Life cycle assessment and cost analysis of fly ash-rice husk ash blended alkali-activated concrete.

The utilization of industrial and agricultural by-products for the production of alkali activated concrete (AAC) has the potential to yield significant benefits towards sustainability goals. To be a viable material, the construction industry requires a construction material that achieves the requisite strength and the other property requirements as specified in codes and standards while demonstrating improved sustainability criteria. Fly ash and Rice Husk Ash (RHA) are abundantly available waste products, principally located in Asian countries. Currently, a significant proportion of these materials are disposed of in landfills, lagoons and rivers but offer potential to utilize in AAC. Hence, the identification of variables associated with fly ash and fly ah-RHA blended AAC by utilizing fly ash and RHA is vital. This study quantifies the environmental and economic factors by assessing the Greenhouse gas (GHG) emission, environmental impacts and benefits, and cost analysis of utilizing fly ash and RHA in AAC compared to Portland Cement (PC) concrete. Alkaline activator is a key component responsible for the highest GHG emission, cost and environmental impact amounts obtained for fly ash geopolymer and blended alkali-activated concrete compared with PC concrete. Alkali activators contribute to 74% of the total GHG emission, while heat curing contributed only 9% to the total GHG emission. The addition of 10% RHA to alkali-activated concrete showed a slight benefit for the analysis. Utilization of waste fly ash and RHA is responsible for providing significant benefits in terms of fresh and marine water ecotoxicity by avoiding waste disposal at the dumpsites, rivers, and storage lagoons.
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