Section 1, Material Selection 1. Cement adopts ordinary portland cement with new standard strength of 42.5. It requires high strength, small shrinkage, strong wear resistance and high frost resistance. When cement enters the site, there must be a product certificate and a test sheet, and its variety, label, packaging, quantity and factory date shall be inspected and accepted, and the cement entering the site shall be sampled for a second interview. Cement with different labels, brands, varieties and production dates shall not be mixed, and mixing is strictly prohibited. Cement with an ex-factory date of more than 3 months or wet must be tested, and the normal use or reduced use shall be decided according to the test results.

2. Coarse aggregate The coarse aggregate shall be hard, durable and clean crushed stone or crushed gravel, and conform to the prescribed grading, with the maximum particle size not exceeding 365,438 0.5 mm. The technical requirements of coarse aggregate shall meet the requirements of technical specifications: crushing value less than 65,438 05%, needle content less than 65,438 05%, silt content less than 65,438 0%, and mud block.

3. Fine aggregate Fine aggregate adopts coarse and medium natural sand with hard and clean texture and fineness modulus above 2.5. At the same time, it must have good gradation, and its technical requirements should meet the requirements of technical specifications. When using machine-made sand, it is also necessary to check the polishing value of sand, which should be greater than 35. It is not advisable to use water-rock machine-made sand with poor wear resistance.

Four, cleaning aggregate, mixing concrete and curing water, should not contain oil, acid, alkali, salt, organic matter, etc. , thus affecting the quality of concrete, and the PH value should be 6-8.

Five, admixture in order to reduce the water consumption of concrete mixture, improve workability, save cement consumption, improve strength, can be mixed with water reducer; In winter construction, in order to improve early strength or shorten curing time, early strength agent can be added; In summer, if it is necessary to extend the operation time, retarder can be added. Admixtures used in concrete can only be used after the mixture ratio test meets the requirements.

Six, connecting rod, dowel bar reinforcement should comply with the design requirements, shall not be replaced by waste steel, can not have cracks, broken, cracks; Oil lines and granular or flaky rust on the surface should be removed.

Section II Mix Design 1, concrete mix design should be designed according to the principles of design flexural strength, durability, workability and economic rationality. 2. Before paving the cement concrete pavement, submit all kinds of materials planned for the pavement to the laboratory, and design the mixture ratio through experiments. The flexural strength, water-cement ratio and cement dosage must meet the relevant requirements. The concrete pressure test strength should be increased by 10- 15% according to the design strength. 3. The determination and adjustment of concrete mixture ratio shall meet the following requirements: the calculated ordinary concrete mixture ratio shall be tested in the laboratory through trial matching, and the mixture ratio shall be adjusted according to the results. The benchmark mixture ratio of the laboratory should be tested by the actual mixing of the mixer and verified by the test section. When adjusting the mixture ratio, the water-cement ratio shall not increase and the unit cement consumption shall not decrease. In general, the unit cement consumption of pavement concrete should not be less than 300kg/m3, nor should it be greater than 400 ㎏/3. (4) During the construction period, according to the change of temperature and transportation distance, fine-tune the admixture content, fine-tune the water addition and sand weighing. 4. Without the consent of the supervision engineer, the approved concrete mixture ratio, various materials and construction methods shall not be changed.

The third quarter, construction preparation

I. General situation of construction

1. Center line lofting: set a central pile every 20m, and set piles at design expansion joints, curve start and end points and longitudinal slope change points.

2. Elevation setting-out: According to the design elevation, set elevation control points, and assign special personnel to track and measure during construction.

Second, the quality inspection at the grass-roots level Before the pavement concrete construction, the compactness, deflection, elevation, cross slope and width of the grass-roots level should be inspected in sections to confirm that they meet the design and specification requirements, and the surface construction can only be carried out after the supervision engineer has passed the acceptance.

Three, before the concrete paving, should also complete the following preparatory work 1. The concrete construction mixture ratio has been approved by the supervision engineer, and the mixing station has been tested and confirmed to be qualified.

