Influence of the Types of Cement on the Dispersing Action of Polycarboxylate-based Superplasticizer

摘要

The effect of the characteristics of cement on the dispersing action of polycarboxylate-based superplasticizer, which is widely used in high performance concrete, was investigated by using four different types of cement. The flow test study indicated that the flow value of paste varied depending on the type of cement. At the same dosage of superplasticizer, the paste made with low heat Portland cement containing the lowest aluminate phase (C_3A) showed the highest flow. Moreover, the correlation of the compound composition of cement and the flow value of the paste, indicated that both the flow value of the paste and the minimum amount of superplasticizer required for fluidizing paste increased in proportion to the amount of C_3A in cement. These results suggest that C_3A in cement may play a dominant role in the compatibility between cement and polycarboxylate-based superplasticizer, and thus the polycarboxylate copolymer adsorbed on C_3A may not significantly contribute to its dispersing action.