A targeted biomineralization strategy for sustainable reinforcement of loess: Waste carbon fiber-guided enzyme-induced carbonate precipitation

Abstract

Loess is prone to erosion and structural failure due to weak cementation and low strength. This study investigates a novel reinforcement method combining enzyme-induced carbonate precipitation (EICP) with recycled carbon fiber. Direct shear tests and disintegration experiments were conducted to evaluate the mechanical strength and water stability of modified loess. Scanning electron microscope (SEM) and mercury intrusion pore measurement (MIP) were employed to explore the reinforcement mechanism at the microscale. Results showed that EICP and carbon fibers synergistically enhanced loess shear strength, with optimal cohesion achieved at 0.1 % fiber content and 1.5 mol/L cementation concentration. The combined treatment significantly improved water stability under prolonged immersion. At the microscopic scale, carbon fibers provided heterogeneous nucleation sites for CaCO₃, promoting the formation of a “fiber–CaCO₃–soil” composite network. Furthermore, carbon fibers mainly contribute to the macro-pore filling, and EICP mainly functions for filling smaller pores. This study offers a sustainable solution for loess stabilization and expands the reuse of carbon fiber waste in geotechnical engineering.