Striving for carbon dioxide emission reduction in high-grade concrete using tyre rubber and brick powder

The widespread applications of waste materials in concrete have been heading towards carbon dioxide (CO 2 ) emission reductions due to their brilliant performances. However, much works on CO 2 emissions of concrete are often based on lower concrete grades. In order to justify the influence of waste materials on concrete CO 2 emissions’ reductions, high concrete grades containing waste materials should be developed in which to embed CO 2 emissions. This research assesses the CO 2 emissions of classes 50, 55 and 60 concrete mixes incorporating clay brick powder (CBP) and waste tyre rubber (WTR). The CO 2 emissions of concrete mixes are validated separately using response surface methodology. The results show that WTR and CBP significantly decrease the CO 2 emissions of high-strength concrete mixes. The response surface models suggest that the influence of WTR and CBP on CO 2 emission response is significant. This behaviour appears to occur via a linear relationship having adjusted R 2 and R 2 values of 1. Moreover, increasing the replacement levels of CBP and WTR is the key to reducing CO 2 emissions of concrete, but this strategy needs not to compromise the mechanical properties of concrete. The solutions in this study provide a reliable benchmark for sustainable construction through reduction of CO 2 emission and serve as a foundation for further studies involving other waste materials.