Effects of triisopropanol amine, sodium chloride and limestone on the compressive strength and hydration of Portland cement

The effect of triisopropanol amine (TIPA), sodium chloride (NaCl) and limestone (LS) on compressive strength and hydration of Portland cement were studied using Design of Experiment (DoE) and isothermal calorimetry, respectively. The results showed that combination of TIPA and NaCl could increase both early age and later age compressive strength of Portland cement mortars and Portland cement-limestone mortars. No major interactive effects on strength enhancement were observed for these three additives. However, the results of isothermal calorimetry showed clear interaction between TIPA and NaCl. It was found that NaCl increased the effectiveness of TIPA through promotion of two transitions: (i) conversion of AFt to AFm for Portland cement sample, (ii) conversion of carboalumiante phases for Portland-limestone cement sample.