Maintenance and repair of cement concrete pavement?

The maintenance and repair of cement concrete pavement is very important. It is very important to understand the purpose and function of pavement maintenance and handle every detail well. Zhong Da Consulting will explain the maintenance of cement concrete pavement for you.

As one of the important types of pavement, cement concrete pavement is widely used. Cement concrete pavement has the advantages of high strength, good durability and low maintenance cost. However, there are still many problems in the use of cement concrete pavement. For example, the imperfection of the original design theory, the lack of construction experience and the neglect of maintenance have led to structural damage or functional defects in many cement concrete pavements, resulting in early diseases and other problems, which have seriously affected the quality of highway use. Therefore, it is necessary to extend the service life of the highway through scientific maintenance and repair, give full play to its social benefits, and achieve the best operating state. This paper discusses how to do well the maintenance of cement concrete pavement as follows.

First, the common diseases of cement concrete pavement

Common diseases of concrete pavement The diseases of concrete pavement in use mainly include joint damage and concrete slab damage. They are described as follows:

1, the connector is damaged

(1) arch: it mainly occurs at construction joints and expansion joints. When the compressive stress caused by plate elongation exceeds the shear strength of concrete, the two sides near the crack may arch upward or collapse, or even arch suddenly and break in summer exposure.

(2) Staggered table: Two adjacent plates will be staggered up and down during the expansion and extrusion process, resulting in staggered table. For example, after the contraction joint is broken, rainwater permeates along the crack to soften the base, or the crack is polished and the force transfer effect is reduced, which will lead to dislocation. When the traffic volume or foundation bearing capacity is unevenly distributed on the transverse plate, the settlement of each plate is inconsistent, and the phenomenon of staggered platform will also occur.

(3) Friction: When the friction between the transverse plate and the foundation is uneven, the traffic volume borne by each plate is also different, which may lead to inconsistent extrusion direction, speed and distance of each plate, resulting in transverse joint friction.

(4) Widening of longitudinal joints: Due to the component action of slab weight along the arch transverse slope, the shoulder has insufficient resistance to the lateral movement of pavement slab, and the slab will slide laterally, thus widening the longitudinal joint gap. In addition, under the action of repeated temperature changes, the longitudinal seam gap will also widen.

(5) The joint sealant falls off: under the expansion and contraction of the plate, the joint sealant will be squeezed out and taken away by the wheel.

2. The concrete slab is damaged

The main manifestations are broken plates, cracks, pockmarks on the plate surface, surface peeling, broken plates, subsidence and so on. The main reasons are as follows:

(1) The foundation is wet and soft with uneven strength.

(2) The floor is too long. When the slab shrinks, the friction between it and the foundation prevents the shrinkage, which leads to tensile stress at the bottom of the slab, and fatigue of the concrete slab under repeated loads, which leads to fracture and crack of the slab.

(3) Due to the defects of raw materials and construction technology, the flexural and compressive strength of concrete failed to meet the design requirements.

Second, the maintenance of water-mixed concrete pavement

Under good maintenance conditions, cement concrete pavement has better service quality and longer service life than other pavements. If the maintenance is not timely, once the damage begins, it will develop rapidly. Therefore, it is necessary to do a good job in prevention and regular maintenance, find out the defects as soon as possible through regular patrol observation, find out the reasons, seize the opportunity to deal with the diseases, and keep the pavement in good condition.

1, cement concrete pavement maintenance

Under the condition of good maintenance, cement concrete pavement has a longer service life than other pavements. But once the damage begins, it sometimes develops rapidly. Therefore, it is necessary to do preventive regular maintenance, find out the defects, find out the reasons, and take timely maintenance measures to keep the pavement intact.

(1) Control the passage of overweight vehicles and large-tonnage vehicles, and prohibit the passage of tracked vehicles.

(2) Keep the road surface clean and tidy, and often clean up the silt and sundries on the road surface, especially the gravel brought to the road surface, so as to avoid the vehicle damaging the road surface.

(3) Keep the drainage of ditches and bridge structures unblocked, especially before the flood season, and ensure that the pavement is free of water and well drained.

(4) Control the distance between the permanent buildings on both sides of the highway and the outer edge of the side ditch not less than 5m, and maintain a good driving environment.

(5) The shoulder width on both sides of the highway is generally not less than 50 cm. Where conditions permit, mortar or dry rubble can be used to harden the shoulder, and dirt shoulder can also be used. If there is any landslide, the soil shall be turned in time, and the cross slope of the shoulder shall be controlled at 1.5%.

