Chinese Concrete Problems



(Shenzhen, China)

A sand scandal is brewing in China, with concerns that low-quality concrete has been used in the construction of many of the country's largest buildings -- putting them at risk of collapse.

The recipe to make concrete is pretty simple -- cement, aggregate and water -- but the strength of the final batch can vary wildly depending on the kinds of aggregate and cement used and the proportions they're mixed in. Commonly the aggregate used in many modern buildings projects consists of crushed gravel or other rock, including sand, and that's the cause of so much distress in the Chinese construction industry at the moment. Inspections by state officials have found raw, unprocessed sea sand in at least 15 buildings under construction in Shenzhen, including a building which, when finished, was set to become China's tallest.

Sea sand contains salt which is corrosive to steel reinforcing bars. So, given time, the concrete structures will weaken and likely fail.