RESEARCH ON PROPERTIES AND THE HYDRATION OF PORTLAND LIMESTONE CEMENT WITH DIETHANOL-ISOPROPANOLAMINE

Diethanol-isopropanolamine (DEIPA) is a new type of alkanolamine used as grinding aids for Portland cement. In this study, the effect of DEIPA on properties of Portland limestone cement (PLC) were investigated by measuring strength of mortar, setting time, compatibility of cement and superplasticizers. A combination of isothermal calorimetry, scanning electron microscopy and mercury intrusion porosimetry was used to investigate the hydration kinetics. The results indicate that the addition of DEIPA markedly enhances the early and late strength of mortar, which gains a 4.4 MPa increment (28.7 %) at 3 d and a 6.3 MPa increment (20.3 %) at 28 d, respectively, and is not significant differences in the setting time. However, the compatibility of cement and superplasticizer becomes poor in the cement paste containing DEIPA. The working mechanism of DEIPA accelerates the hydration of aluminate and alite, and promotes the formation of AFt and monocarboaluminate, as well as the transformation of AFt to AFm. Besides, the addition of DEIPA results in uniformly overlaps hydration products and improves microstructure in hardened cement pastes.