Precast News From China
Tunnel lining, as an important load-bearing structure and “face engineering” of tunnels, both its physical and visual quality are very important.
This article lists some quality problems and prevention measures of secondary lining for your reference.
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A new construction project with a building area of 1500m2, consisting of two underground floors and five above ground floors, and a reinforced concrete frame structure.
There are 3 post tensioned prestressed concrete beams in the lobby on the first floor.
After 25 days of pouring, the production manager judged based on experience that the concrete strength had reached the design requirements.
Immediately, the operators were arranged to remove the beam bottom formwork and prepare for prestressed tensioning.
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The ground of the industrial plant is made of wear-resistant concrete, and the surface layer is made of 160mm thick C30 reinforced concrete cast-in-place and wear-resistant epoxy self leveling layer.
Adopting the seamless construction technology of short distance stress release, that is, setting construction joints in the vertical direction on the concrete ground, dividing the ground into several blocks of a certain size with construction joints, pouring adjacent blocks at intervals (jumping pouring), and after the concrete is poured first and undergoes significant shrinkage deformation, it is connected and poured into a whole.
This seamless construction technology for short distance stress release is based on the non-linear relationship between temperature shrinkage stress and structural length, utilizing the large early temperature and shrinkage deformation of concrete.
The method of releasing stress in a short distance is adopted to cope with early large shrinkage.
After the concrete passes the early large temperature and shrinkage, each block is poured and connected as a whole to cope with smaller shrinkage.
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Policy basis: The Notice of the Ministry of Finance and the State Administration of Taxation on the Application of Low Value Added Tax Rates and Simplified Methods for Collecting Value Added Tax on Some Goods (Caishui [2009] No.
9) clearly stipulates that general taxpayers who sell self-produced commodity concrete (limited to cement concrete produced from cement as raw material) can choose to calculate and pay value-added tax at a simplified rate of 3%.
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Concrete segregation is essentially the phenomenon of the separation of various component materials under the action of gravity and external forces.
The seemingly subtle changes of coarse aggregate sinking, slurry floating, and water secretion may trigger a chain reaction that erodes the quality of the pier body from the inside out.
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If you still hold such thoughts, then you may be laying hidden dangers for future building safety.
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In concrete mix proportions, the water cement ratio is a core parameter that must be mastered.
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On January 30th, in Macheng City, Hubei Province, a massive object resembling a ship completed its final pressure test in the factory area of Wugang Institute New Materials Company of China Communications Second Navigation Bureau.
This is a prestressed UHPC shell cast-in-place inner core ordinary concrete composite cover beam (also known as “Ningbo beam”) independently developed by the company’s technical team.
Its successful development means that multiple global challenges in bridge construction are expected to be solved.
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