Proposed mix design method for producing sustainable self compacting heat cured recycled aggregate concrete and its microstructural investigation

The proposed mix design is based on concept of equivalent mortar volume (EMV) method in conjunction with Nan Su mix design method to develop sustainable self compacting heat cured recycled aggregate concrete (SCHCRAC). The residual mortar content which is adhered to the recycled aggregate is the integral part of total mortar requirement of the proposed design mix. Two stage mixing approaches are followed along with treatment of RCA for enhancing the properties of SCHCRAC. The properties are negatively influenced due to elevated temperature resulting formation of unhydrated cement clinker during heat curing process. To improve the properties and later stage strength, admixtures like fly ash, and silica fume are used. The microstructural investigation is done by using electron probe micro analyzer (EPMA) to justify the improved strength and it is observed that the two stage mixing approach (TSMA_sfc) results clear and stronger interfacial transition zone (ITZ). Quantitative analysis and elemental mapping are also carried out to know the presence of strength contributing elements.