Experimental Study On Compressive Properties And Flexural Performance Of Steel Polypropylene Hybrid Fiber Reinforced Lightweight Aggregate Concrete

Lightweight aggregate concrete as coarse aggregate is the use of lightweight aggregate concrete,it had better heat preservation,fire resistance,seismic resistance and durability.Because of the use of industrial waste in the production of lightweight aggregate,accord with the concept of green building.However,light aggregate concrete has the defects of brittleness and low intensity,which is not conducive to the large-scale application of practical engineering.In this thesis,based on the improvement of the brittleness of lightweight aggregate concrete,steel fiber and polypropylene fiber were chosen to mixed into the test combined with the research achievements of steel fiber and polypropylene fiber lightweightaggregate concrete tostudy the effects of steel-polypropylene hybrid fibers on the performance and flexural strength of lightweight aggregate concrete when the steel fiber shape is corrugated and end hook shape,steel fiber volume rate is 0 to 1.5%,steel fiber aspect ratio is 30,45,60 and 80,polypropylene fiber content is 0 to 1.2kg/m~3.The main contents and conclusions are as follows:(1)In order to analyze the influence of various factors on the working performance(slump)of lightweight aggregate concrete,orthogonal test was used.Through the analysis of the range and the variance analysis,the conclusion was drawn that for the slump of mixed fiber lightweight aggregate concrete,the effect of each factor from was strong to weak as follow:steel fiber's shape?steel fiber's aspect ratio.?polypropylene fiber's contents The mixing of steel fiber and polypropylene fiber reduces slump of lightweight aggregate concrete.(2)In order to study the Cubic Compressive Strength Test,16 groups of(each group of three test pieces)steel-polypropylene fiber lightweight aggregate concrete test block were designed by the method of orthogonal test.By analyzing the research results show that the compressive strength of hybrid fiber reinforced lightweight aggregate concrete cube factors from strong to weak is:the steel fiber volume ratio and dosage of steel fiber and polypropylene fiber aspect ratio,and get the optimal dosage of fiber combination:volume at a rate of 1.5%,45 fiber and the volume content of length to diameter ratio of 0.6kg/m3 of polypropylene fiber mixed.Using SPSS software for linear regression analysis,the compressive strength relationship of hybrid fiber lightweight aggregate concrete was proposed.(3)Orthogonal test was used to design 16 groups of(3 of each group)of steel-polypropylene fiber lightweight aggregate concrete specimens.According to the three-point loading beam in the Fiber Reinforced Concrete Test Method(CECS 13:2009),the anti-bending strength test was conducted for each group of specimens,and the anti-folding strength and anti-flexural modulus were obtained.Discussed the different fiber content of lightweight aggregate concrete flexural strength and flexural modulus of elasticity,the influence of the flexural strength was obtainedthe optimal dosage of fiber combination:volume at a rate of 1.5%,80 the fiber and the volume content of length to diameter ratio of 0.6 kg/m3 of polypropylene fiber mixed.The hybrid effect of mixed fiber concrete was analyzed by using the method of defining mixed effect coefficient.Regression analysis by SPSS software,fitting for hybrid fiber reinforced lightweight aggregate concrete,the flexural strength formula of flexural strength and flexural modulus of elasticity,flexural strength and compressive strength of the relationship between,provide reference for actual project in the future.