Engineered Cementitious Composite (ECC) is one of the versatile building components. The characteristics of materials and curing period are major factors that will influence the eco-friendly nature, and performance of the composite. In this experimental analysis, the impact of alkaline treated sisal fibres with different combinations of Polyvinyl alcohol (PVA) fibres (Mix-1 is 2% Sisal fibres, Mix-2 is 0.5% Sisal fibres + 1.5% PVA fibres) on the characteristics of Indian Zone II fine aggregates (50% river sand + 50% Manufactured sand) based ECC analyzed. For this, high fly ash to Cement dosage (f/c) of 1.4 is considered. These sisal fibres and f/c ratio are responsible for reduction in the disposal (or) environmental problems. The compressive strength of composite slightly improved from Mix-1 to Mix-2 at 28days with the decreased content of sisal fibres. But the split tensile and flexural characteristics highly increased by 8.33%, 5.45% from Mix-1 to Mix-2, respectively. These characteristics highly improved with the increased curing period (28days to 120days). The durability of the composite significantly influenced from 28days to 56days, but slightly improved with the decreased content of sisal fibres. To analyze these characteristics, SEM and XRD analysis are performed. Portlandite and quartz content was highly reduced (formation of C-S-H gel) from 28days to 56days due to hydration of unhydrated fly ash, fine aggregates, and other materials. The microstructure of both the mixes is densified with this gel. Mix-2 is more densified than Mix-1 due to the properties and arrangement of sisal fibres. These fibres are appropriately arranged in the partial replacement of PVA fibres compared to full dosage.