Research On Mechanical Properties Of Machine-made Sand High-strength Fiber Concrete

Rock sand has the characteristics of many edges and corners,fissures,high content of needle and flake,large specific surface area,high content of mud and crusher dust.It has a certain influence on the working performance and strength of concrete,especially in the aspect of high strength concrete,strength and rheological property have become the main contradiction.Considering the characteristics of crusher dust content,using rock sand make up a set of high strength concrete,using the basic mixture ratio,study crusher dust content on the high strength concrete workability and basic mechanical properties,the influence of different crusher dust content can be measured,at the same time,under the stress-strain curve of concrete,fitting out the rising curve of different stone powder content,compared with concrete code.The influence of basalt fiber content on the basic mechanical properties of concrete was studied by adding basalt fiber and steel fiber at 10% and 15% crusher dust content,the influence of the content of steel fiber and the ratio of length to diameter on the basic mechanical properties of steel fiber concrete and the effect on the bending toughness is studied,on the basis of the stress-strain of each experimental group,the dimensionless curve is fitted,and the constitutive structure after fitting is compared with the concrete specification,at the same time,the effects of the content of steel fiber,the ratio of length to diameter,the types of steel fiber and the content of crusher dust on the fracture mechanical properties of steel fiber concrete were studied.For this purpose,this paper has done the following work:(1)By means of orthogonal experimental design,a group of high strength concrete is prepared by means of rock sand.The results show that basic mix ratio of concrete is water cement ratio 0.23,sand ratio 0.41,mineral admixture is slag powder + fly ash + silica powder =20%+10+8%.(2)The effects of five kinds of crusher dust contents on the compressive strength,workability,tensile strength,axial compressive strength,elastic modulus and flexural strength of concrete were studied.and the dimensionless stress-strain curves of concrete with different crusher dust contents are fitted.The results show that the workability and compressive strength of the concrete are improved by 7%～10% crusher dust content in high strength concrete.With the increase of crusher dust content,the static compression elastic model of concrete gradually decreases,but all of them are greater than 48,000 MPa.With the increase of crusher dust content,the flexural strength of concrete decreases.For the axial compressive strength,5% crusher dust content is the best for the axial compressive strength.The curve of the curve of the ascending segment is more conservative than concrete code.(3)The workability and basic mechanical properties of basalt fiber and steel fiber at 10% and 15% respectively were studied.The results show that with the increase of the content of two kinds of fibers and the decrease of workability,the concrete mixture will produce viscosity and agglomeration.As the content of steel fiber increases,the compressive strength increases,and the tensile strength of steel fiber is the best under the content of 0.6%.The bending toughness of steel fiber increases with the increase of steel fiber,the increase of crusher dust content makes the bending toughness decrease,and the axial compressive strength increases with the increase of steel fiber content.For basalt fiber,the increase of dosage,reduce the compressive strength,tensile strength,flexural strength,axis pressure resistance is reduced,elastic modulus is best when 3kg/m3,and rock tensile strength is reduced,at the time of 3kg/m3 exceeded 10% of crusher dust content tensile strength,flexural strength,the flexural strength of The fracture performance of steel fiber concrete was evaluated by fracture toughness and fracture energy,and the effects of steel fiber content,steel fiber length-diameter ratio and stone powder content on the fracture mechanical properties of concrete were studied.Fiber content increases,fracture energy and fracture toughness increase,the greater the length to diameter ratio of steel fiber,the better the fracture energy and fracture toughness,crusher dust content increases,fracture energy and fracture toughness increase,but with increasing of crusher dust content makes the fiber dosage on fracture energy and fracture toughness increase amplitude is reduced,the destruction of the steel fiber reinforced concrete stage can be divided into three stages: stage of crack,crack extension stage and failure stage.steel fiber content increase axial compressive strength is reduced,the static compressive elastic modulus maximum when 3kg/m3,The fitting curve of dimensionless stress-strain curve is more conservative than concrete code.(4)The fracture performance of steel fiber concrete was evaluated by fracture toughness and fracture energy,and the effects of steel fiber content,steel fiber length-diameter ratio and crusher dust content on the fracture mechanical properties of concrete were studied.Fiber content increases,fracture energy and fracture toughness increase,the greater the length to diameter ratio of steel fiber,the better the fracture energy and fracture toughness,crusher dust content increases,fracture energy and fracture toughness increase,but with increasing of crusher dust content makes the fiber dosage on fracture energy and fracture toughness increase amplitude is reduced,the destruction of the steel fiber reinforced concrete stage can be divided into three stages: stage of crack,crack extension stage and failure stage.