Analysis on the supervision points of cement concrete pavement construction by slip-form paver?

Since 1998, Hainan Province has imported concrete slipform pavers from the United States and Germany. At first, it was put into trial production on the urban main road of Sanya exit road in expressway on the west line, and achieved ideal results. Later, concrete pavements were paved in expressway No.9, No.8, Yangpu, Changjiang Exit Road (first-class highway), Lingbao Line and Tongsan Line (second-class highway) on the western line, which attracted many domestic colleagues to visit and study. By the end of 2000, the total area of slip-form paving cement concrete pavement in Hainan Province reached 6,543,880 m2, and all indicators tested by quality supervision departments reached excellent standards. At present, the quality control of Haikou-Wenchang expressway concrete pavement under construction is still ideal. Hainan Traffic Engineering Supervision Company undertakes the construction supervision services of all the above projects. Aiming at the concrete pavement construction supervision of slipform paver, a set of effective supervision experience is summarized, which is introduced as follows for reference by peers.

1 supervision control in construction preparation

The supervision engineer must pay special attention to the work in the construction preparation stage and carefully check the completion of each working procedure to see if it meets the relevant requirements. At this stage, we should focus on: standardizing construction behavior to ensure that the machinery is complete and intact; The quality of raw materials should meet the design and specification requirements, and the process connection should be smooth. Improve the quality assurance system and testing methods to achieve orderly construction.

1. 1 quality control of raw materials

The quality of raw materials will directly affect the construction quality. The quality of raw materials must be inspected according to Technical Specification for Slipform Construction of Highway Cement Concrete Pavement (JTJ/T037. 1-2000). Supervisors and construction technicians should go to the preliminarily selected material manufacturers to take representative samples, test various technical indicators, and select raw materials that meet the specification requirements. The construction unit may sign a supply contract with the supplier, and indicate the technical control of the required materials. For example, in the selection of raw materials for expressway concrete pavement from Haikou to Wenchang, we randomly selected 10 rock strength, 16 gravel screening, crushing value and silt content; The cement products were comprehensively evaluated twice.

Can be sampled; The supervisor carefully inspected the material test and personally operated it, and selected three stone yards in Bian Xi, Huang Zhu and Donglu that met the technical requirements. Sand: Nandujiang No.3 battlefield; Cement: PO42.5 fly ash from Hainan Island: Hainan Thermal Power Plant; Additive: Guangdong Jack brand KJ-70A.

1.2 concrete mixture ratio test

To pave a high-quality cement concrete pavement, we must first have a high-quality concrete mixture ratio. It is very important to design the mixture ratio on the premise that all kinds of raw materials meet the requirements. Therefore, the supervision resident laboratory cooperates with the construction test personnel to master the first-hand information. In the construction of Wenhai expressway concrete pavement, on the premise of meeting the four basic requirements of flexural strength, workability, durability and economy, the selection ratio of various materials was determined through the predetermined scheme and 70 groups of trial matching. In order to meet the construction requirements, considering that Hainan has no frost resistance and salt resistance requirements, it is determined that the air content of concrete is controlled at 2%~4%, and the content of fly ash is determined according to the content of fly ash in cement components. For example, Wenhai Expressway decided to add 57 kilograms of first-class fly ash to Haikou Thermal Power Plant; The river sand in the lower reaches of Nandu River in Hainan is used, and the fineness modulus is 2.8. In Sanjia production

On the basis of the test, the samples were sent to the authoritative appraisal department in Beijing for inspection, and finally Guangdong Jack KJ-70A air-entraining high-efficiency retarding water reducer was selected.

1.3 Measurement and confirmation of working performance of concrete mixing and paving equipment

Hainan introduced five concrete slipform pavers. For example, SF6004 reinforced slipform paver is produced by CMI company in the United States.

This advanced product is equipped with automatic leveling and steering sensors, which can automatically adjust the thickness and paving direction of cement concrete pavement, and can continuously complete paving, vibrating, tamping, leveling, forming, polishing and other processes without fixing templates. It can automatically lay road arches, superelevation, gentle bends and slopes, adapt to the change of panel thickness, automatically set tie rods, and lay bridge deck and reinforced concrete pavement, which is indispensable for building high-grade cement concrete pavement. Elbamdike -C4 mixing station is a fully automatic concrete production system. It consists of 65,438+0 sand silos, 4 stone silos, 65,438+0 additive tanks, 2 cement silos, 65,438+0 fly ash silos and an electronic console. The stirring time of each plate is 35~50s, the productivity is 1.25 m3/h, and the electronic console can suppress it. When the weighing error is 2%, if it exceeds the deviation, it will automatically stop 1min for internal adjustment and secondary replenishment. After reaching the standard, the mixing is resumed. Although the equipment is advanced, each mixing station must be calibrated by the legal department before it can be put into production after each handling and installation. Slipform pavers must also try to spread sand, soil or water-stable materials with a length of 100 m. When the mechanical properties meet the requirements, the construction of the test section can be approved.

1.4 construction organization and management and personnel training

Any advanced equipment must be operated by people. In order to reduce human error, especially how to arrange the construction process of modern large-scale road-building equipment and how to work for operators and auxiliary personnel in the construction process will affect the construction quality and progress. Therefore, the construction process should be strictly reviewed, and pre-job training should be given to the construction personnel, so that they can understand the responsibilities of their posts, how to connect with other posts and processes, and the quality standards of work, as well as what the supervisors should do before each process, especially during the construction management of process connection.

2 Construction process quality system control

2. 1 Establishment of construction quality system

In order to ensure the construction quality, in addition to training personnel, it is more important to establish an effective project quality management system, determine project management objectives, including ideological system, control system and organizational system, and improve various rules and regulations.

2.2 Responsibilities of supervisors.

Rational allocation of supervisors in combination with the construction situation, so that each supervisor can clearly define his/her post responsibilities. Generally, each class is equipped with 3 people to supervise the duty. The two supervisors in the frontcourt are the random supervisor and the paving preparation supervisor respectively. The paving preparation supervisor mainly checks the elevation control at the grass-roots level, cleaning up the sundries at the grass-roots level, checking the lofting elevation and thickness, and rechecking the positions of steel bars and expansion joints. Random supervision mainly controls the distribution and quality of concrete on site, and spot checks slump. If there is any slump abnormality or concrete quality problem, contact the backcourt supervisor in time to check whether the vibrator works during slipform paving and solve the problems of concrete thickness and appearance.

When machining, master the time of roughening and sawing, and check the flatness at any time. Backcourt 1 The supervisor mainly controls the quality of crushed stone, sand, cement and additives, and the raw materials are not allowed to be loaded for use. Randomly select the computer-controlled mixture ratio of the mixing plant at any time, and randomly select the slump of concrete when it leaves the factory. Combined with air temperature and test data, water-cement ratio is controlled by considering water loss during transportation. The construction temperature of Wenhai expressway is 25~32℃, and the transportation distance is 15km. When the concrete is transported to the paving site, the slump loss is 1.0~ 1.5cm, the slump of SF6004 paver in America is 2.0~2.5cm, and that of SP 1600 in Germany is 65438.

I believe that after the above introduction, everyone has a certain understanding of the supervision points of cement concrete pavement construction by slip-form paver. Welcome to Zhong Da for more information.

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