تاثیر فشارهای ارگانیک بر هیدراتاسیون و سخت شدن سیمان پرتلند Influence of Organic Esters on Portland Cement Hydration and Hardening

1. Introduction In recent decades, the new progress in the preparation and application of cement concrete materials has benefited from the development and effective application of chemical admixtures. At present, the chemical admixture has become a cement-based material, which is an important regulatory component or modification method. Addition of a small amount of admixture, especially organic admixture, can effectively adjust the performance of cement-based materials, such as improving work performance or rheology, speeding up or delaying the hydration rate and coagulation time, and improving the physical and mechanical properties and durability of materials [1–5]. 0e performance of the admixture has an important relationship with the functional groups in its molecule. At present, the functional groups or functional groups contained in the organic admixtures used in the concrete materials mainly include hydroxyl groups, carboxyl groups, amino groups, and sulfonic acid groups [6–9]. In addition, it should be noted that the ester groups and phosphonate groups are also important functional groups. On the one hand, the ester-based organics can be used as antifoaming agents. On the other hand, many studies have reported that the esterification modification method is an important means for improving or modifying the performance of hydroxyl- or carboxyl-containing admixtures [1, 10]. In view of the low grinding ability of triethanolamine in cement fine-grinding stage and the disadvantage on the late strength growth of cement, it is studied that the triethanolamine modified by carboxylic acid has a better effect on the grinding and dispersing, and the strength of cement at early and late stage has a significant growth [1, 11, 12]. 0e molecular structure and dosages of the admixtures play an important role in the hydration of cement, such as shorting the hydration time, reducing the hydration heat, and improving the mechanical strength [13–16]. However, it is not clear at present that the increase in the performance of the admixture is caused by changes in the molecular structure or by the action of the newly introduced ester functional groups after modification. Also, there is no research at this point. In order to explore whether the ester groups have an important effect on the hydration and hardening of cement, five common organic compounds, ethyl acetate, dimethyl oxalate, glyceryl triacetate, trimethyl phosphate, and triethanolamine borate, were selected for comparative experiments in this study. 0e effects of five kinds of organic compounds on hydration heat, hydration degree, setting time, mechanical properties, microstructure, and pore structure of hardened slurry were studied in this study.