An accelerated carbonation and its effect on concrete containing natural zeolite

This study examines the influence of varying molar concentrations of carbonated water solutions on accelerated carbonation of normal concrete containing conventional fine aggregates (NAC) and concrete containing natural zeolite powder along with natural zeolite fine aggregates (ZAC). This attempt is made to address the CO 2 emission problem from concrete production and enhance the sequestration of CO 2 within the concrete matrix. In the presented research work, 0.5M and 0.75M sodium bicarbonate (NaHCO 3 ) solutions were used as accelerating medium to enhance the process of carbonation in concrete specimens designed with 0.60 and 0.65 water-to-binder (w/b) ratios. The compressive strength test, carbonation depth measurement, pH measurement along with X-ray diffraction, thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) analyses were performed, and the results for both ZAC and NAC were compared to assess the extent of carbonation. With increment in molar concentration of carbonated water, the ZAC specimens exhibited higher compressive strength, greater carbonation depth, reduced pH values, and enhanced calcium carbonate (CaCO 3 ) precipitation. A higher w/b ratio enhanced the carbonation process due to deeper penetration of carbonated water during exposure. Based on the laboratory evaluations, the performance of ZAC was found to be superior than NAC with reference to the enhanced carbonation process and CO 2 sequestration.