Mix model for self-compacting concrete with recycled aggregate

Abstract

Self-compacting concrete has become a common material in the current scenario of construction of large and complicated structures with heavy reinforcement and complex shapes. Using normal concrete in such situations can often result in inadequate compaction affecting the performance and long-term durability of structures. Also, the use of recycled-aggregate concrete is gaining importance throughout the globe owing to the depletion of natural aggregate sources and the disposal problem of demolished waste. Although there are different particle packing theories to optimise the aggregate proportions for binary and ternary combinations, the compressible packing model seems to be best suited for poly-dispersed mixes. In the present work, three grades of recycled-aggregate self-compacting concrete mixes without and with steel fibres were developed using the compressible packing model. To qualify the mixes developed, fresh properties such as slump flow, J-ring, V-funnel and L-box tests were conducted and checked for the satisfaction of European Federation of National Associations Representing for Concrete specifications. Validation was also done for other intermediate concrete grades, namely, M25, M30, M35, M45, M50 and M55. It was noted that the compressible packing model optimisation of aggregates considers important parameters such as wall effect, loosening effect and perturbed volume, which are important in deciding aggregate portions of self-compacting concrete.