Layered γ-C2S composites with PAM hydrogel interlayers: Simultaneous enhancement of CO2 transport, carbonation kinetics and stress dissipation

CO 2 curing technology for construction materials faces three major challenges: limited CO 2 diffusion due to the dense CaCO 3 layer, inefficient reaction kinetic, and internal stresses induced by volumetric expansion during the carbonation curing process. This study introduces a layered structure strategy employing PAM hydrogel as interlayers between γ-C 2 S layers to address these limitations through the combined functions of PAM incorporation and layered structural design. Layered structure specimens achieved compressive strength of 127.60 MPa, flexural strength of 23.68 MPa, and carbonation degree of 41.8%, representing improvements of 114.63%, 29.05%, and 9.9 percentage points, respectively, over conventional compaction structure. Multiscale characterization indicated that PAM incorporation and its layered spatial arrangement contributed differently to carbonation behavior and mechanical performance. First, the PAM interlayer formed a CO 2 permeation network through horizontal layer channels, enabling carbonation to penetrate beyond surface regions. Second, the polyacrylamide hydrogel maintains optimal humidity conditions coupled with interfacial Ca 2 + -carboxylate coordination accelerates ion leaching and reaction kinetics. Third, the polyacrylamide layer dissipates volumetric stresses during the reaction process through reversible deformation and energy dissipation, thereby enhancing material toughness and strain-bearing capacity. This layered manufacturing strategy provides a viable route to simultaneously optimize CO 2 sequestration and mechanical performance, offering new perspectives for developing carbonation mineralized materials and advancing CO 2 curing technology toward industrial application.