Brief introduction of dangerous buildings in sea sand

Excessive chloride ions in sea sand will seriously corrode the steel bars in buildings and even collapse. The reason why sea sand is so corrosive is that the sand corroded by seawater without desalination contains chloride ions. If this component exceeds the standard, it will be used in engineering construction after being mixed with concrete, which will seriously corrode steel bars.

According to the Opinions on Strict Management of Sea Sand for Building issued by People's Republic of China (PRC) and the Ministry of Construction in September 2004, sea sand must be purified before it can be used to prepare concrete. For reinforced concrete, the chloride ion content in sea sand should not be greater than 0.06%. If sea sand must be used, it should be washed with fresh water, and its chloride ion content should not be greater than 0.02%. If the sea sand used for building does not meet the national mandatory standards, the excessive chloride ion content will seriously corrode the steel bars in the building, causing major safety hazards.

According to the industrial standard "Technical Specification for the Application of Sea Sand Concrete" issued by People's Republic of China (PRC) and the Ministry of Housing and Urban-Rural Development on May 8th, 20 10, the purified sea sand can be used for the construction of concrete structures. Jiaotou and Mawan in Lunan, Shenzhen are one of the few large sand fields in Shenzhen. Thousands of large dump trucks load sea sand here every day and transport them to concrete mixing stations and construction sites in various parts of Shenzhen. Previously, relevant market participants broke the news that in the Shenzhen building materials market, river sand that meets the national building materials safety standards has now disappeared. In the mixing station of building concrete, all sea sand and washed sand are used, and the real river sand has disappeared in the market for many years. In Shenzhen Nanshan and Mawan sand quarries, there is a busy work scene, and a large amount of sea sand is being fished out of salty seawater, loaded on trucks and busy with shipment.

A few years before 20 13, river sand from all over the world was sold in these large sand yards in Shenzhen, but the lowest price of one cubic meter of river sand was 165 yuan. Many builders think that the price of river sand is high, and the construction market in Shenzhen has been in great demand in recent years. So during the period of 20 13, many builders were in the sand yard. Buying a cubic meter of sea sand is cheaper than river sand 120 yuan. Therefore, at present, the building sand sold in Shenzhen building materials market is sea sand and "washing sand" washed with seawater. "Sand washing" is indeed much finer than ordinary sea sand that has just been fished up.

According to the regulations of the state, sea sand belongs to the national mineral resources and may not be exploited without the permission of the marine administrative department. Sand mining at sea is illegal. If the fishery supervision ship does not patrol and enforce the law, these illegal sand mining ships are basically risk-free.