Utilization of ground granulated blast furnace slag (GGBFS) and fly ash (FA) to resolve the problem of increasing discharged and total accumulated industrial waste has attracted public concern. This article presents the research results on the effect of the replacement of up to 60 wt.% cement with GGBFS and FA, separately and in combination. It shows that mineral admixtures improve the workability of concrete mixture and reduce the required water-reducing admixture to reach a defined slump, prolonging the setting time of fresh concrete. The compressive strength of concrete with GGBFS at an early age decreases while increasing at 60 days and 90 days with the GGBFS content from 20 wt.% to 40 wt.%. The compressive strength of concrete with FA well develops at a later age, but it decreases at all ages as the FA replacement ratio increases. Cement replacement with a combined mineral admixture of 20 wt.% GGBFS and 20 wt.% FA does not significantly change the compressive strength at 28 days and later. Based on test result
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The development of the economy and industries in Vietnam inevitably causes environmental problems due to the discharging of large amounts of waste. According to the latest estimates, up to now, Vietnam has 30 coal-fired thermal power plants in operation, discharging about 16 million tons of ash and slag annually. The total amount of ash and slag accumulated over the years is about 100 million tons, of which, by the end of 2021, 48.4 million tons have been treated and reused. Blast furnace slag waste from steel production also reaches about 4.3 million tons per year. In that context, the utilization of industrial wastes, including fly ash (FA) and ground granulated blast furnace slag (GGBFS), is an inevitable development trend of building material production in general and concrete production in particular.
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