Mechanical, physical and durability performance of engineered cementitious composites prepared with calcium aluminate cement

The aim of this research is to fill a gap in existing studies by exploring the use of calcium aluminate cement (CAC) as an eco-friendly substitute for ordinary Portland cement (OPC) in engineered cementitious composites (ECCs). The study investigates the impact of CAC, both with and without the presence of fly ash (FA), on the mechanical, physical, durability and microstructural properties of ECC–CAC mixtures. Various proportions of FA to CAC up to 1.5 were considered, while assessing different engineering parameters of compressive and flexural strengths, ductility, ultrasonic measurements, chloride penetrability and drying shrinkage. Moreover, scanning electron microscopy coupled with energy dispersive X-ray analysis and X-ray diffraction were used to analyse the reaction products related to CAC and/or FA in selected mixtures. Higher strengths of CAC–ECC were achieved at earlier curing ages, although the transformation of CAC’s metastable phases led to reduced strengths in ECC–CAC mixtures compared to the control ECC during extended curing periods. Furthermore, the combination of FA with CAC played a crucial role in avoiding the hydrates conversion and minimising the shrinkage in CAC–ECC, achieving even lower shrinkage levels than those observed in control OPC–ECC.