The pavement base designed in this project is 5% cement stabilized macadam base with a thickness of 26cm.

(1) material requirements

The materials used in the cement stabilized layer must meet the requirements of specifications or procedures. The gravel used in the stable layer should be clean, hard, with water chestnut and continuous grading. Aggregate gradation shall meet the requirements of intermediate gradation in Technical Specification for Construction of Highway Pavement Base. The content of acicular and flaky (≥ 1: 3) particles is less than 20%. The cement content of mixing stable layer is 5%, so it is not suitable to use early strength cement. In this project, ordinary portland cement is proposed. The dosage of cement is determined by mixture ratio test. Each material of cement stabilized macadam layer should be combined with the actual approach materials to determine the mixture ratio. Water content should be strictly controlled during construction, and the water content during mixing is slightly higher than that during test. The specific data should be determined according to the field test, mainly to offset the moisture loss of lime soil during transportation and the evaporation loss during paving.

(2) Mixing and transportation

We use centralized mixing materials for construction, and strictly control the mixing ratio when mixing. The clinker is required to be uniform and consistent, and there is no material clamping phenomenon. The transportation shall be carried by 5 tons dump trucks, and the transportation roads shall be flat and short to avoid segregation and dry materials.

(3) Paving and rolling

Before laying the cement stabilized layer, the quality of the grass-roots unit shall be reinspected, and the cement stabilized layer can be laid only after it meets the quality requirements of the sectional works.

(1) The shop is paved mechanically, and the whole picture is paved and shaped to avoid longitudinal seams. When paving, it is forbidden to use four-toothed rake or spreading. After paving is completed, a three-person team will be set up behind the roller to eliminate the coarse aggregate belt or honeycomb in time and replenish the fine mixture in time to make the paving go smoothly.

(2) When paving, the throwing height should be determined according to the test of the test section. It is forbidden to stick to the layer. When paving, we should master the principle of "rather high than low, rather shovel than make up". It is forbidden to level or throw with a toothed rake. After paving, the mixture must be rolled within 2 hours, compacted by CA25 vibratory roller, and compacted by small vibratory roller or manually around the well. When rolling, it should be static first and then vibrated, edge first and then middle, and the wheel track overlap should be greater than 1/3 of the wheel width. The number of rolling passes shall be determined according to the field test sections. It is forbidden to turn, turn around or brake suddenly on the newly compacted or compacting road section to ensure the quality of the base. The rolling time of the mixture should be close to the optimum water content. When the weather is hot and evaporation is fast, the paving time should avoid noon. When the seal coat is not laid at the grass-roots level, it is forbidden to open traffic to protect the surface layer from pollution and destruction. Construction vehicles should drive slowly, and the driving speed should not be greater than 30km/h.

(4) Health care

After the cement stabilized layer is formed by rolling, attention should be paid to early curing, which is beneficial to the normal development of strength, especially after construction 1 week, and the surface of lime soil should be kept wet. It is suggested to adopt the wet melting curing method of covering sacks and sprinkling water at least twice a day to prevent the surface of lime soil from turning white. All vehicles are strictly prohibited during the health maintenance period.

(5) Quality control measures

(1) The formwork on both sides can ensure the smoothness, and an elevation pile is driven every 5m in the middle of the road to set up a grid, so as to facilitate the timely discovery and deviation.

(2) After the initial pressure of each layer, check the flatness with 3m aluminum alloy ruler, level it in time, and trim the sag after loosening. The renovation depth shall not be less than 10 cm.

③ Combined therapy

The road is built in half-width, with stepped diagonal connection. The seams of the upper and lower floors should be staggered. Transverse joints are also in the form of vertical joints. Oblique joints are strictly prohibited, and the production of vertical joints should be carried out in strict accordance with the specifications.

(4) Shrinkage, cracking and construction joints of lime-soil base course during construction and maintenance should be treated with 400g/m2 geotextile to prevent cracks from reflecting to asphalt surface.

