The Influence Of Polycarboxylate Superplasticizer On Aluminate Cement

Polycarboxylate superplasticizer (PCS) had been increasingly widespread attention because of their higher water reducing rate, lower slump loss, higher strength, better cement compatibility, safety and environmental protection. Aluminate cement was a special kind of cement which main component included Al2O3 and CaO. Aluminate cement had been widely uesd in refractory, building chemistry, wastewater and technical concrete, due to the advantage of early strength, rapid hardening, high strength, resistant high temperature, resistant corrosion of sulfate and biological acid. The influence of PCS on aluminate cement, Water reduction rate of mortar and flowability of paste of aluminate cement were studied using the commercially available ployglycolmethacrylic acid ester PCS in this paper. Results shows the PCS is a kind of hige performance water reducing agent, water reduction rate of mortar could reaching above 30%, and PCS can raise the flowability of paste of aluminate cement in appropriate dosage. According to the results of water reduction rate of mortar and flowability of paste of aluminate cement, appropiate dosage of PCS is determined as 0.1%~0.4% based on cement mass.The ultrasonic, exothermic profile and conductivity test were used to study the infiuence of PCS on the cement hydration process. Results show that PCS has an obvious retarding activity on the hydration process of aluninate cement. The main reason is the retardation of nucleation of aluminate cement mineral according to the results of conductivity test.Working ability of aluminate cement was studied through test on setting time, shrinkage, flow and flow losses. It exhibited that PCS can significantly retard the setting time. At proper PCS dosage is 0.2%; flow was increased 97.9%, and the flow losses were reduced, it still had more than 60% of the initial flow after 120min.The influence of PCS on aluminate cement mortar strength at 20℃and strength after crystal transformation at 38℃were also investigated. It exhibited that PCS can increase air content in mortar, and the air entrained increase along with PCS dosage, and air content in mortar can decrease the cement mortar strength. PCS can retard early strength development of aluminate cement mortar. The speed of strength developed slowly along with PCS dosage. Water reduction effect of PCS being excellent, appropiate dosage of PCS can significantly reduce mixing watercontent of aluminate cement mortar, and it also increase the strength of aluminate cement mortar, and strength of after crystal transformation in high temperature higher than the reference mortar.