Research On Mechanical And Shrinkage Characteristics Of Emulsive Regeneration Old Cement Stabilized Macadam

Cement stabilized macadam is the main material for semi-rigid bases of high-grade highways in China.The recycling of old cement stabilized macadam(OCSM)can play an important role in saving construction resources,reducing engineering costs,and also conducive to environmental protection.At present,the use of emulsified asphalt to regenerate old cement stabilized macadam needs in-depth research.For this reason,based on the recycling of OCSM materials,the physical properties of OCSM materials have been tested and analyzed,studied the gradation design method and mixing method of emulsive regeneration old cement stabilized macadam(ER-OCSM)mixture.On this basis,analyze the influence of emulsified asphalt content,age,temperature and other factors on the mechanical and shrinkage characteristics of ER-OCSM and the mechanism of action;The mechanics response law of the ER-OCSM base asphalt pavement structure is studied,the best mix ratio of the ER-OCSM base is analyzed and the determination method is established.Finally,relying on the test road to verify the application effect of the ER-OCSM grassroots.The thesis mainly achieved the following results:(1)After the OCSM milling material is screened,it is shown that the natural gradation exceeds the specification range.Through the gradual filling test,the design method of the OCSM skeleton compact gradation and the best mixing method of ER-OCSM show that the design gradation is basically all In the range of the specification,and the use of compressive strength stability test can effectively verify and discriminate the mixing effect of different mixing methods.(2)As the content of emulsified asphalt increases,the optimal water content of ER-OCSM mixture shows an overall increasing trend,while the water loss rate,dry shrinkage coefficient,and temperature shrinkage coefficient show a gradual decrease trend,and the high temperature zone(40～60℃)The temperature shrinkage coefficient is greater than the low temperature zone;under the same age and temperature,the mechanical performance indicators of ER-OCSM show a gradual decrease with the increase of emulsified asphalt content,and the higher the emulsified asphalt content,the more obvious the decrease;because ER-OCSM has the characteristics of temperature sensitivity,the mechanical performance indicators are all reduced with the increase of temperature.The more emulsified asphalt content,the more obvious the decrease.(3)Under the effect of vehicle traffic load,temperature load and the combination of the two,the bottom stress of the ER-OCSM base layer decreases with the increase of the emulsified asphalt content;the tensile stress at the bottom of the ER-OCSM base layer is simultaneously affected by the temperature shrinkage coefficient and the influence of elastic modulus,for this reason,adding an appropriate content of emulsified asphalt will help improve the ability of the base layer to resist temperature shrinkage and achieve the effect of rigidity and flexibility.However,the content of emulsified asphalt should be controlled.Too much emulsified asphalt content will adversely affect the comprehensive performance of road use.(4)The method for determining the optimal ratio of ER-OCSM was established.The test analysis results verified that the ER-OCSM mixture meets the specification requirements.It also further clarified that the uniformity of the mixture has an important impact on the construction quality.The paper has 66 figures,39 tables,and 90 references.