As a civil engineer I have worked with reinforced concrete structures throughout my career, from bridging the Great Belt and The Sound from Denmark to Sweden, to airports, swimming pools, factories etc. In my personal opinion there is no doubt that the disaster in Surfside is caused by a collapse of the foundation due to corrosion of the reinforcement. As a building material, reinforced concrete is one of the most durable, yet flexible materials known to man. The combination of steel and concrete in the early 1900’s is nothing less than genius. Concrete can withstand a lot of pressure, whilst steel is superb for tensile forces. Furthermore, the temperature expansion coefficient is exactly the same for both materials, which means their volume change is the same for different temperatures. All in all, a perfect match. But, reinforced concrete does not last forever and needs to be monitored and maintained regularly. Especially Chloride and Carbondioxide are very detrimental, causing the reinforcement to corrode and spalling the structure. There are photos on Google Earth where you can follow the construction of the neighboring apartment block between 2016 and 2019 (this is the place where the collapse surveillance video was filmed from). From these photo’s it is clear that the construction of an underground parking area required extensive groundwater management. I counted at least 10 big pumps which were installed to keep the building pit dry in 2018. So, the groundwater pressure on the basement walls is high in this area. In case of Surfside the groundwater is corrisive salt. On top of that there are reports of large amounts of water in the center of the parking garage (the collapse started in the center of the building), which were pumped out regularly. The garage itself was probably kept fit for purpose, but the cause of the leakage was probably never repaired. So…, NO Chinese copper pipes from hell, directed energy attacks, explosions, or Rods from God, but a schoolbook example of deferred maintenance, with catastrophic results. |