Effect of N, N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid sodium salt and triethanolamine on the hydration and compressive strength of steel slag-cement composite systems: A comparative study

To solve the problem of low cementitious activity of steel slag (SS), N, N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid sodium salt (BES-Na) and triethanolamine (TEA) were used in this study to improve the hydration activity of SS. However, there are no comparative studies on the effects of BES-Na and TEA on the hydration of SS-Portland cement (PC) systems. This study compared the hydration process and strength development of SS-PC systems in the presence of BES-Na and TEA, as well as the complexing ability of BES-Na and TEA. The results showed that both BES-Na and TEA improved the early compressive strength of SS-PC mortar, but TEA did not contribute to the late compressive strength, while BES-Na still improved the late compressive strength. At the same dosage, TEA accelerated aluminates hydration more than BES-Na and retarded/inhibited silicates hydration more than BES-Na. This difference in effect on hydration can be attributed to the difference in their complexing ability. TEA has a stronger complexing ability with metal ions than BES-Na, which is beneficial for accelerating aluminates hydration, but this not only prolonged the hydration induction period but also inhibited silicates hydration. BES-Na has a weaker complexing ability relative to TEA. Although BES-Na has a weaker accelerating effect on aluminates hydration, it has a lesser effect on silicates hydration and even accelerates silicates hydration at low dosage. This study also showed that BES-Na is an alternative additive to TEA, which could help expand the application of BES-Na in cementitious materials.