Design and development of Alkali Pozzolan Cement (APC)

•Eco friendly Alkali Pozzolan Cement (APC) was designed using 30% lime and 70% fly ash.•Scaffolding by 30% OPC and activation by 5% Na2SO4 greatly increased strength of APC.•The best APC mix had early and late strengths comparable to OPC under ambient curing.•XRD showed that mixtures with more hydration products had broader humps.•SEM showed that lower strength mixtures had porous structures and unreacted fly ash. This paper describes the development of an environmentally friendly Alkali Pozzolan Cement (APC), a non-hazardous dry cement powder that incorporates a large percentage of fly ash but needs only ambient temperature curing in order to achieve strengths comparable to OPC controls. APC consists of fly ash, lime, an activator and OPC (a ‘scaffolding’ material). Scaffolding was the most statistically significant factor contributing to the compressive strength of APC paste specimens, compared to activation, age (3days vs 28days) and temperature (ambient vs 15h at 60°C). SEM, EDS and XRD investigations were employed to explain variations in strength.