Study On The Influence Of Ultrafine Limestone Powder On The Properties Of Self-compacting Concrete

In this experiment,cement,fly ash and slag powder were replaced by ultrafine lim estone powder,the substitution rate was 0%,2.5%,5%,7.5%,10%,12.5%and 0%,10%,20%,30%,40%,50%.According to the substitution rate,the test mix ratio of 6 kinds of self-co mpacting concrete was designed in each group,a total of 18 groups of test mix ratio.Effects of ultrafine limestone powder on the working and mechanical properties of self-compacting concrete have been studied.The effects of ultrafine limestone powder on the filling and clearance passability of self-compacting concrete have been studied according to slump expansion and T500、J ring expansion.The effects of ultrafine limestone powder on the basic mechanical properties of self-compacting concrete have been studied according to cube compressive strength test,axial compressive strength test,split tensile strength test and flexural strength test.1.The filling and clearance passability of self-compacting concrete are improved by the appropriate substitution of ultrafine limestone powder.(1)When superfine limestone powder replaced cement,the slump expansion and T500、J ring expansion of self-compacting concrete increased by 4.5%,22.2%and 7.1%,compared with the control group.(2)When superfine limestone powder replaced fly ash,the slump expansion and T500、J ring expansion of self-compacting concrete increased by 3%,28.9%and 4.8%,compared with the control group.(3)Slump expansion,T500、J ring expansion of self-compacting concrete when superfine limestone powder replaces slag powder increased by 3%,15.2%and 3.9%,compared with the control group.2.The proper amount of superfine limestone powder is replaced to improve the basic mechanical properties of self-compacting concrete.(1)The optimum substitution rate of superfine limestone powder for cement was 10%,and the cube compressive strength,axial compressive strength,splitting tensile strength and flexural strength were increased by 13.4%,11.3%,15.3%and 9.6%respectively compared with the control group.(2)The optimum substitution rate of superfine limestone powder for fly ash was 20%,and the cube compressive strength,axial compressive strength,splitting tensile strength and flexural strength were 9.1%,7.3%and 1%higher than those of control group respectively.0.3%and 6.4%.(3)The optimum substitution rate of superfine limestone powder for slag powder was 10%,and the cube compressive strength,axial compressive strength,splitting tensile strength and flexural strength were increased by 5.3%,4.2%,8.2%and 4.9%.3.Through the comparative analysis of the compressive strength of self-compacting concrete and ordinary concrete cube,the early cube compressive strength of self-compacting concrete is greater than that of ordinary concrete.4.Through the analysis of the test strength data of self-compacting concrete with ultrafine limestone powder,the comprehensive fitting curves and fitting formulas of cube compressive strength and axial compressive strength,cube compressive strength and splitting tensile strength,cube compressive strength and flexural strength of self-compacting concrete are obtained.