(6) Check the pavement once a month and repair all kinds of damages in time.

(7) Before the rainy season and freezing period come, the road surface should be inspected, and the general damage should be repaired in time. Attention should be paid to snow removal in winter, especially during snow melting, to prevent water from infiltrating into the base, to maintain and reinforce the shoulder, to keep the connection between the road surface and the shoulder smooth, and to maintain the due cross slope. Clear and dredge the side ditch, and do a good job of road drainage.

2. Joint maintenance

The maintenance of cement concrete pavement focuses on joints, and redundant joint fillers should be filled or removed frequently to keep the joints intact, the surface smooth and the traffic not jumping. When the temperature drops, the gap at the joint becomes larger, so it is advisable to fill the joint when the local temperature is the lowest. When the temperature rises, the outstanding joint filler should be removed to prevent mud and sand from squeezing into the joint and affecting the normal expansion and contraction of the plate.

3, concrete slab crack maintenance method

Non-expansive cracks with a width below 3mm shall be filled with low-viscosity asphalt or epoxy resin; If it is an expansion crack, gouge along the crack and inject joint filler; For cracks caused by hard objects buried under the structure or concrete slab, the caulking material should also be poured after being dug along the cracks.

Third, the maintenance of cement concrete pavement

1, maintenance of joints and cracks

The maintenance of joints and cracks is mainly to change the joint filler regularly, give full play to the role of various joints and avoid the invasion of moisture. When replacing the joint filler, first remove the old joint filler, remove the sundries in the joint with compressed air, and then fill the joint with new joint filler. Key points of its construction:

(1) Carefully clean up in advance, remove the old joint filler, sand, dust and other sundries, and expose the joints in the concrete area as clean as possible.

(2) The pouring material shall be of the same quality as the original material. If the poured materials are of the same quality as the raw materials, and the remaining materials are intact and firmly bonded to the concrete, it is not necessary to dismantle them all.

(3) Before joint filling and joint filling, the joint and joint filling must be dry and not wet, otherwise the joint filling agent will not bond firmly.

(4) When there is a missing corner at the edge of the joint plate, if the size, width and depth of the missing corner are below 30mm and exist independently, the loose concrete can be removed and poured into the joint filling material.

2. Maintenance of errors

Cement concrete pavement will move down as a whole due to poor local compaction between subgrade and base, or the infiltration of pavement water into base through joints to soften it, or the insufficient load transfer capacity of joints. If the dislocation is caused by the immersion of joints or cracks, resulting in fine particles at the base and cracks at the bottom of the slab, the treatment method is to inject oxidized asphalt under the concrete slab to fix it, or to repair the pavement slab. If the joints of cement concrete pavement and bridge and culvert structures are staggered, asphalt mixture should be filled.

3. Road arch repair

When the cement concrete panel is blocked by expansion, the panels on both sides of the joint will suddenly arch upward. This is due to the expansion joint opening when the panel shrinks, the joint filler fails, and the incompressible materials such as hard debris fill the expansion joint, which causes greater hot-pressing stress when the panel expands, resulting in longitudinal buckling instability and arching of the panel. The main methods to deal with the arching of cement concrete pavement are cutting and turning some arched panels and pouring new concrete slabs.

(1) Conduct joint inspection in combination with emergency repair. When the uplift degree is slight, in order to make the upturned plate fall, a cutter is placed parallel to the seam 50 ~ 60 cm away from the seam of the upturned plate, and this part is destroyed by a crusher.

(2) After the old concrete slab is demolished, soil, gravel, etc. This part is in urgent need of filling, asphalt mixture is laid after rolling forming, and traffic is opened after leveling and compaction.

(3) After the plate is completely stable, the plate is renovated.

4, local wear and potholes repair

Due to the construction, maintenance or mixture ratio of cement-cement concrete pavement, and the action of traffic load, some diseases such as pits, peeling, wear, pits and grooves will occur on the surface of the panel. The maintenance method of these diseases is to clean up the surface dust and sundries first, and then fill them with 1:2 cement mortar or sulfur cement. It can also be repaired by cement mortar mixed with 50% concentration polyvinyl acetate emulsion. Or coat epoxy resin or cement slurry first, and then pour concrete with early strength agent.

