1, Introduction
After the highway is completed and put into use, with the passage of time, the technical condition and service capacity of the highway will gradually deteriorate. In order to maintain the good service performance of the highway and prolong its service life, we must follow the principle of "preventive maintenance combined with prevention" at different stages of the life cycle, take appropriate maintenance technical measures, adhere to preventive maintenance, repair damaged parts in time, keep the highway intact, smooth, tidy and beautiful, carry out regular major and medium-sized repairs, gradually improve the technical situation, and improve the use quality and disaster resistance of the highway.
Therefore, the research and popularization of rural highway maintenance technology and the development of related special equipment are of great significance for reducing construction costs, protecting ecological environment and harmonious development of highway construction. With the increasing amount of rural road maintenance in China, it is more necessary to strengthen the theoretical research of rural road maintenance technology and develop corresponding technical schemes, management methods and mechanical equipment.
2. Common types of pavement damage
2. 1 asphalt pavement damage type
Damage of asphalt pavement can be divided into four categories: cracks, looseness, deformation and others. Among the common damage types, cracks include transverse cracks, longitudinal cracks, cracks and push cracks; Loose categories include pits and grooves, loose and so on. Deformation types include settlement, etc. Other categories are immersion, frost heaving, boiling, etc.
2.2 Common damage types of cement concrete pavement
The diseases of cement concrete pavement can be divided into four categories: surface fracture, vertical displacement of surface, surface joint and surface.
Among the common damage types, surface cracks include longitudinal, transverse, oblique cracks, cross cracks, broken plates and so on. The vertical displacement of the surface layer includes settlement and expansion. Surface joints include joint filler damage, joint fragmentation, etc. ; Surface wear and exposure, etc.
3, rural highway maintenance technical scheme
3. 1 asphalt pavement maintenance technology
3. 1. 1 crack sealing
Cracks in the range of 2 ~ 5 mm:
(1) First, use high-pressure air equipment to slowly blow from one end of the crack to the other, until there are no sundries and dust in the crack, and clean it up.
(2) Pour hot asphalt or low-consistency emulsified asphalt into the cracks from one end with a flat pan until all the cracks are filled.
(3) Scatter clean stone chips or sand into the cracks and tamp them.
(4) Remove asphalt, stone chips and sand outside the overflow joint.
(5) Open traffic.
3 ~ 5 mm above the crack:
(1) Mix the joint filling mixture with particles below 5~ with emulsified asphalt (17%-2 1% of aggregate) in proportion. If there is a small amount of stone powder in the fine stone, the amount of emulsified asphalt can be appropriately increased.
(2) Remove loose edges and sundries in the seam, and remove loose edges. For larger sundries in the gap, remove them with a flat iron sheet, aim them at the gap from one end with an air pump, and slowly blow them to the other end until there are no sundries, loose objects and dust in the gap, and clean them up.
(3) Filler in the crack Fill the mixed sealing mixture into the crack, and then tamp it with flat steel. If the crack is deep, it can be filled in layers, and the filling place can be slightly higher than the original pavement.
(4) Clean up the site and remove the redundant sealant outside the joint.
(5) Open traffic.
West longitudinal road Y433 and Zhu Mo road Y390K 1+ 100 adopt joint filling technology? -—K5+000, etc. And the curing effect is good.
3. 1.2 pit and groove repair paper
(1) Setting up construction safety signs: Set up complete and eye-catching construction safety signs at the job site according to the safety operation procedures for highway maintenance.
(2) Contour drawing: according to the principle of "square compensation for round holes and square compensation for inclined holes", outline the pits and grooves that need to be repaired on the road surface; The contour line must be a square or rectangle parallel or perpendicular to the road centerline, and the size is moderate.
(3) Slotting:
Dig along the contour manually with a pickaxe, or cut straight and slot along the inner side of the contour at 1cm with a cutting machine. When grooving, if the basement is damaged, dig deep to the stable part of the groove bottom (the shallowest groove depth is not less than 20cm).
(4) Backfilling at the grass-roots level: backfilling, tamping and curing on the same day after slotting. Backfill soil should be compacted by layers, from outside to inside, generally three times. Pay attention to the density of corners.
(5) Oil layer laying: firstly, remove the healthy soil, cut the edge of the oil layer with a cutting machine to make the edge neat, and clean the edge of the oil layer and the surface of the base to be dust-free. Then brush the edge oil and pour the bottom oil neatly and evenly. Pave the asphalt mixture evenly into the tank for leveling. After compaction, the newly filled part should be slightly higher than the original pavement asphalt mixture, and then rolled. When rolling, it should still be carried out according to the basic rolling method until there are no wheel tracks.
(6) Site cleaning: After the surface layer is rolled, immediately clean the site, and then dismantle the safety facilities in the construction area against the traffic flow direction to restore normal traffic.
No matter the roads in the plateau area or the roads in the plain area, the potholes should be repaired in strict accordance with the technical specifications. In this way, the county roads of Hangu Road X2 19 and Weiqiao Road X 10 1 have been well maintained.
3. 1.3 settlement treatment
L) Local pavement subsidence caused by differential settlement of subgrade, if the soil foundation and base have been compacted stably and will not continue to sink, only the surface layer can be repaired. And according to the pavement damage, take the following treatment measures respectively:
(1) If the pavement is slightly sunken, there is no damage or only a small amount of slight cracks, viscous asphalt can be sprayed or painted in the subsidence area, and then the subsidence part is filled with asphalt mixture and compacted and leveled;
(2) Subgrade subsidence leads to serious pavement damage, and mineral materials have loosened and fallen off to form pits and grooves, which should be treated according to pit and groove maintenance methods.
