Influence of fiber content and length on the mechanical behavior of the grout slurry mixtures used for earthen sites conservation: a study of coir fibers and basalt fibers

The grouting materials commonly used in earthen sites conservation have poor ductility. When applied in anchoring and crack sealing projects, it may lead to sudden failure of the reinforcement measures under significant deformation, thus threatening the safety of the sites. To improve the mechanical strength and ductility of existing cement-free grouting materials, Coir fibers and Basalt fibers with varying lengths and contents were added into the grout matrix. The influence of these fibers on the failure modes and mechanical properties were analyzed through DIC-based mechanical tests, to provide recommendations for the optimal fiber mix ratio. The fiber influence mechanism was also discussed through three positive and two negative aspects. The results indicate that the fiber cluster effect can not be ignored, the optimal fiber mix ratios for various indicators may conflict, necessitating a balance based on specific engineering requirements. In addition, to facilitating engineering applications, a normalized constitutive model was established using a length classification method.