Influence of novel shrinkage‐reducing polycarboxylate superplasticizer on the nature of calcium–silicate–hydrates

Abstract

AbstractCurrently, a novel shrinkage‐reducing polycarboxylate superplasticizer (SR‐PCA) is used to control cementitious shrinkage. To clarify its mechanism when applied in cementitious materials, the influence of SR‐PCA on the composition, morphology, and structure of synthetic calcium–silicate–hydrate (C–S–H), together with the interaction between SR‐PCA and C–S–H at the atomic level, is investigated. For comparison, a commercial polycarboxylate superplasticizer (PCA) is also employed. The results show PCA and SR‐PCA can adsorb on the C–S–H surface rather than intercalate into the layers. Compared with PCA, SR‐PCA has a milder impact on C–S–H crystallinity. SR‐PCA refines the pore structure of C–S–H drastically, whereas PCA loosens the structure by increasing the mesopore volume. In addition, the adsorption effect of SR‐PCA on the C–S–H surface is less significant than that of PCA. At the atomic level, this less adsorption of SR‐PCA is attributed to the lower adhesion energy of the C–S–H/SR‐PCA interface due to the weaker Ca–O bond strength.