Architecture Engineering and Science

Addressing the challenge of chloride-induced corrosion in marine environments and aligning with “dual-carbon” goals, this study designed an alkali-activated material (AAM) system based on the synergy of multiple industrial solid wastes (slag/fly ash). An orthogonal experiment (L9(3³)) was employed to optimize the mix proportion, and range analysis and variance analysis were conducted to quantify the influence weights of key factors. The resistance to chloride penetration was evaluated via the Rapid Chloride Migration (RCM) test, while the microstructural evolution was characterized by X-ray Diffraction (XRD), Mercury Intrusion Porosimetry (MIP), and Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS). The results indicate that the synergistic effect of multiple solid wastes optimizes the pore structure by converting harmful macropores (>50 nm) into gel pores (<10 nm) and promotes the formation of C-A-S-H gel and Friedel’s salt. Consequently, the chloride migration coefficient is substantially reduced through a dual mechanism of “physical barrier” and “chemical binding”. Under the optimal mix proportion (slag/FA=7:3, activator modulus=1.2, alkali equivalent=8%), the material exhibits excellent mechanical performance (3-day compressive strength=45.2 MPa, 7-day compressive strength=56.8 MPa, 28-day compressive strength>60 MPa) and low permeability (chloride migration coefficient of 3.8 × 10⁻¹² m²/s). This study clarifies the microstructure-durability relationship, providing a theoretical basis for engineering applications of low-carbon marine construction materials.