Development of sustainable water-resistant binder with FGD gypsum & fly ash, and its environmental impact evaluation via carbon footprint and energy consumption analysis

Abstract

A sustainable water-resistant binder was developed utilizing flue gas desulphurized (FGD) gypsum and fly ash (FA), which are byproducts of coal-based thermal power plants. FGD gypsum was subjected to calcination, resulting in the formation of β-hemihydrate plaster. Various trial mixes of binders were then formulated, incorporating different proportions of β-hemihydrate (50–75%) and fly ash (15–40%), along with a fixed amount of OPC (10%) and activators. The physio-chemical and mechanical properties of the sustainable binders were evaluated, leading to the recommendation of a binder mix (P4) containing 30% fly ash and 60% β-hemihydrate plaster due to its favorable cost-effectiveness. Binder mixes P4 exhibited a compressive strength of 10.25 MPa after 28 days, with a water absorption rate of 9.25%. To assess the durability of the binders, they were subjected to extreme weather conditions, evaluating their strength under hot and cold temperatures. The binder mixes displayed low thermal conductivities (0.140–0.153 W/m.K), making them suitable for insulation applications. Furthermore, the binders achieved a Class 1 classification based on fire test analysis according to BS 476–1997. The development of these binders serves the dual purpose of waste management by utilizing byproducts and providing an economical alternative to the cement industry for both internal and external applications. It propels the construction industry toward a future characterized by reduced carbon emissions.