Fresh state, mechanical & durability properties of strain hardening cementitious composite produced with locally available aggregates and high volume of fly ash

This paper presents the effect of locally available mortar sand (MS) instead of Silica Sand (SS) and high volumes of Class-F fly ash with 55% and 70% cement replacement rates on the properties of engineered cementitious composite (ECC). ECC is a mortar based composite with a strain capacity of 300-500 times higher than normal concrete by using only 2% of fiber content. The ability of ECC to achieve strain hardening behaviour with closely spaced multiple microcracks can enhance the ductility and durability of concrete structures as well as increase their service life. In this study, the performance of ECCs made with MS and SS with high volumes of fly ash (HVFA) was judged based on the heat of hydration, slump flow, flexural and compressive strengths, ultrasonic pulse velocity, linear expansion/drying shrinkage, sorptivity and frost resistance characteristics in an attempt to produce cost-effective, sustainable and greener ECC mixtures (especially with mortar sand) for different construction applications. Replacing the silica sand by mortar sand at the same HVFA content in ECC mixtures, decreased slump flow and flow velocity, did not have a significant influence on strength (compressive and flexural) or bending capacity and reduced drying shrinkage and expansion properties by about 5% and up to 30%, respectively. Overall, the more or less similar fresh state, mechanical and durability properties confirmed the viability of producing ECC mixtures with mortar sand instead of silica sand in combination with high volumes of Class-F fly ash.