Study on flexural behavior of CO2 cured recycled coarse aggregate concrete steel bar trusses composite slab

The effects of aggregate carbonation, overall specimen carbonation, and the combined method of aggregate carbonation and overall specimen carbonation on the mechanical properties of recycled coarse aggregate concrete (RAC) were investigated. Furthermore, the flexural behaviors of steel bar trusses composite slab (SBTCS) prepared by RAC and cured by the three carbonation methods were studied through experiments and numerical analysis. The results indicated that: (1) The mechanical properties of RAC after carbonation were significantly improved, and the concrete prepared by the combined method of aggregate carbonation and overall specimen carbonation showed the highest strength. (2) The stress-strain constitutive models of RAC under different carbonation methods were built according to the experimental results. (3) The failure modes of the carbonated concrete SBTCSs were basically consistent and the precast layer and the cast-in-situ layer deformed coordinately during the loading process. (4) The SBTCS prepared by the combined method of aggregate carbonation and overall specimen carbonation showed the best bending performance, and the ultimate load bearing capacity increased by 16.2% compared to the SBTCS made by non-carbonated RAC. (5) The load-displacement curves and damage contours of the SBTCSs obtained from the numerical analysis were in good agreement with the experimental results, and the maximum deviation between the simulated ultimate load and the experimental value was 8.8%.