Diversifying two-stage mixing approach (TSMA) for recycled aggregate concrete : TSMA_s and TSMA_sc

Recycling demolished concrete as recycled aggregate can be applicable to most construction applications. Lower-grade applications, including sub-base and roadwork, have been practicing in many countries; however, higher-grade activities are rarely discussed. This paper develops two mixing approaches by adding silica fume into certain percentages of Recycled Aggregate (RA) in the pre-mix procedure, named as two-stage mixing approach_{(silica fume)} (TSMA_s) and adding silica fume and proportional amounts of cement into certain percentages of RA in the first mix, named as two-stage mixing approach_{(silica fume and cement)} (TSMA_sc). Experimentation highlights that improvements have been recorded resulted from the use of various RA percentages from both TSMA_s and TSMA_sc. The additions of silica fume and proportional cement content in the pre-mix on TSMA_s and TSMA_sc can fill up the weak areas in the RA and thus develop a stronger interfacial layer around aggregate, and hence a higher strength of the concrete. It, thus, concludes that TSMA_s and TSMA_sc can provide alternative methodologies for further improvement in quality of this recyclable material. © 2007 Elsevier Ltd. All rights reserved.