5, the treatment of large area wear and tear

Due to the poor construction quality or unreasonable mixture ratio of cement concrete pavement, the surface of cement concrete pavement slab will be worn and smooth under the action of traffic load, which is prone to wet traffic accidents. When the surface of cement concrete pavement is worn and peeled off, hard stone can be used for asphalt surface treatment. Thick asphalt should be used for adhesive layer oil, and the dosage should be a little more to prevent peeling. For the polished pavement, the anti-skid asphalt sand seal layer can be laid, or the pavement can be cut into small transverse grooves with a grooving machine to restore the anti-skid force.

6, local plate crushing treatment

(1) corner repair: ① according to the size and depth of the fracture surface, determine the cutting range and set out. (2) Cut the edge seam with a cutting machine, and chisel away the damaged part to make it a regular vertical plane. When there are steel bars, care should be taken not to cut them. If it is difficult to keep all the steel bars, at least 20 ~ 30cm steel bar heads should be kept, and the lengths should be staggered. (3) Check the original sliding dowel bar. If there is any defect, repair or reset the new bar immediately. (4) The joint surface with the original pavement. If there is shrinkage joint, plastic film should be isolated or coated with asphalt to prevent new and old concrete from sticking together. If there are expansion joints, connecting plates shall be provided. ⑤ After the concrete hardens, slit the slot with a slit machine, and then pour the joint filler.

(2) Local repair of longitudinal and transverse cracks in pavement slab: ① Marking and setting out, cutting edge seams with a cutting machine, and chiseling away damaged parts. (2) Drill holes in the center of plate thickness on both sides of the edge seam, with a depth of 10cm, a diameter of 2-4cm and a horizontal spacing of 30-40cm. (3) Remove and wet the broken materials in the hole, fill them with cement mortar, and insert a piece with a diameter of 18 ~ 20 cm. About 20 cm long threaded steel bar. (4) Tamp, smooth and spray curing agent with cement concrete. ⑤ For the pavement slab with steel wire mesh, when the crack position is less than 3m away from the joint, it can be repaired locally according to the method of dealing with the corner couple fracture; When the crack position is more than 3m away from the joint, it should be treated as shrinkage joint and repaired.

7, paving asphalt layer repair

When the middle surface of cement concrete is damaged, asphalt layer can be used to repair it. The construction points are as follows:

(1) Broken slab treatment: Dig out broken slabs such as serious broken slabs, serious cracks and broken slab angles of the original pavement, and repair them with early strength concrete or early strength reinforced concrete until they are flush with the original pavement. The pavement of the original culvert cover plate should also be treated together.

(2) Stabilize the original pavement slab: grout the hollow concrete slab soaked in mud and the slab with light and moderate cracks at the bottom of the slab to keep the concrete slab in a stable state. For the road sections with long service life and the original pavement base with poor water stability such as lime soil, all the original concrete slabs can be grouted and insured.

(3) Improve the waterproof ability of the original pavement: after all shrinkage joints, longitudinal joints and cracks are cleaned, use joint filling materials to fill the joints. Then add 1.5 ~ 2.5 cm geotextile isolation layer or asphalt mixture isolation layer on the original concrete pavement, and sprinkle adhesive oil on the surface without isolation layer to reduce the underwater seepage of the pavement and improve the bonding ability between the overlay and the original pavement.

(4) Overlay asphalt layer: The overlay asphalt concrete on the isolation layer (adhesive layer) should generally be divided into two layers, the lower layer is thick (generally 4-8 cm), and the open graded coarse-grained or medium-grained asphalt macadam or asphalt concrete with good thermal stability is used, while the upper layer is thin (generally 2-9 cm thick), and the dense graded fine-grained or medium-grained asphalt concrete with good waterproof performance is used.

8. Innovation

When the cement concrete pavement reaches a certain service life, large-scale damage or cracks spread all over the slab, which seriously affects the normal traffic, it should be completely renovated or partially renovated according to the specific situation. Pavement thickness design should be carried out during comprehensive reconstruction. Local renovation usually adopts the same thickness as the original pavement design.

Four. conclusion

With more and more expressways put into operation. In the process of highway use, various diseases will inevitably appear on the pavement. Under the guidance of Scientific Outlook on Development, we must firmly establish that vigorously building highways is development, and scientific maintenance is also a new idea of development. Therefore, strengthening the maintenance and repair of pavement is an important task for highway builders. Scientific and timely maintenance can not only ensure the normal operation of the highway, but also improve the quality and service life of the highway.

Want to know more detailed information about "cement concrete pavement maintenance", Zhong Da Consulting Construction Design link is simple, convenient and reliable.

For more information about project/service/procurement bidding, and to improve the winning rate, please click on the bottom of official website Customer Service for free consultation:/#/? source=bdzd