Prepare for work
2. 1 Lime-flyash macadam shall be properly watered on the subbase to keep wet before paving.
2.2 According to the center line of the road, the width of the basement, the geometric dimensions of the median and the shoulder fill, use an excavator or a manual soil-lifting trough to hang the line for construction. The height of the soil trough needs to exceed the virtual paving height of lime-fly ash macadam, and at the same time, it should be cut vertically to ensure that the soil trough has a certain compactness, so as to prevent the soil trough from being squeezed out during paving or rolling, and waste lime-fly ash macadam materials.
2.3 The side piles shall be nailed every10m in the longitudinal direction on both sides of the road, and every 5m in the longitudinal direction of the curve section. In the process of lime-fly ash macadam paving, surveyors will check the baseline construction elevation and height difference with loose pavement at any time to avoid mistakes.
2.4 Before discharging, the surveyors shall calculate the discharging amount per 10 linear meter at the grass-roots level according to the actual paving thickness and cross-sectional area, and hand over the data to the material engineer, so that the material engineer can reasonably and accurately direct the discharging, meet the needs of paving construction, and avoid the phenomenon of secondary transportation in the field or too long pushing distance of bulldozers (the material engineer shall check the discharging amount in time to avoid over-metering).
At this stage, the lime-fly ash macadam mixture is basically a finished product, so it is necessary to ask the manufacturer for product certificate, lime calcium and magnesium content of lime-fly ash macadam raw materials, crushed value of macadam and other relevant test documents in time when feeding. In the process of acceptance, mainly check the water content and fly ash content of the mixture. If the water content and fly ash content are large, it will affect the later paving, leveling and rolling work, and have a great influence on the strength of the whole lime-fly ash macadam base.
3. The main construction methods of lime-fly ash macadam base
3. 1 Paving is divided into bulldozer with grader, manual paving and paver paving.
(1) The paving method of paver is the same as that of cement stabilized macadam. For manual paving, refer to Article 2.4(2)b of Chapter 5 for lime-soil base construction.
(2) The bulldozer cooperates with the grader for paving. According to the design section and loose laying thickness, lime-fly ash macadam will be spread evenly in the road groove. According to the design width of the road, the paving width on each side should be at least 15㎝. In fact, the loose paving coefficient is measured according to the elevation difference method, that is, 5- 10 datum points are prepared at the construction site, and the elevation of the lower bearing layer is measured first, and then the loose paving elevation of the datum point is accurately measured after the mixture paving is completed, and then the elevation of the selected datum point is re-measured after the roller is rolled, and the loose paving coefficient is calculated from the average elevation difference. The general initial loose coefficient can be 1.3— 1.35. If the compaction thickness of each layer is 20cm, the loose laying thickness can be controlled at 26cm.
(3) When paving lime-fly ash macadam, the water content should be controlled between-65438 0% and+65438 0.5% of the optimal water content. At the same time, strengthen the detection of water content and water content in the construction process, and adjust the water content in time by sprinkling water or drying in the sun to make it reach or approach the optimal water content. When coarse and fine particles are separated, they should be mixed again before paving.
(4) Before paving, shaping and rolling lime-fly ash macadam, traffic should be completely interrupted.
(5) According to the width and length of the operation section, the lime-fly ash macadam paving can be leveled by graders and bulldozers, and the local leveling can be leveled manually or roughed by bulldozers, and finished by artificial rice noodles. Mechanical paving and leveling method: bulldozer rough leveling mechanical leveling vibrating roller static pressure once leveling mechanical leveling manual leveling, compaction corner rolling mechanical paving manual leveling method: bulldozer rough leveling hanging rice noodles manual leveling and rolling.
(6) The maximum compaction thickness of lime-fly ash macadam base is 20㎝, and the minimum compaction thickness is 10㎝. If the design thickness of lime-fly ash macadam exceeds 20㎝, it should be paved in two layers. After the paving of the first layer is completed, use a bulldozer to relieve the pressure, press it in place, and there is no dead angle of vibration leakage, and then use a self-propelled vibratory roller to vibrate and press it twice. After the rolling is completed, the construction of the second layer will be carried out immediately to facilitate the good combination of the two layers and form a high-quality slab. According to the actual paving situation, master the virtual paving thickness, and evenly pave the mixture according to the design section and loose paving thickness. Try to use full-width paving, extend the paving section and reduce construction joints. 3.2 When the mixture is rolled, it shall be rolled when the water content of the mixture is slightly greater than the optimal water content. Rolling work must be completed in the initial stage of mixture strength formation. When rolling, follow the principles of light before heavy, slow before fast, and from low to high. When the mixture is compacted in sections, about 5m should be left at the joint, so that it can be planted in summer. The initial pressure shall be leveled in time, and it is forbidden to stick a thin layer for leveling. After leveling, use 18t vibratory roller to vibrate for 3-4 times, and then use 12- 15t vibratory roller to stabilize the voltage twice to eliminate wheel tracks. The paved and pressure-relieved road sections on the same day must be rolled flat on the same day and finally formed. During construction, there will be no longitudinal joints, leaving1-2m before overlapping, and mixing and rolling together during the latter construction. During the rolling process, the straight segment vibrates from the outer edges of the soil shoulders on both sides to the center (the soil shoulders are compacted together), and the flat curve segment vibrates from the outer edges of the inner soil shoulders to the outer soil shoulders (the soil shoulders are compacted together). The sign that the rolling is basically completed is that a thin layer of mortar overflows on the surface of the base. 3.3 Treatment of construction joints Longitudinal joints are not allowed during lime-fly ash macadam base construction. Horizontal seam adopts flat seam form. Before paving the next section, manually remove the section with poor flatness at the end of the formed lime-fly ash macadam base (check along the paving direction with 5m aluminum alloy ruler to prevent the phenomenon of "slanting head" or "bowing head"), manually chisel away stubble, and then pave the mixture after wetting the joints with water, so that the new and old construction sections can be well combined. When rolling, the formed base should be prevented from loosening.
