Research On Compressive Mechanical Properties Of Crumb Rubber Concrete Based On Meso-Simulation

Crumb rubber concrete is a kind of green concrete,which can improve the durability of concrete.The rubber in crumb rubber concrete mainly comes from waste rubber tires,which can solve the inherent brittleness of concrete to some extent and improve the toughness and impact resistance of concrete by adding it as aggregate after processing.Based on the meso analysis method,the generation algorithm of rubber concrete is completed through computer programming language,and the two-dimensional meso structure of rubber concrete composed of multiphase materials is established.Aiming at the main influencing factors of rubber concrete strength,the rubber concrete is numerically studied,and the effects of meso phase components such as rubber,mortar and rubber mortar interface area on the macro mechanical properties of concrete are analyzed,The specific research and analysis work is as follows:(1)Based on the theory of maximum density curve and the basic principle of Monte Carlo method,the algorithm of mixed aggregate generation and random throwing is put forward and written in Python language.And the algorithm can be directly embedded into ABAQUS without any other software such as CAD to generate a two-dimensional meso-structure of numerical crumb rubber concrete "specimens",which is closer to the real structure,composed of four-phase materials,such as natural stone aggregate,hardened cement mortar and rubber particles,as well as the interfacial zone between rubber and mortar.These specimens satisfies homogeneity,randomness and meet the requirements of numerical calculation.(2)The two-dimensional random aggregate model of crumb rubber concrete with different aggregate distribution is subjected to the uniaxial compression numerical test.The results show that although the calculated results are different due to the different distribution of random aggregate in the model,the relative errors are less than 10%,which shows that the model algorithm is stable and reliable.By comparing the simulation results with relevant tests,the effectiveness and accuracy of the calculation model are further verified.(3)Uniaxial compression damage numerical tests were carried out on 5%,10% and 15%rubber replacement ratio numerical concrete "specimens" to study and analyze the stress-strain behavior of rubber concrete at different rubber content.The results show that the stress-strain curve of rubber concrete is similar to that of ordinary concrete.Compared with ordinary concrete,the uniaxial compressive strength of rubber concrete is reduced by 18%～30%,the peak strain is increased by 20%～70%,and the decrease/increase increases with the increase of rubber content,which makes the curve more "short and fat".By comparing the results of meso-simulation and macro-test,the damage mode of rubber concrete under uniaxial compression is similar to that of ordinary concrete.The damage zone starts from the weakest interfacial zone and gradually converges to the hardened mortar zone around the aggregate at an angle of 45 degrees from the height edge of the specimen,thus forming a macro-crack which destroys the integrity of the specimen.However,the peak strain and ultimate strain of rubber concrete are larger than that of ordinary concrete.The stress-strain curve is relatively flat without obvious brittle failure but presents a "progressive" ductile failure characteristic.(4)Variable parameter analysis was carried out on the "specimen" of 1-3 mm and 3-6 mm rubber particle groups at 5%,10% and 15% rubber substitution rates respectively.The structure shows that the replacement ratio of rubber and the strength of mortar have a significant influence on the strength of rubber concrete,while the particle size of rubber and the strength of interfacial transition zone have a slight influence on the strength of rubber concrete.When the strength of mortar decreases by 10%,the overall compressive strength of the specimens with small particle size group decreases by 2.48%～8.88%,while that with large particle size group decreases by 4.11%～13.52%.When the interfacial strength decreases by 10%,the overall compressive strength of the specimens with small particle size group decreases by6.23%～10.85%,while that with large particle size group decreases by 3.75%～10.47%.Mechanical properties of small-particle rubber group specimens are significantly better than that of large-particle rubber group specimens.When the strength of mortar increases by 20%,the overall compressive strength of the specimens with small particle size group increases by7.44%～14.04%,while that with large particle size group only increases by 3.02%～8.10%.When the interfacial strength increases by 20%,the overall compressive strength of the specimens with small particle size group increases by 8.15%～11.89%,while that with large particle size group only increases by 3.23%～8.41%.