Strict raw material standards, in line with relevant regulations, qualified by technical personnel, can be allowed to enter the arena. For the influence of the boundary, the poured pavement slab should be slotted as soon as possible, and the concrete pavement should be caulked in time after maintenance to prevent the base from being exposed for a long time. If cracks appear during construction, they should be filled before pouring to prevent them from reaching the surface of pavement slab.
The design should consider the traffic conditions of this section, control the traffic of large-tonnage vehicles, and select raw materials suitable for the environment. Strengthen the maintenance work, deal with the junction of new and old subgrade and road and bridge, and improve the drainage system.
2. Prevention and repair of surface damage
Control the water cement ratio and slump, and the raw material ratio should be tested before putting into use to ensure the construction quality. During construction, raw materials shall be selected in strict accordance with requirements, allocated in proportion, water quantity shall be controlled, good binder shall be selected, and pavement damage shall be repaired in time.
3. Prevention and repair of joint problems
First of all, the quality of the selected filler should meet the requirements, and it has strong waterproof ability, which can effectively prevent the problems caused by rain washing and soaking. Loose aggregate should not be used on the surface of the base, and the surface of the base should be flat and solid. In the aspect of pavement design, drainage system should be added to effectively drain stagnant water, reduce the erosion of filler by rain, and prevent small sundries from infiltrating into joints. When uneven settlement occurs, it should be reinforced in time.
4, material requirements
Materials used as cement concrete surface layer include ordinary concrete, reinforced concrete, continuous reinforced concrete, steel fiber concrete, roller compacted concrete, etc.
When preparing pavement concrete, ordinary portland cement No.425 or No.525, medium sand or coarse sand, and first-and second-grade crushed (gravel) stones should be used. The 28-day ultimate compressive strength of concrete is not less than 30 ~ 40 MPa, the ultimate flexural strength is not less than 4.5 ~ 5.5 MPa, and the dosage of cement per cubic meter of concrete is 300 ~ 350 kg. For the lower material of double-layer concrete pavement, the requirements can be appropriately reduced.
In order to improve the performance of concrete, a small amount of additives such as early strength agent, air entraining agent, plasticizer, water reducing agent or polymer can be added (see concrete additives).
The joint filler poured on the upper part of the joint is usually asphalt cement (also called asphalt cement) made of asphalt, mineral powder, asbestos chips, soft sawdust or rubber powder in a proper proportion. In addition, neoprene hollow belt, plastic fillet or PVC cement are used as caulking materials, and the effect is also good.
5. Reinforce and add stories
When the concrete pavement is damaged, an asphalt concrete layer with a thickness of at least 15 ~ 20cm can be added to prevent cracks and joints from being reflected on the asphalt layer. If new concrete is added, there are three forms:
Combined adding layer: firstly roughen the old pavement, coat it with cement slurry or epoxy resin, and then lay a new concrete layer to make it well combined with the old pavement.
Adding layer by local combination: clean the old pavement first, and then lay a new concrete layer, which has poor combination with the old pavement.
Isolation and adding layer: first lay a layer of 2 ~ 3 cm thick linoleum or coarse sand or asphalt sand on the old pavement, and then lay a new concrete layer.
Concrete pavement is durable, can meet the requirements of modern high-speed, heavy-duty and dense automobile transportation, and has low maintenance cost, so it is widely used in airport runways, expressway, trunk highways, urban roads, factory roads, parking lots and so on. It is also especially suitable for the pavement of tunnels and water roads.
Baidu encyclopedia-concrete pavement
Baidu encyclopedia-cement concrete pavement