Asphalt concrete pavement construction

(1) preparation before construction

A. Carry out acceptance of grass-roots units in strict accordance with the acceptance criteria. If there are unqualified sections, carefully clean up the grass roots and blow them clean with a forest fire extinguisher.

B. Before paving, technical disclosure shall be made to all construction technicians, with clear responsibilities, and the responsibilities shall be carried out by people, so that every construction worker knows his work.

C, using the car distributor to carry out the construction of the lower seal coat.

② Mixing of asphalt mixture

The asphalt mixture is mixed with a gap mixer, and the aggregate heating temperature is controlled between 175- 190℃. After that, the asphalt mixture is transported to the vibrating screen by the hot material lifting bucket, screened by four sieves with different specifications of 33.5 mm19 mm13.2 mm.5 mm, and then stored in five hot ore bins. Asphalt is heated to 160- 170℃ with heat transfer oil. Five kinds of hot materials, mineral powder and asphalt materials were determined through production mix design. Finally, the mineral powder is blown into the asphalt mixture and stirred until the asphalt mixture is uniform, all mineral particles are wrapped by asphalt, and the binder has no flowers, lumps, lumps or serious segregation of coarse and fine materials. The mixing time of asphalt concrete is determined by trial mixing, and the ex-factory temperature of asphalt mixture is strictly controlled between 155- 170℃.

③ Hot-mixed asphalt mixture transportation

A. When the car unloads from the mixing plant to the truck, move the position of the car for each bucket of mixture to reduce the segregation of coarse and fine aggregates. After the truck is filled with hot-mixed asphalt, it must be covered with a cover cloth or a thermal insulation cloth to prevent dust from causing secondary pollution to the hot-mixed asphalt.

B the traffic volume of the mixture transport vehicle is greater than the mixing or paving speed. During construction, stop at 30cm in front of the paver to avoid hitting the paver. During unloading, it should be placed in neutral position and pushed by paver.

C the transportation of asphalt mixture must be fast and safe, so that the temperature at which the asphalt mixture reaches the paving site is between 145℃ and 165℃, and the mixing quality of asphalt mixture should be checked. When the warehousing temperature does not meet the requirements or the silo is caked, it is not allowed to spread on the road due to rain.

④ Paving of asphalt mixture

A. This project is paved by German ABG paver, with staggered joints of 0.5m between upper and lower layers, and the paving speed is controlled at 2-4m/min. The lower asphalt layer is paved with steel wire rope to control the elevation and smoothness, and the upper asphalt layer is paved with balance beam device to ensure the paving thickness and smoothness. The paving speed should be balanced according to the set speed, and it is not allowed to change the speed and stop at will. The loose laying coefficient should be determined according to the test section. The normal paving temperature should be between 140- 160℃. In addition, when the upper surface is paved, 4cm thick battens shall be made at the vertical and horizontal joints to ensure that the joints are straight.

B. In the process of paving, the manhole on the pavement should be covered with steel plates before paving, so as to avoid lifting the paver when encountering the manhole during paving and ensure the smoothness. Before laying fine materials, lift the inspection well to the actual laying elevation. When paving the paver, the lifting method of the manhole should be adjusted according to the paving condition of the bottom material and the paving thickness of the fine material combined with the road surface condition to ensure the smoothness of the manhole and the road surface without bumping. After the fine materials are laid, use a spatula to remove the powder accumulated on the inspection well.

C. When paving the pavement, avoid manual operation as far as possible, and pave with a small paver to ensure the smoothness and uniformity of the mixture.

D. When paving, the edge of the flat stone should be slightly 3mm away from the flat stone, at least flat, and the mixture overlapped on the flat stone should be removed with a shovel, and the rake should be pushed together to keep a straight line.

⑤. Matters needing attention in paving process:

A. The driver of the car should cooperate closely with the paver to prevent the vehicle from hitting the paver, causing it to deviate, or discharging materials from the machine. The rear wheel of the dump truck is preferably about 30cm away from the paver. When the paver touches the material, the trolley will lift and dump the material.

