◆ Subgrade construction
First of all, we must carefully remove the roots, grass roots and garbage within the subgrade. When approaching the design elevation, the virtual height and leveling should be reserved appropriately according to the soil conditions to ensure that the compaction conforms to the design elevation and cross slope, and the width of subgrade on both sides should be checked according to the road centerline to prevent deviation.
◆ Cement stabilized macadam base construction
1. Material preparation: the cement stabilized macadam base material is mixed by large-scale centralized on-site mixing method, and the proportion is strictly controlled, with the cement content not less than 5%; When transported to the construction site by dump truck, the initial setting time shall not exceed that before rolling.
2. Shoulder cultivation: restore the road centerline and sideline, artificially cultivate the shoulder with a height of 30cm and a width of 150cm outside the sideline, and sprinkle water to wet the base.
3. Setting-out: Calculate the amount of water-stable materials on the pavement according to the transport vehicles, spread white lime lines on the pavement and divide them into grids, so that the water-stable materials will be discharged, which is convenient for the next leveling work.
4. Shaping and rolling: firstly, rough with bulldozer, with a virtual paving coefficient of 2cm, and then leveled with grader, with a virtual paving coefficient of 1cm. After leveling, use a roller to level the road, and follow the principle of "first two sides, then middle, then static pressure, then vibration". During the rolling process, the measured items such as water stability, elevation and width of the top surface, vertical and horizontal slopes, etc. are detected at any time.
5. Curing: After the cement stabilized macadam base is formed by rolling, do a good job of curing to ensure that the surface layer is moist, and the curing period is not less than 7 days.
6, quality requirements:
Appearance: The compacted surface is solid and smooth, and the caulking material shall not float on the surface or aggregate into layers. After the roller is rolled, the depth of wheel track shall not be greater than 5 mm
Frequency of allowable deviation inspection of measured items
Thickness 10% 1000m2 detection 1 min.
Roughness 15mm is measured at 2 points every 20m.
The width shall not be less than every 40m 1 point specified in the design.
The height of the center line is 20 mm, and it is measured every 20m 1 point.
The transverse slope is 20mm, not exceeding 0.3%. Measure 4 points every 20 meters.
Measure the degree of compaction at 1 point per 1000m2.
◆ Permeable oil structure
After the base course is rolled and formed, the prime coat oil shall be sprayed in time. The prime oil should be cationic slow-cracking emulsified asphalt PC-2. The technical requirements of emulsified asphalt shall be in accordance with Technical Specification for Highway Asphalt Pavement Construction (JTGF40-2004). Before the prime coat construction, the top surface of the base should be thoroughly cleaned to keep it clean. The prime emulsified asphalt shall be sprayed uniformly by the asphalt distributor at one time; If the asphalt distributor sprays unevenly, it should be sprayed by manual asphalt distributor.
◆ Asphalt concrete surface construction
1. Preparation: Before the construction of asphalt pavement, the sundries of cement stabilized layer should be cleaned, and the damaged stabilized layer and potholes should be repaired and leveled in time. Check whether paving stones, kerbs, inspection wells, manhole covers and other structures are installed firmly. If there is a problem, deal with it on the spot.
2. Survey and lofting: The elevation of asphalt macadam layer and asphalt concrete surface layer can be marked on paved paving stones or kerbs, and indicator piles can be set at intersections or bell mouths to control the elevation.
3. Material: petroleum asphalt is used as binder, and its performance should meet the requirements of three indexes. The aggregate shall be hard, unweathered and clean crushed stone or gravel, with proper gradation, compressive strength greater than 800kg/cm2, impurity content such as mica clay less than 2%, needle-like and flaky particles less than 65,438+00%, and water absorption less than 3%. The sand is coarse sand or medium sand, with hard and weathered particles and good grading, with the maximum particle size less than 5mm and the content less than 5%. The stone chips are hard, clean and angular, the maximum particle size is less than 10mm, the powder content below 0.07mm is not more than 5%, the void ratio of stone powder is not less than 45%, and the fineness should all pass through the 100 sieve, and the particle content of 0.075~0.005mm should account for 80-90% of the total weight.
4. Mixing and transportation of asphalt mixture:
(1), the asphalt mixture shall be trial mixed according to the designed asphalt content, Marshall stability test shall be conducted after sampling, and the test value shall be compared with the indoor mixture ratio test result to verify whether the asphalt content is appropriate, and appropriate adjustment can be made if necessary.
(2), determine the appropriate mixing time, the asphalt mixture after mixing is uniform, no gray, no separation of coarse and fine materials and caking.
(3) Determine the appropriate heating and conveying temperature. The ex-factory temperature of petroleum asphalt mixture is 130 ~ 160℃.
(4) The asphalt mixture shall be transported to the construction site by dump trucks, and the floor and surrounding walls of the carriage shall be coated with a thin layer of oil and water (diesel: water is a mixture of 1:3), and the transport vehicles shall be covered.
(5) The temperature of asphalt mixture transported to the paving site shall not be lower than 130℃.
5. Asphalt mixture paving: This project adopts mechanical and manual paving. For small intersections along the line that cannot be paved by mechanical paving or have been paved by mechanical paving, such as local lack of materials at the edge of the structure, obvious segregation of local mixture, and obvious unevenness of the base surface, manual paving is adopted.
During construction, paving should be done in frames, joints should be tight and straight, and template piles should be set to control the thickness. Control the paving temperature, the asphalt mixture shall not be lower than 100, the loose paving coefficient of mechanical paving shall be 1. 15 ~ 1.35, and two adjacent paving belts shall overlap 10cm, and assign special personnel to fill the longitudinal joint gap with hot materials, and level the summer-planting to make it smooth. When the paving work is interrupted and the paved asphalt mixture is cooled to normal temperature, if the paving is continued, the method of "direct stubble hot joint" should be adopted for careful and meticulous treatment.
6, rolling:
(1), control the temperature of asphalt mixture at the beginning of rolling and the rolling speed of roller.
(2), roller rolling from the outside to the center. Adjacent rolling belts overlap with wheel width 1/3 ~ 1/2, and finally the central part of the road is rolled completely. When there are baffles, kerbs, shoulders and other supports on the edge, roll them near the supports.
(3) During initial pressing, use a 6 ~ 8 t double-sided roller or a 6- 10 t vibratory roller (closed vibration device) for initial pressing twice. After initial pressing, check the flatness and road arch, and make trimming if necessary. When recompressing, use 10 ~ 12t three-wheel roller, 10t vibratory roller or corresponding tire roller, and roll it for 4 ~ 6 times until it is stable without obvious wheel tracks. During final compaction, use 6 ~ 8t double roller or 6 ~ 8t vibratory roller (with the vibration device turned off) for 2 ~ 4 times.
(4) When the asphalt mixture sticks to the roller during the rolling process of the roller, sprinkle a small amount of water on the roller, and it is forbidden to sprinkle diesel oil.
(5) The roller turns on the road section that has not been cooled by rolling, and stops by turning around. When driving on the formed road surface, the vibratory roller should be turned off.
(6) Open traffic: After the asphalt concrete pavement survives rolling, the traffic can be opened when the surface temperature drops to atmospheric temperature, but in general, it will be opened the next day after the construction is completed.