3.4 After the rolling is completed, keep in good health immediately. The way to preserve one's health is to cover water with plastic sheets or preserve one's health with water. The curing period is 7 days. During the health maintenance period, the whole traffic is closed, and no other vehicles can pass except the sprinkler.
3.5 Construction measures of lime-fly ash macadam base in winter and rainy season
(1) Don't mix too much lime-fly ash macadam mixture at one time, as long as it can meet the construction needs of the day. If it rains, the lime-fly ash macadam mixture needs to be stored in large quantities, and it is forbidden to spread it and roll it in time. Finish feeding, paving and rolling on the same day.
(2) For the lime-fly ash macadam base that has been paved but not rolled, it should be rolled after the rain stops and dried to an appropriate water content. If the lime-fly ash macadam base is seriously soaked by rain and lime and fly ash are lost, the paved mixture should be turned up again, and then spread and rolled after adding ash. The construction of lime-fly ash macadam base should be suspended in continuous rainy days. (3) When the temperature is below -5℃, it is not allowed to construct lime-fly ash macadam base. In case of special circumstances, the water content of the mixture should be reduced. At the same time, a certain proportion of cement or sodium chloride antifreeze should be added when mixing the mixture. After the lime-fly ash macadam base is rolled and formed, the connecting layer and asphalt surface layer should be built immediately to avoid the direct exposure of the base to the atmosphere for a long time, which makes the surface of the base loose and fails to meet the specified strength index for a long time.
3.6 Common Faults and Problems Encountered
(1) Avoid segregation caused by separation of coarse and fine materials during paving. In the process of transportation or mechanical paving construction, it is likely that coarse materials will be concentrated. If it is not re-mixed, the lime-fly ash macadam will be loose and will not form a board. Therefore, before paving, the segregation during loading, unloading and transportation should be re-stirred, so that the coarse and fine materials can be mixed evenly before paving. If the coarse and fine materials are concentrated in the rolling process, the coarse and fine materials should be mixed separately before paving and rolling. (2) Lime-fly-ash macadam should not be crushed when there is too much water loss without water supplement or the water content is too large. Because the water content has a great influence on the strength of lime-fly ash macadam after compaction. Water content should be detected before rolling, and the water content must be close to the best state during the whole compaction process. Sprinkle water when the water content is low, and dry it when the water content is high.
(3) After the lime-fly ash macadam is compacted and formed, it is not suitable to be exposed to the sun and air-dried, because quicklime must be added to fly ash to stimulate its activity and generate compounds with certain hydraulic properties, so that the macadam can be solidified into boards. Therefore, after compaction, it must be kept in a wet state, and the curing time is not less than 7 days.
(4) When the bulldozer spreads lime-fly ash macadam, the pressure must be discharged in place. Especially on roads and roadsides, bulldozers generally don't discharge pressure in place, which leads to different compactness of the cross section of the whole grass-roots unit, and there is a large elevation deviation after rolling. Therefore, in paving construction, technicians must use the manipulator to make disclosure, and roll the pavement and roadside for many times before roughing, and at the same time reduce the loose paving coefficient of the two ribs to ensure the elevation of the top surface of the base after rolling.
4. Certificates and test items to be collected
(1) Proof of materials to be collected: lime-fly ash macadam;
(2) Testing test: compactness (sand filling method, irrigation method), lime dosage of lime-fly ash macadam and unconfined compressive strength of lime-fly ash macadam. 5. Mechanical and labor consumption Mechanical consumption: dump trucks, bulldozers, loaders, graders, vibratory rollers, smooth rollers, sprinklers, a ton of turnover, etc. Mechanical consumption: When the lime-fly ash macadam is divided into two layers, the bulldozer pushes the bottom layer 5000m2/ machine-team, the bulldozer pushes the top layer 3000m2/ machine-team, the grader 5000m2/ machine-team, the roller 5000m2/ machine-team and the loader. Labor cost: 3000 m2/ man-day for managers, 2000 m2/ man-day for technicians, 700m2/ man-day for bottom lime-fly ash macadam and 300m2/ man-day for top lime-fly ash macadam. 6. Quality assurance measures: Lime-flyash macadam shall comply with the allowable provisions of 7.3 and 7.8. 1 lime-soil base in Code for Construction and Quality Acceptance of Urban Road Engineering. The allowable deviation shall comply with the provisions in the following table:
7. Safety measures:
1) When rolling with bulldozers, scrapers and road rollers, people should keep a safe distance from the machinery to avoid collision.
2) During the construction of bulldozers and road rollers, obvious signs shall be set on the above-ground facilities (cables, optical cables and other pipelines) and underground facilities (cables, optical cables, gas, tap water, telecommunications, wired, thermal and other pipelines) to protect various facilities and avoid scraping, touching and digging.
3) When erecting a tower ruler for measurement, technicians should pay attention to avoid touching ground cables to prevent electric shock accidents.
4) Non-mechanical equipment operators are not allowed to work on the machine.
5) During plastic surgery, prepare labor protection articles such as masks for all personnel to avoid respiratory diseases.