Abstract: As a typical poor foundation soil, the collapsibility and structural fragility of loess significantly restrict the safety of
the project, although the traditional cement curing effectively improves the mechanical properties, it is accompanied by high carbon emissions, and the green improvement technology needs to be improved urgently. In this paper, the direct shear test and scanning electron microscopy (SEM) analysis were carried out to systematically explore the effects of fiber content on their strength deformation characteristics and microstructure, and to evaluate their carbon emission reduction potential. The test results show that the fiber significantly enhances the shear performance of loess, and the cohesion is mainly improved. The cohesion showed a trend of “first increasing and then decreasing” with the increase of the content, and the optimal content was 0.5% for polypropylene fiber and 0.4% for polyester fiber, respectively. The microscopic analysis reveals that the fiber can fill the pores and enhance the structural compactness, and the friction effect and network restraint mechanism at the interface between the fiber and the soil can effectively impede deformation and inhibit crack propagation. In addition, introduction of fiber can replace part of cement consumption, and the carbon emission is reduced by about 50% compared with traditional curing solutions. This study provides a theoretical basis and engineering support for the low-carbon improvement of loess.

Key words: fiber, loess, strength, microstructure, environmental benefits