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Abstract The ultrafine composite admixture used in this study is composed of 50% S95 mineral powder and 50% fly ash, which is obtained by mixing and grinding with ultrafine ball mill. The application mode of ultrafine composite admixture in cement, concrete of different strength grades and ultra-high performance concrete was explored, and its influence on the properties of cement and concrete was studied. The results showed that the superfine composite admixture can replace 10%~20% of P·O 42.5 cement, the 3 d strength of cement does not decrease, the 28 d flexural strength and compressive strength increase by more than 0.5 MPa and 10 MPa respectively, and other properties can meet the standard requirements. In the C30, C50 and C80 strength grade concrete, the ultrafine composite admixture completely replacing the mineral powder can improve the fluidity and compressive strength of concrete, and the durability of C30 strength grade concrete is obviously improved. When the ultra-fine composite admixture replaces 20%~50% cement in ultra-high performance concrete, the fluidity and 28 d compressive strength of ultra-high performance concrete increase first and then decrease, and the replacement amount of 40% is the best.
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Published: 30 October 2023
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2023, Vol. 0 
