Construction plan of cement concrete pavement with slip film
Cement concrete pavement refers to a pavement composed of cement concrete panel and base (cushion) layer, also known as rigid pavement, which includes Ordinary concrete, reinforced concrete, roller compacted concrete, steel fiber concrete, continuously reinforced concrete, etc.
Ordinary concrete (also known as unreinforced concrete or plain concrete) pavement refers to a cement concrete pavement that is not reinforced outside the joint area and local areas.
Cement concrete pavement is a rigid advanced pavement. It has the characteristics of high strength, good stability, fatigue resistance, impact resistance, anti-skid and good environmental adaptability. Therefore, cement concrete pavement is popular at home and abroad. It is widely used on high-grade road surfaces. Domestic and foreign countries attach great importance to the construction of cement concrete pavements, which has led to good development of cement concrete pavements, especially in high-grade highways and heavy-duty traffic pavements, which have been more widely used.
Although cement concrete pavement has these advantages and my country's cement concrete pavement is developing very rapidly, cement concrete pavement only accounts for about 25% of expressways and first-class highways, and the proportion of second-class and lower roads is relatively small. big. The reason is that cement concrete pavement construction requires high technical requirements. Therefore, construction management and quality control during the construction of cement concrete pavement are particularly important.
The construction methods of cement concrete pavement mainly include: first, manual construction with small machines; second, three-axis leveling machine construction; third, slip form paver construction.
Since cement concrete pavements constructed manually with small machines or three-axis screeders are seriously damaged after being put into operation, the currently widely used construction method is slipform paver construction. This construction method is commonly used abroad and is currently being promoted in my country. Therefore, this article focuses on the construction management and quality control of concrete pavement using the slipform paver as the construction method.
1. Preparations before construction
1. Technical briefing, determination of construction plan and personnel training
Before construction, the construction unit shall conduct detailed technical briefing and determine Construction plan, strengthening personnel training is a must. The construction unit should prepare a detailed construction organization design and implementation plan based on the unit's construction machinery, site conditions, and the new process flow of slip-form paving concrete pavement construction. Provide construction management personnel, test technicians and operating technicians with technical training on slip form paving construction. Untrained personnel are not allowed to operate alone.
2. Reasonable arrangement of mixing stations
The installation of mixing stations for concrete pavement slip form construction is the focus of construction preparations.
(1) The mixing station should be installed in the middle of the paved road section. The internal layout of the mixing plant should meet the requirements for raw material storage and transportation, concrete transportation, water supply, power supply, steel bar processing, etc., and should be as compact as possible to reduce the floor space. The mixing building should be installed upwind. If the sand and gravel field area is insufficient due to terrain conditions, a sand and gravel storage and transfer yard can be set up near the mixing station.
The ground of the sand and gravel site should be hardened with concrete and other materials for 10-15cm, and a rainproof, snowproof, and sun-proof ceiling should be built on the upper part to prevent water accumulation, secondary pollution and mixing of concrete raw materials in the mixing station. ; Prevent the use of sand and gravel materials contaminated by water, snow, excessive local humidity or surface dust to configure concrete. Otherwise, the uniformity and flexural and tensile strength of fresh concrete will be seriously affected. If the aggregate is soaked in water and a water film is adsorbed on the surface, and no cement is mixed during mixing, or the water absorption rate is too high, a large amount of slurry will occur at the bottom of the slab under the ultra-high frequency vibration of the paver, seriously affecting the flexural and tensile strength of the concrete. ; In addition, systematic drainage facilities within the site must be provided.
(2) The mixing station should provide water for mixing, cleaning and health care, and ensure that the water quality meets drinking water standards. If the water supply is insufficient, a water storage tank with a volume of no less than 250-500m3 should be set up, and the water storage capacity should be enough to meet the construction needs for at least half a day.
(3) The mixing station should ensure sufficient power supply and implement safety measures.
(4) Ensure fuel supply. The fuel supply for power equipment such as slipform pavers, transport vehicles and generators should be ensured.
(5) Reserve sand and gravel materials. Before construction, it is required to reserve sand and gravel materials required for normal construction for more than one month.
(6) Reasonably arrange the passages in the venue. The raw material transportation and concrete transportation vehicles of the mixing station should not interfere with each other. Circular roads for vehicle entrances and exits should be reasonably laid out. Each or every two mixing buildings installed together should have a relatively independent entrance and exit for transporting materials, and a temporary parking lot. The loading area below the mixing building should be paved with a concrete road surface about 20 cm thick, and wastewater treatment and recycling equipment for cleaning sewage discharge pipe trenches, water seepage pits or cleaning the mixing building should be installed.
