Mechanism of triethanolamine on Portland cement hydration process and microstructure characteristics

Influence of triethanolamine (TEA) on Portland cement hydration heat evolution process, hydration product, pore structure, setting time and concrete strength were investigated; and mechanism of TEA on the cement hydration process and microstructure is discussed. Research results indicate that TEA accelerates hydration process of C3A and retards that of C3S, such effects enhance with the increase of TEA dosage. TEA also promotes rate of AFt formation and its conversion to AFm. As a result, TEA accelerates setting of cement paste but jeopardizes strength of concrete. Depending on its dosage, TEA can either optimize or harm cement paste pore structure. The types of calcium sulfoaluminate hydrate (AFt or AFm) produced in cement paste containing TEA depends on the abundance of calcium sulfate, before depletion of calcium sulfate, AFt is produced, after that, AFm is produced (converted from AFt).