Abstract
Anchorage and crack sealing are two primary reinforcement methods employed to minimize the impacts of crack on earthen sites. The effectiveness of these methods relies heavily on the mechanical properties of the grouting material. 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 mixture. The DIC-based 3-point bending tests and UCS tests were conducted, to analyze the influence of fibers on the failure modes, flexural and compressive strength, elastic modulus, flexural toughness, etc. of the grout mixture. Afterwards, a normalized constitutive model was established using a length classification method, to meet the requirements of engineering assessment. The results indicate that the mixture of fibers significantly enhanced the mechanical strength and ductility of the grouting material, with the failure mode shifting from brittle to semi-brittle. However, at higher fiber contents, the fiber clustering effect will lead to deterioration in both mechanical strength and elastic modulus. Moreover, the optimal fiber ratios for various indicators may conflict, necessitating a balance based on specific engineering requirements. These influence mechanism can be elucidated through the effects of fiber bridging, fiber skeleton, toughness pull-out, fiber cluster, and fiber expansion-contraction.