Influence of limestone powder mixing method on properties of manufactured sand concrete

For the purpose of enhancing the utilization rate of limestone powder (LP) in concrete and maximizing its activity effect. In this paper, the replacement methods for replacing fly ash (FA) with fine particles and manufactured sand (MS) with coarse particles were proposed. The content of LP replacing FA increased from 10% to 50%, and the content of LP replacing MS increased from 5% to 20%. The effects of LP replacing FA alone, replacing MS alone and particle-screened LP replacing both FA and MS on the workability, mechanical properties, durability of concrete were compared. Analysis of variance (Anova) was used to determine the importance level of the test parameters on the performance characteristics of concrete. The results suggested that LP replacing MS improved the workability and strength of concrete, and ameliorated the carbonation and chloride ion permeability resistance. However, the amount of LP substitution was very low, only 10%. Compared with LP replacing FA alone, the screened substitution improved the cohesion and water retention of concrete. The improvement in strength at 7 and 28 days was better, which was 1.6 MPa and 1.3 MPa higher than replacing FA alone. And there was no significantly adverse effect on the durability of concrete. Moreover, it was conducive to enhancing the utilization rate of LP. According to the research results, the effect of the interaction between LP content and the mixing method on the performance of concrete cannot be ignored. In addition, the screened substitution method was more environmentally friendly and economical, because it was conducive to the recycling of solid waste and landfill waste treatment.