Portland cements ground with surfactants

The rational use of surfactants based on their effect on the grinding process should also take into consideration the subsidiary effects of surfactants on the handling (flow characteristics) and curing processes (hardening) of the obtained cements. The hardening behaviour of admixed cements on grinding has therefore been investigated with regard to chemical behaviour, that is, the evolution of the hydration process, and structural—mechanical behaviour, that is, the consequent structural evolution of mechanical strength of the hardening cement. Two kinds of cement were used in this investigation; ordinary Portland cement (D) and ferro-Portland cement (M). The surfactants used were dihydroxy compounds (dialcohols and dihydroxy ethers) and aminoalcohols. Information on the fundamental processes that take place on hardening of cements with additives is obtained, in particular their interaction with water and development during hardening, including their mechanical strengths. It was ascertained that the presence of grinding additives influences the kinetics of hydration processes, with delaying effects in the early stages and acceleration of the kinetics subsequently, correlated with the nature of the surfactant. The effects of grinding additives on the microstructure of hardened cements differ according to their nature; among the surfactants used, aminoalcohols and diethylene glycol affect the porosity of hardened cement. Our studies prove that the mechanical strength of hardened cements is a relatively complex result of the effects of grinding additives on both hydration processes and structural development as well as on the proportion of mixing water, and is correlated with the nature of the cement and surfactant.