Before loading, turn the tank upside down to ensure that there is no water in the tank car.
The unit weight must reach 2600kg / m3, so as to ensure the concrete strength; (2) the water content of sand and gravel shall be strictly controlled during production.
6 experience summary ⑴ for high performance concrete, the optimization of raw materials is the key.
(2) crushed stone: 5 ~ 20mm continuous graded crushed stone of Furong quarry in Heyuan city shall be selected, with mud content of no more than 1%, apparent density of 2610kg / m3, mud content of 0.2%, mud block content of 0.1% and crushed stone crushing index of 3.5%.
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Ⅱ 42.5R Portland cement with 3D strength of 36.3mpa, 28 day strength of 58.7mpa, 3D flexural strength of 6.2mpa, 28d flexural strength of 8.7mpa, specific surface area of 385m2 / kg and standard consistency water consumption of 25.8%.
The civil business center project supplied by our company consists of four towers as the main building, of which three towers have C70 high-performance concrete for the outer frame columns below the 30th floor.
(3) the production and construction personnel shall have a deep understanding of the relevant specifications of high-performance concrete and carry out the construction in strict accordance with the requirements.
See Table 1 for the mix proportion of concrete; (4) three hours before the opening of concrete, organize technicians to verify the mix proportion according to the design proportion according to the on-site materials and retain samples, and detect various performance indexes of concrete for 1 ~ 3 hours.
We will delete it within 24 hours.
(7) water: clean tap water is used.
The concrete mixing time during production shall not be less than 180 seconds; (3) maintain the equipment before opening.
The operator shall not reduce the water content without authorization or add water at will to adjust the fluidity of concrete.
3 mix proportion design (1) by optimizing the mix proportion and adding high-quality fly ash and mineral powder, the amount of cement is reduced, so as to reduce the heat of cement hydration as much as possible and avoid concrete cracks caused by too high hydration heat of concrete; (2) select retarding polycarboxylic acid high-performance water reducer to reduce the shrinkage strain of concrete; (3) according to the construction needs of the project, C70 high-performance concrete is required to be used on the construction site.
After loading, the concrete can be sampled and tested at the charging platform.
If there is any infringement, please contact us in time.
It is only for the concrete companies to transmit, share and check.
At present, the production and use of high-performance concrete are more and more common.
If it is inconsistent, the mix proportion shall be adjusted again, and the strength does not matter.
In addition, as the “commodity” attribute of commercial concrete, its economy is also the focus.
The outer frame columns from the basement to the 30th floor are C70 high-performance concrete.
4 production control (1) before the formal start of production, the admixture in the tank shall be sampled again for trial mixing, and the previous state shall be compared to see whether it is consistent.
(4) fly ash: Grade II fly ash produced by Mawan Power Plant is adopted, with fineness of 26.2% and loss on ignition of 2.2%.
In order to improve the durability of concrete, employees need to continuously improve the mix proportion design, production process and construction process of high-performance concrete.
5 construction process control (1) C70 high performance concrete must be poured within 2h after arriving at the construction site to ensure its workability; (2) before the concrete is pumped and discharged, the driver shall be notified to refuel and mix the tank for 1 minute to ensure the workability of the concrete; (3) for the state of poor workability of concrete caused by too long waiting time on site, it is firmly not allowed to forcibly adjust the pouring; (4) before concrete pouring, the on-site technician must arrive at the site with the first truck to assist the on-site construction personnel in concrete detection, on-site detection of concrete pouring time, fluidity, expansion, etc., do a good job of on-site test pieces, timely feed back the on-site situation to the production personnel, and take videos of on-site pumping and pouring of concrete.
The quality control on duty shall make clear the materials and positions in the stockyard, and explain the disclosure to the forklift driver on duty; (4) do a good job in the transportation coordination of the team, so that the special vehicle can be used for special purpose.
The concrete can be delivered only after it is in good workability and in good condition.
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Source statement: the source of the article is Guangdong building materials and concrete.
(6) admixture: the retarding polycarboxylic acid high-performance water reducer produced by Dongguan concrete Fan Industry Co., Ltd.
shall be selected, with solid content of 20% and concrete water reduction rate ≥ 25%.
Combined with the actual case of the project, this paper makes technical disclosure to C70 high performance concrete from the aspects of mix proportion design, raw material selection, production control and construction process control.
With the increasing population and higher floors in Shenzhen, in order to meet the needs of urban construction, the demand for bulk material concrete in engineering construction is also higher and higher.
The concrete quality cannot be handed over to the on-site construction workers, who can customize the working performance of concrete mixture.
It is strictly prohibited to add water to the tank car and flush the feeding port halfway.
2 raw materials (1) cement: Yingde conch P.
In order to ensure the quality of C70 high-performance concrete and the smooth completion of pumping, pouring and vibrating, a series of effective technical measures have been implemented for the use of materials after repeated tests on the mix proportion of concrete, and good results have been achieved.
⑵ for production technicians, the design and application of high-performance concrete comes from a large number of basic tests and data accumulation.
The inspection items are as follows: slump, expansion, V-shaped funnel and other tests.
(4) considering the importance of the project, the construction party and the concrete mixing plant must fully cooperate to ensure the smooth progress of each supply.
The total construction area of the project is 81488m2.
The design life of the project is 100 years.
(3) sand: Dongguan Dongjiang River sand is selected, which is well graded medium sand, with apparent density of 2560kg / m3, fineness modulus of 2.7, chloride ion content of 0.002%, mud content of 0.8% and mud lump content of 0.3%.
The working performance of concrete is shown in Figure 1.
(5) mineral powder: grade S95 mineral powder of Shenzhen starfish port building materials Co., Ltd., with a specific surface area of 420m2 / kg, a 7-day activity of 85% and a 28 day activity of 104%.
