Dynamic deformation characteristics of fiber and geopolymer-stabilized coarse-grained fillers

The utilization of fiber and geopolymer to stabilize coarse-grained fillers can enhance their engineering performances such as strength and rigidity, and reduce the cumulative plastic deformation caused by long-term dynamic loadings. In this study, a series of unconfined compression tests are conducted to investigate the ideal material composition design of metakaolin-based geopolymer and the optimal mixing ratio of fiber and geopolymer for soil stabilization. Then, the unconfined compressive strength and cyclic loading/unloading tests on fiber and metakaolin-based geopolymer stabilized coarse-grained fillers are carried out. Their cumulative deformation characteristics and failure modes affected by rock content and loading stress level are discussed. The results show that the ideal mixing ratio of metakaolin, Na₂SiO₃, and CaO for preparing geopolymer is 3.6:1:0.8, and their optimal dosage for soil stabilization is 15%. The optimal content and length of basalt fiber are 0.4% and 12 mm, respectively. The compressive strength of fiber and geopolymer-stabilized coarse-grained fillers increases first, then decreases, and then increases with the rock block content. Their best mechanical performances are achieved when the rock block content is 30%. The cumulative strain rate of fiber and geopolymer-stabilized coarse-grained fillers increases first, then slowly, and then rapidly as the number of cycles increases. With the increase of the rock block content and loading stress level, the number and propagation rate of cracks increase significantly, and the failure mode of fiber and geopolymer-stabilized coarse-grained fillers changes from shear-slip to vertical splitting. This study can provide references for the dynamic cognition and engineering application of fiber and geopolymer-stabilized coarse-grained fillers.