Hainan Province has introduced concrete slipform paver from the United States and Germany in 1998. It first conducted trial production on the urban main road at the Sanya Exit Road of the West Expressway and achieved ideal results. Subsequently, concrete pavement was carried out on the Jiusuo, Basuo, Yangpu and Changjiang exit roads of the Western Expressway (first-class highways) and Lingbao Line and Tongsan Line (secondary highways), attracting many domestic colleagues to visit study. By the end of 2000, the total area of ??cement concrete pavements constructed with slipform paver in Hainan Province reached 1.88 million m2, and all indicators tested by the quality supervision department reached excellent standards. At present, the quality control of the concrete pavement of the Haikou-Wenchang Expressway under construction is still relatively satisfactory. Hainan Transportation Engineering Supervision Company undertakes construction supervision services for all the above-mentioned projects. For the construction supervision of slipform paver concrete pavement, a set of effective supervision experience has been summarized, which is introduced as follows for reference by peers.
1 Supervision control during construction preparation
Supervision engineers must do a good job in the construction preparation stage and carefully check the completion of each process and whether it meets the relevant regulations. This stage should focus on: standardizing construction behavior, ensuring that the machinery is equipped and in good condition; the quality of raw materials should meet the design and specification requirements, the process connection should be smooth, and the quality assurance system and testing methods should be improved to achieve orderly construction.
1.1 Quality control of raw materials
The quality of raw materials will directly affect the quality of construction and must be in accordance with the "Technical Regulations for Sliding Form Construction of Highway Cement Concrete Pavement" (JTJ/T037.1-2000 ) requires the quality of raw materials to be inspected. Supervisors must accompany construction technicians to the preliminarily selected material manufacturers to take representative samples, test various technical indicators, and select raw materials that meet the requirements of the regulations. Only then can the construction unit Sign a supply contract with the supplier and indicate the technical control indicators and requirements of the required materials in order to control the quality of the materials entering the site and organize the materials to enter the site in a timely manner according to the progress needs. For example, in the selection of raw materials for the concrete pavement of the Haikou-Wenchang Expressway, we randomly inspected 10 groups of rock strength, 16 groups of gravel screening, crushing value, and mud content; we conducted two comprehensive inspections of cement products
< p>Ability to conduct random inspections; supervisory staff carefully checked the material testing and conducted the operations themselves, and selected three stone quarries from Xibian, Huangzhu, and Donglu gravel manufacturers that met the technical requirements. Sand: Nandujiang No. 3 sand field; cement: Hainan "Haidao" PO42.5; fly ash: Hainan thermal power plant; admixture: Guangdong Kejie brand KJ-70A.1.2 Concrete mix ratio test
To pave a high-quality cement concrete pavement, you must first have a high-quality concrete mixture. On the premise that the various raw materials meet the requirements It is crucial to do a good job in mix design. To this end, the supervision station laboratory works together with the construction test personnel to obtain first-hand information. During the construction of the concrete pavement of the Haiwen Expressway, on the premise of meeting the four basic requirements of bending and tensile strength, workability, durability and economy, the selected materials were determined through predetermined plans and 70 groups of trial fittings. proportion. In order to meet the construction requirements, considering that Hainan has no requirements for frost resistance and salt resistance, it is determined that the air content in the concrete is controlled at 2% to 4%, and the amount of fly ash needs to be determined according to the amount of fly ash contained in the cement component. For example: Haiwen Expressway determined to mix 57kg of first-grade fly ash from the dry discharge of Haikou Thermal Power Plant; used river sand from the lower reaches of Nandu River in Hainan with a fineness modulus of 2.8; and used 3 admixture manufacturers
Among the products, based on the test and testing, the samples were sent to the authoritative appraisal department in Beijing for inspection, and Guangdong Kejie KJ-70A air-entraining high-efficiency retarding water-reducing agent was finally selected.
