On the generation of heat during the mixing of cement pastes

A substantial amount of heat is generated during high-speed shear mixing of low water/cement ratio pastes (w/c = 0.24). It was found that the major source of this heat is mechanical friction. Under constant temperature conditions, no evidence was found to suggest that the degree of hydration is greater after high-speed shear mixing than after typical low-speed paddle mixing for the same period of time. Whether or not the temperature is controlled, shear mixing reduces the apparent viscosity of pastes having a low water/cement ratio, as compared with pastes from paddle mixing.