Performance of Natural Pozzolans (NPs) in Field Concrete Mixtures

Cement, the binding component of concrete, the most widely used construction material in the world, accounts for 8% of global CO2 emissions. Its significant contribution to global warming has motivated researchers to aim for achieving carbon neutrality by 2050, in alignment with the 1.5°C global warming temperature limit stipulated by the Paris Agreement. A successful strategy to reduce CO2 emissions in concrete production is through the use of supplementary cementitious materials (SCMs) as a partial replacement for cement. However, it is estimated that by 2030, the demand for the most common SCM, fly ash, will exceed its supply. Natural pozzolans (NPs), such as calcined clays and volcanic ashes, can help fill this supply gap. However, the long-term field performance of concretes with varying water-cementitious (w/cm) ratios and temperatures is not well understood for these materials. This research study aims to fill this knowledge gap by investigating the hydration kinetics of cementitious pastes and compressive strength concretes prepared with these materials. This knowledge can help the concrete industry and transportation agencies with the adoption of NPs to address a projected decline in the supply of SCMs and environmental challenges.