The Effect of Shrinkage-Reducing Polycarboxylate Superplasticizers in Cement-Based Materials

摘要

Shrinkage-reducing polycarboxylate superplasticizer (SRPC) has a good effect on reducing shrinkage of cement-based materials because of its low surface tension. However, the effect of SRPC on the properties of cement-based materials needs to be further explored. A comparative study of SRPC and polycarboxylate superplasticizer (PCE) was carried out with the aim of correlating the adsorption in fresh cement pastes with their dispersing capability and the impacts on cement hydration. The results indicate that the adsorption amounts of SRPC are less than PCE. Both of them exhibit a multilayer adsorption; the fluidity of cement pastes with SRPC and PCE are related to the first adsorbed layer, and the secondary adsorbed layer does not contribute to the enhancement of fluidity. The retarding cement hydration of SRPC is weaker than PCE because of weak adsorption capacity of SRPC.