| With the phenomenon of natural sand being non-renewable,gradually decreasing,decreasing in quality,and increasing in price,machine-made sand has emerged at the historic moment.Its production can be obtained from local raw materials,which saves costs,and at the same time,the quality is controllable and stable,therefore,the application of mechanical sand in concrete is an inevitable trend.At present,domestically applied manufactured sand concrete is generally C30～C60,in contrast,C80 manufactured sand concrete has less research and application.In order to improve the performance of manufactured sand concrete with high strength and improve its strength,this paper selects a variety of high-performance mineral admixtures to prepare and study high-strength and high-performance manufactured sand concrete.Focused on the following work:First,by studying the effects of different amounts of mineral admixtures,under different ages(3d,7d,28 d,56d,90d),analyse the single-mixed S105 slag powder,microbeads,silica fume and double-mixed S105 slag powder,or microbeads or silica fume on the change trend of workability and mechanical properties of cement-based materials,then the specific strength method is used to infer the activity effect of different age mixed with different proportion of mineral admixtures,the specific strength and activity effect indicators are used to infer the strength contribution rate of single and double mineral admixtures to the internal activity effect of cement-based materials,and get a better mineral admixture ratio.The results show that the increase of S105 slag powder content has a positive effect on the active effect of cement-based materials,and gradually increase with the increase of the amount of S105 slag powder,when the content of S105 slag powder is25%,the active effect ratio and strength contribution effect reach a better level.When the ratio of cement: S105 slag powder: microbeads is 15: 4: 1,the activity of the cement matrix is better.Secondly,the orthogonal test design of high-strength and high-performance manufactured sand concrete sand concrete is carried out with a better mineral admixture ratio,under thecube compression test and split tensile test,investigate the changes in the workability,compressive properties,and split tensile properties of high-strength manufactured sand concrete under different orthogonal test mix ratios in each group;At the same time,the workability,compressive performance and splitting tensile performance of high strength and high performance manufactured sand concrete with different silica fume content were studied.Finally,the optimal ratio of S105 slag powder are adopted and the water-binder ratio,sand ratio,and amount of cementitious material determined by orthogonal experiment are adopted,test of single-mixed S105 slag powder under different stone powder contents in the mechanism sand and the experiment of double-mixed S105 slag powder and different admixtures when the content of stone powder in the mechanism sand is constant,the workability and mechanical properties of C80 high-strength manufactured sand concrete and their changes trend in drying shrinkage were studied.The result shows that when the stone powder content in the mechanism sand is 6%,the C80 manufactured sand concrete has the best workability and strength effect,increasing the stone powder content will make the concrete workability worse and the compressive strength will decrease.Compared with single-mixed S105 slag powder,when the double-mixed S105 slag powder and microbeads,the early compressive strength first increases and then decreases,when the double-mixed S105 slag powder and silica fume,the early compressive strength decreases,the 28 d compressive strength increased by 11.5% and 14.2% respectively,the 60 d compressive strength increased by 8.6% and 10.7% respectively.In addition,the double-mixed S105 slag powder and ultra-fine powder may cause the C80 manufactured sand concrete compressive strength to shrink. |
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