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<p>The use of Hydration Controlling Admixtures (HCA) represents a promising strategy for extending the workable time of cementitious mixtures. Nevertheless, the lack of understanding regarding the interactions between different HCAs and the diverse chemical and mineralogical compositions of cements has hindered broader adoption of these products in real-world applications. For this reason, this work aimed to evaluate the impacts of using different kinds and dosages of HCA, based on sodium gluconate and sucrose, on the hydration reactions of six types of Portland cement. The water-to-cement ratio was kept constant at 0.4, and hydration was monitored using isothermal conduction calorimetry for up to 7 days at a consistent temperature of 23&#xa0;°C. The key findings indicate that the admixtures act primarily on the clinker particles. In the case of CP V ARI, which contains a higher proportion of clinker, increasing the gluconate content had a limited effect on extending the induction period (related to workability) and on the intensity of the acceleration peak, although it notably reduced the reaction rate. Conversely, increasing the sucrose concentration markedly prolonged the induction period and significantly reduced the heat release at the end of the acceleration stage, while exerting minimal influence on the overall reaction rate. For the other cements, the effects of the admixtures varied, with no consistent trend observed. Furthermore, particularly during the deceleration stage, the overlapping of characteristic peaks related to clinker hydration and supplementary cementitious materials suggests complex interactions between cement phases and the chemical admixtures. Different dosages of HCA were required for each type of cement to achieve a standardized induction period of 36 h. So, the type and content of HCA, as well as the type of cement, influenced the hydration reactions. Therefore, the study proves that when there is any change in the composition, whether due to the availability of cement on the market or the change of admixture, it is essential that the dosage study be reevaluated, highlighting their influence on construction practices.</p>

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Impacts of HCA based on sodium gluconate and sucrose on the hydration of Portland cements

  • 期刊论文

  • 发表日期：

    2025年12月20日

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  • Caio Quaresma Santos,
  • D. F. Ferraz,
  • M. A. Cincotto,
  • R. C. O. Romano,
  • R. G. Pileggi

摘要

The use of Hydration Controlling Admixtures (HCA) represents a promising strategy for extending the workable time of cementitious mixtures. Nevertheless, the lack of understanding regarding the interactions between different HCAs and the diverse chemical and mineralogical compositions of cements has hindered broader adoption of these products in real-world applications. For this reason, this work aimed to evaluate the impacts of using different kinds and dosages of HCA, based on sodium gluconate and sucrose, on the hydration reactions of six types of Portland cement. The water-to-cement ratio was kept constant at 0.4, and hydration was monitored using isothermal conduction calorimetry for up to 7 days at a consistent temperature of 23 °C. The key findings indicate that the admixtures act primarily on the clinker particles. In the case of CP V ARI, which contains a higher proportion of clinker, increasing the gluconate content had a limited effect on extending the induction period (related to workability) and on the intensity of the acceleration peak, although it notably reduced the reaction rate. Conversely, increasing the sucrose concentration markedly prolonged the induction period and significantly reduced the heat release at the end of the acceleration stage, while exerting minimal influence on the overall reaction rate. For the other cements, the effects of the admixtures varied, with no consistent trend observed. Furthermore, particularly during the deceleration stage, the overlapping of characteristic peaks related to clinker hydration and supplementary cementitious materials suggests complex interactions between cement phases and the chemical admixtures. Different dosages of HCA were required for each type of cement to achieve a standardized induction period of 36 h. So, the type and content of HCA, as well as the type of cement, influenced the hydration reactions. Therefore, the study proves that when there is any change in the composition, whether due to the availability of cement on the market or the change of admixture, it is essential that the dosage study be reevaluated, highlighting their influence on construction practices.