Formwork

  1. It is advisable to use steel formwork, which should be straight and flat, and set up 1 support device for every 1m. If wooden formwork is used, it should be solid, small deformation, no decay, distortion, cracks, and must be soaked before use, the straight part of the wooden formwork should not be less than 50mm plate thickness, every 0.8 ~ 1m set 1 support device; the curved part of the plate thickness should be 15 ~ 30mm, every 0.5 ~ 0.8m set 1 support device, the contact surface of the formwork and concrete and the top surface of the formwork should be planed. Formwork production deviation should meet the requirements of the specification.
  2. Formwork installation should comply with: Before supporting the formwork should check the road elevation, panel block, expansion joints and structure location; formwork should be installed firmly, straight, flat, no distortion, adjacent formwork connection should be tight and smooth, not misaligned; strictly prohibited in the grass-roots embedded in the formwork; the use of track paver should use special steel track mold; formwork installation is complete, should be inspected and qualified before use; formwork installation inspection after passing the surface should be coated with release agent or isolating agent, the joint should be taped or sealed with plastic film, etc.

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Rebar Installation

Before the installation of reinforcing bars, the quality of raw materials, specifications and processing should be checked to confirm that they meet the design requirements and specifications; reinforcing bars, corner bars, etc. Should be firmly installed and accurately positioned. The installation of reinforcement should be checked and qualified before use; the installation of the transmission bar should be firm and accurately positioned. The expansion joint transfer bar should be installed together with the expansion joint plate and the lifting joint plate.

Paving And Vibration

  1. When the three-roller unit paving concrete surface layer, the roller diameter should match the thickness of the paving layer, and must be equipped with a row-type vibrating machine with inserted vibrator set at the same time; when the surface layer paving thickness is less than 150mm, the vibrating beam can be used; when paving double-lane surface layer at one time should be equipped with longitudinal joint tie insertion machine, and equipped with insertion depth control and tie spacing adjustment device.Cement Concrete Pavement Panel Construction Steps

Paving operation

Paving operations should be uniform unloading, fabric should be adapted to the paving speed; with longitudinal joints, shrinkage of the concrete surface ties, should be timely installation of ties in the construction of the surface; three-roller shaft leveling machine segmental leveling unit length of 20 ~ 30m, pounding machine vibration and three-roller shaft leveling process between the time interval should not exceed 15min; in the length of an operating unit, should be used forward vibration, backward static rolling mode of operation, the best rolling number of times should be determined after a test paving section.

  1. When using track paver paving, the minimum paving width should not be less than 3.75m, and choose a suitable paver; slump should be controlled at 20 ~ 40mm, according to the different slump when the loose paving coefficient to calculate the height of loose paving; track paver should be equipped with vibrator group, when the panel thickness exceeds 150mm, slump less than 30mm, must be inserted into the vibrating; track paver should be equipped with vibration beam or vibrating plate to vibrate and trim the concrete surface, when using vibrating plate vibrating slurry finish, slurry thickness should be controlled at (4±1) mm; surface surface surface leveling, should be timely removal of residual material, finish surface trimming with trowel plate.
  2. Using the slide film paver paving should lay the reference line, clean and wet the grass-roots level, and firmly install the expansion joint support at the proposed expansion joint plate, with a support point spacing of 40-60cm.

Adjust the working parameters of the slip film paver to the best state, according to the front unloading position, timely rotation of the fabricator, laterally and evenly on both sides of the fabric. The height of the material level in the vibrating bin should generally be 10cm above the road surface. Concrete slump is small, apply high frequency vibration. Low-speed paving; concrete slump, the application of low-frequency vibration, high speed paving.

In the paving process to do: Slow start, smooth mechanical operation, uniform speed, crew cooperation, paver walking speed of 1-3m / min, pounding frequency of 8000-9000r / min.

  1. The use of small machinery paving concrete construction, loose paving coefficient should be controlled at 1.10 ~ 1.25; paving thickness reaches 2/3 of the concrete slab thickness, should be pulled out of the mold brazing, and fill the brazing hole; concrete surface layer in two paving, the upper layer of concrete paving should be in the lower layer of concrete before the initial set, and the lower layer thickness is appropriate for the total thickness of 3/5; concrete paving should be with reinforcing steel network, transmission bars and the concrete paving should be coordinated with the placement of reinforcing bars and corner reinforcement at the edges; a concrete slab should be poured continuously at one time and be properly vibrated as required.

