Research On Application Of Warm Mixing Technology Of Modified Asphalt Pavement In Expressway Tunnel

Highway tunnel modified asphalt pavement construction temperature is usually very high,environmental heat and exhaust gas is difficult to discharge the tunnel in time,causing serious harm to the health of construction personnel and environmental pollution.Asphalt warm mixing technology can effectively reduce the production and construction temperature of asphalt mixture and reduce greenhouse gas emissions,which is of great significance to energy conservation and emission reduction.In this paper,based on the asphalt pavement project of Renmuxin highway tunnel in Sichuan,aiming at SBS asphalt,AC-20 C and SMA-13 mixture,the technical performance and road performance of warm mix modified asphalt are studied by using organic viscosityreducing warm mix agent ACMP-1(dosage is 4%,5%,6%)and surface active agent warm mix agent XT-WY2(dosage is 0.4%,0.6%,0.8%).The action mechanism of warm mix agent was analyzed from the microscopic and molecular perspectives through fluorescence microscope test and infrared spectrum test.The cooling effect of warm mix asphalt mixture was comprehensively evaluated by viscosity-temperature curve method,variable temperature compaction method and variable speed mixing method.The pavement performance of warm mix asphalt mixture was studied.The construction technology of warm mix asphalt pavement is summarized and the road performance is tested.The ambient temperature and gas emission in the paving process of tunnel warm-mixed modified asphalt pavement were monitored on site,and the construction temperature field of tunnel asphalt pavement was constructed.Based on the quota calculation method and carbon emission factor method,the effect of energy saving and emission reduction was quantitatively evaluated,and the economic benefits of warm-mixed asphalt pavement were analyzed.The results show that :(1)Organic viscosity-reducing ACMP-1 warm mix agent changes the technical performance of asphalt,which is characterized by increased penetration and ductility,decreased softening point and viscosity;Surface active agent type XT-WY2 warm mix agent has no obvious effect on asphalt properties;(2)The compatibility of SBS asphalt was improved by the two types of warm mix agents.The hydrogen bond formed by ACMP-1warm mix agent in SBS asphalt released light components,which reduced the viscosity of asphalt,while XT-WY2 warm mix agent and asphalt were mainly physical blending.(3)The two types of warm mix agents both improve the compactness of the mixture and reduce the mixing viscosity of the mixture.Compared with SBS asphalt mixture,the construction temperatures of the mixture after adding ACMP-1 warm mix agent(5%)and XT-WY2 warm mix agent(0.6%)are reduced by 25°C and 20°C,respectively.(4)Both types of warm mix agents slightly reduce the high temperature performance of the mixture and improve the low temperature performance of the mixture,and the low temperature performance of ACMP-1warm mix asphalt mixture is significantly improved;(5)The ACMP-1 warm mix agent was used in the test road,and the dosage was 5% of the asphalt quality.It can effectively reduce the construction temperature by 25°C,and the road performance meets the requirements.Compared with HMA,the construction temperature of tunnel asphalt pavement is reduced by 8.4°C,the energy consumption is reduced by 15.6%,and the carbon emission is reduced by 16.5%,which has good social and economic benefits.