Hernández-Carrillo Guillermo, Durán-Herrera Alejandro, Tagnit-Hamou Arezki
Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Ciudad Universitaria, Ave. Universitaria S/n, San Nicolás de los Garza 66455, NL, Mexico.
Faculté de Genié, Université de Sherbrooke, 2500 Boulevard de l'Université, Sherbrooke, QC J1K 2R1, Canada.
Materials (Basel). 2022 Nov 2;15(21):7711. doi: 10.3390/ma15217711.
Ultra-high-performance concrete (UHPC) is a material developed to maximize the engineering characteristics of hydraulic concrete, in terms of durability and mechanical properties, but the adoption of this technology in practice has not turned out as desired, mainly due to the high amounts of cement and silica fume required for its production, and for its consequences on both economic and ecological costs. As an option to improve the impact of UHPC, both on costs and on sustainability, this work evaluates four UHPC series with metakaolin additions of 5%, 10%, 15% and 20%, and the substitution of 37.5% of the Portland cement volume by limestone or quartz filler. The compressive strength, the bulk electrical resistivity and a set of tests for microstructural characterization (TGA, XRD and quantitative EDS) were utilized to better understand the role of calcite on the hydration and pozzolanic reactions in ternary Portland cement-metakaolin-limestone filler. Results indicate that the reaction of calcite is scarce and should be considered as a mere filler, as no increase in AFm phases were found. Nevertheless, the ternary mixture with 15% of metakaolin in addition to cement, and with 37.5% of the Portland cement volume substituted by limestone filler, was the one that presented the best performance in terms of compressive strength and bulk electrical resistivity. The results of the microstructural characterization indicate that the high kaolin content in the metakaolin originated the most significant hydration and pozzolanic reactions development between the ages of 7 and 28 days, as between 28 and 91 the reaction remained dormant. In general, the whole set of results included in this work indicate that limestone filler doesn't act as a better filler than other kind of powders when used in ternary Portland cement-metakaolin- filler systems.
超高性能混凝土（UHPC）是一种旨在最大限度提升水工混凝土工程特性（耐久性和力学性能方面）而研发的材料，但该技术在实际应用中的效果并未达到预期，主要原因在于其生产所需的大量水泥和硅灰，以及由此带来的经济和生态成本问题。作为改善UHPC对成本和可持续性影响的一种选择，本研究评估了四个超高性能混凝土系列，其中偏高岭土的添加量分别为5%、10%、15%和20%，并用石灰石或石英填料替代37.5%的波特兰水泥用量。利用抗压强度、体积电阻率以及一系列微观结构表征试验（热重分析、X射线衍射和定量能谱分析），以更好地理解方解石在三元波特兰水泥 - 偏高岭土 - 石灰石填料体系中水化和火山灰反应中的作用。结果表明，方解石的反应较少，应仅视为一种填料，因为未发现AFm相增加。然而，除水泥外含有15%偏高岭土且37.5%波特兰水泥用量被石灰石填料替代的三元混合物，在抗压强度和体积电阻率方面表现出最佳性能。微观结构表征结果表明，偏高岭土中高含量的高岭土在7至28天龄期引发了最显著的水化和火山灰反应，而在28至91天龄期反应处于休眠状态。总体而言，本研究纳入的所有结果表明，在三元波特兰水泥 - 偏高岭土 - 填料体系中使用时，石灰石填料并不比其他类型的粉末表现更好。
