Discussion on the Performance and the Reduction of Shrinkage Induced by Polycarboxylate Superplasticizer

Abstract

The shrinkage-reducing type polycarboxylate superplasticizer (SRPCA) has become a hot research issue both at home and abroad for its perfect water-reducing ability, outstanding shrinkage-reducing and slump retaining ability. The effect of ordinary polycarboxylate superplasticizer (PCA) and shrinkage-reducing PCA on the drying shrinkage of cement mortar was studied thoroughly in this paper. The result showed that the SRPCA can effectively reduce the drying shrinkage of cement mortar. Moreover, the shrinkage-reducing mechanism was discussed from the aspect of molecular structure to the solution surface tension and also mortar water retention. It indicated that the solution surface tension had certain impact on the PCA shrinking-reducing ability, meanwhile the perfect water-retaining ability conduce to the shrinking-reducing improvement. esides, the introduction of shrinking-reducing functional groups to the ordinary PCE molecular structure can reduce the polymer solution surface tension, control the air content in the concrete and decrease the drying shrinkage of cement-based materials.