Effect of the Cellulose Ether on Water Loss of the Calcium Sulphoaluminate Cement Mortars

Abstract

Cellulose ether (CE) is widely used in cement-based materials because of its good water retention capacity that can improve the workability of the fresh mortars significantly. However, in the high temperature conditions, the CE modified cement mortars sometimes are easy to lose their good workability, which may be due to the change of the water-retention capacity of CE. This work investigates the changes in the water loss rate (WLR) of the CE modified calcium sulphoaluminate cement (CSAC) mortars at 20 ℃, 40 ℃, 60 ℃ and 80 ℃ respectively, and the effect of the types and contents of the CE was also considered. Additionally, isothermal calorimeter and 1H low-field NMR were carried out to monitor the changes of chemically bound water and CE adsorbed water content during the reaction. The results show that the WLRs of the CE modified CSAC mortars changes with temperature and the types and contents of the CE. These changes are mainly based on the fact that CE affects the state and relative contents of water molecules in mortar, and the microstructure of the CSAC mortars.