Experimental Study On Basic Mechanical Properties Of Rubber-basalt Fiber Concrete

Recently,the state has accelerated the recycling and utilization of waste tires.In 2021,The State Council issued the Guiding Opinions on Accelerating the Establishment and improvement of green low-carbon circular development Economic System,putting forward new requirements for the recycling and utilization of waste tires and other renewable resources.Nowadays,a large number of domestic and foreign scholars engaged in research of comprehensive utilization of waste rubber,and combining the waste rubber concrete with application is the most effective one way,not only consume large amounts of waste tyres,promote resource recycling,scrap tire damage the environment problem is solved,and can improve the concrete performance of energy consumption.This article is using rubber to replace part of natural sand as fine aggregate,with 5%,10%and 15% of the volume ratio of mixed with rubber particles,the fiber volume rate method is adopted and all material volume of 0.1%,0.2% and 0.3% of basalt fiber,the introduction of fly ash admixture,set the replacement of rubber,rubber mesh,basalt fiber volume rate of three variables,Based on the mixture ratio of C30 concrete,rubber-basalt fiber concrete with high rubber utilization rate and good performance was prepared,and its compressive performance test was carried out to clarify the influence of rubber particles and basalt fiber materials on concrete performance and basic mechanical strength and the law.The main research results are as follows :(1)the addition of rubber particles and basalt fiber significantly affects the working performance of concrete,the increase of friction between fiber and sand,the roughness of rubber surface and water absorption,will greatly reduce the working performance of concrete.Adding 0.45(kg/m3)high efficiency water reducing agent can effectively improve the performance of rubber-fiber concrete.(2)The cube compressive strength and axial compressive strength of rubber-fiber concrete decrease significantly with the increase of rubber replacement rate.At the age of 28 days,the axial compressive strength value is about 68% of the cube compressive strength value,which conforms to the numerical variation rule between the cube compressive strength and the axial compressive strength of ordinary concrete.(3)When the fiber volume ratio is reasonable,the fiber can improve the compressive strength of rubber-fiber concrete cube specimen,but when the fiber volume ratio exceeds 0.2%,the compressive strength is weakened to some extent,and the overall compressive strength increases first and then decreases with the increase of fiber volume ratio.(4)The flexural strength of rubber-fiber concrete decreases significantly with the increase of rubber content,but increases significantly with the increase of fiber volume ratio.However,excessive rubber content can weaken this strengthening effect.When the fiber volume ratio increases from 0.2%to 0.3%,the flexural strength of rubber-fiber concrete plummets and is even far lower than that of reference concrete.On the other hand,the rubber mesh has no obvious effect on improving the flexural strength of rubber-fiber concrete.(5)Through the failure mode analysis of specimens,it is found that after the compression and flexural tests,the surface crack width of rubber-fiber concrete specimens is smaller than that of ordinary concrete specimens,and the overall damage degree of the specimens is lighter and the preservation is relatively complete.(6)The elastic modulus of rubber-fiber concrete decreases with the increase of rubber replacement rate,and increases with the increase of fiber volume rate and rubber mesh.The results show that the concrete with 40 mesh 5% rubber replacement ratio and 0.2% fiber volume ratio has the best comprehensive properties.