(a), the construction scheme
Lime-fly ash macadam base is mixed by centralized factory mixing method, paved by fogler 2500 paver, rolled by heavy roller and covered with plastic film for curing. The design mix ratio is lime: fly ash: crushed stone = 7: 18: 75, and the mix ratio of crushed stone is 50: 32: 18.
1. Before construction, do a 200m long test section to obtain various data (virtual paving coefficient, optimal combination of rolling equipment, rolling times and speed, etc. ) and write a conclusion, submitted to the supervision engineer for approval before normal construction.
2. During the construction period, the aggregate mixing station will be equipped with 1 500t/h mixer (electronic metering) and 5 ZL50 loaders. Fogler 2500 paver is used to spread the mixture on the construction site, and 2 sets of 18-2 1t steel wheel rollers and 2 sets of 18t and 16t vibratory rollers are used.
3. Before laying the base, the lower bearing layer should be strictly checked. After all the indicators meet the quality requirements, they should be thoroughly cleaned up to remove all kinds of sundries, and at the same time keep the lower bearing layer in a wet state, and do a good job of measuring and setting out before construction.
4. When the mixture is mixed, the metering device should accurately ensure the realization of the production mixture ratio, and the mixed mixture should be uniform without segregation. And pay special attention to prevent the inlet and outlet from being blocked, so as not to cause the ingredients to be broken and lead to inaccurate measurement.
5. In the process of mixing the mixture, the control of water content is the key. According to the construction speed, transportation distance, equipment operation and weather conditions, the construction site shall sample and detect the water content and compactness, and contact the mixing station in time to adjust the water content within a certain range.
6. Transport the mixture from the mixing station to the site as soon as possible with a large-tonnage transport vehicle. When the site mixture is completely prepared (8- 10 vehicle), start the paver for paving.
7, paving, virtual paving coefficient is determined by the test. Elevation control adopts the method of setting datum points. That is, every 10 meter is a section, and a section is set with four reference points. Paver paving, according to the loose paving thickness evenly, slowly, if there is segregation phenomenon, with mechanical or artificial feeding, and tracking measurement, determine the elevation, cross slope, found that the problem is adjusted in time.
8. When the compaction thickness of base course is 15cm, it shall be paved and compacted once. When the compaction thickness is 25cm and 28cm, it will be constructed in two layers. The first layer is 14cm, and the second layer is 1 1cm or 14cm. After the first layer is paved and compacted, the second layer will be constructed immediately, with a construction period of 300m m.
9. After paving, when the mixture is higher than the optimum water content 1%, it can be rolled. When rolling, the straight section is rolled from the edge of the outer soil shoulder to the center of the road, and the curved section is rolled from the edge of the inner soil shoulder to the edge of the outer soil shoulder. Rolling overlap is 1/2 wheel width. First, use a vibratory roller to stabilize the pressure, then use a vibratory roller to vibrate for 1~2 times, then use a smooth roller for 2~3 times, and finally use a rubber roller for 1 time. The sign of basic completion is that a thin layer of mortar overflows on the surface of the base without wheel tracks. In the process of rolling, the roller with light weight first should be used for rolling, and the rolling speed and times should be paid attention to. According to the conclusion of the test section, the rolling speed and times are finally controlled.
(2) Basic mixture construction control points:
1, the raw material inspection of the mixture, its main quality indicators should meet the requirements of technical specifications, and the mixture ratio should meet the design requirements.
2, the approach of lime and fly ash should be covered with tarpaulin, to prevent the rain from getting wet and affect its chemical composition, and reduce the pollution to the environment. At the same time, quicklime should be fully digested before use and sieved with a 2 cm mesh sieve.
3. When mixing, adjust the amount of water in time according to the weather conditions, so that the water content of the mixture is 65438 0% higher than the optimal water content, and ensure that the mixture is compacted under the optimal water content condition.
4. The paved mixture should be rolled in time.
5. The formed road section is covered with plastic film for curing, and the curing period is 7 days.
(3) Specific measures to ensure the smoothness of the grass-roots surface
1, segregation of mixture should be reduced as much as possible during paving, so as to prevent bulging after rolling and affect flatness.
2. At the transverse joint, it should be carefully leveled manually and filled with small pieces of material. After the completion of rolling, use a 3m ruler to detect, and manually level the excess.
3. After rolling, close the traffic to prevent social vehicles and heavy vehicles from passing and leaving the wheel tracks.
(4) General requirements of lime-fly ash macadam base material
1, the composition of granular materials shall conform to the provisions of document No.67 of Changnongban (20065438+0), and the aggregate crushing value shall not be greater than 30%.
2. The quality of lime shall conform to the Grade III technical standard in Table 4.2.2 of Technical Specification for Highway Pavement Base Construction (JTJ034-2000).
3. The total content of SiO _ 2+Al _ 2O _ 3+Fe _ 2O _ 3 in fly ash should be greater than 70%, the ignition loss of fly ash should not exceed 65,438+05%, and the specific surface area of fly ash should be greater than 2,500 cm2/g. ..
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