In recent years, with the rapid development of the World economy, the annual cement production has also increased rapidly. As a high energy consumption industry, cement is an arduous task in energy conservation and emission reduction. In the cement grinding process, the addition of grinding aids can effectively improve the grinding efficiency, reduce energy consumption and production costs. Therefore, the study of cement grinding aids is of great significance for environmental protection and socio-economic development.
Triisopropanolamine (TIPA) is one of the commonly used components of cement grinding aids. At present, TIPA has studied the strength and hydration properties of Portland cement and Portland cement containing fine limestone particles. However, TIPA's research on the hydration mechanism of limestone portland cement and its effect on the micro structure of Portland cement and limestone portland cement hardened paste is not comprehensive enough. Therefore, this paper focuses on the experimental research on the strength, hydration process and micro structure of hardened slurry of Portland cement and limestone Portland cement.
The main conclusions are as follows.
The effect of TIPA on the strength of Portland cement and limestone Portland cement was investigated by TIPA. It was found that the strength of TIPA was not significantly enhanced at the early stage of the cement, but TIPA gradually showed its reinforcing effect with the age increasing. The effect of TIPA on the post-strength of limestone Portland cement is more pronounced than that of Portland cement. When TIPA is used together with NaCl, both the early and late strength of the cement can be enhanced. By analyzing the results of cement hydration calorimetry and X-ray diffraction experiments, TIPA can promote the hydration of C4AF to produce AFt in cement. However, TIPA has no significant effect on the hydration of C3S in cement. In limestone portland cement, TIPA promotes the formation of AFt until the gypsum is depleted, and CaCO3 reacts with the calcium aluminate hydrate to produce calcium aluminate, while inhibiting the conversion of AFt to AFm. The pore structure analysis of the hardened paste using the mercury intrusion test shows that TIPA has the effect of bleed air, which increases the porosity in the hardened paste, especially the number of macropores. However, the dispersive effect of TIPA reduces the pores of the hydration gel and has a dense structure. The effect of TIPA, NaCl, and limestone powder on the strength of Portland cement was studied using the Center Composite Design (CCD) method. The regression equations and the regression equations between the three factors and cement strength at each age were obtained good mixing ratio.