Steps to Build expressway (Details)

Construction procedure: there are two methods for asphalt surface treatment by layered paving method: oil before material and material before oil. The former is widely used.

Now take the three-layer type as an example to illustrate its technological process.

The construction procedure of three-layer asphalt surface treatment pavement is as follows:

Preparing materials → cleaning the base → setting out and installing kerbs → pouring prime asphalt → paving the first layer of asphalt → paving the first layer of mineral aggregate → rolling → paving the second layer of mineral aggregate → paving the third layer of asphalt → rolling → initial maintenance.

The construction procedures of single-layer and double-layer asphalt surface treatment are the same as those of three-layer asphalt surface treatment, only two or one procedures of asphalt paving, mineral aggregate paving and rolling need to be reduced accordingly.

Treatment of pavement appendages:

1. kerbs: kerbs (vertical kerbs), flat kerbs (horizontal kerbs) and public kerbs (horizontal kerbs) of urban roads are collectively called kerbs.

Kerbstone should have sufficient strength, weather resistance and wear resistance, and its surface should be smooth without peeling.

The outer kerbs include cement concrete, strip stone, block stone, etc. , should be selected according to the requirements and conditions. The protracted war dimension (length, width and height) deviation of cement concrete kerbs shall not exceed 5 mm, and the length of missing edges and corners on the exposed surface shall not exceed 20 mm, and shall not exceed one place.

The construction of kerbs shall meet the following requirements:

(1) kerbs shall be paved before the construction of asphalt pavement;

(2) The kerb foundation should be solid and stable, and cement sand, lime stabilized soil, lime stabilized industrial waste residue (soil) and crushed stone can be used as the operation foundation;

(3) After paving stone or cement concrete kerb, jointing shall be conducted with cement mortar;

(4) After paving the kerb, backfill it in time or take other protective measures.

2. Rainwater inlet and outlet: Rainwater inlet can be divided into horizontal, vertical and horizontal. The vertical edge should be set at the position of kerbstone, and the horizontal edge should be set at the position of flat stone. The distance between the outer edge of the cover seat of the horizontal water inlet and the edge of the side stone shall not be greater than 5cm, and shall not extend into the edge of the side stone.

3. Inspection wells: inspection wells include inspection wells for rainwater, sewage, water supply, gas, telephones, cables and other ancillary facilities. Before pavement construction, inspection wells should be installed and maintained for a certain period of time, and the pavement can only be paved after cement mortar hardens. The manhole cover base should be firmly laid and the surrounding area should be carefully tamped. The elevation of the top surface of the manhole cover should be consistent with the elevation of the road surface.

Sweep grass roots

Before the construction of surface treatment layer, the pavement base should be cleaned to expose most mineral materials at the base and keep dry. The bumpy road section should be repaired and leveled first. If the overall strength of the foundation is insufficient, it should be strengthened first.

Sprinkle with high-quality asphalt

The prime coat is a thin layer that penetrates into the surface of the base in order to make the asphalt surface layer and the non-asphalt base well combined, and is formed by pouring emulsified asphalt, coal asphalt or liquid asphalt on the base. Graded gravel, graded crushed stone base of asphalt pavement and stabilized soil or granular semi-rigid base of inorganic binder such as cement, lime and fly ash must be sprayed with prime asphalt.

The prime asphalt should be slow-cracking emulsified asphalt, or medium or slow-setting liquid petroleum asphalt or coal asphalt. The consistency of prime asphalt should be determined by trial sprinkling. Thin prime asphalt with good water permeability should be used for semi-rigid base with dense surface, and thick prime asphalt should be used for granular base such as graded crushed stone and graded gravel.

Asphalt surface treatment construction shall meet the following requirements:

(1) Asphalt surface treatment should be carried out in the dry and hot season of the year, and should be completed half a month before the arrival of the daily maximum temperature below 15℃.

(2) Each working procedure must be closely connected and not disjointed, and the length of each working section should be determined according to the number of road rollers and oil sprinkling equipment. The road section constructed on the same day should be completed in several days to avoid the adverse consequences of not being able to wrap the mineral materials due to asphalt cooling and mineral dust pollution.

(3) Except cationic emulsified asphalt, oil shall not be sprinkled on wet mineral aggregate or base. In case of rain during construction, the construction can only continue after the mineral materials are dried. The rainy season construction should know the weather forecast day by day, and each construction section should complete all processes before it rains.

(4) Exposed parts such as various manhole covers, sides, platforms and pavements on the road should be covered when oil spills, so as to prevent pollution and affect the beauty of the road.

When pouring prime asphalt, you should also pay attention to the following items:

(1) Before pouring the prime coat, the pavement should be kept clean, and kerbs and artificial structures should be properly protected to prevent pollution;

(2) The prime asphalt should not flow after spreading, and an oil film should not be formed on the surface when it penetrates into the base to a certain depth;

(3) In case of strong wind or heavy rain, the asphalt shall not be poured thoroughly;

(4) When the temperature is lower than 10℃, prime asphalt should not be poured;

(5) asphalt should be poured evenly at one time according to the designed asphalt dosage. When there is any omission, it should be added manually;

⑥ After pouring through the prime asphalt, vehicles and pedestrians are prohibited from passing;

⑦ Before paving the asphalt surface, if there is redundant prime asphalt in some places that has not penetrated into the base, it should be removed.

