Abstract
Plain recycled aggregate concrete (RAC) struggles with issues of inferior mechanical strength and durability compared to equivalent natural aggregate concrete (NAC). The durability issues of RAC can be resolved by using mineral admixtures. In addition, the tensile strength deficiency of RAC can be supplemented with fiber reinforcement. In this study, the performance of RAC was evaluated with individual and combined incorporation of microfibers (i.e., glass fibers) and various potential waste mineral admixtures (steel slag, coal fly ash (class F), rice husk ash, and microsilica). The performance of RAC mixtures with fibers and minerals was appraised based on the results of mechanical and permeability-related durability properties. The results showed that generally, all mineral admixtures improved the efficiency of the microfibers in enhancing the mechanical performance of RAC. Notably, synergistic effects were observed in the splitting tensile and flexural strength of RAC due to the combined action of mineral admixtures and fibers. Microsilica and rice husk ash showed superior performance compared to other minerals in the mechanical properties of fiber-reinforced RAC, whereas slag and fly ash incorporation showed superior performance compared to silica fume and husk ash in the workability and chloride penetration resistance of RAC. The combined incorporation of microsilica and glass fibers can produce RAC that is notably stronger and more durable than conventional NAC.
Highlights
The five types of binders used in this cement were Portland cement type I ASTM; uncondensed MS with up to 98.4% silica content; siliceous FA known as type F coal ash; blast furnace steel slag (BFS) produced in the blast furnace with iron smelting; and RHA produced by calcining rice hull at about 760 ◦ C for 2 h
The slump test results show that BFS and FA are useful in enhancing the workability The following conclusions be derived from thethat experimental of concrete
The slump test results show that are useful in enhancing the workability addition of glass fibers in recycled aggregate concrete (RAC)
Summary
RAC shows lower mechanical and durability performance compared to natural aggregate (NA) concrete (NAC). The authors of [39] showed the properties of concrete with various replacement levels of cement with RHA They reported that RHA did not show any effect on compressive strength at an early age, but it improved the strength at later ages. Wu et al [51] showed that MS helps in enhancing the efficiency and dispersion of steel fiber by increasing the bond strength between the fibers and binder Admixtures such as FA and BFS are useful in improving the workability due to their lubricating effects, and these admixtures have shown water-reducing effects on the fresh properties of concrete [9,18]. The development of these types of composites can resolve the major issues associated with conventional plain cement concretes
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