SUSTAINABLE HIGH-VOLUME FLY ASH GROUTS FOR TWO-STAGE CONCRETE

摘要

Two-stage concrete (TSC) is a special type of concrete in which coarse aggregates are pre-placed in the formwork and subsequently injected with a grout. Beneficiating fly ash in TSC grouts increases TSC sustainability through the ecological use of large quantities of fly ash, reduced carbon-dioxide emissions associated with cement production, and enhancement of resource productivity of the concrete industry. Limited research has explored the effects of using high volume of fly ash as partial replacement for cement in TSC grout mixtures. Therefore, the flowability of grout mixtures incorporating various fly ash addition rates (i.e. 0%, 30%, 50% and 70%) was evaluated using the flow cone method and spread flow test. Correlations between the efflux time and spread flow for the grout mixtures were developed. Results show that increasing the fly ash addition reduced the grouts efflux time while increasing its spread flow. The optimum high-volume fly ash dosage for achieving high flowability and acceptable TSC compressive strength was identified.