A Study On High-performance Emulsified Asphalt Cold Recycled Mixture Development

As most of the highway in China have been developed into a wide range of repair phase gradually,emulsified asphalt cold recycling technology helps improve the quality of the original road,eliminate the pavement diseases,reduce the reflection crack,and has good economic and environmental benefits.But in practical engineering,the application of cold recycled mixture has many problems,such as bad construction workability,low early strength and poor service performance.Aiming at the problems of emulsified asphalt cold recycling technology in China,high-performance emulsified asphalt cold recycled mixture development had been studied systematically,the main work and conclusions are as follows:(1)Eight kinds of emulsified asphalt had been developed by the optimization and composite of the emulsifiers,adding a stabilizer,the use of modified materials and other means.Original formulations of emulsified asphalt that applicable for cold recycling,had been determined through the test studies of the sieve remaining amount,breaking speed,storage stability,mixing performance with cement and the indicators of modified asphalt emulsion residue.(2)The working time,early performance and mechanical properties of different emulsified asphalt formulations of cold recycled mixture were evaluated,and the suitable process,conditions and application layer of each emulsified asphalt formulations,were analyzed.Test shows that: the emulsified asphalt cold recycled mixture with domestic emulsifier E1 type,import emulsifier E4 type and composite emulsifier E5 type emulsified asphalt formulations got better workability,asphalt emulsion used e4 as raw material modified with WE and SBR got higher bond strength and early strength,but the working time was reduced to 2h.(3)The technical indexes of reclaimed asphalt pavement was analyzed,and considering the variability of the RAP gradation,the better aggregate synthesize gradation of cold recycling mixture was suggested.The molded specimen compacted with SGC got higher density and strength was checked by different laboratory test comparison analysis.The optimum water determined by SGC was 0.2% lower than heavier compaction.Considering the impact of different construction site conditions,the Marshall compaction molding and curing methods of cold recycling mixture was amended.(4)The road performance of cold recycled Mixture was studied.The rational use of modified materials were able to improve the water stability,high temperature stability and temperature sensitivity of cold recycled mixtures.But the viscoelastic property was declined by the increase of WE amount,and the low temperature brittleness of cold recycling mixture was larged,this disadvantage was balanced composited with SBR.(5)The initial stage of cold recycled mixes bonding capacity was enhanced by the increase of emulsified asphalt,but the strength of the performance was reduced when the amount exceeded 4.5%.The strength,high temperature stability resistance,compressive resilient modulus of cold recycled mixture were improved when the amount of cement increased from 0% to 3%,but the low temperature crack resistance was reduced after the initial increase on the turnning point of 2%.The intensity and dynamic stability of cement emulsified asphalt cold recycled mixtures was improved substantially in combination with WE and SBR.(6)Combined with the Cold In-plant Recycling engineering cases,the emulsifiedasphalt cold recycled mixtures that designed systematicly had excellent workability,early strength and road service performance was validated,the engineering quality of cold recycled mixture was ensured by the control of construction key technology.