Experimental Study On Preparing Lightweight & High Strength Concrete With Fly Ash

The future development direction of concrete includes light weight,high strength,energy conservation,environment,environment protection and good durability.Use high carbon content fly ash sintered ceramsite as lightweight aggregate,Use low carbon content,active fly ash as mineral admixture partly replace cement as cementing material.The use of lightweight,high strength concrete is an effective way to achieve large-scale utilization of fly ash in the western region of China.In this dissertation,by using ceramsite as coarse aggregate,and partly replacing cement with mixed grade?fly ash and ultra-fine fly ash?average particle size of 4microns?as cementing material,lightweight aggregate concrete?UL?was prepared.The mechanical properties and dry apparent density of lightweight aggregate concrete were optimized by orthogonal test method,and the durability and microstructure were studied by using the method of design control test with,the lightweight aggregate concrete?L?not blended with ultra-fine fly ash,the ordinary concrete?CC?with the same mixture ratio design,the ordinary concrete?CS?with the same strength grade.The result shows:According to the method of orthogonal test,the mechanical properties and dry apparent density of lightweight aggregate concrete was optimized,and the proportion of the optimal lightweight aggregate concrete was designed as 480kg·m^-3 cementing material?with the fly ash content is 40%?,the ratio of grade?fly ash to ultra-fine fly ash is 1:1,the sand ratio is 30%,and the water-binder ratio is 0.28.The 28-day compressive strength of the light weight aggregate concrete is 56.4MPa,and the dry apparent density is 1790kg·m^-3.According to the compressive strength and corrosion resistant coefficient,the performances of the above four kinds of concrete against sulfate attack are:CC>CS>UL>L.It is indicated that the ordinary concrete has a higher sulfate attack resistance than the lightweight aggregate concrete,and the admixture of the ultra-fine fly ash could improve the sulfate attack resistance performance of lightweight aggregate concrete.The freezing and thawing cycle test showed that the abilities of the concretes against freezing and thawing:CC>UL>CS>L.It is indicated that the admixture of ultra-fine fly ash could improve the resistance freezing and thawing ability of lightweight aggregate concrete.Pore structure analysis showed that the blending of ultra-fine fly ash made the internal pore structure of lightweight aggregate concrete concentrated under1000?,which reduce the content of the pore between 1000?.and 2000?in concrete.