Influence of the structures of polycarboxylate superplasticizer on its performance in cement-based materials-A review

Polycarboxylate (PC) superplasticizers are being widely used in concrete mixtures due to their high water reduction rate and good slump retention at low dosage. The chemical structure of PC, including their anchoring group, main chain, side chain, molecular weight and molecular architecture, has a great impact on the performance of cement-based materials. This paper reviews the relationship between chemical structure of PCs and their performance in cement-based materials. Generally, adsorption capacity of PCs with maleic anhydride, phosphate and silanol group is higher than that of –COO− group, and is less affected when sulfate ions (SO42−) exist. Their initial dispersibility increases with the anchoring group content. PCs with long main chain, long side chains or large molecular weight exhibit higher flowability slump retention of cement pastes. The retardation effect of PC on cement hydration increases with the main chain length. Moreover, hyperbranched and star-shaped PCs show significantly better dispersion ability then conventional ones.