1.3 Concrete mixing and paving equipment performance measurement confirmation
Hainan has introduced 5 concrete sliding mode paver, for example: SF6004 reinforced sliding mode paver is a product of CMI Company of the United States. Produced
's advanced products are equipped with automatic leveling and steering sensors, which can automatically adjust the thickness of the cement concrete surface layer and the paving direction, and can continuously complete paving, vibration, tamping, scraping and forming. , troweling and other processes without fixed formwork, it can automatically pave highway arches, super-elevations, smooth curves and slope changes, can adapt to panel thickness changes, can automatically set tie rods and perform bridge deck paving and reinforced concrete pavement Paving is an indispensable mechanical equipment for building high-grade cement concrete pavement. ELBAMTIC-C4 mixing plant is a fully automatic batch production concrete system. It consists of 1 sand silo, 4 stone silos, 1 admixture tank, 2 cement tank silos, 1 fly ash tank and electronic console. , the mixing time of each plate is 35~50s, and the productivity is 125m3/h. The electronic console can automatically control the feeding, weighing, metering and sand moisture content measurement according to the settings. The weighing error is 2%. If the deviation exceeds the deviation, the machine will automatically stop for 1 minute, perform internal adjustments, and perform secondary replenishment. After reaching the standard, resume stirring. Although the equipment is advanced, each mixing station must pass the measurement and calibration by the legal department after each transportation and installation before being put into production. The slipform paver must also be trial-paved with sand, soil or water-stabilized material, 100m long. Only when the performance of the machine meets the requirements can the construction of the test section be approved.
1.4 Construction organization management and personnel training
Any advanced equipment must be operated by humans. In order to reduce human errors, especially how to arrange the construction process of modern large-scale road construction equipment, How operators and auxiliary personnel work during the construction process will affect the construction quality and construction progress. Therefore, the construction process should be strictly reviewed and pre-job training should be conducted for construction personnel to make them understand the responsibilities of their positions and how to connect with other positions and processes. , as well as work quality standards, what inspections supervisors should do before each process, especially during the connection of processes, construction management personnel should understand and guide operators to do a good job.
2 Construction process quality system control
2.1 Establish a construction quality system
In order to ensure construction quality, in addition to training personnel, it is more important to establish a professional The effective "Project Quality Management System" determines the project management objectives, including ideological system, control system, organizational system, and improves various regulations and systems.
2.2 Supervisors are responsible for their own responsibilities
Supervisors should be reasonably allocated in conjunction with the construction, so that each supervisor should be clear about their job responsibilities. Generally, each work shift is equipped with 3 supervisors. The two front-line supervisors are the random supervisor and the paving preparation supervisor. The paving preparation supervision mainly checks the elevation control of the base layer, the cleaning of debris on the base layer, the verification of the laying out elevation and thickness, and the review of the steel bars and positions of the expansion joint plates, etc.; Random Supervision mainly controls the distribution of concrete, the quality of concrete on site, and spot checks of slump. If there is an abnormal slump or quality problems with the concrete, you should contact the back-site supervisor in time. During slipform paving, check whether the vibrator is working and the thickness of the concrete. , Appearance problems should be dealt with in a timely manner, master the time of roughening and sawing, and check the flatness at any time. A supervisor in the back yard is mainly responsible for controlling the quality of gravel, sand, cement and admixtures. If there are differences in raw materials, loading and use will not be allowed. The computer-controlled mix ratio of the mixing plant will be randomly checked at any time, and the slump of concrete when leaving the machine will be randomly checked. degree, combined with atmospheric temperature and test data, the water-cement ratio is controlled by considering moisture loss during transportation. The construction temperature of Haiwen Expressway is 25~32℃, the transportation distance is 15km, the concrete is transported to the paving site, the slump loss is 1.0~1.5cm, the slump of the paver working area: American SF6004 model is 2.0~2.5cm and 1.8~2.3cm for German SP1600 type are the best workable concrete.
I believe that after the above introduction, everyone has a certain understanding of the key points of supervision for the construction of cement concrete pavement using slip form paver. Welcome to log in to Zhongda Consulting for more relevant information.
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