Mix design methodology for greener concrete
  Swanand Raikar
  The environmental hazards caused by the construction industry are a pressing concern in present time. CO2 emissions are one of the most prominent issues. This report aims to develop a mix design methodology with a CO2 reduction percentage as one of the initial parameters along with strength, workability and durability. This allows the user to obtain the mix proportions of concrete, and achieve a desired CO2 reduction. The incorporation of this CO2 reduction percentage into the mix design was done by developing two graphs which linked the CO2 reduction to the amount of cement substitution. To develop this method, current methods of mix design were reviewed and their individual limitations were noted. A compilation of steps from these established mix design methods was done to develop the new method. This report also deals with the potential CO2 reduction and possible cost feasibility when higher grades of concrete are used to design structural members. It was found that for flexural members (beams), using higher grades of concrete (from M20 to M40), increases the CO2 emissions by approximately 26% and increases the cost by 13.07%. For compressive members under pure axial loading, the use of higher grades of concrete has proven to be both more eco-friendly and more economical. The CO2 saving and economy achieved for a grade shift from M20-M40 was 35.7% and 39.6% respectively. These findings and the methodology developed are extremely significant and can be implemented in order to reduce the environmental impact by the CO2 emissions of the construction industry.