Preparation Of Bio-based Warm Mix Asphalt And Study On Properties Of Its Asphalt Mixture

Hot Mix Asphalt(HMA)has excellent performance and is the mainstream asphalt pavement material.However,its mixing temperature is high,smoke pollution is large,and excessive construction temperature will also lead to asphalt aging and affect its pavement performance.In contrast,the mixing temperature of Warm Mix Asphalt(WMA)can be reduced by 20 °C ～ 60 °C on the basis of traditional temperature,which can significantly reduce the emission of harmful gases,and the requirement of construction temperature is also low.However,the current mainstream surface active warm mix agent is mostly water-soluble warm mix agent.Because the freezing point of water is 0 °C,the lower ambient temperature will limit the construction.In view of this,this thesis uses bio-based surfactants as the base material to compound bio-based oil-soluble warm mix agent suitable for low-temperature environment construction,discusses the influence of oil-soluble warm mix agent on asphalt performance,evaluates the warm mixing effect of oil-soluble warm mix asphalt mixture,and verifies the reliability of hot mix asphalt mixture for low-temperature environment construction through test road,so as to provide technical support for low-temperature construction of hot mix asphalt mixture in autumn and winter.Firstly,this thesis studies the compound scheme of oil-soluble asphalt warm mix agent based on bio-based surfactant.Nine kinds of surfactants were selected for the compounding of warm mix agents.The three major indicators and contact angle were used as characterization indicators to analyze the effects of surfactant types and dosage on the three major indicators and spreading and wetting behavior of asphalt.The results show that the conventional properties of matrix asphalt are improved by formula 4 and formula 5 bio-based warm mix agent.By comparing the effects of two bio-based warm mix agents on the rheological properties and wetting characteristics of matrix asphalt,the best bio-based warm mix agent formula is determined as formula 4 composed of C-35 and NS-T at 7 : 3.Secondly,the adaptability of bio-based oil-soluble warm mix agent to matrix asphalt and modified asphalt was studied.Taking domestic 70 # asphalt and SBS modified asphalt as the research object,the effects of warm mixing agent on the technical properties,microscopic characteristics,storage aging,rheological properties and fatigue properties of asphalt were investigated.The results show that the addition of warm mix agent can significantly improve the ductility and wetting characteristics of matrix asphalt.At the same time,after 10 days of heat storage,the formula 4 bio-based warm mix agent and the finished formula warm mix agent have an inhibitory effect on the performance attenuation of warm mix asphalt,and the formula 4 bio-based warm mix agent is better than the finished formula warm mix agent in improving the wetting characteristics of asphalt.Moreover,formula 4 bio-based warm mix agent and finished formula warm mix agent can improve the creep recovery rate and high temperature rutting resistance of asphalt.The addition of formula 4 bio-based warm mix agent can significantly improve the fatigue performance of matrix asphalt and SBS modified asphalt.Compared with the warm mix asphalt with finished formula warm mix agent,the anti-fatigue effect is increased by 29.8 % and 79.5 % respectively.Thirdly,the warm mixing effect of asphalt mixture based on bio-based oil-soluble warm mixing agent is studied.The warm mix asphalt mixture was prepared by wet method.The cooling range of asphalt mixture with matrix asphalt and SBS modified asphalt as binder was explored with the optimization of bio-based warm mix agent content as the goal and the void ratio of the mixture as the characterization index.The results show that when the dosage of formula 4 bio-based warm mix agent and finished formula warm mix agent in matrix asphalt is 0.1 % and 0.5 % of asphalt quality respectively,the cooling range of mixture molding can reach 40 °C;when the content of SBS modified asphalt is 0.5 % and 0.8 % of the asphalt mass,the molding temperature of the mixture can be effectively reduced by 30 °C.Finally,the performance difference of bio-based warm mix asphalt mixture was studied,and the feasibility of its construction in low temperature environment was verified by test road.In order to explore the influence of formula 4 bio-based warm mixing agent and finished formula warm mixing agent on the road performance of matrix asphalt and SBS modified asphalt mixture under the two mixing types of conventional hot mixing and warm mixing with30 °C cooling,the dynamic stability,failure strain,freeze-thaw splitting strength ratio and cycle times were used as the characterization indexes,and compared with the original asphalt mixture.The research shows that the formula 4 bio-based warm mix agent can improve the high temperature rutting resistance and fatigue performance of the matrix asphalt and SBS modified asphalt mixture,and still has good low temperature crack resistance and water stability after adding.The performance of the mixture is consistent with the asphalt performance.For the warm mix SBS modified asphalt mixture,the dynamic stability of the formula 4 bio-based warm mix agent was increased by 72.9 %,and the fatigue performance of the finished formula warm mix agent was increased by 18.6 %.Based on the Jiwei expressway project,the feasibility of hot mix asphalt mixture based on bio-based warm mix agent in low temperature environment is verified.