The last issue talked about the problems of oil spills, waves and gnawing edges on asphalt pavement and how to deal with them. Today I will mainly share with you how to deal with congestion, cracks and subsidence on asphalt pavement.
Bulges
There are three main factors that cause bulges on asphalt pavement. One is that when paving asphalt pavement, there is a lot of asphalt left in the area that has not been removed or leveled, forming bulges. This type of encrustation can be directly removed or milled. Second, due to the excessive use of fine aggregate when laying the road surface, the bumps can be milled directly. After milling, the original bumps should be positioned not less than 10mm below the original road surface. Then pave the original road surface, that is, spread a layer of asphalt adhesive layer first, then spread 3 to 6 mm thick stone chips, and use a road roller to roll it to the specified strength. The third reason is that the unstable roadbed causes bulges on the road surface. After the road milling is completed, the roadbed must be excavated together, and then the roadbed and road surface must be re-paved in sequence.
Cracks
Pavement cracks need to be treated differently according to different conditions. If cracks occur due to thermal expansion and contraction (usually with a crack width less than 2mm), no treatment is required. The cracks will disappear when the temperature rises. For joints with a width greater than 2mm and less than 4mm, an overlay can be added to the original road surface for maintenance. For joints with a width greater than 4 mm and less than 10 mm, the joints must be expanded, cleaned, and then filled using the correct sealing process. For seams with a width of more than 10 mm, grooves and seam filling repair processes are required. Grooving requires using a crack router to create grooves with neat edges of a certain width along the cracks, cleaning and drying the grooves. Then use a crack sealing machine to heat the road sealant to about 180°C, and pressure-pour the sealant into the groove. The crack sealant should be 3mm higher than the surrounding road surface so that its edges fit closely and the surface is flat and smooth.
Subsidence
Subsidence is mainly due to the decrease in foundation bearing capacity, the uneven subsidence of the road surface caused by the vertical effect of the load on the road surface itself or the driving load. According to its causes, it can be mainly divided into pavement subsidence and reflection subsidence. The former is mainly caused by the use of substandard materials when paving the asphalt surface layer and the gradual accumulation of vehicle loads after driving. The latter is due to improper handling of the roadbed during paving, which later causes disease, resulting in road surface subsidence.
Simple road surface subsidence can be treated separately according to the degree of subsidence. If there is less subsidence, simple preventive maintenance can be carried out and an asphalt protective layer can be added. If the subsidence is serious, all the sunken parts of the road surface can be removed and a new asphalt surface layer can be paved again. For pavement subsidence caused by subgrade quality problems, the subgrade must be removed together with the surface layer. Depending on the condition of the roadbed, piling measures can be used to strengthen the stability of the roadbed when necessary, and then the roadbed and road surface can be re-paved according to specifications.