| dc.description.abstract | Climate change is a popular topic in the 21st century. Industrial development has led to increasingly severe greenhouse effects, with carbon dioxide emissions having the most significant impact. Reducing the carbon footprint during the construction process has become a new trend. This study produced concrete cylinder specimens with a diameter of 10 cm and a height of 20 cm, and added baking soda and quicklime based on the percentage of cement weight. Waste concrete aggregates were used to replace a portion of the fine aggregates, and air-cooled blast furnace slag was used to replace a portion of the coarse aggregates. The specimens underwent accelerated carbon dioxide curing to sequester CO2 within the concrete.
The experiment controlled two curing durations and pressures as carbonation conditions, and designed two carbonation timings: carbonation curing after demolding and pre-carbonation of waste concrete aggregates. The study investigated the effects of different carbonation conditions, additives, and carbonation timings on the carbon absorption potential of concrete. Compressive strength, elastic modulus, neutralization, TGA, and XRD tests were conducted to understand the engineering and microstructural properties of the specimens.
The results showed that CO2 absorption was greatly influenced by the carbonation curing duration and pressure. Under 6 hours of carbonation curing and a pressure of 4.08 bar, various types of concrete reached maximum carbon absorption. Pure concrete specimens had the highest carbonation rate at 6.08%, followed by specimens with 2% baking soda at 4.69%. Other types of concrete showed less effective carbon absorption. Combining carbon absorption effects and compressive strength tests, the appropriate proportions of additives were determined: 2% baking soda, 5% quicklime, 50% waste concrete aggregates, and 50% air-cooled blast furnace slag.
Carbonation curing had little impact on the elastic modulus coefficient, which was mainly influenced by the type of concrete. The maximum neutralization depth after carbonation curing was 0.54mm, indicating minimal overall neutralization impact. XRD and TGA tests confirmed the presence of calcium carbonate. The specimen with 50% waste concrete aggregates showed the maximum calcium carbonate mass loss of 4.179% under 6 hours of curing and a pressure of 4.08 bar. | en_US |