Editor's Note: Construction projects should adhere to quality first, and construction quality is the most important, which is a century-long plan. If building materials are not properly selected, the quality of construction projects will decline and potential safety hazards will increase. Hidden dangers are latent, just completed and not exposed in the initial stage of use, but with the passage of time, once "deflagration", the consequences are extremely serious. Even if there is no "deflagration", in order to avoid its occurrence, a large number of people, money and materials need to be invested, and the effect is not necessarily as people wish. It is better to strangle the hidden danger in the cradle and cut off its roots. The author of this article is a senior person in the cement industry. He solemnly suggests that "aluminoferrite cement with excellent seawater corrosion resistance should be popularized and applied in new construction and renovation projects of coastal buildings, so as to greatly enhance the seawater corrosion resistance of buildings, reduce the risk of seawater corrosion damage to buildings and reduce maintenance costs", which is indeed the heartfelt words of the cement elite. In the early morning of June 24,
2021, an apartment building in the town of Surfside, Miami-Dade County, Florida, USA, partially collapsed, causing heavy casualties and causing widespread concern around the world. According to reports, the accident building was a 12-storey seaside apartment built in 1981, with a total of 136 housing units, 55 of which collapsed in an avalanche during the accident (Figure 1, Figure 2). According to a report by Sina.com on July 8, the search and rescue of the collapsed building was stopped on July 7, resulting in 54 deaths and 86 missing. According to Xinhua News Agency, the Miami-Dade County Fire Rescue Department announced the end of the search for the bodies of the victims on the 23rd. At least 97 people have been confirmed dead so far.
Figure 1 Seaside location
of collapsed apartment
. Marine environment has serious corrosion damage to concrete materials. According to the data released by the Federal Highway Administration of the United States, the cost of concrete corrosion of highway bridges in the United States in 1998 was as high as 27.6 billion US dollars. The Chesapeake Bay Tunnel Bridge in the United States is 37 kilometers long and is divided into two parts in both north and south directions, with a total investment of 2. In 1998, 623 piers damaged by sea erosion in the north part were repaired at a cost of 12.5 million US dollars, which took two years. The erosion of other piers is further expanding and needs to be repaired in a few years. A survey of 103 seaport wharfs by the Ministry of Transport of Japan found that all concrete wharfs that had been in service for more than 20 years were seriously corroded. European surveys show that 75% of concrete bridges in England and Wales are corroded by seawater, and the cost of repairing them is twice as high as the cost of building them. More than half of the more than 100 concrete bridges and more than 10,000 concrete wharfs along the Norwegian coast are affected by seawater corrosion. According to the investigation report of the Ministry of Transport, 16 of the 18 cement concrete wharves in the south coast of China, which have been used for 7 to 25 years, have obvious corrosion, and 9 of them have serious corrosion; Among the 22 wharfs along the southeast coast that have been used for 8 to 32 years, 55. In 2020, we inspected a cross-sea bridge that had been completed and opened to traffic for 12 years, and found that the piers, pile caps, slope protection embankments, etc. of the bridge had been significantly corroded to varying degrees (Fig. 4).
3. Aluminoferrite cement
with high resistance to seawater corrosion Aluminoferrite cement is a cement variety independently invented by China in the 1980s, and has won the second prize of national invention. China is the only country in the world to realize the continuous industrial production of aluminoferrite cement. At present, China has a production capacity of more than 10 million tons of aluminoferrite cement, and ordinary cement production lines can also produce aluminoferrite cement after simple transformation.
Ferroaluminate cement has the characteristics of early strength, high strength, frost resistance, impermeability, corrosion resistance and the like, and particularly has excellent impermeability and seawater corrosion resistance. The impermeability of aluminoferrite cement concrete is significantly better than that of Portland cement concrete of the same grade (Table 1).
Fig. 5 Seawall
at South Gate of Dongshan Island Built with Ferro-aluminate Cement Fig. 6-1 Small Wharf
Built with Ferro-aluminate Cement and Portland Cement on Dongshan Island
Figure 7 Liaoning Products Science and Trade Building
1. Use aluminoferrite cement instead of Portland cement to produce high-strength prestressed pipe piles to solve the problem of bearing capacity decline or even damage caused by seawater corrosion of coastal building pile foundations.
2. Use aluminoferrite cement instead of Portland cement to construct important load-bearing structures such as beams and columns in coastal buildings, and solve the problem that the bearing capacity of key load-bearing structures such as beams and columns in coastal buildings is reduced or even damaged due to seawater corrosion.
3. Carry out the application demonstration and related research work of aluminoferrite cement in coastal construction projects, and establish a sound system of application technical standards and specifications.
浙公网安备33010802003254号