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.
Why does a continuous casting mould powder, which works successfully on a particular caster with respect to semi quality, fail to perform on a caster of a similar design utilising liquid steel from a similar route for an identical product without some tuning of its make-up and composition? In casting sequences of the same steel grade why do some apparently random heats produce poor surface quality with respect to cracking when otherwise good surface quality is realised? The answer to these questions lies in the interaction of the mould powder, the casting hardware, and the casting process variables. Using, as examples, data collected from within Corus UK and during collaborative work on the assessment of mould powder performance and its effects on surface quality, the interaction of the mould powder, the casting hardware and the casting process variables is explored. The steelmaking route and its associated alumina load, unexpected changes to slag chemistry, infiltration of the slag into the mould-strand gap and the nature of the slag film are all shown to affect powder performance.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.