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precast-tech
precast-tech
Reasons and Countermeasures for the Generation of Yin Yang Mix Proportion in Concrete
Concrete technicians can only seek theoretical basis from other standard specifications, but the requirements of the standard specifications are difficult to understand and conflicting with each other.
For example, the “Technical Specification for Waterproofing of Underground Engineering” stipulates that the total amount of cementitious materials should not be less than 320kg/m3, and the amount of cement used should not be less than 260kg/m3, while the “Quality Acceptance Specification for Underground Waterproofing Engineering” stipulates that the amount of cement used should not be less than 300kg/m3, and when active admixtures are added, the amount of cement used should not be less than 280kg/m3.
Due to the fact that most underground or waterproofing projects belong to large volume structures, the above regulations make the provisions on concrete mix proportions in the “Code for Construction of Large Volume Concrete” virtually non-existent.
The standard does not provide detailed explanations for these regulations, leaving concrete technicians at a loss and unable to provide reasonable explanations when consulting relevant departments, which hinders the development of modern concrete.
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Concrete segregation prevention and treatment measures
Concrete segregation refers to the phenomenon of various constituent materials (such as cement, sand, stone, water, etc.
) in concrete mixtures separating from each other during mixing, transportation, pouring, etc.
, resulting in uneven distribution of each component and affecting the overall performance of concrete.
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From “flowability” to “precise control”: Southeast University team systematically sorts out a new path for rheological control of ultra-high
The team led by Teng Le and Liu Jiaping from the School of Materials Science and Engineering at Southeast University collaborated with Kamal H.
Khayat from the University of Missouri Science and Technology in the United States to publish a research article titled “Recent Advances in the Hydrological Properties of Ultra High Performance Concrete: A Critical Review” in the Chinese Academy of Engineering journal “Engineering”.
The article focuses on the requirements of advanced construction methods such as self compacting, pumping, spraying, and 3D printing, and systematically analyzes key issues such as how to smoothly construct ultra-high performance concrete (UHPC), how to stably form it, and how to accurately control it.
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Daily science popularization: Isn’t cement slurry the most fragile part of concrete? After reading it, I suddenly realized
Many people subconsciously think of concrete as a whole gray stone when they look at it.
Those who are more careful will know that it is actually a composite material composed of aggregates, cement slurry, pores, and hydration products mixed together.
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Summary of concrete cracking problems, one article clarifies all causes
Load cracks are cracks formed in concrete under conventional static and dynamic loads and secondary stresses.
They are divided into two types: direct stress cracks and secondary stress cracks: the former are directly induced by external loads, while the latter are generated by secondary stresses derived from external loads.
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The academic community is buzzing with excitement! Youth postdoctoral champion consecutively kills one district top! Concrete materials are
In traditional methods, analyzing the evolution laws of concrete material properties, mechanical response mechanisms, and service behavior characteristics often starts from fragmented experimental data and limited scale engineering case analysis, requiring tedious experimental design, parameter screening, feature extraction, and empirical model construction processes.
The term ‘fragmentation’ here is not due to insufficient data collection by researchers, but rather because concrete materials themselves have characteristics such as multiple components, multiple scales, strong heterogeneity, and complex nonlinearity.
At the same time, they are influenced by multiple factors such as differences in raw materials, changes in mix proportions, curing conditions, load environments, and long-term service factors, like ‘peering into the whole from a local perspective’.
The hydration process of cement, the evolution of the transition zone between aggregate and slurry interface, changes in pore structure, initiation and propagation of microcracks, and the coupling effect of environment and load still result in significant uncertainties in traditional research methods for predicting concrete strength, durability evaluation, damage evolution analysis, and life prediction.
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The impact of harmful aggregates in concrete on structural degradation and prevention and control techniques 3- Hazards and mechanisms of
Sulfur containing aggregates mainly come from sulfur-containing mineral rocks, commonly found in geological environments such as coal mines, pyrite waste rocks, some shale, schist, and surrounding rocks of metal deposits.
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Hazards and Effective Preventive Measures of Cracks in Hydraulic Concrete
Cracks in hydraulic concrete structures are one of the most common diseases in hydraulic engineering.
The composite structure composed of concrete and steel bars jointly undertakes the task of resisting water pressure and maintaining engineering stability.
However, once cracks appear in the concrete, it not only affects the appearance of the structure, but also seriously threatens the safe operation and durability of the project.
Cracks expose the internal steel bars to corrosive environments, and under the combined action of water pressure, chemical erosion, and physical scouring, both the “bones” and “flesh” of the structure may gradually lose their function.
The following elaborates on the hazards, causes, and comprehensive preventive measures of cracks.
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