Research And Application Analysis Of Fiber Reinforced Self-Compacting Lightweight Concrete

Self-compacting lightweight concrete（SCLC）combines the advantages of self-compacting concrete without vibration and low weight of lightweight concrete,conforms to the concept of green and sustainable development advocated by the current society,and meets the needs of environmental protection and social development for new building materials.In order to meet the needs of seismic structure,high-rise building and long-span structure for lightweight and high-strength concrete,this paper coarse steel fiber,micro steel fiber,polypropylene fiber,polyvinyl alcohol fiber and basalt fiber into SCLC to improve the brittleness,large shrinkage and uneven distribution of coarse aggregate of self-compacting lightweight concrete.Based on the SCLC benchmark mix ratio,the working performance,homogeneity and corresponding rheological properties of fiber reinforced SCLC with different dosages were compared and analyzed.According to the test results,the maximum dosage of several fibers was determined,and the mechanical properties and dry shrinkage performance of fiber reinforced SCLC were tested.Based on the experimental results of mechanical properties and dry shrinkage performance,a fiber reinforced SCLC with optimal performance is determined.The finite element model of profiled steel plate-fiber reinforced SCLC composite slabs is established,and the influence of stud,shear span and profiled steel plate thickness on the longitudinal shear performance of composite slabs is considered to provide theoretical support for its engineering application.The results of study are shown below:（1）The mix proportion design of SCLC combines the absolute volume method and the fixed sand volume method,and the prepared concrete can satisfied the requirements of working performance indexes SF3 and VS1,and the specific strength reaches 22.3 k N·m/kg.（2）On the premise of meeting the requirements of SF3 and VS1 of self-compacting performance index of fiber reinforced SCLC mixture,the maximum dosage of fiber was determined by combining the rheological properties of fiber reinforced ceramic mortar and the homogeneity of fiber reinforced SCLC.The dosage of coarse steel fiber and fine steel fiber was 0.9%,the proportion of polyvinyl alcohol fiber and basalt fiber is 0.05%,and the ratio of polypropylene fiber is 0.10%.（3）Passing the homogeneity research,the results found that the distribution of fly ash ceramsite in SCLC specimen is uniform and the homogeneity is good.After adding fiber,the floating of ceramsite is restrained,which makes the distribution of fly ash ceramsite more uniform.The addition of fibers could effectively improve the homogeneity of SCLC.（4）The experimental results of mechanical properties of different types of fiber reinforced SCLC show that micro steel fiber has the best effect on improving mechanical properties.Compared with SCLC,the cube compressive strength,axial compressive strength,splitting tensile strength,flexural strength and elastic modulus of micro steel fiber are increased by 28.8%,12.46%,115.22%,95.2%and 17.8%,respectively.The equivalent flexural strength and flexural toughness are increased by 4.6 times and 2.73times,respectively.（5）By comparing the drying shrinkage tests of SCLC and fiber reinforced SCLC,the results show that fiber has obvious inhibitory effect on drying shrinkage.Among them,fine steel fiber has the most dramatic inhibitory effect on drying shrinkage.and the drying shrinkage rate of SCLC specimens reinforced with 0.9%fine steel fiber at 180d is 327.6×10^-6,which is 29%lower than that of SCLC.（6）The finite element model of profiled steel plate-fiber reinforced SCLC composite slab is established.The results show that when the shear span increases from 450 mm to 600 mm,the ultimate load of the specimen decreases by 25.50%and 19.31%for each increase of 75 mm.When the thickness of profiled steel plate increases from 0.8 mm to 1.0 mm,the ultimate load increases by 14.11%,and the mid-span deflection and end relative slip decrease by 6.07%and 13.48%,respectively.With the increase from1.0 mm to 1.2 mm,the ultimate load increases by 10.71%,and the mid-span deflection and the end relative slip decrease by 11.87%and 12.99%,respectively.After adding studs,the ultimate load increased by48.39%,the mid-span deflection decreased by 26.50%,and the end slip decreased by 64.07%.