EVALUATION OF CONCRETE INJECTED WITH CO2 AND EXPOSED TO COASTAL ENVIRONMENT

Abstract

Producing concrete that incorporates carbon dioxide (CO2) into the mix is leveraged to reduce the carbon footprint and produce more sustainable concrete. As the concrete dries, the CO2 is mineralized and permanently incorporated into the early carbonation. Experimental work has been conducted, and hundreds of specimens with varying ratios of CO2 to binder content were cast. CO2 to binder ratios of (0, 0.135, and 0.2%) were used to test concrete in workability (slump), mechanical properties (compressive strength, and density), and durability performance (chloride permeability, and water absorption). The chemical tests (water-soluble chloride, and acid-soluble sulfate ion contents) were also conducted to identify the changes in hardened concrete composition for the three mixes (standard concrete without CO2, standard concrete with CO2 to binder ratio of 0.135%, and standard concrete with CO2 to binder ratio of 0.2%). All specimens were field cured and exposed to the coastal environment of Ras Al-Khair industrial city in Saudi Arabia. The results showed that the CO2 to binder ratio of 0.2% improved the concrete properties, in particular, the effect was clear with higher slump and comparable strength compared to the standard concrete without CO2. However, the CO2 to binder ratio of 0.2% shows a negligible increase in the chloride permeability and the internal chloride ion content compared to the standard concrete without CO2, whereas the internal sulfate ion content has not increased for both CO2 to binder ratios (0.135 and 0.2%) in comparison with the standard concrete without CO2, which indicate no reduction in concrete durability.