1.YSNSHAN University;2.Hebei Province Engineering Research Center for Harmless Synergistic Treatment and Recycling of Municipal Solid Waste, Yanshan University;3.Tianjin Transportation Technical College;4.Hebei Green High-Performance Building Material Application Technology Collaborative Innovation Center, Hebei Construction Materials Vocational and Technical College;5.School of Architectural Engineering and Mechanics, Yanshan University
针对传统灌浆料收缩变形大、早期强度低的问题，采用硫铝酸盐水泥-硅酸盐水泥-石膏三元复合体系制备了低收缩早强型灌浆料，探究了其结构形成的微观机理。根据最优配合比制备的灌浆料1 d、3 d抗压强度可分别达到60.1 MPa、75.5 MPa，3 d自缩率为351.39×10-6，28 d干缩率低至239.75×10-6，均高于国家标准要求。微观测试结果表明，灌浆料水化产物中的钙矾石(AFt)相互交错搭接构成致密的晶体骨架，使其具有较高的早期强度，而C-S-H凝胶则促进了后期强度发展。AFt表现出的微膨胀作用使其收缩变形逐渐变小，进一步保障了灌浆料的早强与低收缩特性。
To address the issues of large shrinkage deformation and low early-age strength of traditional grouting materials, this study prepared a grouting material using ternary composite system (sulphoaluminate cement, Portland cement and gypsum), which featured low shrinkage and high early-age strength. Moreover, the formation mechanism of the microstructure of the obtained grouting material was explored. Results showed that the grouting material prepared according to the optimal mix proportion can exhibit the 1-day and 3-day compressive strengths of 60.1 MPa and 75.5 MPa and 3-day autogenous shrinkage and 28-day drying shrinkage of 351.39×10-6 and 239.75×10-6, respectively, all of which were higher than the national standard requirements. The results of microscopic testing suggested that the ettringite (AFt) in the hydration products of the grouting material overlapped to form a compacted crystal skeleton, resulting in the high early-age strength of the grouting material. At the same time, C-S-H gel in the hydration products promoted the later-age strength development of the grouting material. Furthermore, the micro-expansion effect of AFt gradually reduced the shrinkage deformation of the grouting material, ensuring its high early-age strength and low shrinkage characteristics.