Construction Precast Development
Precast News From China
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According to JGJ/T104-2011 “Winter Construction Regulations for Building Engineering”, winter construction begins when the daily average outdoor temperature remains below 5 ℃ for five consecutive days.
Concrete structure engineering should adopt winter construction measures and take anti freezing measures for sudden temperature drops.
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The exterior of the residence continues the strong characteristics of brutalism, with the geometric shape of the concrete facade quietly disappearing in the shade.
The square holes and deep slanted window sills on the facade not only enhance the changes in light and shadow, but also soften the visual impression of the building.
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The concrete industry in 2025 is undergoing a deep adjustment from scale expansion to quality survival.
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In 2024, the global shotcrete market size is expected to reach $10.
46 billion, and it is projected to increase to $15.
36 billion by 2029.
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On December 22nd, Hainan Ruize (002596) hit the limit up, with a limit up price of 5.
89 yuan, an increase of 10.
09%.
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Vertical cracks appear in the middle of the beam span, penetrating along both sides of the beam.
The reason is that when the concrete is subjected to a load, the steel bars in the lower tensile zone are jointly stressed with the concrete.
When the fiber strain at the edge of the tensile zone is greater than the ultimate tensile strain of the concrete under bending, concrete cracking occurs in the tensile zone.
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This article is based on the extended finite element method (XFEM) for numerical simulation of three-point bending of concrete with precast cracks.
The model dimensions and parameters are shown in Figure 1.
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With the promotion of year-round operations in the construction industry, winter construction has become increasingly common.
However, whenever the temperature drops sharply, the core challenge faced by construction is whether pouring concrete in cold winter weather is feasible?.
As a key indicator for engineering quality control and acceptance, concrete strength naturally attracts the attention of technical personnel and construction units in concrete enterprises.
In concrete production and engineering practice, there is often a phenomenon of “early stage deformity, later stage defects”, that is, the early strength of concrete is higher at 7 days, and the strength growth is slow after 28 days.
Excessive early strength growth not only inhibits later strength improvement, but also increases the difficulty of controlling concrete cracks due to high hydration rate and heat of hydration, thereby adversely affecting the durability of concrete.
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After decades of development, both the mix proportion and production process of concrete are relatively mature.
However, the uneven quality and frequent fluctuations of raw materials, as well as the frequent occurrence of concrete quality problems caused by untimely or inadequate adjustment of concrete mix proportion, are the current difficulties in concrete quality control.
For example, the phenomenon of pipe blockage caused by poor aggregate wrapping, segregation, bleeding, or significant loss of slump over time in concrete mixtures is rampant.
The problem of unqualified engineering quality caused by fluctuations in raw materials, such as insufficient strength of concrete test blocks to meet design requirements or large strength dispersion, is not uncommon.
With the increasing efforts in environmental protection, unstable raw material quality has become the norm.
Understanding the current status of concrete raw materials, adapting concrete production to fluctuations in raw material properties, and improving concrete quality are of great significance.
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