B. continuous feeding. When waiting for materials, the mixture in the machine should not be scattered to ensure that there are enough materials in the hopper to prevent the feeding plate from being exposed. Due to the failure, the materials in the bucket are caked, which should be removed when repaving.

C the operator should correctly control the paving sideline and accurately adjust the screed.

D. The inspector shall regularly check the loose laying thickness, check a section every 5 meters, and each section shall be no less than 3 o'clock, and make records, and feed back information to the operator in time; Check the cross slope every 50 meters, and regularly check the flatness.

E. When paving, pavement workers should pay close attention to the paving trend. If the cross section does not meet the requirements, the structural connection parts are short of materials, the edge of the paving belt is partially short of materials, the surface is obviously uneven, the local mixture is obviously separated, and there are obvious drag marks after paving, the mixture should be repaired or replaced manually. And it must be carried out under the guidance of technicians. Workers should not stand on the hot asphalt surface when repairing manually.

F it is forbidden to clean the machinery with diesel oil on the paved road after work every day.

G. During the construction process, the contact between the front and back offices should be strengthened to avoid production losses caused by untimely information transmission.

H. In order to ensure that the kerb of road green belt is not affected by asphalt concrete construction when paving, a small road roller will be left at the edge of kerb for rolling.

First, before the paver starts to receive materials, the hopper should be coated with a small amount of diesel oil to prevent material sticking, and plastic sheets should be laid under the paver to prevent road surface pollution.

⑥ Rolling of asphalt mixture

A. The compacted asphalt mixture meets the requirements of compactness and smoothness.

B. Choose reasonable roller combination and rolling steps to achieve the best effect. Asphalt mixture compaction adopts the combination of steel wheel static roller and tire roller or vibratory roller. The number of rollers is determined according to the production site.

C. Compaction of asphalt mixture shall be carried out in three stages: initial compaction, secondary compaction and final compaction (including molding). The roller rolls at a slow and even speed.

D the initial pressure of asphalt mixture meets the following requirements

A. After the mixture is paved, initial compaction shall be carried out with ingersoll DD- 1 10 roller at a higher temperature, which shall not cause displacement and cracking. Compaction temperature shall be determined by trial paving and pressure test according to asphalt consistency, roller type, paving layer thickness and mixture type.

B. the roller rolls from the outside to the center. Adjacent rolling zones shall overlap 1/3— 1/2 wheel width, and finally the central part of the road shall be rolled and fully rolled. When there are fenders, kerbs, shoulders and other supports at the edge, they should be rolled close to the supports. When there is no support at the edge, the mixture at the edge can be slightly raked up with a rake, and then the outer wheel of the roller will crush more than 10cm on the edge.

C. When rolling, orient the driving wheel towards the paver. Don't suddenly change the rolling route and direction, which will cause the mixture to move. The roller must be started and stopped slowly.

E. Re-pressing shall be carried out after initial pressing and meet the following requirements:

Re-pressing adopts tire roller. The number of rolling passes should be determined by pressure test, not less than 4-6 times, to achieve the required degree of compaction, and there is no obvious wheel track.

Final compaction shall be carried out after recompression. The final pressure shall be rolled by a two-wheel steel roller, which shall not be less than twice, and there shall be no wheel tracks.

When steel drum roller is used, adjacent rolling belts should overlap the rear wheel width 1/2.

All landowners roller rolling matters needing attention:

A the length of the rolling section of the road roller is selected according to the principle of balance with paving speed, and generally remains stable. Every time the roller turns back from both ends, it advances in a ladder shape with the paver, so that the place where it turns back is not on the same cross section. In the process of continuous paving by paver, the roller does not stop at will.

B when the asphalt mixture sticks to the roller during the rolling process of the roller, a small amount of water or washing powder water can be sprinkled on the roller, and diesel oil is strictly prohibited.