2) Pavement subsidence caused by the destruction of soil foundation or base structure shall be cured at the base before redoing the surface layer;
3.2 Cement concrete pavement maintenance technology
Subsidence diseases mostly occur in places with imperfect pavement drainage facilities, such as X3 16 of Xiaoyi section of Daoguan oil road in our district. Because of the uplift of village basement along the highway, the pavement drainage is not smooth, so we apply this method to settlement treatment.
3.2. 1 split level maintenance
L) For slight cracks with a width less than 3~, expansion joint grouting method can be adopted:
(1) widened along the crack into a groove of 1.5~2cm. The groove depth can be determined according to the crack depth, and the maximum depth shall not exceed 2/3 of the plate thickness;
(2) using compressed air to clear the soil and concrete chips in the cracks, blowing off the dust, and filling in clean stone chips with the particle size of 0.3-0.6 cm;
(3) According to the selected caulking material, the caulking material is prepared and poured into the expansion joint;
(4) After the sealing material is cured, the traffic can be opened when it reaches the opening strength.
2) For the medium cracks that run through the whole thickness and are more than 3mm but less than 0.5mm, the strip cover can be used to repair them;
(l) When cutting the joints on both sides of the crack, the distance from the crack shall not be less than15cm; ;
(2) The concrete depth of two transverse joints shall be 7cm.
(3) Punch a pair of nail holes every 50cm, the size of which should be slightly larger than the diameter of the nail, and punch a pair of nail grooves with the same diameter between the two nail holes;
(4) Nails shall be reinforced with 16 thread, and rust shall be removed before use. The nail length is not less than 20cm, and the hook length is 7cm.
(5) Before inserting the nail into the hole for installation, the nail hole must be filled with mortar;
(6) The inner wall of kerf shall be chiseled, and loose concrete fragments, surface dust and exposed stones shall be removed;
(7) Concrete shall be vibrated and compacted in time, leveled and sprayed with curing agent;
(8) On both sides of the patch panel, the contraction joint should be deepened, and caulking material should be poured.
3.2.2 Settlement treatment
L) Drainage facilities shall be set for settlement treatment;
Pavement and shoulder should keep the design cross slope; Pavement cracks and joints should be sealed; It is provided with a longitudinal water accumulation pipe and a transverse water outlet pipe.
2) Basic requirements for panel jacking:
(l) Before jacking up the panel, measure the sinking amount of the sinking plate with a level meter. The distance between the station and the sinking place should be more than 50m, draw a vertical section to find out the upward appreciation;
(2) drilling holes in the concrete panel, the hole depth should be slightly greater than the thickness of 2cm.
(3) The lifting equipment or jack should be used for plate jacking;
(4) Cement mortar can be used as grouting material;
(5) After the grouting material is pressed in, each hole should be blocked with a wooden wedge. After grouting is completed, the wooden wedge should be pulled out and the hole should be blocked with high strength cement mortar;
(6) Only after the compressive strength of grouting material reaches 6MPa can it be opened to traffic.
3.2.3 Joint maintenance and repair
(l) Use a chisel or seam cleaner to remove the old joint filler and sundries in the joint, and blow off the dust in the joint;
(2) When repairing expansion joints, hot asphalt should be coated on the joint wall first, and then the joint plate should be pressed into the joint. The joints of the joint plate and the gaps between the joint plate and the dowel bar must be filled with asphalt or other joint filler.
(3) When repairing with heated joint sealant, the joint sealant must be heated to the pouring temperature to filter out impurities, and it can be filled manually or mechanically. At the same time of joint filling, it is advisable to hook it back and forth with an iron hook to increase the bonding with the joint wall and the fullness of filling. During construction in low temperature season, the joint should be preheated with blowtorch first.
Pit repair
L) For individual potholes, sundries in potholes should be removed and filled with materials such as cement mortar, so as to achieve the purpose of smoothness and compactness.
2) For many connected potholes, cement concrete thin-layer repair method is adopted to repair them.
(l) The graphic edge of the cutting area should be parallel or perpendicular to the road centerline.
(2) the cutting depth should be greater than 6cm. Take out the defective concrete in the repair area and cut the smooth surface in the cutting surface.
(3) Remove the concrete chips in the tank. Wet or scrape with water,
(4) put the concrete mixture into the tank, vibrate it tightly, and keep it flush with the original concrete panel. Before initial setting, emboss with embossing equipment, and the embossing depth should be controlled at about 3rnrn.
(5) spraying curing agent for curing.
3) Asphalt concrete can be used to repair large-area potholes with a depth of less than 3 cm.
(l) chisel away the treatment area with a pneumatic pick, and the graphic sideline shall be parallel or vertical to the road centerline;
(2) The cutting depth should be 2-3cm, and the concrete crumbs should be removed.
(3) Before paving asphalt concrete, sprinkle viscous asphalt on the trench bottom and trench wall with the dosage of 0.4-0.6kg/m..
(4) Asphalt concrete shall be compacted and leveled.
4. Conclusion
Regular and preventive maintenance should be strengthened in the initial stage of rural roads, local and minor initial damages must be repaired in time, remedial maintenance should be carried out when necessary, and cracks, pits and grooves and asphalt macadam seals should be filled in time; In the rural road management system, it is necessary to combine with the local administrative departments, list the management of rural roads as the administrative assessment of the local government, and strengthen the management of agricultural vehicles.
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