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precast-tech
precast technology developments
The Problems of Denitrification Fly Ash in the Application of Cement Concrete
In response to the national requirements for NOx emissions, China’s coal-fired power plants have basically completed denitrification transformation.
At present, coal-fired power plants usually choose three combination technologies for denitrification: low nitrogen combustion+selective catalytic reduction (SCR), low nitrogen combustion+selective non catalytic reduction (SNCR), and low nitrogen combustion+SCR+SNCR.
After combustion, denitrification is mainly achieved by reducing NOx in the flue gas to N2 to achieve emission control.
SCR denitrification occupies an absolute proportion in the denitrification market of thermal power plants, with the largest market share and a much higher market share than other denitrification technologies.
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Concrete mix design volume method
Modern concrete is a multi aggregate composed of cement, mineral admixtures, sand, stone, air, water, and additives, and can meet the basic requirements of “high workability, high early strength enhancement, and high durability”.
Modern concrete should include high-performance concrete, high-strength concrete, fluid concrete, pumped concrete, self leveling and self compacting concrete, anti-seepage and crack resistant concrete, underwater pouring concrete, and commercial concrete.
The traditional concrete mix design method based on strength cannot meet the requirements of modern concrete mix design.
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The key link of quality control of sand and gravel aggregates in concrete production
Against the backdrop of accelerated urbanization and booming infrastructure construction, concrete has become the undisputed “cornerstone material” in the field of architecture due to its excellent performance.
As a key component of concrete, sand and gravel aggregates account for up to 60% to 80% of the concrete, deeply participating in the shaping process of various properties of concrete.
They play an irreplaceable role in enhancing concrete strength, improving durability, and adjusting workability.
However, with the rapid development of the construction industry, the supply of sand and gravel aggregates is facing severe challenges.
Natural sand resources are gradually depleted due to long-term exploitation, and reserves are decreasing day by day; Although machine-made sand has become an important substitute, its production is affected by various factors such as raw material quality, processing equipment, and process parameters.
The quality of machine-made sand varies significantly from different origins and batches, making it difficult to ensure the stability of aggregate quality.
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The survival dilemma of concrete enterprises under the environmental protection shutdown
It’s winter again, and the air diffusion is poor, making it easy for mild and severe pollution to occur.
Environmental control has become an insurmountable rigid threshold for the manufacturing industry.
The concrete industry, as a fundamental industry in infrastructure construction and a typical representative of traditional high energy consuming and high polluting industries, is facing severe environmental governance pressure.
The implementation of a series of policy requirements, from regional peak shutdown to full process environmental protection transformation, has led concrete enterprises to face multiple challenges such as high raw material procurement costs, limited production and operation, pressure on labor costs, and a sharp increase in environmental investment.
The survival and development space is continuously squeezed, and the industry is undergoing an unprecedented structural adjustment.
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Are you afraid of freezing when pouring concrete in winter? Senior engineer reveals key winter construction technologies for you
As temperatures gradually decrease, many construction projects are facing the challenge of winter construction.
For property owners and construction parties, the most concerning issue is undoubtedly whether they are afraid of freezing when pouring concrete in winter.
The answer to this question is affirmative – the low temperature environment in winter can indeed have a serious impact on the quality of concrete construction, but if scientific and reasonable protective measures are taken, concrete can be completely avoided from being damaged by freezing.
As professional engineers of Beijing Zhitai Jiahe Reinforcement Company, we will systematically analyze the technical points of winter concrete construction from the perspectives of material science and engineering practice.
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Study on the influence of adding mineral admixtures on the compressive strength of concrete
Concrete, as the most critical foundation material in modern construction engineering, is widely used in various building structures such as high-rise buildings.
The compressive strength of concrete is the core element for measuring its quality, which not only reflects the ability of concrete to withstand external loads, but is also closely related to other properties of concrete.
With the continuous development of construction technology and the increasing demand for building material performance, the application of mineral admixtures in concrete is becoming more and more widespread.
The addition of mineral admixtures is mainly aimed at reducing costs and improving resource utilization, but in recent years, their improvement effect on concrete performance has gradually become a research focus.
Based on this, this article intends to study the effect of adding mineral admixtures on the compressive strength of concrete.
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What quality issues may occur when the pouring temperature of large volume concrete in hydraulic engineering exceeds 30 ℃?
In the construction of water conservancy projects, the pouring of large volume concrete is a crucial step, and its quality directly affects the safety and lifespan of the entire project.
As one of the key factors affecting the quality of concrete, pouring temperature has attracted the attention of engineering personnel.
When the pouring temperature exceeds 30 ℃, it will bring a series of potential quality problems to the concrete.
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Crack control in concrete construction under low temperature conditions
The construction of concrete under low temperature conditions is one of the widely recognized technical issues both domestically and internationally.
Low temperature concrete construction, also known as “winter concrete construction,” refers to concrete construction where the average temperature during construction is below 5 ℃ or the lowest temperature is below -3 ℃.
According to the frost resistance theory of concrete, when the early strength of concrete is below 5 MPa (critical strength), it will be subjected to freezing, which will deteriorate the physical mechanical and architectural technical properties of concrete and produce cracks.
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Technical Guidelines for Jumping Construction of Ultra Large Volume Concrete Structures
To ensure the safety and effectiveness of the building structure, many structural joints such as expansion joints, seismic joints, and settlement joints will be set up in the structural design.
Expansion joint refers to a structural joint set at an appropriate location along the direction of the construction joint of a building or structure to prevent cracks or damage to the structure due to climate and temperature changes (thermal expansion, contraction).
Expansion joints are used to divide building components such as walls, floors, and roofs (excluding wooden roofs) above the foundation into two independent parts, allowing the building or structure to expand horizontally along its length.
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