The Influence of Different Curing Environments on the Mechanical Properties and Reinforcement Mechanism of Dredger Fill Stabilized with Cement and Polypropylene Fibers

An effective method widely used in geotechnical engineering to solve the shrinkage and cracking issues in cement-stabilized soil (CS) is evenly mixing randomly distributed fibers into it. Dredger fills stabilized with cement and polypropylene fibers (PFCSs) are exposed to rainwater immersion and seawater erosion in coastal areas, influencing their mechanical performance and durability. In this study, direct shear and consolidation compression tests were conducted to investigate the influence of different curing environments on the mechanical properties and compressive behavior of PFCSs. Dominance and regression analyses were used to study the impact of each factor under different curing regimes. The reinforcement mechanism of different curing environments was also explored using scanning electron microscopy (SEM) imaging. The results show that the cohesion and elastic modulus of the specimens cured in seawater were reduced compared with those cured in freshwater and standard curing environments. The best fiber content for the strength and compressive modulus of PFCSs was determined to be 0.9% of the mass of dredged fill. The results of value-added contributions and the relative importance of each factor in different curing environments show that the overall average contribution of cement content in the seawater curing environment is reduced by 6.79% compared to the freshwater environment. Multiple linear regression models were developed, effectively describing the quantitative relationships of different properties under different curing conditions. Further, the shear strength was improved by the coupling effect of soil particles, a C-S-H gel, and polypropylene fibers in the PFCSs. However, the shear strength of the PFCSs was reduced due to the structural damage of the specimens in the freshwater and seawater curing environments.