3. Prepare the transportation road
Before slip-form paving, the cement concrete transportation road should be built in advance. When there is no road access or other difficulties, there should be construction access roads. Ensure that the road for construction and transportation of concrete is basically smooth and smooth.
4. Prepare an on-site laboratory
An on-site laboratory should be established at the construction site. The construction unit should have its own testing personnel to survey and sample raw materials and conduct regular inspections during the preparation and construction process. Sampling inspection and testing according to the prescribed test methods; testing the concrete mix proportion and providing test reports according to the prescribed requirements to control the working performance of the mixture; making test pieces according to the regulations and conducting relevant tests; conducting other related tests and providing Self-inspection results such as bending and tensile strength, core splitting strength, flatness, plate thickness, structural depth, etc. should be recorded in a standardized manner. The construction site where concrete pavement slip form construction is carried out should establish an on-site laboratory with complete testing equipment for raw materials, fresh concrete, and concrete pavement. Standard conditions are used for all concrete tests to prevent and timely detect problems such as insufficient concrete flexural and tensile strength, and effectively Control quality to ensure construction quality.
5. Strictly control the quality of incoming raw materials
Slippery construction progresses quickly, and the quantity and daily supply of raw materials used is large, and raw materials are the main components of engineering structures. , not only to ensure the required quantity, but especially the quality. That is to say, no work stoppages may occur due to insufficient quantity supply, and unqualified materials must not be used in projects. Therefore, according to the construction schedule, timely supply of various qualified raw materials should be ensured. The quality of raw materials should be inspected in batches, and unqualified raw materials should not be allowed to enter the site. The registration, storage, custody, issuance and other corresponding management work of all raw materials should be done well.
6. Do a good job in safeguarding construction machinery
Slippery construction equipment must be fully equipped, always in good construction condition, and meet the required quality level. Therefore, before construction, it is necessary to check the construction machinery such as mixing buildings, transport vehicles, material feeders, sliding form pavers, roughening machines, sawing machines, theodolite, level or total station and other measuring baseline instruments and artificial auxiliary construction equipment. Conduct comprehensive inspection, debugging, calibration, calibration, repair and maintenance of vibrator rods, leveling beams, formwork and other machines, tools and test instruments to ensure normal trial operation. Pay special attention to the reserve of wearing parts. Generally, most of the vibrators need to be replaced every 20km of highway construction.
7. Carefully prepare for construction re-testing work
Pavement construction must carry out re-testing of base control piles and restoration of measurement and setting out of lost pavement piles in the base layer. The plane and elevation control piles should be checked according to the design documents, and all basic pile numbers such as the pavement center line and edge lines handed over by the base layer should be re-measured and restored. The measurement accuracy should meet the requirements of the corresponding highway grade pavement construction measurement and design requirements.
8. Determine the paving position
At present, the paving width of the paver cannot meet the requirements for full-width construction of all road surfaces. It is difficult for the paver to move the work point, and the joints and The construction sequence arrangement should be carefully studied and determined. The paving width and position of the paver should coincide with the lane, shoulder width and line drawing position as much as possible, and ensure the width required to set the construction baseline. The paver tracks should be walked on the base, sub-base or compacted and stable cushion, and shall not be walked on the central divider with water accumulation or on the soft soil base.
9. Clarify the construction procedures for paving bridge decks or viaducts
Determine the construction procedures for bridge deck paving and the reinforcement measures for track positions for slipform paving of bridge decks. Basic premise.
When the slipform paver is continuously paving the middle-separated small and medium-sized bridges and passage bridge decks, the crawler tracks should avoid the separation belt or take temporary reinforcement measures for construction. The guardrails should be manufactured and installed after the bridge deck paving is completed. . When paving the road surface of the viaduct, the crawler tracks should avoid the middle pier of the viaduct, and reinforcement measures should be taken to pass through the communication wellhead.
10. Requirements for construction preparation of road shoulders and curbs
When the paver is set to cantilever paving hard shoulders or conjoined construction of curbs, the base position of the bottom of the shoulder should be in line with the paver. The paving shoulder and the outside of the curb should overlap or be slightly wider. The trenches eroded by rainfall on the soil shoulder must be backfilled, leveled and compacted.
11. Make preparations for communication dispatching
The lack of effective wireless communication will cause the coordination of all aspects of the construction to be out of coordination and even cause the command system to malfunction, which will seriously affect the speed and efficiency of the construction. . Therefore, fast and effective communication between the paving site and the mixing station should be established. During the construction process, a dedicated person must be on duty at the command podium continuously to communicate at any time and conduct production scheduling and command in a timely manner.