| In order to solve the problem that the initial strength and forming strength of cold patch asphalt mixture for pavement repair are low,and it can’t be constructed under the condition of wet pothole or water accumulation,at the same time,because the traditional cold patch asphalt mixture mostly uses petroleum products as diluent,it will cause energy waste,environmental pollution and other problems.In this paper,a bio-based cold patch agent was developed by using bio-oil as diluent,and bio-based cold patch asphalt and its mixture were prepared,which can effectively solve the above problems.At the same time,the strength characteristics and road performance were studied.The thesis enriched the related research from domestic and abroad.In this paper,bio-based cold patch agent was prepared by using bio-oil and additives,and it was added to 70~#asphalt to prepare bio-based cold patch asphalt.Two types of mineral aggregate gradation were selected to prepare bio-based cold patch asphalt mixtures.In order to shorten the strength formation time and improve the strength,we mixed the curing agent with water to promote the strength formation,and finally obtained two kinds of gradation types of water reaction type bio-based cold patch asphalt mixtures.In this paper,the viscosity,flash point,adhesion grade and anti-aging performance of bio-based cold patch asphalt were tested,then the technical performance of bio-based cold patch asphalt was analyzed.The effects of curing agent,water consumption and other factors on the bio-based cold patch asphalt mixture were analyzed by workability test,cohesion test and strength test.Afterwards,a set of evaluation methods and evaluation indexes for the performance of bio-based cold patch asphalt mixtures were proposed.Finally,through the repair of the test section,the actual road effect of the bio-based cold patch asphalt mixtures was verified.The results show that:(1)The optimum ratio of two bio-oils is bio-oil 1:bio-oil 2=20:80,and the optimum amount of bio-oil diluent is 35%.(2)The storage stability of bio-based cold patch asphalt at room temperature is excellent,and there is no component volatilization.When the temperature is 30°C,the viscosity of bio-based cold patch asphalt is 18.3Pa s,which follows the ideal compaction viscosity range in“The Shell Bitumen Handbook”.When the temperature is 60°C,the viscosity is 1.4Pa s,which can be used for production,at the same time,the aging test results show that after 24h at 100°C,the viscosity of the bio-based cold patch asphalt increases by nearly twice,so the temperature should be avoided to reach 100°C.(3)The strength test results show that the addition of curing agent can significantly improve the strength of cold patch asphalt mixtures.Before adding curing agent,the strength of bio-based cold patch asphalt mixtures is equivalent to that of petroleum cold patch asphalt mixtures.After adding curing agent,the strength increases by 2～5 times.(4)The optimum water consumption of the bio-based cold patch asphalt mixture is 8%of total mass of the mixture.The water consumption test results show that the optimal water consumption of the biological system cold patch asphalt mixture is 8%of the total mass of the mixture.If excessive water is used,the strength will be reduced by 23%.The results of immersion Marshall test show that the strength of the repaired road block can be increased by 15%by sprinkler maintenance after forming.(5)The forming strength of bio-based cold patch asphalt mixture is 9 times that of petroleum-based cold patch asphalt mixture,and the dynamic stability at 40°C is much higher than that of petroleum-based cold patch asphalt mixture. |
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