Study of the effect of calcium nitrate, calcium formate, triethanolamine, and triisopropanolamine on compressive strength of Portland-pozzolana cement

This study aims to assess the effect of using some chemical admixtures including Calcium nitrate tetrahydrate (CN) and Calcium formate (CF), Triethanolamine (TEA), and Triisopropanolamine (TIPA) on the early-age compressive strength of Portland cement mortar containing natural pozzolan (Portland-pozzolana cement: PPC). To this end, CN and CF were added to the PPC mortar during its preparation step. Afterward, TEA and TIPA as an aqueous solution were added to the mixture of clinker and natural pozzolan during grinding; finally, the physical and chemical properties of produced cement mixtures were investigated by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR), respectively. The results showed that the effect of TEA and CF was far better than TIPA and CN, so that, adding 0.01 wt% of TEA to PPC was led to a 62% increase in the 1-day compressive strength of this sample. Moreover, the compressive strength of samples indicated, on average, an increase of 54% and 39% on days 2 and 3, as well as 7-to-56 respectively, compared to cement (as the control group). While adding 1 wt% of CF to PPC was led to a 41%, 23%, and 22% increase in its compressive strength on days 1, 2, and 3, as well as 7-to-56, respectively, than the control group.