Effects of sucrose and sorbitol on cement hydration applications to cement stabilization of metal waste

Abstract

Cement-based stabilization/solidification (S/S) is a widely used technique to treat industrial wastes containing toxic metal ions before land disposal. To prevent the fast setting of the treated waste during its transportation from the treatment plant to the disposal site, small amounts of sucrose or sorbitol can be added to slow down the speed of cement setting, thus adding flexibility to the handling of the treated waste. However, sucrose and sorbitol may also affect the leachability of the metal ions present in the treated waste because of their ability to alter the microstructure of hydrated cement pastes. In the first stage of this research, various types of cements (pure tricalcium silicate [C3S], white Portland cement [WPC] and ordinary Portland cement [OPC]), which represent systems of increasing compositional complexity, were investigated to better understand the contribution of individual cement components to the properties of hydrated pastes. The degree of hydration was measured as a function of curing time by SEM grey level analysis and loss-on-ignition testing. The hydration rate was found to decrease as C3S > WPC > OPC, correlating with the relative content of C3S and tricalcium aluminate (C3A).