Mechanical Properties And Engineering Application Of Cement Stabilized Granules Containing RAP

Plenty of waste asphalt mixture has been producted during construction orreconstruction of highway nowadays, which squanders resources as well aspollutes the environment undoubtedly. On the other hand, semi-rigid base alwaysshows brittle fracture due to its weak tensile strength, this may cause reflectioncracks of pavement and then shorten the service life. Various studies have beendeveloped to investigate the exploitability of wasted asphalt pavement inpavement, and more and more asphalt pavement is reused. The mechanicalevaluating index of cement stabilized base containing RAP is nothing exceptstrength, one indicator is not enough to evaluate the effects of RAP according totheory of mechanics of materials. This thesis is focus on the multi-index systemto analyze the influence of RAP content on tensile mechanical behavior ofsemi-rigid base.1) Experimental study on compaction characteristics and compressive strength ofcement stabilized granules containing RAP was carried out in laboratory. It isfound that RAP content has significant influence on maximum dry density andcompressive strength, and proper amount of RAP is beneficial to improvecompressive strength of the mixture. The relationship between compressivestrength and RAP content was determined by regression analysis. And therecommended appropriate RAP content in semi-rigid base was defined accordingto the requirement on base strength in Specifications for Design of HighwayAsphant Pavement.2) Five indexes, splitting strength, splitting resilient modulus, peak strain, energydensity and brittleness, were taken to evaluate the splitting properties of cementstabilized granules. Four factors, RAP content, test temperature and cementdosage were explored in splitting tensile test. Studies shows that splitting tensilestrength should be the main indicators, peak strain and the brittleness index asauxiliary indicators to evaluate splitting behavior of cement stabilized RAPmaterial. Same time, the relationship between splitting tensile strength andimpact factors was analyzed, tensile strength prediction model which takesaccount of RAP content, test temperature and the age was setup;3) A splitting stress-strain relationship prediction model of cement stabilized granules containing RAP was established. To describe the characteristics ofstress-strain curve in loading state, modified Ramberg-Osgood model and cubicalparabola model were introduced, derivation and fitting results indicates that thecubic parabola model is more suitable to describe the stress-strain behavior ofcement stabilized material containing RAP. further, the determination of modelparameters from splitting strength was obtained. All the above is a posotiveexploration on constitutive relation of semi-rigid base containg RAP;4) A analysis on key technologies of RAP application in actual project wasdeveloped, and the impact of RAP on the mechanical responses of pavementstructure was also analyzed, it is found that mixture containing RAP can improvethe strainedcondition of pavement structure, so that the load transfers moreuniformly and reasonablly.