2. The template has been installed and passed the inspection.

3. The machines for concrete paving, curing and molding have passed the trial operation.

4. Transportation and on-site pouring channels meet the construction requirements.

5. According to the design, delimit the concrete plate in advance, combine the plate division with the expansion joint, and divide the plate reasonably. The fourth quarter concrete transportation

A, concrete must use commercial concrete.

1. The number and configuration of transport vehicles shall be determined according to the transportation distance and paving capacity during construction. Dump trucks should be used for transportation, and mixer trucks should be used for transportation when the transportation distance is far away.

2. When transporting concrete mixture, it is not advisable to leak slurry to prevent segregation. If there is segregation, the concrete truck should be mixed twice before unloading to the site for paving.

3. After the concrete arrives at the site, it is transported to the paving point for paving, vibrating and kneading, and the longest time allowed until the pouring is completed is determined by the laboratory according to the initial setting time of cement and the construction temperature.

Section 5, concrete paving and vibrating

A, concrete pavement

1. Before concrete paving, the spacing, height, lubrication and support stability of formwork, flatness and humidity of base course, and the position of reinforcement and dowel bar device shall be comprehensively checked.

2. After the concrete is transported to the paving point, it can be directly poured into the road groove where the side formwork is installed, and the mixture will be leveled evenly by manpower. If the mixture is separated, stir it evenly with a shovel. When paving, it shall not be scattered, and the method of square shovel and buckle shovel shall be adopted for paving to maintain the uniformity of the mixture.

3. When the thickness of the concrete panel is not more than 22cm, it can be paved at one time; When it is more than 22cm, it can be paved twice, and the thickness of the lower part should be 3/5 of the total thickness. The paving of the upper concrete shall be completed before the initial setting of the lower concrete.

4. The paving thickness should consider the reserved height of compaction, and the loose paving coefficient should be controlled at 1. 10- 1.25.

5. The concrete slab shall be continuously poured at one time, that is to say, in the area where continuous pouring is needed, the pouring process shall not be interrupted, and dry mixing with water shall not be used.

Second, the concrete vibrating

1. Vibrate the paved concrete mixture quickly and evenly with plug-in vibrator and plate vibrator. Should be vibrated with plug-in vibrator first, and then vibrated with flat vibrator. First, at the corner of the template edge where the flat vibrator can't vibrate, use the plug-in vibrator to vibrate once, and the same position shall not be less than 20s. The moving distance of the plug-in vibrator shall not be greater than 1.5 times the effective radius, and collision between the formwork and the steel bar shall be avoided. If the thickness of the plate is greater than 22cm, if it is paved at one time, it needs to be vibrated in full sequence with an internal vibrator. If paved in two layers, when vibrating the upper concrete mixture, the internal vibrator should be inserted into the lower concrete mixture by 5cm, and the vibrating of the upper concrete mixture must be completed before the initial setting of the lower concrete mixture. Secondly, use a flat vibrator to vibrate in all directions. When vibrating vertically and horizontally, it should overlap 10-20cm. When the same part is vibrated, the vibrating time should not be less than 30s when the water-cement ratio is less than 0.45, and not less than 15s when the water-cement ratio is greater than 0.45, subject to bubble-free and floodlit cement mortar.

2. After the concrete is fully vibrated, it will be further dragged and vibrated with a vibrating rod for preliminary leveling. Drag the vibrating beam back and forth for 2-3 times to make its surface pan-slurry and drive away bubbles. The moving speed of vibrating beam should be slow and uniform. For uneven places, it should be filled in manually in time. When filling, fine mixture should be used for grouting. It is forbidden to fill with pure mortar, and the vibrating beam shall not stop over when traveling. The traction rope should not be too short to reduce the inclination of the bottom of the vibrating beam. The bottom of vibrating beam should be kept straight, and it should be adjusted or replaced when the bending exceeds 2mm. 3. Finally, the surface is further rolled and kneaded with a straight roller to further slurry the surface and mix it evenly. If it is found that there is still a big height difference between the concrete surface and the arch slab, it should be filled in again and rolled and leveled again. Finally, hang up the line to check the flatness. If it is found that it does not meet the requirements, it should be further processed and scraped until the flatness meets the requirements.

