Technology

Florida apartment collapse heralds concrete cracking

Most likely It will take several months before we can determine what caused the catastrophic collapse of the Champlain Tann Building in Surfside, Florida last week, killing at least 18 people. But it is clear that at least one culprit is concrete failure. In 2018, an engineering company warned that the concrete under the building’s pool and entrance driveway showed “significant structural damage” and that “a large number of cracks” were found in the underground parking lot. Just a few months ago, the chairman of the apartment association of the building wrote: “Concrete degradation is accelerating.”

Although this kind of sudden and large-scale building collapse is very rare, the problem of collapse specific Not at all. This is a slow-developing crisis affecting most parts of the world. In the coming decades, billions of tons of concrete in the form of buildings, roads, bridges and dams may need to be replaced. This will cost trillions of dollars and will generate an astonishing amount of climate change carbon emissions.

Concrete is basically just sand and gravel bonded together with cement. It is by far the most widely used building material on the planet. The amount of water we pour each year is enough to build a wall 88 feet high and 88 feet wide around the equator. This is mainly because the number and scale of cities are exploding. The number of urban residents has more than quadrupled since 1960, reaching more than 4 billion, and it is still increasing. We will add the equivalent of 10 New York City to the planet every year.

Without concrete, cities could not develop so fast. This is an almost magical, cheap and simple way to quickly build roads, bridges, dams, and relatively sturdy, sanitary housing for a large number of people. It is estimated that 70% of the world’s population now lives in structures that are at least partially made of concrete.

But none of these structures will exist forever. Concrete fails and cracks in many ways. Heat, cold, chemicals, salt, and moisture will attack the seemingly strong man-made rock, weakening and crushing it from the inside. (Rising temperatures and atmospheric carbon content are expected to make things worse.)

This not only threatens apartment buildings, but also our concrete infrastructure. A 2021 report from the American Society of Civil Engineers found that More than 20,000 concrete bridges in the U.S. have structural defects Nearly half of the public roads in the country are in “poor” or “fair” conditions.

In many developing countries, the situation is much worse, where building standards are very low and regulations are often ignored. In order to reduce costs, builders often use unwashed sea sand to make concrete. These grains are cheaper, but they are coated with salt, which can dangerously corrode steel bars. In the 2010 Haiti earthquake, dozens of people made concrete buildings made of sea sand. Poor-quality concrete may also be the key cause of the collapse of a factory in Bangladesh in 2013, which caused more than 1,000 deaths.according to Financial Times, As much as possible 30% China’s cement grade is so low that it produces a dangerous and fragile structure called “tofu building”. Cheap concrete was one of the reasons why many schools collapsed in the 2008 Sichuan earthquake in China, which caused thousands of deaths.

Considering that most of the concrete in the world was laid in the last few decades, and most of it is in developing countries-first of all, China, all of this is terrible. The cement used in China between 2011 and 2013 alone surpassed the cement used in the United States throughout the 20th century. Therefore, economist Vaclav Smir wrote, “The world after 2030 will face an unprecedented burden of concrete degradation…The cost of replacing materials in the future will reach trillions of dollars.”

Excavating the billions of tons of sand and gravel needed to make all the concrete will inevitably destroy countless river beds, lake bottoms and floodplains. The poor management of sand and gravel mining in many countries has wiped out a large number of fish and birds that inhabit the river, destroyed coral reefs, and caused river banks to collapse.The industry even spawned a criminal black market, flooded with Corruption and violence.

As if all this is not enough, making all this concrete will have a serious impact on the environment. The carbon dioxide emissions generated by the cement industry account for 5% to 10% of the world’s carbon dioxide emissions, second only to coal-fired power plants and automobiles, which are sources of global warming gas.


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