Quartz sand gradation effect of ultra-high performance concrete
Two schemes of single grain gradation and continuous gradation are designed,the effects of quartz sand grade on mechanical properties and microstructure of ultra-high performance concrete(UHPC)were studied.The microstructure and pore structure of UHPC samples prepared with different quartz sand gradations were analyzed by SEM and mercury injection method.The results show that when the maximum particle size of quartz sand is less than 0.63 mm,the flexural strength of UHPC increases with the increase of the maximum particle size of quartz sand,but when more than 0.63 mm,the flexural strength decreases with the increase of the maximum particle size.When the maximum particle size of quartz sand is the same,the flexural strength of UHPC prepared by continuous grading is higher than that of single grading.The compressive strength of UHPC increases with the increase of the maximum particle size of quartz sand,and the compressive strength of UHPC prepared by continuous graded quartz sand is higher than that of single particle gradation.The porosity of UHPC decreases with the increase of the maximum particle size of quartz sand.When the maximum particle size is the same,the UHPC prepared by continuous graded quartz sand has lower porosity and more reasonable pore size distribution,which is the reason for its excellent macroscopic mechanical properties.
gradingultra high performance concretemechanical propertiesporosity
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