Benefit-cost analysis model of using class F fly ash-based green cement in masonry units

Green Cement (GC) is considered as a potential alternative to Ordinary Portland Cement (OPC). There are major drawbacks associated with OPC, such as the emission of greenhouse gasses and high-energy consumption from cement production. Recycling fly ash and using it to replace cement has positive impacts on our environment, such as conserving landfill spaces, conserving natural resources, reducing CO2 emissions, and saving energy. Fly ash can be further recycled into value-added building products by developing fly ash-based green cement. This study presents an examination of the Benefit-Cost Analysis Model (BCAM) to characterize the environmental impact of masonry units produced from OPC or GC. Output from BCAM includes the monetary value of energy use, raw materials, atmospheric emissions, social costs of CO2, tax costs of carbon's emissions, and avoiding land filling of fly ash. This study has found that Mix (1) which is for OPC has a direct cost of raw materials only, on average $0.460/square foot, and an indirect cost (the monetary value of benefit-cost analysis model, as a result of negative impacts) of on average $0.152/square foot. Therefore, the total cost is $0.612/sf. Mix (2) which is for GC with NaOH as an activator has a direct cost of raw materials only, on average $2.28/sf, and a saving (the monetary value of benefit-cost analysis model, as a result of positive impacts) of on average $-1.057/sf. Therefore, the actual cost (direct cost - savings) is on average $1.222/sf. Mix (3) which is for GC with Na2SO4 as an activator has a direct cost of raw materials only, on average $0.943/sf and a saving of on average $-1.057/sf. Therefore, the actual cost is on average $-0.114/sf. The negative cost means that there is a saving as a result of monetary value of the positive impacts.