A mix design procedure for fly ash and ground granulated blast furnace slag based treated recycled aggregate concrete

Abstract

It appears that the perception and desire to utilize recycled aggregate in concrete is growing across the world, decreasing the environmental impact of landfills and virgin aggregate mining while also making building projects more cost-effective and environmentally friendly. However, the practical utilization of RA has not gained attention to date because of the weaker characteristics of porous attached mortar. Although various mix designs for recycled aggregate concrete (RAC) have been proposed earlier by many authors, still using RA is not made practical for many reasons. One of them is the unavailability of an easy and effective design mix methodology using RAC. Thus, an attempt has been made in the present investigation to advance a mix design methodology for RAC by providing w/b to strength relation, embracing the two-stage mixing approach (TSMA) by completely substituting the CNA with CRA. DIN standard was followed to get the maximum particle packing of aggregates and improved RAC performance. Again, to make RAC more sustainable, a mix design is also proposed to replace cement with widely used SCMs-coal fly ash (CFA) and ground granulated blast furnace slag (GGBS) at 30 and 50% replacement level, respectively. The synergetic effect of the proposed design mix that contains DIN standards, TSMA, and SCMs on fresh, hardened properties, and evaporation studies of RAC was studied. In this context, the comparative analysis manifested the encouraging outcomes to use the proposed mix design methodology for preparing RAC incorporated with CFA and GGBS.