Jiang Lili, Li Zhuhui, Li Zhenguo, Wang Dongye
College of Civil Engineering and Architecture, Xiamen City University, Xiamen 361008, China.
College of Civil Engineering and Architecture, Harbin University of Science and Technology, Harbin 150080, China.
Materials (Basel). 2024 Sep 17;17(18):4567. doi: 10.3390/ma17184567.
Magnesium sulphoaluminate (MSA) cement has good bonding properties and is suitable as an inorganic adhesive for repairing materials in civil engineering. However, there are still some problems with its use, such as its insufficient 1 day (d) strength and poor volumetric stability. This paper aims to investigate the influences of metakaolin (MK) on the physical and mechanical properties of magnesium sulphoaluminate (MSA) cement. The hydration products and microstructures of typical MSA cement samples were also analysed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The results showed that the addition of metakaolin reduces the fluidity and shortens the setting time of the MSA cement. The initial setting time and final setting time shortened maximally by 15-27 min and 25-48 min, respectively, with the addition of 10-30% metakaolin. Moreover, the compressive strength and flexural strength of the MSA cement improved significantly with the addition of 10-30% metakaolin at a curing age of 1 d. Compared with the compressive and flexural strengths of the control sample at 1 d, the compressive strengths of the modified samples showed obvious increases of 98%, 101%, and 109%, and the flexural strengths increased by 39%, 31%, and 26%, respectively, although they decreased slightly when the curing ages were 7 d, 14 d, and 28 d. The addition of 10% metakaolin improved the water resistance of the MSA cement immersed in water for 7 d and resulted in even higher water resistance at 28 d. The addition of 10-30% metakaolin improved the volumetric stability of the MSA cement with increasing dosages before 28 d of ageing. XRD and SEM-EDS analyses showed that the metakaolin accelerated the early hydration reaction and optimised the phase composition of the MSA cement. The results indicate that the addition of 10-20% metakaolin improved the strength after 1 d of ageing, water resistance, and volumetric stability of the MSA cement, providing theoretical support for the application of MAS cement as an inorganic bonding agent for repairing materials.
硫铝酸镁（MSA）水泥具有良好的粘结性能，适合作为土木工程中修复材料的无机粘结剂。然而，其使用仍存在一些问题，如1天（d）强度不足和体积稳定性差。本文旨在研究偏高岭土（MK）对硫铝酸镁（MSA）水泥物理力学性能的影响。还使用X射线衍射（XRD）、扫描电子显微镜（SEM）和能量色散X射线光谱（EDS）分析了典型MSA水泥样品的水化产物和微观结构。结果表明，偏高岭土的加入降低了MSA水泥的流动性并缩短了凝结时间。加入10%-30%的偏高岭土时，初凝时间和终凝时间分别最大缩短了15-27分钟和25-48分钟。此外，在养护龄期为1天时，加入10%-30%的偏高岭土可显著提高MSA水泥的抗压强度和抗折强度。与1天时对照样品的抗压强度和抗折强度相比，改性样品的抗压强度明显提高了98%、101%和109%，抗折强度分别提高了39%、31%和26%，不过在7天、14天和28天养护龄期时略有下降。加入10%的偏高岭土可提高MSA水泥在水中浸泡7天的耐水性，并在28天时具有更高的耐水性。在28天龄期前，加入10%-30%的偏高岭土可随着用量增加提高MSA水泥的体积稳定性。XRD和SEM-EDS分析表明，偏高岭土加速了早期水化反应并优化了MSA水泥的相组成。结果表明，加入10%-20%的偏高岭土可提高MSA水泥在1天龄期后的强度、耐水性和体积稳定性，为MAS水泥作为修复材料的无机粘结剂的应用提供了理论支持。