Section 6, Joint Construction

1. Expansion joint construction: the expansion joint spacing shall meet the design requirements and be perpendicular to the road centerline. The joint width should be 2cm, and the joint width must be consistent. There should be no cement slurry at the joint, and the joint wall must be vertical. The reserved gap on the expansion joint should be reserved by the joint lifting plate, and the expansion joint plate should be set at the lower part.

1. The movable end of expansion joint dowel bar can be set at one side of the joint or staggered. Take measures to fix dowel bar, which must be parallel to the center line of slab and pavement.

2. After the curing period of the concrete panel expires, the joint should be filled in time, and the mortar, mortar and other sundries left in the joint should be removed. Joint sealant should be selected according to the design requirements.

3. The joint sealant must be carried out in the dry state of the joint slot, and the joint sealant should be closely attached to the concrete joint wall without water seepage.

4. The filling degree of joint sealant should depend on the season, and the normal temperature construction, flat pavement and winter construction should be slightly lower than the board surface.

Third, contraction joint construction: the contraction joint is constructed by slit method.

. 1. When the concrete strength reaches 25-30% of the design strength, cut the joint with a cutting machine.

2. When cutting, mark the cutting position with ink lines first, and then use the cutting machine to cut. During operation, the blade, pointer and guide wheel of the slitting machine should be in a straight line and coincide with the ink cutting line. When the kerf depth is less than 6cm, the diamond saw blade with 7mm thickness can be used to cut directly at one time, or the diamond saw blade with different thickness can be used to finish it twice.

3. The contraction joint should be perpendicular to the board surface, with a width of 4-6mm. Incision depth: when setting dowel bar, it should not be less than 1/3 of the surface layer thickness and not less than 7 cm; When there is no dowel bar, it should not be less than 1/4 of the surface thickness and should not be less than 6cm.

4. The key to ensure the quality of slotting is to accurately grasp the slotting time. Too early will lead to edge drop, corner drop, burr, loose aggregate and aggregate falling off. If it is too late, it will cause cracks in the concrete pavement and even scrap the plates.

Second, the construction joint construction

1. The position of transverse construction joints shall be consistent with the design position of expansion joints or contraction joints. Construction joints shall be perpendicular to the center line of the pavement. Half the length of dowel bar of construction joint is anchored in concrete, and the other half is coated with asphalt, allowing sliding. The dowel bar must be perpendicular to the seam wall.

2. The construction method of longitudinal joints shall be determined according to the design requirements. When dowel bar is set in longitudinal seam, it should be set in the middle of plate thickness. Set the longitudinal seam template of the tie rod, and pay off and drill holes in advance according to the design position of the tie rod. Section VII, Surface Maintenance 1. After the concrete surface survives, it should be cured in time. Maintenance can be done by moisturizing method and plastic film covering. When the temperature is high, the curing period should not be less than 14 days, and when the temperature is low, the curing period should not be less than 2 1 day. 2. During the maintenance period, traffic should be closed and no heavy objects should be piled up.

3. After the concrete slab reaches 40% of the design strength, pedestrians are allowed to pass. Before the bending and tensile strength of surface concrete reaches the design strength and joint filling is completed, traffic shall not be opened.

A, summer construction

1. When the temperature of concrete mixture is 30-35℃, the concrete panel shall be constructed according to the summer construction specifications.

2. Shorten the time of transportation, paving, vibrating and kneading. As far as possible, it shall be carried out during the pouring of concrete mixture, and it shall be covered and watered in time after pouring.

3. Before pouring, the surface at the grass-roots level shall be wetted with water. 4. If the temperature is too high, the construction should be avoided at noon and can be carried out at night.