| The Gravel seal is more economical and improves the pavement performance.It is widely used in road maintenance projects at home and abroad,but there are some problems such as broken stone peeling and poor durability.The main reason is that the adhesive property of asphalt is insufficient.Therefore,this paper selected water-based epoxy emulsified asphalt to prepare the gravel sealing layer,characterized the bonding force between water-based epoxy emulsified asphalt and aggregate,and evaluated whether the application of water-based epoxy emulsified asphalt in the gravel sealing layer could solve the problems of stone spalling and poor durability.The main research contents are as follows:(1)Based on tensile test and fluorescence microscopy test,the optimal ratio of water-based epoxy emulsified asphalt was explored.The dosage of water-based epoxy resin,curing agent and emulsified asphalt was determined.The results show that the optimum dosage ratio of aqueous epoxy resin,curing agent and emulsified asphalt is 1:3:3.(2)Based on universal testing machine and self-designed test fixture,drawing and direct shear tests were carried out on water-based epoxy emulsified asphalt,SBS emulsified asphalt and ordinary emulsified asphalt,and the different bonding forces between different emulsified asphalt and the effects of stone type,test temperature and loading rate on their bonding forces were studied.In order to solve the problem that the drawing and direct shear tests can not simulate the contact state between emulsified asphalt and aggregate,the"impact"test and"twisting"test were designed to evaluate the bonding force of the gravel sealing layer according to the test methods of low temperature impact test and twisting loose test,and the related parameters such as the material ratio of the gravel sealing layer and sample production were optimized.The"removal rate"and"twisting loss rate"were put forward as the evaluation indexes of its bond strength.(3)Based on the test method designed in this paper,the adhesive properties of water-based epoxy emulsified asphalt gravel sealing layer were evaluated and studied.The results show that the test results of drawing,direct shear test,impact test and twisting test are consistent.The larger the drawing and shearing strength between emulsified asphalt and stone,the smaller the"stone removal rate"and"twisting loss rate".The drawing strength,shear strength,"stone removal rate"and"screw loss rate"of water-based epoxy emulsified asphalt are 0.76MPa,0.45MPa,16.4%and 34.9%,respectively,which increase the bonding performance of SBS emulsified asphalt and ordinary emulsified asphalt by more than 20%.According to the evaluation results of the bond strength of the gravel sealing layer,the optimal ratio is as follows:the dosage of water-based epoxy emulsified asphalt is 1.4kg/m~2,and the dosage of limestone is 7kg/m~2.(4)Based on the BPN value and structure depth of the gravel sealing layer under different wear times in the accelerated loading wear test and the accelerated loading wear test after ultraviolet aging,the durability was studied.The results show that the BPN value and structure depth of water-based epoxy emulsified asphalt in the wear process are about 15%higher than those of SBS emulsified asphalt and common emulsified asphalt.By comparing the test results of the gravel sealing layer after ultraviolet aging with those of the non-aging gravel sealing layer,it can be found that the effect of ultraviolet aging on the water-based epoxy emulsified asphalt gravel sealing layer is minimal,which indicates that its durability is better.In summary,it can be seen that the application of water-based epoxy emulsified asphalt in the crushed stone sealing layer can improve its bonding property and durability,and is a very ideal bonding material. |
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