Influence of naphthalene sulphonated and polycarboxylate acid-based superplasticizer on the mechanical properties and hydration behavior of ternary binder: A comparative study

Abstract

The effect of two superplasticizers, naphthalene sulphonatedsuperplasticizer (BNS) and polycarboxylate acid-based (PCS), on the setting time, fluidity and compressive strength of ordinary Portland cement - calcium aluminate cement - gypsum (OPC-CAC-CSH) ternary binder and C3A-C3S-CSH system was studied. In order to explore the influence of BNS and PCS on the ternary binder, the hydration products and microstructure were analyzed by XRD, TG and SEM. Results show that the effect of BNS on the fluidity of OPC-CAC-CSH was better than PCS. BNS prolonged the setting time of OPC-CAC-CSH, but PCS had little effect on it. The compressive strength of OPC-CAC-CSH was slightly promoted with the increase of BNS content, while that was gradually reduced with the increase of PCS content. Moreover, the morphology and size of ettringite crystals were changed after adding PCS.