Construction Precast Development
Precast News From China
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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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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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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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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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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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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The fiber material added to the concrete matrix can bear the tensile stress between cracks, reduce the deformation of the component, and highlight the tensile hardening characteristics of concrete.
However, this effect cannot be fully utilized in compressive tests.
Referring to the HFRC test mix ratio mentioned earlier, the required specimens for bending tests are prepared and corresponding finite element models are established to study the mechanical performance of different steel-concrete fiber reinforced concrete in bending tests.
The three-dimensional finite element model is shown in Figure 4-7, and the boundary conditions and mesh division of the model are set according to the previous description.
At the same time, in order to make the numerical simulation results closer to macroscopic experiments, it is necessary to focus on the contact relationship between the support and the specimen, and refer to reference [54] to define the friction properties of the contact surface here.
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On the evening of July 13th, the leading company in the domestic ready mixed concrete industry, Western Construction (002302), disclosed its performance forecast for the first half of 2026.
The company expects a net profit loss attributable to shareholders of the listed company of RMB 170 million to RMB 330 million, further expanding from the loss of RMB 96.
2749 million in the same period last year.
The net profit after deducting non recurring gains and losses is expected to be a loss of 195 million to 355 million yuan, compared to a loss of 172 million yuan in the same period last year.
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