Curbs are mark stones set between pavement and other structures. Curbs are generally required between the separator and pavement of urban roads, and between sidewalks and pavement. Curbs are often required at the edge of the central separator, the right edge of the carriageway, or the outer edge of the shoulder.
Curbs shall be firmly installed, with straight lines, straight bends, and no corners. The top surface shall be flat and free of staggered teeth. Cement mortar shall not be used for pointing as required by the Owner. Curbs must be installed before asphalt pavement construction and protected during asphalt pavement construction to prevent pollution. After the curb is buried, the backfill material shall be compacted or protective measures shall be taken to prevent the deformation of the surface course during construction. It is strictly prohibited to excavate the surface course and bury the curb after paving the asphalt surface course. Curb back concrete C20 concrete.
Main construction methods
The curbs transported to the construction site shall be inspected again and shall be handled with care to avoid damage. Those unqualified in strength, color, and luster, appearance dimension error of 5mm, lack of edges, corners, pits, cracks, color, and other phenomena shall not be used.
1. Before the installation of measuring and setting out curbs, check the road centerline, measure and set out curbs to install side piles and elevation control piles. The pile spacing in the straight section is 10m, the curve section is not more than 5m, and the intersection is 1-5m. A control survey shall be conducted according to the design elevation.
2. Curb transportation
⑴ For the transportation of curbs, the manufacturer is required to install plywood between curbs and blocks, and between layers, and carry out corner packing to ensure that the curbs are intact.
(2) Curbs shall be processed and manufactured in the factory approved by the Owner and the Supervisor. Curbs must pass the inspection when leaving the factory. After being transported to the construction site, the material quality inspector shall check and inspect the components according to the specifications, timely sample for inspection and witness sampling, and have the quality certificate and quality inspection report.
(3) For the first transportation, the processing plant will use a forklift to load, and the truck will be transported to the two tree pools on the footpath of the site for storage, with safety warning signs.
(4) Before the second transportation and installation, a small forklift shall be used to transport to the installation site for stacking at intervals. After installation, the remaining curbs shall be transported back to the designated place on the sidewalk in time, and safety warning signs shall be covered with a green net.
(5) During transportation, curbs shall not be collided and handled with care to avoid damage. Curbs transported to the construction site shall be installed in time.
(6) Before processing the special-shaped curb, the radius value of each intersection arc marked on the design drawing shall be compared with the actual value on site. If there is any error, the designer shall be notified in time to modify, recheck, summarize the number and provide it to the manufacturer for processing.
3. Curb installation
① Cushion is made of C20 concrete; M7.5 cement mortar is used as the base, and the proportion is controlled. A scale is set on the site to weigh the sand and gravel water according to the weight of each bag of cement. The sand and gravel water are measured by standard barrels.
② The curb shall be installed manually according to the setting out position. Before installation, the foundation shall be cleaned and kept wet. During installation, the straightness of curbs shall be controlled with wire rope first, and then checked with a level ruler. After the installation is qualified, C20 concrete shall be used for back pouring in time. Curb masonry shall be smooth. Adjacent granite curb joints shall be controlled by a 4mm thick iron plate or plastic plate. Adjacent concrete curb joints shall be controlled by an 8mm thick iron plate or plastic plate. The gaps between adjacent curbs shall be uniform, and there shall be no gap or water leakage between the curb and the pavement.
③ The width of the granite curb joint is 5mm.
④ The number of curb blocks at each intersection shall be calculated in advance. During masonry, the road section shall be built from the intersection cut point on one side to the intersection cut point on the other side for a short time; When the road section is long, it shall be paved from the middle to both ends and connected with the special-shaped curb at the intersection. The curb of the intersection shall be controlled according to the contour slope.
⑤ Granite curbs at curved sections such as intersections and the ends of isolation strips should be prefabricated according to the design arc, and the length of a single block should not be less than 70cm. Small standard blocks shall not be used for splicing. The installation speed of curbs shall meet the needs of on-site construction and must be completed before the construction of the upper layer.
⑥ After the installation of the curb, the line must be hung again. Adjust the straightness, smoothness, flatness, and elevation detection of the curb. One point shall be detected every 20m. When the plane and elevation exceed the standard, it shall be adjusted.
⑦ Site cleaning: After the installation of curbs, clean the contaminated sites and roads in time.
⑧ Finished curbs shall be covered with plastic film for finished product protection to prevent damage and surface pollution.
4. Barrier-free crossing and maintenance
① When building curbs, it is required to reserve blind passage entrances and exits at zebra crossings according to the design requirements of construction drawings. Barrier-free facilities shall be built at each intersection according to the specifications.
② During the construction, if there is any discrepancy on the site, it shall be reported to the Supervisor and the Designer in time to discuss solutions.
5. Inspection and finished product protection
A level ruler shall be used for control during construction. The masonry shall be stable, the top surface shall be flat, the lines shall be straight, the curves shall be smooth, the joint width shall be uniform, and there shall be no foreign matter pollution. Then, the plastic film shall be used to cover the finished product for protection.
6. Construction of a special-shaped curb
(1) Before laying the special-shaped curb, the arc shall be set out first, the standard-size arc shall be set out on the ground, and then pre-assembled according to the detail drawing, compared with the set-out arc line. Formal masonry can only be carried out after meeting the arc requirements. If the arc requirements are not met, the curb shall be processed for the second time with machines such as a grinding machine, and can only be used after meeting the arc requirements.
(2) The special-shaped curb shall be laid from one side in sequence, and the appearance shall be smooth.
(3) The top surface of barrier-free curb ramps at intersections and pedestrian crossings shall be flush with the asphalt concrete pavement.
7. Material requirements:
① The top surface of the granite curb is machine-cut.
② For curbs, manufacturers with large scale, good reputations, advanced processing equipment, and technology shall be selected, and the manufacturer must supply time to ensure the quality of supply.
Construction precautions
(1) Before leaving the factory, the curbs shall be inspected and accepted and can be used only after meeting the design quality standards.
(2) Surveying and setting out:
① First check the center line of the road and re-nail the side piles. The pile road in the straight part is 10m, and the arc in the curve and intersection is 1-5m.
② The setting out shall be carried out according to the new nail pile. A small line can be used for setting out in the straight part and a line shall be drawn in the curve part. Recheck again after grooving and before installation, and measure the top surface elevation of the abutment and make marks.
③ After the installation of the nail pile and hanging line, the curb shall be arranged along one side of the foundation. After the mortar is mixed, it shall be evenly paved on the foundation with an imaginary thickness of about 2cm. The curb shall be installed according to the setting out position. The top surface of the curb shall be flat, straight, and smooth, and the curve shall be smooth.
(3) Curing: The curing period of road teeth shall not be less than 3 days, during which collision shall be strictly prevented.
