Jianjiantong media ID: jianzhong001 according to the website of Tongling housing and Urban Rural Development Bureau of Anhui Province on January 18, the Bureau recently released the notice on the handling of relevant responsible units and responsible persons of the 10 and 11 buildings of AVIC International Plaza project, saying that since August 2020, some floors of the 10 and 11 buildings of AVIC International Plaza in Tongling City have experienced structural concrete burst, mainly due to commercial reasons Mineral admixtures (steel slag) are added into the concrete, and the free calcium oxide content in the concrete expands when it is hydrated, which causes the local structure concrete to burst and fall off, which has seriously affected the normal life of residents
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In view of the above situation, the project construction unit Tongling Zhongkai Real Estate Co., Ltd
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is ordered to immediately establish a special disposal leading group with relevant responsible units, formulate specific maintenance and disposal plans, actively communicate and coordinate with the residents’ representatives involved, and reach an agreement with the residents’ representatives before January 20
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At the same time, 3 points will be deducted for recording the company’s credit information once, and the release period will be 6 months
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At the same time, the bad credit information of China Aviation Technology International Engineering Co., Ltd
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and Zhang Zhenjian, the project manager, will be recorded once respectively, 6 points will be deducted, and the release period will be one year
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Yang Xiaoping, the chief project supervision engineer of Zhejiang Great Wall Engineering Supervision Co., Ltd., is required to record the bad credit information once, 6 points will be deducted, and the release period is one year
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Previously, Tongling City’s travel style hotline office issued the “reply to the question of” after moving in AVIC Plaza, the wall is bulging and cracking in a large area, and black unidentified substances are also dropped, please coordinate to solve it “on September 18 last year
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According to Mr
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Chen, a resident of 11 buildings in AVIC Plaza, on September 7, he reflected that after living in the community, the wall is bulging and cracking in a large area, and black unidentified substances are also dropped, please coordinate and mediate No
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On September 10, the reply of Tongling Municipal Bureau of housing and urban rural development was as follows: on August 24, 2020, Tongling Municipal Bureau of housing and urban rural development convened the construction, construction, Masteel Jiahua (commercial concrete enterprise) and other relevant units to hold an enterprise interview in the conference room on the fourth floor of the Municipal Bureau of construction and engineering, and put forward the following treatment opinions on the concrete ash explosion problems reflected by some residents of the 11th floor of AVIC Changjiang Square: require the developers to solve the problems as a whole Check and make observation records; entrust professional testing institutions with corresponding qualifications as soon as possible to take cores for the problem components and test the strength, chemical composition and chloride ion content; organize relevant experts to demonstrate the engineering structure safety and treatment scheme
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On August 27, 2020, China Aviation Technology International Engineering Co., Ltd., the construction unit, entrusted the second supervision station of Anhui construction engineering quality to the blasting point of AVIC Changjiang square for chemical analysis and physical coring test
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On September 3 and September 8, respectively, it entrusted the second supervision station of Anhui Construction Engineering quality to the AVIC Changjiang square for concrete strength test
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Because the second supervision station of Anhui construction engineering quality was blocked by some owners when it arrived at the site to prepare for testing, it was unable to complete the sampling and testing work
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So up to now, the strength of the engineering entity has not been tested, so that the follow-up work can not be carried out in time
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In view of the above situation, the construction unit China Aviation Technology International Engineering Co., Ltd
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has actively dealt with it according to the requirements of the notice
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However, due to the obstruction of some owners, it is unable to further test the concrete strength of the Yangtze River Plaza project of AVIC, and it is unable to implement the content requirements of the meeting minutes on the morning of August 24
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On the morning of September 11, 2020, Tongling Municipal Bureau of housing and urban rural development went to the project site and asked: first, the Bureau of housing and urban rural development under its jurisdiction, together with the construction unit, should assist the construction unit in the detection work; second, the construction unit should conduct a comprehensive investigation on the two buildings and five floors that appear in the current reaction
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The next step will be based on the results of detection and identification
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What will the owners block the main testing unit? Is it not a good thing that the housing construction bureau takes the lead and the developers cooperate to solve the problem? Is the fear of detection results out, resulting in secondary sales difficulties in the community, not easy to pick up? Or do not believe that developers commissioned testing institutions? It is not an example that steel slag is mixed into concrete as aggregate to cause construction quality problems
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A few days ago, the media revealed that a 5-storey building beside the old 104 National Road in panjiaba, Xushe Town, Yixing City, Jiangsu Province, had been abandoned for many years due to concrete quality problems
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According to the news, nearly every one of the thousands of beams on the fifth floor of the uncompleted building has concrete burst, and the warping area of the ground continues to expand, crushing with one hand
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It is understood that the project is “Yixing western suburb agricultural and sideline products trading market”
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In 2013, the project was handed over to the local construction company for construction
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However, the concrete used by the construction company had serious construction quality problems due to the addition of a large number of waste steel slag, and the project was immediately suspended for several years
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What is steel slag? What is steel slag? Why do most concrete enterprises use it as the aggregate of concrete, and why does it lead to the large-area burst of buildings? Steel slag is a kind of industrial waste discharged in the process of steelmaking, which has large discharge and low utilization rate
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The application of industrial waste slag (fly ash, slag, steel slag, etc.) in concrete (used as admixture or aggregate) can not only reduce the occupation of land and environmental pollution caused by industrial waste slag, but also reduce the material cost of concrete
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Therefore, it is widely used by many concrete enterprises, but it is usually ground into fine powder and used as concrete modification material
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When steel slag is used as aggregate of concrete, due to its high strength and certain activity, it is easy to meet the strength requirements of concrete instead of part of natural aggregate, which is conducive to reducing the production cost of concrete
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In addition, the steel slag grinding to the appropriate fineness and scientific formula can make the concrete play the role of “micro expansion” of the overall uniformity, and then bring a series of extremely valuable properties such as low hydration heat, low slump, high impermeability, high strength, high frost resistance, high wear resistance, high seawater corrosion resistance, high carbonation resistance and more than 100 years of service life that the conventional cement does not have
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However, due to the poor grindability of steel slag itself, low activity of active components and high content of inactive components in steel slag, and high content of free CaO and free MgO which affect the stability, the use of steel slag as aggregate in engineering will lead to spalling and cracking of concrete around steel slag aggregate
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The dispersion of the stability of steel slag aggregate is very large
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A small amount of aggregate with serious stability problems may cause surface damage or structural damage to hardened concrete
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In fact, there are very few steel slag suitable for concrete aggregate in China
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In engineering, it is generally forbidden to use untreated and qualified steel slag
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Since steel slag used as aggregate in concrete will bring so much damage and is strictly prohibited, why should the construction party use it “recklessly”? On the one hand, steel slag can significantly improve the strength of concrete, which means that less cement and other raw materials can be used to reduce the production cost of concrete; on the other hand, what we have to mention here is the shortage of aggregate and the soaring price in recent years
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Especially in recent years, due to the increasing efforts to crack down on illegal sand mining, prohibition of river mining, and mine renovation, there is a shortage of sand aggregate in many places and the soaring price of sand
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Some areas even affect important construction, so steel slag as aggregate appears to have a more market
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