C. The roller shall not turn, turn around or stop waiting on the section that has not been cooled by rolling. Vibrating roller will turn off vibration when driving on a flat road.

D for local areas, such as joints, corners, widened parts of structures such as bridges and retaining walls, and some road edges that cannot be compacted by road rollers, vibrating rammers should be used for compaction.

E on the asphalt mixture layer formed by rolling that day, it is forbidden to park mechanical equipment and vehicles, and it is forbidden to scatter mineral materials, oil and other sundries.

⑧ Joints and trimming

A. the construction of longitudinal joints shall meet the following requirements:

Surface 10- 15cm, fully compact the joint. The longitudinal seams of the upper and lower layers are staggered by 0.5m, and the longitudinal seams of the surface layer should be straight and stay in the line drawing position of the driveway.

B the transverse joints between two adjacent plates and the upper and lower floors are staggered by more than 5m. The horizontal seam of the upper and lower layers can adopt oblique seam, and the upper layer should adopt vertical flat seam. When paving joints, some hot mixture can be paved on the compacted part for preheating and softening, so as to strengthen the bonding between the old and new mixture. But before rolling, the mixture for preheating should be removed.

C flat joints shall be closely combined, fully compacted and smoothly connected. The following construction methods can be adopted: at the end of construction, before the paver approaches the finish line, lift the screed slightly away from the site for about 1 m, and manually shovel off the end mixture before rolling. Then use a 3 m ruler to check the flatness, and if it is not cold enough, vertically eliminate the parts whose end flatness or layer thickness does not meet the requirements, so as to facilitate the construction of right-angle connection in the next step.

D. Before paving the mixture from the joint, use a 3 m ruler to check the flatness of the end. If it does not meet the requirements, it should be removed. When the shop is stuck, the reserved height should be well controlled. After the shop is stuck at the joint, check the flatness with a 3 m ruler. If there is any nonconformity, it should be dealt with immediately when the mixture is not cooled.

E. The transverse joints shall be horizontally rolled by a two-wheel steel roller. On the outer side of the rolling belt, there is a slide rail for the rollers to run. When rolling, the roller is located on the compacted mixture layer, and the width of the roller extending into the new layer is 15cm. Then move 15-20 cm to the mixture every time it is pressed, until it is completely pressed on the new layer, and then roll it longitudinally. When adjacent paving layers have been formed and there are longitudinal joints at the same time, the longitudinal joints can be rolled once with a steel wheel roller with a rolling width of 15-20 cm, then rolled horizontally along the transverse joints, and finally rolled normally.

F the exposed edge of the finished paving layer shall be accurate to the required line position. Remove trimming and cutting materials and any other waste asphalt mixture from the road.

Pet-name ruby test part

A before the asphalt concrete paving layer starts, a test road with a length of not less than 200m shall be paved with each asphalt mixture on the site selected by the engineer according to the requirements of this specification under strict supervision. To this end, all equipment used in normal production will be provided and used.

B. The purpose of this test is to prove the stability of the mixture, eliminate obvious defects in mechanical equipment, and satisfy the engineer, and make reasonable improvements to the equipment or operation free of charge according to the requirements that the engineer may put forward according to the results of the test section.

C. At each test, the test piece shall be drilled from the compacted material and tested after paving 12 hours.

D sampling, sample size and sample identification are all in accordance with the provisions of chapter 1 1 of GB50092-96.

E. If the test section is approved, it will be included in the whole project and the cost of the completed project will be paid. If the engineer doesn't accept it, all unqualified sections will be removed, and the reasons will be analyzed and resurfaced, and all expenses arising therefrom will be borne by the engineer.

Pay attention to climatic conditions

A paving of asphalt mixture should be avoided in rainy season, and construction should be suspended when the road surface is stagnant or wet.

B. When the construction temperature is lower than 10℃, stop paving.

C the asphalt mixture stored in the rain without compaction shall be completely removed and replaced with new materials.