Performance Analysis And Quality Control Of Rubber Self-compacting Concrete

With the development of industry,there are more and more waste rubbers.How to effectively and environmentally deal with waste rubber is the focus of current research.One of an effective treatment methodis adding waste rubber into concrete to improve the deformability of concrete by using rubber elastic properties.However,compared with normal concrete,the strength of rubber concrete is lower than that of normal concrete.By contrast,self-compacting concrete has the advantages of large amount of cementation and high strength,but the disadvantage is the large shrinkage.As a result,this paper proposed a novel self-compacting concrete combined with waste rubbers,which can not onlyimprove the strength of self-compacting concrete but also reduce the shrinkage performance of self-compacting concrete.Consequently,rubber self-compacting concrete has a wide range of application prospects.This paper conducted 41 groups of 123 cubic compressive tests,26 groups of 78 flexural tests and 26 groups of prisms were subjected to compressive stress-strain curves,which are taking rubber content and rubber particle size as the main factors.As a result,the prediction formula for the compressive strength of rubber self-compacting concrete cubes,the prediction formula of prismatic bending strength and the stress-strain constitutive relation of compression are fitted by means of the factor comparative analysis and the least-squares method.Finally,according to the test results and the investigation of construction site,this paper proposed the quality control measures for rubber self-compacting concrete.The main conclusions list as follows:(1)With the incorporation of rubber,the flow of self-compacting concrete decreases.In addition,the flowability of rubber self-compacting concrete also sharply decreases,with the increase of rubber content.Furthermore,the smaller the rubber particle size is,the more the flowability of rubber self-compacting concrete decreases.(2)This paper conducted cubic compression tests for 7 days,28 days,60 days,and 90 days,respectively.The results show that the strength of the concrete increased with the age,but the strength of the concrete became stable at 60 days.Based on the experimental results,this paper regressed the cube strength prediction formula by means of the least squares method.In addition,this paper fitted the relationship between the strength in 28d and in 7d,the strength in 60d and in 7d,respectively.(3)With the increase of rubber content,the strength of rubber self-compacting concrete rapidly decreases,by the contrast,the folding pressure ratio increases.However,when the rubber particle size is 1 to 2 mm,the reduction range is relatively small,and the folding ratio is relatively large.Based on the predictive formula of compressive strength of rubber concrete,this paper regressed the prediction formula for the flexural strength of rubber self-compacting concrete.(4)With the increase of the rubber content,the peak strength of the stress-strain curve of the self-compacting concrete prismatic prism specimen decreases,but the decreasing segment of the curve becomes flatter.Based on the experimental results,this paper fitted the axial stress-strain relationship constitutive model of rubber self-compacting concrete.(5)The surface of rubber and concrete was analyzed by electron microscopy.The results show that there are cracks at the interface between rubber and concrete,and rubber-removed holes are left on the concrete’s failure surface.this indicates that the bond between rubber and concrete is the main reason for the decrease in the strength of rubber concrete.(6)This paper proposed the rubber self-compacting concrete quality control measures.It is recommended that the rubber particle size should be selected from 1 to 2 mm.In addition,the rubber content should be controlled within 40%.Furthermore,the mixing and feeding sequence should be fine aggregate sand,rubber particles,cementitious materials,and gravel in turn.According to the research on the rubble self-compacting concrete,this paper provide reference for the promotion and application of rubber self-compacting concrete.