High-performance green concrete with high-volume natural pozzolan: Mechanical, carbon emission and cost analysis

The expected shortage of pulverized fly ash and other supplementary cementitious materials (SCM) in the future drives the current need to search for alternative pozzolanic SCMs that can reduce carbon emissions of concrete. Natural pozzolan, such as volcanic ash (VA), is one of the promising alternatives. Previous limited studies mainly focused on the properties of concrete containing low volume of VA. Therefore, this study aims to (i) develop high-strength concrete with high volume of VA, and (ii) evaluate the CO2 emissions based on the lifecycle assessment (LCA) technique and the associated cost compared to the conventional ones. In addition to the comprehensive mechanical and durability performances of the designed concretes, the sustainability potential index was developed based on the corresponding CO2 emissions and cost. The best VA concrete mixture developed in this study shows comparable compressive strength to the controlled OPC concrete, yet with lower carbon emissions and a much better ability against chloride ingress. Based on the analysis of the sustainability potential index, VA concrete with a water/binder ratio of 0.33 and a VA replacement percentage of 30% is the most "sustainable". The overall results show that VA can be effectively used as a substitute of OPC by 30-50% in volume to produce durable and sustainable concrete with comparable cost while catering to various strength grade requirements for different applications.