Feasibility study of using fine recycled concrete aggregate in producing self-consolidation concrete

Abstract

Concrete recycling provides sustainability benefits in conservation of virgin aggregate resources, landfill reduction, energy savings, and reduced greenhouse gases emission. Effective and new uses of recycled concrete aggregate (RCA) in cement and concrete industry have attracted a lot of researchers’ attention from the perspective of environmental preservation and sustainable utilization of resources. While local RCA could be successfully used in portland cement concrete, most of the RCA, particularly fine recycled concrete aggregate (FRCA) are currently only used in low-profile applications. A feasibility study of usage of FRCA (up to 100% replacement of natural fine aggregate) in high-performance concrete such as self-consolidation concrete (SCC) is needed. This paper presented a preliminary study in using FRCA to obtain SCC with comparable properties as such of using natural fine aggregate. In order to evaluate the influence of different portions of FRCA in SCC, tests including slump-flow, J-ring, V-funnel, L-box, and visual stability index were used to assess the flowability, passing ability, and segregation resistance of concrete mixtures. In addition, a concrete rheometer was used to measure the rheological properties of concrete. Strength properties of concrete were evaluated through compressive strength and volume stabilities of harden concrete were measured by drying shrinkage tests. Results showed that while the higher amount of fine particles in FRCA does affect flowability, passing ability, segregation resistance, and rheological performance as well as hardened concrete behaviors of SCC, most of the mixtures included in the study show good flowability, passing ability and stability, and well satisfy criteria of SCC. Both compressive strength and drying shrinkage tests indicate good performance with SCC made with FRCA. The study demonstrated that it is possible to obtain SCC using FRCA with appropriate mix proportions and the feasibility of utilizing FRCA for SCC has been demonstrated.

Keywords:

• self-consolidation concrete
• recycled aggregate
• flowability
• rheology
• passing ability

Acknowledgment

The authors would like to thank Texas State University-San Marcos for funding support and the help from Mr Daniel Calhoun, Mr Garrett McSpadden, Mr James Mulhall, and Mr Jake Seagraves for their assistant during the experiment study.