The dynamic and static mechanical properties of agricultural straw fiber reinforced cement soil and the evolution mechanism of the fiber-matrix interface microstructure

Abstract

The research on the mechanical properties of agricultural straw fiber modified cement waste soil aims to explore the deficiencies in the mechanical performance of cement soil when using waste soil as raw material and its potential hazards. As a commonly used building material, the mechanical properties of cement soil are influenced by various factors, especially when waste soil is used, problems such as insufficient strength and poor compressive resistance often occur. Waste soil contains a large amount of unstable substances, which can easily lead to the expansion, cracking and long-term strength reduction of cement soil, thereby affecting the quality and safety of the project. To improve the mechanical properties of cement soil, the study proposes to add agricultural straw fibers for modification. Agricultural straw fiber, as a natural fiber material, have excellent reinforcing effects and can effectively improve the tensile strength, toughness and stability of cement soil. According to the study, agricultural straw fiber cement-stabilized waste soil (FCS) samples' unconfined compressive strength (UCS) first rises and then falls as the amount of agricultural straw fiber increases, peaking at 1%. An appropriate amount of fiber (1%) significantly enhances the stiffness of the soil, while excessive fiber (1.5%) may introduce additional pores and weaken the material's stiffness. The Maximum dynamic shear modulus ( G max ) of FCS samples shows a trend of first increasing and then decreasing with the increase of agricultural straw fiber content. The synergistic effect of fibers and confining pressure is obvious, and the samples with 1% fiber content perform best under high confining pressure, indicating that fibers and confining pressure jointly improve the shear stiffness of the matrix. An appropriate amount of straw fibers can significantly improve the mechanical properties of cement soil and reduce the negative impact of waste soil on the structure of cement soil. Thus, agricultural straw fibers' modification effect offers a fresh concept for using waste soil as a resource and crucial technical assistance for boosting the mechanical qualities of cement soil and project quality.