Segregation Of Asphalt Pavement Construction And Its Control Technology

Asphalt pavement is the main type of pavement in China,the major cause of early damage of road surface is the uneven pavement performance resulting from mixture segregation,temperature segregation and rolling segregation during construction.Therefore,to reduce and eliminate the segregation in each construction link has the important practical significance to improve the quality of asphalt pavement,ensure its performance,prolong the service life of pavement,and reduce the cost of maintenance.The degree of compaction and water permeability coefficient of ATB-25 in the lower layer,the surface layer of Superpave-20 and the upper layer of AC-13,were statistically analyzed,respectively.The transverse distribution law of pavement compactness was analyzed,and the degree of compaction and water permeability coefficient were measured at the same measuring point.Then,the correlation between them was analyzed.The deviation ratio between aggregates passing rate and production mix ratio was calculated by drilling cores from the road,extracting asphalt from them and sieving the aggregate.The segregation degree for asphalt mixture with different nominal maximum size was evaluated.For the asphalt mixtures ATB-25 and Superpave-20 with serious segregation,the method of increasing passing rate at the nominal diameter of the particle and its vicinity was used to reduce the segregation.The results show that the segregation degree for asphalt mixtures ATB-25 with 50% severe segregation,30% moderate segregation and 20% mild segregation can be controlled in the range of 30% segregation and the segregation degree for asphalt mixtures Superpave-20 with 33% severe segregation and 33% moderate segregation can also be controlled in the range of 30% segregation.The temperature segregation of mixture during mixing,transportation,paving and rolling was detected by infrared thermal imaging technology.The temperature segregation degree for asphalt mixture at various stages and the distribution of the temperature was analyzed and the influence of asphalt mixture temperature,ambient temperature,construction machinery on the mixture temperature segregation was studied.The existing construction technology by stirring,transportation,paving,compacting was changed into stirring,transport,paving and compaction construction technique by using transport vehicles.The temperature segregation value was controlled within 15 ? at the beginning of compaction process.Then test the structure depth and evaluate the degree of segregation.The results show that no segregation and mild segregation ratio was 82.5% and 17.5% respectively after two times mixing and without moderate and severe segregation.The lateral distribution,vertical distribution,steel wheel roller width range and compaction degree distribution of adjacent rolling zone was detected by the non nuclear density gauge for pre-compaction of asphalt mixture without rolling.The large width paving of 5m width instead of one paving forming 11 m width and the method of installing V type blade on paver was proposed.The results show that the uniformity of installing the V type blade and the narrow paving is better than that without the V type blade and the width paving.