Construction Precast Development
Precast News From China
precast technology developments
Mineral admixtures have become an indispensable component of concrete, and their use has shifted from simply pursuing economic benefits to a technical means of improving concrete performance.
The physical “filling effect” and chemical “volcanic ash effect” of mineral admixtures, especially the secondary hydration, cause changes in the microstructure of concrete, improve the compactness of concrete, and promote the improvement of later strength.
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In the post architectural era, AAC is not facing the question of whether it can survive, but rather the question of how to change its way of living.
Its way out does not lie in catering to all grand trends, but in finding its niche and being irreplaceable in these specific fields.
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On October 11th, during the “High Quality Completion of the 14th Five Year Plan” series of press conferences organized by the State Council Information Office, the Ministry of Housing and Urban Rural Development introduced the application of new materials, and a concrete that can “cure diseases” on its own unexpectedly became the focus – “self-healing concrete” was explicitly mentioned as a model for improving building performance.
This kind of material that sounds like “black technology” is no longer a laboratory concept, but is quietly changing the buildings around us.
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The author of this book, Burrows, has been engaged in concrete durability research at the United States Bureau of Reclamation (USBR) since 1946.
He conducted 53 years of observation, testing, and research on 104 concrete experimental panels at Qingshan Dam in Colorado.
Based on extensive practice, he put forward many unique viewpoints, opinions, measures, and suggestions to improve concrete durability, which have important inspirations for the quality control and technological development of modern concrete engineering.
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There is no fixed “most suitable” standard for concrete slump, and its value needs to be determined comprehensively based on specific engineering requirements, construction conditions, concrete types, and transportation methods.
The core principle is to ensure the strength and durability of concrete after hardening while meeting construction and workability requirements.
The following provides specific explanations from two aspects: key influencing factors and common reference ranges:.
Have you ever seen a concrete building collapse with a loud bang during an earthquake? Traditional concrete is like a compressed biscuit, extremely hard under compression, and prone to sudden fracture once stretched.
This phenomenon caused a painful lesson in the 2008 Wenchuan earthquake.
But now, a new material that can make concrete “bend over” is changing this situation.
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On November 21st, the national concrete price index recorded 90.
47 points, a month on month decline of 0.
33% and a year-on-year decline of 19.
47%.
The national market has entered the traditional off-season, and the overall market is characterized by generally weak demand and weak prices, with significant regional differentiation.
In the north, demand has shrunk significantly due to low temperatures, while in the south, prices are difficult to support due to insufficient demand or weather factors.
The specific demand and price situation in each region are as follows:.
Immediately stop tensioning: Remove the oil pressure as soon as possible and stop all tensioning operations.
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With the acceleration of urbanization, urban surface hardening has led to a decrease in rainwater infiltration capacity, causing environmental problems such as waterlogging and a decrease in groundwater level.
Therefore, building “sponge cities” has become a goal for more and more cities.
Permeable concrete, as a new type of eco-friendly building material, has a special pore structure that can effectively discharge surface water, alleviate urban heat island effect and waterlogging, and has been widely used in urban roads, squares, parking lots and other projects.
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Self compacting concrete was first proposed by Japanese scholar Okamura in 1986.
Its excellent workability, flowability, and uniformity are significant characteristics of self compacting concrete (SCC).
SCC can use its own gravity to fill the formwork without compaction or vibration, and the hardened surface is relatively smooth and flat.
Coarse aggregates usually account for 28% to 35% of the volume of SCC, significantly affecting its performance.
The rheological properties of self compacting concrete are largely influenced by the characteristics of coarse aggregates, including shape, particle size, gradation, surface features, etc.
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