on July 23, the command center of Qiqihar Fire Rescue Detachment received a report that the roof of the gymnasium of Qiqihar No.34 Middle School collapsed. Qiqihar Fire Rescue Detachment quickly mobilized forces to rush to the scene to carry out rescue.
After verification, there were 19 people in the museum at the time of the accident. So far, 11 people have been killed in the accident. At present, the responsible person of the construction unit of the teaching complex building has been controlled by the public security organs.
It is understood that the building area of the collapsed gymnasium is about 1200 square meters. The wall is a grid structure and the ceiling is a concrete slab. This light grid structure is very sensitive to load changes. After preliminary investigation on the spot, during the construction of the teaching complex adjacent to the gymnasium, the construction unit illegally piled perlite on the roof of the gymnasium. Under the influence of rainfall, the perlite soaked in water increased its weight, which led to the increase of roof load and the collapse. What is the perlite that
caused the accident?
We can see in the live broadcast of the accident rescue that fire rescue workers cleared a large number of bags of perlite building materials at the collapse site. Mr. Chen, an architectural designer in
Nanjing, told reporters that perlite is a commonly used building insulation material in the industry and is often used in external wall insulation. "This material is not only used in cold areas in the north, but also in newly built houses in the south.". However, it has strong water absorption and is easy to seep and gain weight, so it is necessary to make a layer of waterproof paint on the outer layer when it is used for external wall insulation. According to the survey, the weight of perlite after absorbing water is 3-4 times that of the previous one.
It is understood that perlite, also known as expanded perlite, is an inorganic non-metallic mineral. It is a kind of glassy rock formed by rapid cooling of acidic lava from volcanic eruptions. It belongs to a porous material and has a large number of cavity structures, which leads to its thermal insulation, thermal insulation and water absorption characteristics.
It has a wide range of uses in the construction industry because of its thermal insulation and thermal insulation characteristics. It can be used as concrete aggregate, and can be made into light, heat-insulating, heat-insulating and sound-absorbing board, and can be used as filler, mortar and other building materials for fireproof roof, light antifreezing, shockproof, fireproof, radiation-proof and other high-rise building engineering walls. Its strong water absorption ability makes it absorb 2-3 times more water than its own weight when it fully absorbs water, and the smaller the particles, the higher the water absorption rate. Whose responsibility
is it? Mr.
Chen introduced that the roof of the gymnasium in the accident itself was a very weak part. The construction unit dared to put a large amount of perlite directly on the roof of the gymnasium in rainy days, which not only showed that the construction personnel had no safety knowledge and awareness, but also reflected that the construction party completely violated the construction safety standards.
"The stadium is a large space with few pillars in the middle to support the roof, so the load bearing capacity of the roof is very low.". The roof of the stadium is like a big tent, and no building materials are allowed to be stacked. Mr. Chen told Ziniu News. According to
CCTV, Li Zhu, vice president of Perlite Association of China Building Material Industry Federation, said that the way they pulled perlite directly to the scene was wrong, because the water absorption of perlite was very high. If the mixed mortar arrives at the site, the tarpaulin should be stacked in the open air. Without rainproof measures, any building material will increase its weight after absorbing water. From the point of view of structure and safety, both the construction party and the supervision party should make a correct judgment on the load of how many building materials are stacked on the top of the gymnasium, which is caused by the non-standard construction management.
According to the current official announcement, it can be determined that the construction party has the main responsibility for the incident, and whether the stadium built more than 20 years ago has quality problems still needs to be investigated in depth by the authorities.
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