Modelling and Optimizing the Durability Performance of Self Consolidating Concrete Incorporating Crumb Rubber and Calcium Carbide Residue Using Response Surface Methodology

The world is now focusing on a sustainable environment and reducing the effects of global warming. One way to achieve such targets is to properly utilize waste and reduce greenhouse CO2 emissions. The cement industry is responsible for almost 10% of global CO2 emission due to the high demand for cement in the construction industry. One of the ways to minimize this effect is the partial replacement of cement by other materials in concrete. Therefore, in this study, calcium carbide residue (CCR), which is highly rich in calcium oxide, partially replaced cement for waste management. Waste tires were grinded to fine sizes in crumb rubber (CR) and partially replaced the fine aggregate. Therefore, this paper investigared the influence of CR and CCR on the durability properties and heat/temperature resistance of self-compacting concrete (SCC). The experiment was designed using response surface methodology to investigate the effects of CR and CCR on SCC properties, design models for properties of the SCC, and optimize the mixes to achieve the best results. The properties considered were the durability of acid attack resistance (H2SO4 attack), salt attack resistance (MgSO4 attack), and water absorption. The heat resistance considered was weight reduction and residual compressive strength after heating the samples at a 200 °C and 400 °C. The results findings showed that CR and CCR negatively affect the acid and salt resistance of the SCC. Furthermore, CR negatively affects the heat resistance of the SCC, while CCR slightly improved it at 200 °C. The models developed using RSM were significant with high degrees of correlation and predictability. The optimum properties achieved 2.9% CR as a fine aggregate replacement and 5.5% CCR as a cement replacement. The developed models can predict the durability performance of SCC mixes in terms of acid and salt attack resistance and the effects of elevated temperatures using CR, CCR, and fly ash as the variables. This will reduce the need for carrying out experimental work, thereby reducing cost and time.

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