Investigation And Analysis On Diseases Of The Asphalt Overlay On The Urban Pavement

Because of the advantages of asphalt pavement, the way of paving asphalt surface on city old concrete roads are more and more popular.Especially the characters of short construction perid and comfort are fit for the roads reconstruction. Wuhan brushed almost all old roads between 2002-2005,and the completion of the reconstruction had brought significant improvements to the city's image and traffic quality.At the same time, as time went on,many fatigue damage apeared,and the speed of expansion of the cracks are so high that the control to the damage became useless.For the different traffic type and construction cycle,the characteristics and mechanism of destructionurban of urban roads are different from the highway.And domestic research are focused on the highway diseases.Take several main roads of Wuhan City for sample, we have carried out systematic survey and analysis about their disease. Survey showed that crack and deformation disease were particularly common, most of the crack diseases were performed as the reflective-crack;In this paper,We take Hongshan Road, Wuluo Road, Guanshan Road, Jiefang Road, Jianshe Avenue, Zhongshan Avenue, Baishazhou Bridge, the Yangtze River I bridge and the Yangtze River Bridgeâ…¡for research object.Based on investigation and theoretical analysis as well as relevant experience in construction design, we do experiments to the sample,then we did some research and analysis to the common diseases which caused great harm to the urban roads.Our research work and main results are as follows:1.Take survey to the nine roads, list PCI values and the individual disease comparison chart of each roads. Statistics show that crack and deformation disease were major disease among these roads.The quality gap between each roads is large. Deformation diseases were mainly performed as rut,which was consistent with urban traffic feature:slow traffics,uncertain direction,multi-lane traffic,lots of start and brake. Compared to highways, urban roads rut are more serious and groove are deeper.and its distribution is more acattered.Rut has the highest frequency at the bus stations and cross roads.2. We drilled 102 samples in all.It showed that 90% of the cracks are reflective cracks. There are so many differences between base of highway and urban roads which determine that the type and distribution of highway and urban roads diseases have great differences.3.Strength and water-stability test results show that the mixture's strength and water stability achieve standard and do not adversely affect the cracks and pits. Asphalt mixture were compacted well, but several roads with much traffics show uneven thickness and uneven mineral. Thick and complex asphalt pavement take negative affect on the forming of the rut.4. Combined with the experience of domestic processing to the asphalt concrete pavement and the theoretical analysis,We have confirmed the reflective-cracking's harm and universality,it should be viewed as the most important part of the design;We also make a brief analysis about the relationship between water damage and cracks & pits.asphalt mixture's compaction is essential for the prevention of water damage.