Fly Ash Induced Self Compacting Concrete with Recycled Concrete Aggregate

摘要

The use of recycled concrete aggregate (RCA) from construction and demolition wastes are showing potential relevance in construction industry as substitute to natural coarse aggregate (NCA) and to date very limited research exists exploring the use of RCA in self-compacting concrete (SCC). This paper examines the flowability and strength characteristics of fly ash induced self-compacting concrete with different percentage replacement levels of RCA with NCA. High Range Water reducing agent (HRWR) with and without VMA was used as chemical admixture to achieve the required flow ability. The results for various flowability index observed were within the specified range recommended by EFNARC (2005). Higher flow time in case of SCC mixes with HRWR having inbuilt VMA was observed and can be attributed to the fact that VMA provides stability to the mix and is helpful in minimizing segregation and bleeding. In general, the strength of SCC mixes with recycled concrete aggregate was lower than that of conventional concrete made with natural coarse aggregate. Further, beyond 20% replacement level the rate of decrement in compressive strength was almost in the range of 17 to 22% when compared to reference mix. Minimal reduction in tensile strength of fly ash induced self-compacting concrete with RCA was observed.