Joints

  1. The expansion joint of ordinary concrete pavement should be set up with expansion joint reinforcement steel bracket, expansion joint plate and transmission bar. The expansion joints should be perpendicular to the center line of the pavement; the wall of the joints must be vertical; the width of the joints must be the same, and the joints must not even be pulp. The upper part of the seam is filled with caulking material, and the lower part of the expansion plate and the transmission rod are installed.
  2. There are two methods of fixing and installing the transmission rod. One is the end of the wooden mold fixed force-bearing rod installation method, suitable for concrete slab not continuous pouring when setting the expansion joint. Half of the length of the transfer bar should be passed through the end stopper and fixed in the outer positioning formwork. Concrete mix should be checked before pouring the position of the transfer bar; when pouring, the lower layer of concrete mix should be paved first with the insertion of the vibrator vibrating solid, and should be corrected after the position of the transfer bar, and then pour the upper layer of concrete mix. When pouring the adjacent plate, the end wooden mold should be demolished and removed, and the expansion joint plate, wooden inserts and transfer bar casing should be set. The width of expansion joints should be 20~25mm. When using asphalt or plastic film sliding closure layer, the width of expansion joints and caulking joints should be widened to 25~30mm. More than half of the length of the transfer bar should be coated with anti-adhesive coating on the surface. The other is the bracket fixed force-bearing rod installation method, which is suitable for expansion joints set when the concrete slab is poured continuously. Half of the length of the transfer bar shall pass through the expansion joint plate and end stopper, and shall be fixed in place with steel brackets. When pouring, check the position of the transfer bar first, then spread the concrete mix to the surface of the slab in front of both sides of the expansion joint, pound it tightly, pull out the end baffle, fill the concrete mix in the gap part, and vibrate it with the inserted vibrator. It is advisable to reject the concrete on the expansion joint plate when the concrete is not hardened, embed (20~25)mm×20mm wooden strips and level the surface. The expansion joint plate should be continuous through the entire width of the road panel.
  3. Transverse shrinkage joints are constructed by cutting machine, and there are three types of cutting methods: All hard cutting joints, combined hard and soft cutting joints and all soft cutting joints. It should be determined by the temperature difference between day and night during the construction period when the concrete panel is paved to cut joints. If the temperature difference <10 ℃, the longest time shall not exceed 24h, hard cutting joints 1/4 ~ 1/5 plate thickness. Temperature difference of 10 ~ 15 ℃, soft and hard combination of seam cutting, soft cutting depth should not be less than 60mm; inadequate hard cutting to fill the depth of 1/3 board thickness. Temperature difference > 15 ℃, it is appropriate to cut all soft seams, compressive strength level of 1 ~ 1.5mpa, people can walk. Soft cut joints should not exceed 6h. Soft cut depth should be greater than or equal to 60mm, unbroken cut joints, should be hard cut to fill the depth to not less than 1/4 board thickness. For the longitudinal but connected joints that have been inserted into the tie rod. The cutting depth should not be less than 1/3 to 1/4 board thickness, the shallowest cutting depth should not be less than 70mm, and the longitudinal and horizontal shrinkage joints should be cut at the same time. The width of shrinkage joints should be controlled at 4-6mm, the depth of caulking groove should be 25-30mm, and the width should be 7-10mm. Longitudinal construction joints are in the form of flat joints, enterprise joints, etc. The concrete slab should be filled in time after the maintenance period.
  4. Before filling the caulking material, remove the sand and gravel, condensed mud, debris, etc. From the joints and rinse them clean. Seam wall must be dry and clean. Seam material filling depth should be 15 ~ 20mm, hot day construction seam material should be flat with the plate, cold day seam material should be filled with concave liquid surface, the center should be lower than the plate surface 1 ~ 2mm. Filling seam must be full and uniform, consistent thickness, continuous through, caulking material shall not be missing, cracking, water seepage. Caulking material maintenance period should be closed to traffic.Cement Concrete Pavement Panel Construction Steps

Maintenance

Concrete should be timely maintenance after the completion of pouring, can be taken to spraying conservative or moisturizing cover and other ways; in the case of rain or maintenance water is sufficient, can be used insulation film, geotechnical felt, sacks, grass bags, grass curtains and other cover sprinkling wet maintenance way, should not use the water around the maintenance; day and night temperature difference is greater than 10 ℃ above the region or the average daily temperature is less than 5 ℃ construction of the concrete slab should be used for insulation maintenance measures. Maintenance time should be based on the growth of concrete bending and tensile strength, should not be less than 80% of the design bending and tensile strength, generally suitable for 14 ~ 21d. Should pay special attention to the first 7d of moisture (temperature) maintenance.

Open Traffic

After the concrete reaches 40% of the design bending strength, pedestrians can be allowed to pass. After the concrete has completely reached the design bending strength and caulking is completed, the traffic can be opened.