The Research On Preparation And Properties Of Composite Modified Cold Mix Asphalt Material

With the rapid development of road construction and road maintenance and repair engineering,environmental protection issues have been highly valued by governments and organizations around the world.To this end,the domestic and international road industry continues to rely on the research of Cold Mix Asphalt(CMA)mixture to reduce greenhouse gas emissions and reduce energy consumption.In view of the shortcomings of hot mix asphalt in construction,such as pollution,energy consumption,etc.,based on the existing research results,this paper develops and prepares two kinds of cold mix asphalt materials suitable for different purposes,namely rock asphalt modified polyurethane(MDI).Type CMA material and composite ion emulsified asphalt material.In order to successfully develop these two CMA materials and verify the performance of the mixture,this paper mainly carried out the following work:(1)The MDI performance was studied firstly.The MDI modified asphalt was prepared by using the MDI moisture curing reaction to increase the strength and dissolving the MDI in the asphalt.The three major indexes,rotational viscosity and rheology of MDI modified asphalt were tested by experiments respectively,and the incorporation of MDI was confirmed to be 15%.Through experimental comparison and analysis,it is concluded that the incorporation of MDI has a certain improvement on the low temperature performance of asphalt,and the ductility of base asphalt 5 °C is increased from 89 mm to 180 mm;however,it causes poorer high temperature performance with softening point reducing from 47 ? to 36.8 ?,therefore,the rock asphalt was once again incorporated to improve the high temperature performance of the modified asphalt.(2)The MDI modified asphalt was prepared by the MDI moisture curing reaction principle.Through the test of the three major indexes of modified asphalt,rotational viscosity and rheology,it is determined that the reasonable MDI incorporation is 15%.Tests show that the addition of MDI has a good effect on the low temperature performance of asphalt,but the high temperature performance is poor.In this paper,composite modification is carried out by incorporating rock asphalt to improve the high temperature performance of the modified asphalt.(3)The design and performance evaluation of rock asphalt modified MDI cold mix asphalt mixture was carried out.The laboratory test shows that the mechanical properties,high temperature performance and water damage resistance of the prepared rock asphalt modified MDI asphalt mixture meet the requirements of the specification.The outdoor repair test showed that the road surface was in good condition during the observation period of half a year.(4)Research and preparation of high solid content cationic and nonionic emulsified asphalt.The experimental research shows that the stability of non-ionic type is higher than that of cationic type;the stability and emulsifying properties of the emulsified asphalt which are proportioned by both can be improved.The strength of the composite ion emulsified asphalt mixture can meet the specification requirements and is higher than the cationic emulsified asphalt mixture.(5)Comparison of comprehensive performance of composite emulsified asphalt and rock asphalt modified MDI asphalt mixture.The results show that although the rock asphalt modified MDI asphalt is inferior to the composite ion emulsified asphalt in environmental protection,it is superior to the composite ion emulsified asphalt in initial strength,final strength and preparation process.This paper recommends the use of rock asphalt modified MDI asphalt.The mixture was used as a CMA mix.