Road performance of ordinary Portland cement improvement of strongly weathered phyllite filler

• Hydrodynamic properties of phyllite after cement improvement. • Effects of particle gradation on performance of the improved phyllite roadbed filler. • Modelling of road performance of cement-amended strongly weathered phyllite. Phyllite is widely disseminated in China, to solve the problems of the shortage of filling soil and using farmland soil or deserted soil from other places, and to protect the environment and save investment, the strongly weathered phyllites were used to the fill the roadbed. This paper takes the strongly weathered phyllite in the Nanchang area as the research object. Based on both the physics and mechanics experiments and the engineering properties tests of the phyllite, the fillers that do not meet the mechanical properties of the first-class highway roadbed filler were improved with cement. The effects of different particle gradation characteristics (20%, 30%, 40%, 50%, and 60%) on the performance of the improved phyllite roadbed filler were analyzed, and the finite element software was used to verify the suitability of the improved strongly weathered phyllite as the roadbed filler. The results show that the unconfined compressive strength of the strongly weathered phyllite filler first increases and then decreases with the increase of the stone content, and the permeability first decreases and then increases with the increase of the stone content. After the improvement of cement content of 25%, moisture content of 25%, and stone content of 50%, the mechanical properties and permeability of strongly weathered phyllite fillers have reached the optimal values, which can greatly reduce the settlement of roadbeds and prolong the life cycle of highways.