Construction technology of cement concrete bridge

2022-07-22
  • Detail

1. Construction preparation after the completion of the anti-collision guardrail construction, thoroughly remove the slurry, soil, concrete slag, etc. on the surface

1. Construction preparation

after the construction of the crash barrier is completed, thoroughly remove the slurry, soil, concrete slag, etc. on the surface

2. Surveying and setting out

control the rail elevation according to the design layout elevation control network. The construction personnel shall pop up the guide rail construction line according to the inner deviation of the anti-collision guardrail skirting line of 30cm, pop up the elevation control line under the skirting top line of 16.5cm, and recheck the guide rail position and elevation before and after the reinforcement mesh binding and before the concrete pouring, so as to achieve frequent measurement, verification and correction

3. Reinforcement and formwork

(1) reinforcement engineering

bind the reinforcement according to the size required by the drawing. Before use, check whether the surface of the reinforcing mesh is clean, and remove the floating skin, rust, oil stain, paint skin, dirt, etc. before use. In order to ensure the design thickness of the concrete protective layer, high-quality plastic cushion blocks are set under the reinforcement mesh and between the top of the concrete slab. The cushion blocks are staggered, and there is no cushion block at the joint of the reinforcement mesh

reinforcement mesh spacing 10 × 10cm, of which the long side is perpendicular to the transverse bridge direction. The reinforcement mesh adopts the flat connection method, that is, the reinforcement of one mesh is inserted into another mesh, so that the longitudinal and transverse reinforcement of the two meshes are overlapped in the same plane, the overlapping length is not less than 20cm, and tied firmly with binding wires. No reinforcement mesh is set within 30cm on both sides of the expansion joint

scaffolds are set up on the working face, and scaffold boards are set up on them as passageways for people and objects. Operators are strictly forbidden to step on reinforcement during construction. For local places where the protective layer is insufficient due to construction, cushion blocks should be added at any time

(2) formwork and guide rail

cement mortar guide rail is also used as pavement formwork, and the elevation and plane alignment must be strictly controlled. A 7-10CM wide cement mortar belt guide rail is set 30cm away from the inner side of the anti-collision barrier, and the elevation of the guide rail is led out by the elevation line of the anti-collision barrier skirting

before pouring concrete, inspect, repair and accept the formwork, support, reinforcement layout, position, etc. according to relevant regulations, and conduct concealed works acceptance with relevant personnel. Mainly pay attention to: whether the elevation of the guide rail and its section size conform to the design; Whether the strength of guide rail mortar belt meets the requirements; Whether the quantity, diameter, installation position and spacing of reinforcement meet the design requirements, and whether the installation and binding of reinforcement are consistent with the design

4. Concrete pouring

before pouring, wash the bridge deck with water and maintain a wet state, but pay attention to the low-lying areas without ponding. The concrete pouring shall be carried out continuously, and the slump test shall be carried out by the tester at the same time. The unqualified ones shall not be used. The pouring sequence is from low to high. When paving concrete, considering the settlement of concrete after vibration, the height of distribution should be 2-3cm higher than the guide rail. First, use the vibrating beam to vibrate, place the vibrating beam on the guide rail, and vibrate and level it twice along the paving surface to make the surface flat and flush the slurry. Scrape the higher concrete with the vibrating beam, and fill and vibrate the concave part with concrete in time, and pay attention to prevent mortar overflow on both sides. After vibration, the surface is flat and formed without exposed stones. Finally, use the aluminum alloy square tube as a scraper to scrape over the elevation line and level it accurately

the first plastering is carried out immediately after the full amplitude vibration and leveling. First, use a plastic trowel to knead and flatten, so as to remove the high and fill the low, knead and press out the mortar to make it evenly distributed on the concrete surface. The second plastering work shall be carried out next, and the plastic trowel shall be used to further level the concrete slab surface to make the surface uniform. If the formwork is found to be offset or damaged, it shall be hung and leveled in time. Finally, use a roughening brush to gently and evenly roughen the bridge horizontally. The depth of the groove shall be controlled within 1-2mm

5. Curing and formwork removal

due to the large surface coefficient of pavement concrete and rapid water loss, it affects the growth of concrete strength and causes concrete surface cracks. Therefore, a reasonable maintenance method is an important link to ensure the growth of concrete strength and reduce cracks. The curing method of the project adopts wet curing, that is, cover the concrete 6-8 hours after pouring, cover the surface of the concrete slab with geotextile, and spray water for wet curing after 10-12 hours to ensure that the concrete is in a wet state during the curing period (within a week). Plastic cracks and dry shrinkage cracks before covering shall be eliminated by secondary troweling

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