Exploring the Impact of CO2 Sequestration on Plastic Properties, Mechanical Performance, and Microstructure of Concrete

In view of global warming, carbon sequestration techniques are being employed across the globe to minimize the damaging impact of greenhouse gases on the environment. Findings of ongoing research have shown that adding CO ₂ during the mixing or curing stage of concrete enhances its mechanical properties. The purpose of this study is to examine the effect of CO ₂ addition during the mixing stage on the initial hydration and mechanical properties of concrete. Various CO₂ dosages, ranging from 0.1–1%, were injected during mixing to analyze fresh and hardened properties of concrete, and the test results were compared with the control mix. CO ₂ primarily reacts with calcium hydroxide in concrete to form calcium carbonate, thereby densifying its microstructure and improving its compressive strength by 10–20%. Thermal Pyrolysis tests, microscopy and infrared spectroscopy analysis indicated the presence of CaCO₃, thereby confirming the carbonation process. However, CO ₂ dosages above 0.5% by weight of cement resulted in a drop in the workability of fresh concrete, which was rectified by an additional dose of superplasticizer. The present research attempts to create a simplified CO ₂ sequestration process in concrete, develop a predictive model to estimate the compressive strength and use basic characterization techniques to identify the mineralization process. Findings from this research will provide simplified solutions to the construction industry that plans to implement CO ₂ sequestration in concrete.