest CMEA reaction mechanisms in tuff MS mortar may diverge from those in NS mortar and limestone MS mortar systems.