Utilization of coal bottom ash in zero-carbon footprint pavement quality geopolymer concrete

Abstract

Worldwide demand for natural fine aggregates (NFA) in the construction sector has skyrocketed in recent decades, but NFA supply is becoming scarcer. At the same time, thermal power plants are producing massive quantities of coal bottom ash (CBA) which impacts the environment. As per the latest research, CBA can be used as NFA in concrete preparation. This study examines the fresh and mechanical properties, durability characteristics, and fatigue life of pavement quality geopolymer concrete (PQGPC) mixes prepared with the partial addition of CBA as NFA. Results found that after 28 days of curing, the basic properties like workability, compressive and flexural strength with the addition of 30% CBA-based PQGPC (GPC-30) mix are safe as per the requirement of rigid pavements. Furthermore, compared to the PQGPC mix, GPC-30 has a 2% lower endurance limit against fatigue at 2 million cycles at different stress levels of 0.55, 0.60, 0.65, and 0.70, respectively. Even though GPC-30 possesses 19% lower flexural strength than regular PQGPC, the fatigue life is comparable. So, incorporating CBA in the preparation of green PQGPC pavements not only lessens the reliance on NFA but also mitigates the need for landfills.