Construction process flow chart (omitted)

Prepare the lower bearing layer of subgrade, that is, clean up the stones and chores on the paved road.

1. Construction lofting: Before construction, restore the center line on the subgrade, and set out the side lines of the left and right roads according to the center line. One pile shall be set every 10-20m for the straight line section and every 5- 10m for the flat curve section. Indicator piles shall be set at the outer side of the subgrade centerline and the shoulder edges on both sides, and the design height of the subbase edge shall be marked with obvious signs on the indicator piles on both sides.

2. Material preparation and equipment preparation: According to the design ratio of cement stabilized macadam subbase mixture, the width and thickness of subbase and the predetermined dry density, the requirements of macadam, cement and river sand are calculated. According to the construction plan and tasks, the mixing station guarantees to reserve or implement enough qualified crushed stones, river sand and cement in advance. Transport vehicles, operating tools and personnel required before construction. Should be comprehensive and specific calculation, unified configuration, overall arrangement, to ensure that in place in advance. At the same time, the production capacity of mixing equipment, transportation equipment and construction equipment must match, and the slowdown should be avoided as far as possible. Check and maintain the corresponding mixing equipment, transport vehicles and operating tools to ensure that they are put into use in good condition and reduce abnormal downtime. Before formally mixing the mixture, debug the equipment used to make the particle composition and water content of the mixture meet the specified requirements.

3. Mixing and transportation: Cement stabilized macadam is mixed by factory mixing method. Adopt advanced electronic metering equipment and check it regularly. Ensure accurate ingredients and uniform mixing. Before mixing, the quantity of cement, macadam and water shall be determined according to the designed construction mixture ratio and the production capacity of the mixing station, and the relevant parameters shall be input into the computer to ensure that the particle composition and water content of the mixing mixture meet the specified requirements. When mixing, the water content is slightly greater than the optimal value, so that the water content of the mixture is not less than the optimal value when it is rolled after being transported to the site for paving.

According to the production capacity and transportation distance of the mixing station, the demand for transportation vehicles is calculated, and the vehicles for transporting the mixture are fully configured to ensure the full-load operation of the mixing building, improve work efficiency, speed up the construction progress and reduce the downtime of the mixing building; Phenomenon, and transport the mixture to the site in time, and pay attention to the uniform loading at the same time, so that the site cloth. Transport vehicles should try to avoid rutting and uneven rolling. According to the thickness, width and predetermined dry density of cement stabilized macadam subbase, the vertical and horizontal distance of each vehicle is calculated, and the unloading point is marked with lime. From far to near, discharge the materials on the subgrade according to the above calculated distance or discharge sign, and strictly control the discharge position to avoid insufficient or excessive mixture in the road section and reduce the workload of the grader. When discharging, control the speed and drop to prevent the mixture from separating.

5. Paving and molding

According to the characteristics, theoretical dry density and experience of the mixture, the loose laying thickness of the mixture is calculated. The paving of the mixture shall be carried out by machinery approved by the supervision engineer, and the mixture shall be evenly spread on the specified width according to the above loose paving thickness. It is required that the surface is smooth and there is a specified road arch. When paving, the water content of the mixture should be 0.5%- 1.0% higher than the optimal water content to compensate for the water loss during paving and rolling. Paving is carried out with the help of grader and manpower. In a straight line, the grader should scrape from both sides of the road to the center of the road; In the flat curve section, the grader should be leveled from the inside out. If necessary, go back and shave again. Set up a team of 3-5 people, carry a load of fresh mixture, follow the grader and remove coarse aggregate in time; Nest; Supplementing the coarse aggregate belt with the newly mixed uniform mixture, or supplementing the already mixed fine mixture and uniformly mixing with the coarse aggregate. Immediately use a roller to quickly roll on the initially flat road surface to expose the potential unevenness. Then use a grader for shaping. Before shaping, loosen the surface of the low-lying parts of wheel tracks by more than 5cm with a tooth rake, level them with the newly mixed mixture, and then roll them with a roller. Finally, use the grader to finalize the design again. It is necessary to scrape the high material directly out of the road surface, and the phenomenon of thin layer repair cannot be formed. Every plastic surgery must reach the specified slope and road arch, and special attention should be paid to the smoothness of the joints.

Areas where local graders cannot construct should be paved manually. Manual paving area also strictly controls its related technical indicators. When artificial shaping is adopted, the mixture is first spread out with a shovel and a rake, and the road arch plate is used for preliminary shaping. After the initial pressure 1-2 times, according to the measured loose laying coefficient, determine the elevation of vertical and horizontal sections, and set signs and hanging lines. Use a shovel and rake to shape according to the line, and then use the road arch plate to correct the shape. Strictly control the segregation of coarse and fine aggregates. If it has been separated, discard the unqualified materials and re-lay the qualified materials before rolling. Especially removing local coarse aggregate; nest t； . No vehicles are allowed to pass during paving. After laying is completed, the edges shall be inspected and repaired manually. For areas with excessive width and thickness, the available materials should be recycled, and for areas with insufficient width or too thin thickness, the same materials should be used for repair, and they should be quickly trimmed, so as to compact the subbase before the initial setting of cement.

6. Rolling: According to the width of the road surface, the wheel width and the wheel pitch of the road roller, the rolling times of each part should be the same as far as possible, and the two sides of the road surface can be appropriately pressed for 2-3 times. Immediately after molding, it will be rolled with a 20t roller within the full width of the structural layer. When rolling, the wheel width should overlap 1/2, and the rear wheel must exceed the joint of two sections. When the rear wheel is pressed to the full width of the road, it will repeat. Generally, it needs to be rolled 6-8 times. The rolling speed of the roller is 1.5km- 1.7km/h for the first two times, and then it is 2.0-2.5km/h.. During the rolling process, the surface of cement stabilized macadam is always wet. If the surface moisture evaporates quickly, sprinkle a small amount of water in time, but it is forbidden to sprinkle water for rolling. It is forbidden for the roller to run on the completed or rolling road section; Turn around; And that surface of the cement stabilize macadam layer is not damage. During rolling, if any; Spring, looseness and peeling; Such as phenomenon, timely mixing (add the right amount of cement) or use other methods to deal with, make it meet the quality requirements. After molding, the mixture shall be rolled within a suitable delay time determined before the initial setting of cement to achieve the required compactness without obvious wheel tracks. Before the end of rolling, the grader shall be used for final leveling again, so as to make it longitudinal and comfortable, and the road arch and superelevation meet the design requirements. The final leveling needs the driver to do it seriously, and the local high part must be scraped and swept away. For local low-lying parts, no patching will be carried out, and they will be treated when paving the base. .

7. Maintenance: After the rolling is completed and the compaction degree is qualified, the maintenance shall be carried out immediately. The curing time shall not be less than 7d. Subbase course can only be laid after 7 days of curing. The method of keeping in good health is to sprinkle water with a sprinkler. During the whole curing period, the surface of the subbase is always wet. During the maintenance period, all vehicles except sprinklers are prohibited.

8. Other matters: try to shorten the delay time from mixing to rolling, but the paved mixture should be compacted as soon as possible; Subbase shall be sampled every 2000m2 to check whether the gradation of the mixture is within the specified range; The water content, cement content and unconfined compressive strength of the mixture are tested according to the standard method of Test Specification for Stabilized Materials of Inorganic Binders in Highway Engineering (JTJ057-94). On the paved road section, compaction test shall be carried out according to Code for Field Test of Highway Subgrade and Pavement (JTJ059-95), and each operation section shall be inspected for 6 times or less than 2000m2.

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