Recently, People's Daily reprinted the news from Science and Technology Daily that the Shenzhen-Zhongshan Bridge used 20,000 tons of anti-corrosion steel bars, with the subtitle of passive maintenance turning into active prevention. According to the news, the research team led by Xue Qunji, academician of the Chinese Academy of Engineering, and Wang Liping, researcher of Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, jointly developed by Ningbo Kexin Corrosion Control Engineering Co., Ltd., a two-dimensional nanomaterial reinforced high-durability fusion bonded epoxy coated steel bar technology, which was first applied in deep and medium channels. This kind of steel bar changes the traditional passive maintenance into active prevention, which can effectively resist the corrosion of seawater, acid rain, chemicals and concrete additives, and greatly prolong its service life. There is an economic account in the
news content, the cost of stainless steel bars is high, and the price per ton is about 35000 yuan. The production cost of epoxy coated steel bar is about 2000 yuan per ton, and the price of the original steel bar is about 3500 yuan per ton. Relatively speaking, the production process of epoxy coated steel bars is simple and cost-effective. The foundation structure of the
bridge is concrete in addition to steel. Steel bars should be anticorrosive, so that passive maintenance becomes active prevention, and the concrete wrapped with steel bars should also be anticorrosive, which is more important than steel bar anticorrosion in a sense.
The following quotes the actual situation of corrosion in the article "Developing Aluminoferrite Cement to Improve the Performance of Building Cement" written by Wang Yanmou and Qi Dongyou. It is not too shocking to say. The Chesapeake Bay Tunnel Bridge in Virginia,
USA, is divided into two parts, north and south, with a total length of 37 kilometers in one direction. The northbound section was completed in 1964 at a cost of $200 million. In 1989, it was inspected and found that the concrete of the pier had corrosion problems, which were repaired at that time. When it was re-inspected in 2000, it was found that the corrosion had further expanded, and it was decided to repair it completely. Construction began in 2007 and was completed in 2009 at a cost of $12.5 million over a two-year period. The Ministry of Transport of
Japan has investigated 103 cement concrete seaport wharfs and found that all those in service for more than 20 years have serious corrosion and must be repaired. In a survey report, the National Institute of Civil Engineering of Japan pointed out that a marine concrete bridge built in 1965 began to incur maintenance costs after 16 years of use, and after 35 years, the maintenance costs increased to 250% of the cost of building the bridge, so it was decided to demolish it. On June 24,
2021, a 12-storey seaside apartment building built in 1981 collapsed in Miami, Florida, USA, causing heavy casualties. The New York Times and the Economist quoted a preliminary investigation by authoritative scientific institutions as showing that the possible cause of the collapse of the apartment was the long-term retention of a large amount of seawater in and around the foundation of the apartment building caused by the rising sea level brought about by climate change, which caused corrosion damage to the cement concrete of the building structure and the internal reinforcement steel. According to the investigation by the
Ministry of Transport, 16 of the 18 cement concrete wharves in the south coast of China, which have been used for 7-15 years, are obviously corroded, and 9 of them are seriously corroded, while 55.6% of the 22 wharves in the southeast coast of China, which have been used for 8-32 years, are seriously corroded; Almost all of the 14 wharves along the northern coast, which have been used for 2-57 years, are corroded by cement concrete. A sea-crossing bridge in a famous bay
in China was put into use in 2008. During the investigation in 2019, it was found that the resin coating of the bridge concrete had begun to peel off; the concrete of the bridgehead concrete revetment had been corroded, and sand and gravel were exposed on the surface; the water level of the concrete pier had also been corroded and damaged. At present, the bridge needs to invest funds to carry out heavy maintenance work.
China Cement Network has just published an article entitled " On the Innovation of Cement Varieties" written by Wang Yanmou, an authority in the cement industry, and the team of the Key Laboratory of Sulphoaluminate Cement. Compared with Portland cement, sulphoaluminate cement and ferroaluminate cement invented in China belong to different mineral systems, which is a revolutionary breakthrough in cement technology. This breakthrough makes ferroaluminate cement have the performance advantages of seawater, saline-alkali non-corrosive and negative temperature construction, as well as outstanding energy-saving and low-carbon characteristics.
It has been more than 40 years since the accumulation of engineering case testing data and research results, which fully show that aluminoferrite cement has the special performance of non-corrosive in seawater and saline-alkali. What is more exciting and amazing is that with the passage of time, the intensity does not decrease but increases. In the battle against seawater corrosion. It can be said that the Vietnam War is more brave! It is the "stainless steel" in cement.
If there is only the anticorrosion of steel bars and no anticorrosion of concrete, it is incomplete to change the passive maintenance of marine engineering into active prevention, and active prevention can only be "lame".
