Microcracking and fracture behavior of cement grout under tensile loading

Cement grout is a fundamental material used in diverse engineering applications, such as mining, civil engineering, geothermal energy, and oil and gas industries, due to its role in stabilizing rock masses and sealing wellbores. Despite its widespread usage, grout's susceptibility to cracking, particularly under tensile stress, remains a major concern, compromising structural integrity and long-term performance. This study investigates the micro-cracking behavior of cement grout under tensile loading to gain a deeper understanding of the mechanisms governing fracture initiation and propagation. By employing acoustic emission monitoring and analyzing fracture surface characteristics, this research reveals the complex interplay between microcracking mechanisms and macro-fracture morphology. The results reveal significant differences in fracture behavior between the two loading regimes. Brazilian tests exhibited higher tensile strength due to the dominance of non-tensile microcracking mechanisms, such as compaction and shear, which enhance strength and dissipate more energy. These specimens showed smoother, less tortuous fracture surfaces, corresponding to lower with tensile strengths. In contrast, direct tensile tests, governed by tensile microcracks, produced lower strength and rougher, more tortuous fractures, highlighting the distinct influence of microcracking mechanisms on fracture morphology. Correlation analyses indicated consistent roughness characteristics across different fracture orientations and underscored the link between smoother surfaces and non-tensile microcracks. This study offers new insights into the interplay between microcracking mechanisms, fracture surface roughness, and tensile strength, emphasizing the impact of loading conditions on the fracture behavior of grout. The findings provide a deeper understanding of grout fracture processes, contributing to enhanced design and performance of grout-based structures in engineering applications. Future research could further explore the role of material microstructure on fracture development, aiming to improve the durability and reliability of cement grout in critical infrastructure.