After pouring prime asphalt on semi-rigid base with stable inorganic binder, 2 ~ 3m3/km2 of stone chips or coarse sand shall be paved immediately. After pouring the prime asphalt on the semi-rigid base without binder stability, when the surface layer cannot be paved in time and the construction vehicle needs to be driven out, an appropriate amount of stone chips or coarse sand should also be paved. In this case, the amount of prime asphalt should be increased by 10%. After paving stone chips or coarse sand, use 6 ~ 8t steel wheel roller for compaction. When passing the vehicle, the speed should be controlled. Before paving the asphalt surface, if local asphalt peeling is found, it should be repaired, and if there are redundant floating stone chips or sand particles, it should be swept away.

The asphalt surface layer should be paved as soon as possible after the layer is paved. When emulsified asphalt is used as the prime coat, the asphalt surface layer should be fully permeated and evaporated before paving, and this period of time should not be less than 24h.

First asphalt paving

The first layer of asphalt can be paved after the permeable asphalt is fully infiltrated, or after the base layer that has been permeable and opened to traffic is cleaned. The pouring temperature of asphalt should be selected according to the construction temperature and asphalt grade. The pouring temperature of petroleum asphalt should be 130℃ ~ 170℃, and that of coal asphalt should be 80℃ ~ 120℃. Emulsified asphalt should be sprayed at room temperature. When the temperature is low and the demulsification and formation are too slow, the emulsion can be heated and sprayed, but the emulsion temperature cannot exceed.

The paving length of asphalt should match the paving of mineral aggregate, so as to avoid waiting for a long time before paving mineral aggregate after asphalt paving.

At each section of summer-planting place, iron plate or construction paper can be laid horizontally before and after the watering point in this section, with the width of1.0 ~1.5m. If two pieces of cloth are needed, the summer-planting should be well connected, and the longitudinal overlapping width is 10 ~ 15 cm. When paving asphalt for the second time and the third time, the joints shall be staggered.

Spread out the first batch of ore materials

After the first asphalt spreading (without waiting for the whole section to be finished), the first mineral aggregate should be spread immediately (when emulsified asphalt is used, the aggregate spreading must be completed before emulsification and demulsification). Its quantity shall be leveled at one time according to regulations. Where the local materials are insufficient or excessive, they shall be properly filled by manpower, or excess mineral materials shall be swept out. Where two pictures overlap, the width of 10 ~ 15 cm should be temporarily maintained after the first picture is paved with asphalt, and the mineral aggregate should be paved together after the second picture is paved with asphalt.

Regardless of mechanical or manual paving of mineral aggregate, it should be swept evenly after paving, generally covered with a layer of the same thickness, and asphalt should not be exposed.

submerge

After paving a section of mineral aggregate (it is not necessary to wait for the whole section to be paved), it should be immediately rolled with a 6 ~ 8t steel cylinder double roller or tire roller. When rolling, it should be gradually moved from the roadside to the center of the road, and then pressed from the other side to the center of the road. The overlapping width of each wheel track is 30cm, and it will be rolled for 3 ~ 4 times. The running speed of the roller should not exceed 2km/h at first, and it can be increased appropriately in the future.

Build the second and third floors.

The construction methods and requirements of the second and third floors are the same as those of the first floor. But 8 ~ 10t roller can be used. When emulsified asphalt is used, S 12 crushed stone should be spread on the second layer as sealing material, and then a layer of sealing material should be paved. Its specification is S 14, and its dosage is 3.5 ~ 5.5m3/km2.

Initial maintenance

Except for the surface treatment of emulsified asphalt, which needs to be evaporated after demulsification and basically formed before it can be opened to traffic, other treatments can be rolled and opened to traffic. At the beginning of opening to traffic, a special person should be appointed to direct traffic or set obstacles to control driving, so that the road surface will be compacted evenly. Before molding, the driving speed should be limited to 20 km/h.

In the early period of opening to traffic, if there is flooding, the maintenance materials with the same specifications as the last layer of mineral aggregate should be supplemented at the flooding site (the urban road maintenance materials should be paved together with the last layer of materials during construction) and carefully cleaned. Excessive floating mineral materials should be swept off the road surface to avoid rubbing other mineral materials that have been stuck in place. When there are other damage phenomena, it should be repaired in time.

Extended data:

Kerbstone refers to the vertical kerb used to protect and support the edge when the sidewalk or green belt is higher than the road surface in urban roads.

Shi Ping refers to the horizontal kerbs used for drainage and roadside protection in urban roads, which are close to kerbs and road edges.

Kerbstone refers to the horizontal kerbstone used to separate the road surface from the shoulder and keep the roadside. Kerbstone should have sufficient strength, weather resistance and wear resistance, and its surface should be smooth without peeling. The protracted war dimension (length, width and height) deviation of cement concrete kerbs shall not exceed 5mm, and the length of missing edges and corners of exposed surfaces shall not exceed 20mm, and shall not exceed one place.

Reference Link: Pavement Structure Highway