Precast News From China
During the construction process, it is required that the concrete must have good workability, and there should be no layering, segregation, or bleeding of the concrete.
The workability of concrete is a comprehensive indicator, which includes fluidity, cohesiveness, and water retention.
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Cross sea bridges, underwater tunnels, offshore airports.
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The “bone collagen” of these marine concrete structures – hydrated calcium silicate C-S-H – is being gradually dismantled at the nanoscale by two “invisible killers” in seawater (sulfate SO42- and magnesium ion Mg2+).
The latest research by Wu Kai and Xu Linglin from Tongji University, using 9 types of C-S-H combined with molecular dynamics (MD) shear simulations, has for the first time seen how this “collapse” occurs at the atomic level.
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(1) Before installing the concrete pump and delivery pipe, the dirt and cement mortar inside the pipe should be thoroughly removed, and washed clean with pressure water.
Check in a timely manner after installation to prevent detachment and leakage of grout.
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Research has shown that the main component of bubbles in freshly mixed concrete is air; The main components of bubbles that emerge from concrete after pouring are ammonia, hydrogen, oxygen, carbon dioxide, etc.
The main raw materials that cause abnormal bubbling in poured concrete include denitrifying fly ash and polycarboxylate superplasticizer (PCE).
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With the increasing demand for both engineering aesthetics and functionality in the construction industry, the appearance quality of concrete has gradually become an important evaluation indicator for construction technology.
In traditional concepts, concrete is only regarded as a load-bearing structural material, and its appearance defects are often overlooked.
However, appearance issues such as honeycomb, rough surface, color difference, and cracks not only affect the visual effect of the building, but may also reduce the compactness and durability of the structure.
Therefore, the systematic study of the formation mechanism and control methods of concrete appearance quality has important strategic significance.
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At present, concrete is widely used as the main load-bearing body for building structures.
To a certain extent, the performance of concrete has a significant impact on the overall quality of buildings, and the design of concrete mix proportions is a decisive factor affecting the quality of concrete.
The design method of ordinary concrete mix proportion is based on the calculation of water cement ratio, including trial mixing, adjustment, calculation, determination, re mixing, and forming.
For concrete with design requirements for durability, relevant durability tests are conducted to verify and determine the final mix proportion.
Following this process for mix design often increases the design cycle.
The concept of pure water cement ratio is adopted in the ordinary mix design method, while the liquid admixture currently used has a large dosage.
Considering the water in the admixture, the concept of total water cement ratio is proposed.
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The preparation of self compacting concrete generally uses Portland cement or ordinary Portland cement, which should comply with the provisions of the national standard GB175-2007 “General Portland Cement”.
For large volume self compacting concrete with temperature control requirements, slag silicate cement, medium or low heat cement should be selected.
Cement should have low water demand and good compatibility with the high-efficiency water reducing agent used.
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The particle size, shape, and strength characteristics of aggregates have a direct impact on the compressive strength of concrete.
Choosing aggregates with good physical and chemical stability is an important means to improve the strength of concrete.
Strict control over the content of various substances in both coarse and fine aggregates is essential, especially the chloride ion content.
Excessive chloride ion content, such as using sea sand, can have a strong corrosive effect on steel bars, which not only seriously threatens the durability of concrete, but also weakens its structural integrity.
Therefore, ensuring the high quality of aggregates plays a crucial role in ensuring the compressive strength of concrete.
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The 2026 Concrete and Cement Products Industry Conference and the 2026 China International Concrete Expo are scheduled to be held in Guangzhou from September 17th to September 20th.
As the parallel high-end sub forum of this industry conference, the 8th Innovation and Development Forum of Light Aggregate and Light Concrete will be held at the same time with the theme of “light weight and high performance, high value of solid waste, new expansion of application”, bringing together experts and scholars from colleges and universities, chief engineer of Transport Design Institute, and experts from solid waste environmental protection enterprises to share special topics.
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In order to fully implement the overall requirements of the country on the upgrading and renovation of urban pipeline networks, urban renewal, and the construction of urban infrastructure lifeline safety projects, promote the intelligent, green, and integrated development of the manufacturing industry, assist in the construction of underground pipeline networks in cities during the 15th Five Year Plan period, and promote the deep integration of scientific and technological innovation and industrial innovation, the Cement Concrete Pipe Culvert Branch of the China Concrete and Cement Products Association and the Quality Innovation Working Committee of the Prestressed Steel Tube Concrete Pipe of the China Concrete and Cement Products Association will jointly hold the 7th Concrete Pipe Culvert Production and Application Technology Innovation Forum during the 2026 Concrete and Cement Products Industry Conference and the 2026 China International Concrete Expo.
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