Evaluation of environment and economy viable recycling cement kiln dust for use in green concrete

The use of industrial plant wastes such as fly ash (FA) and cement kiln dust (CKD) is an optimal solution to improve some of the fresh and hardened properties of concrete and also a rational choice to reduce the effect of carbon dioxide in the construction industry. In this study, different amounts of CKD (0-40%), as a waste material, and FA (0-30%) as a pozzolanic material, were used as a single and hybrid replacement of cement. Then, Taguchi method with two parameters of water to binder ratios and cement replacement ratio was used to determine the optimal mixing designs before construction from environmental and economic points of view. Comparison of the Taguchi method and experimental results for selecting the most favorable mixture designs showed that Taguchi method exhibited suitable choices in the range of optimal experimental results with regard to the initial parameters. This means that if the water-to-cement, CKD-to-cement, and the fly ash-to cement ratios were 0.45, 9%, and 14%, respectively, it would be possible to obtain the best possible values for the strength to price, CO2 emission factor, and the standard deviation ratio.