Hydration of Portland cement in the presence of triethanolamine and limestone powder: Mechanical properties and synergistic mechanism

Abstract

The study systematically examined the hydration and strength development patterns within ordinary Portland cement (OPC) when triethanolamine (TEA) and limestone (LS) powder were introduced, with a particular emphasis on unraveling their synergistic effects. The findings reveal that 0.02 % TEA addition has a beneficial impact on the early strength of OPC while diminishing later strength. However, the co-incorporation of LS powder effectively eliminates the detrimental effect of TEA on later strength while maintaining the growth of strength. In addition, the concurrent addition of TEA and LS powder reduces the overall cement porosity as well as modulates the pore size distribution, increasing the proportion of non-harmful pores. Through monitoring the hydration process of the OPC, a notably positive synergistic effect between TEA and LS powder is revealed. Firstly, the complexation of TEA indirectly enhances the dilution impact of LS powder, leading to a substantial enhancement in early cement hydration. Secondly, the nucleation effect of LS powder effectively counteracts the inhibitory influence of TEA on C3S, thus eliminating the associated drawbacks. Most significantly, the synergistic effect between TEA and the chemical effect of LS powder accelerates the hydration of C3A and C4AF while preserving ettringite, ultimately resulting in reduced porosity of the samples.