The Pavement Performance Evaluation Of Crumb Rubber/SBS Composite Modified Asphalt And Mixture

The performance of CR/SBSCMA(crumb rubber/SBS composite modified asphalt)with high content of crumb rubber was further improved by adding a small amount of SBS and a variety of new reactive assistants to CRMA(crumb rubber modified asphalt),which is a modification technology with both social and innovative effects.Firstly,CRMA and SBS modified asphalt SBSMA(SBS modified asphalt)were prepared by wet process.Then the conventional properties,rheological properties,aging properties,micro-modification mechanism,storage stability and mixing properties were compared with CR/SBSCMA.The results show that CR/SBSCMA has better high temperature properties and rheological properties.In the aspect of low-temperature cracking resistance,SBSMA has the best low temperature ductility and CRMA has the best low temperature crack resistance.In terms of aging property,CR/SBSCMA is comparable to SBSMA,both of which are superior to CRMA.In terms of modification mechanism,both CRMA and SBSMA are mainly physically blended,while CR/SBSCMA is physically blended with chemical reactions.Under the microstructure,the crumb rubber particles in CR/SBSCMA,under the action of a variety of reactive assistants,basically disappear the interface between the crumb rubber and SBS,and the surface presents rough and potholes shape,which makes the combination of the three more tight and improves the performance.CR/SBSCMA.thermal stability is better than CRMA and SBSMA,SBSMA is the weakest.CR/SBSCMA has better storage stability than CRMA and SBSMA.At last,on the basis of SMA-13 mineral aggregate gradation,a skeleton dense asphalt rubber concrete for CRMA and CR/SBSCMA was designed,and the performance of designed gradation was compared with that of SMA-13 gradation of SBSMA.The results showed that the optimum proportion of CRMA,SBSMA and CR/SBSCMA were 6.1%,5.6%and 6.3%,respectively.CR/SBSCMA mixture has better high temperature performance and low temperature crack resistance.In terms of water damage,the performance of CR/SBSCMA mixture is better than that of CRMA mixture and weaker than that of SBSMA mixture.In terms of fatigue performance,CRMA mixture is the best,SBSMA mixture is the second worst,CR/SBSCMA mixture is the weakest,and there is no significant difference between the three.The fatigue property of CR/SBSCMA mixture attenuates at the slowest rate with stress.