Investigation of Carbon Dioxide Sequestration Potential of Concrete Mixtures Incorporating Cement Kiln Dust

The mineral carbonation of concrete through accelerated carbonation curing (ACC) has recently gained attention. In ACC, a young concrete is exposed to CO2 under appropriate pressure, temperature and relative humidity, for a few hours, serving as a means of CO2 sequestration. Portlandite and other phases in the hydrating cement react with CO2 to form thermodynamically stable carbonates, offering improvements in the physico-mechanical and durability characteristics of concrete and results into environmental benefits owing to consumption of CO2. Cement kiln dust (CKD) is a candidate material that could be considered for improving the CO2 sequestration capacity of concretes. CKD is a by-product of the production of cement clinker, and has been studied extensively as one of mineral admixtures for producing concrete. However, the CO2 sequestration performance of concrete mixtures containing CKD has not been studied. The proposed research aims to investigate the CO2 sequestration potential of concrete mixtures containing cement kiln dust (CKD) towards developing cement-CKD blended concrete mixtures with optimal performance under ACC. In the proposed study, firstly, mortar specimens with varying mixture parameters will be prepared. The mortar specimens will be subjected to initial curing and then exposed to CO2 under predetermined ACC conditions. The compressive strength and CO2 uptake of CO2 cured mortar specimens will be evaluated. In addition, the chemo-physical characteristics, mineralogy and microstructure of selected CO2-cured mortar specimens will be assessed at predetermined stages, through a set of complementary empirical and analytical methods. From the results of the mortar experiments, cement-CKD blends with optimal CO2 sequestration potential will be identified and then utilized to prepare concrete specimens that will be CO2 cured under the respective ACC parameters, and characterized for compressive strength, depth of carbonation front, and chloride ion penetrability. Based on the experimental data, practical avenues for the use of the developed cement-CKD blended concrete mixtures will be identified, while the outcomes of the study will be used as inputs for more advanced and detailed research in future. The significance of this proposed work lies in its attempt to bridge the knowledge gap on the behavior of concrete mixtures incorporating CKD in terms of their CO2 sequestration potential. A successful development of methodology for the use of CKD concrete to advance the concrete-based CO2 sequestration technology will be beneficial economically and also contribute to cleaner environment, locally and globally.