Study On Evaluation Indexes Of Rubber Asphalt And Technology Of Warm Mix Rubber Asphalt SMA Mixture

Waste tire is a resource that contains many ingredients that are beneficial to improving the performance of asphalt.Using waste tire rubber powder to improve the performance of the asphalt,no matter for improving the performance of the asphalt pavement,reducing cost,or in terms of social resource conservation and environmental protection are of great social significance and economic value.However,rubber asphalt technology is still a new technology for China’s highway industry,and due to lack of experience and normative requirements,there are still many technical problems in rubber asphalt binder and mixture composition design,production technology,testing standards,evaluation indexes,construction technology and quality control,etc.In this paper,evaluation indexes and quality control technology of rubber asphalt,technology of warm mix rubber asphalt SMA mixture were studied.This paper through researches on the correlation between penetration and cone penetration in the evaluation of the rubber asphalt consistence,the discreteness of test data and the mechanical principle differences of the experiments,revealed the cone penetration is more scientific and applicable as evaluation index of asphalt rubber of the solid-liquid two phase material,and proposed using cone penetration(25℃)instead of the present penetration as performance evaluation index of asphalt rubber.In addition,through the further researches on the laws,feasibility as evaluation index,and the index range of shear strength of asphalt rubber,firstly proposed in this paper the cone shear strength(25℃)can be used as a technical evaluation index of rubber asphalt.To optimize domestic existing rubber asphalt elastic performance evaluation indexes,the similarities and differences between the elastic recovery and resilience in the evaluation of asphalt rubber elastic properties,differences of test principle,the special influence of rubber asphalt material were researched.The results show that the stress state of rubber asphalt in resilience test is more close to the stress state in actual pavement,and the detection results are not affected by the stress concentration around the powder particles,so resilience(25℃)is more scientific and reasonable in evaluating the elastic characteristics of asphalt rubber.Therefore,the resilience(25℃)was proposed alternatives to the current elastic recovery as evaluation index of elastic properties of rubber asphalt.The existing technology evaluation system of rubber asphalt in our country mainly follows the evaluation system of SBS and other polymer modified asphalt.This paper corrected the existing rubber asphalt technology evaluation system in our country,and put forward a more suitable technology evaluation system for the solid-liquid two phase cementation material of rubber asp halt and a set of corresponding test instruments and test methods.In the construction control,according to the weak control status of the powder content deviation in the production process of rubber asphalt,this paper studied the effects of crumb rubber content deviation on the performance indexes of asphalt rubber and put forward construction control indexes of rubber asphalt.Through the study of Sasobit and surface active agents on the influence of asphalt rubber,the influence characteristics of different warm mix agents to rubber asphalt were obtained,and gave the suggestions of choosing warm mix agent types for rubber asphalt road construction.Through the study of viscosity stability of rubber asphalt and warm mix asphalt,Sasobit can not only reduce the viscosity of rubber asphalt,but also make the viscosity stability of rubber asphalt better,which is conducive to maintaining the stabilities of the material properties and construction process.The types and dosages of warn mix agent,mixing and compaction temperature determination,warm mix process and other issues of rubber asphalt SMA mixture were studied.Research suggests that for the construction of rubber asphalt SMA mixture,according to the variable temperature Marshall compaction test method,Sasobit mixed with rubber asphalt quality of 2% in wet process,can make the rubber asphalt SMA mixture mixing temperature decreased by 20~30℃ than the corresponding hot mix temperature,and the SMA mixture can be produced at the mixing emperature of 150 ~ 160 ℃.And then,the pavement performance and evaluation indexes of Sasobit warm mix rubber asphalt SMA mixture were verified.The mixing technology,production technology and quality control technology of rubber asphalt were studied in this paper.Through theoretical analysis and fluid dynamics simulation,the rubber asphalt mixing equipment and process parameters were optimized.The PID temperature control system was used to control the reaction temperature of rubber asphalt,which improved the precision of temperature control.Finally,paving test road shows,the construction quality of warm mix rubber asphalt SMA mixture met the technical requirements of the project for hot mix asphalt construction,and the effects of energy saving and emission reduction were obvious.Therefore the warm mix construction technology was feasible.