In total, the construction of the Burj Khalifa required 330,000 cubic meters of concrete, the foundation alone using over 45,000. This foundation consists of 192 concrete piles, which are each buried 50 meters beneath the surface. 31,400 metric tons of steel rebar were used to reinforce the concrete. All this rebar laid end to end would stretch over more than a quarter of the Earth. In addition to concrete and steel, other major materials used are glass, silicone, and aluminum, which make up the outside façade of the tower.
In massive structures like the Burj Khalifa, the concrete used in construction must be able to withstand the thousands of tonnes bearing down on it. Consequently, a special mix of reinforced concrete with high compressive strength was used on the Burj Khalifa.
Because of the extremely high temperatures in Dubai during the day, which can be as high as 48°C (118 °F), concrete was poured only at night when it is cooler and more humid. In addition, ice was added to the concrete during mixing to cool it further. The reason behind these procedures is that concrete dries more evenly when cool and is thus less likely to form cracks. In such a massive project, such cracks could have disastrous consequences. The concrete’s flow behavior also had to be kept in check. To test it, a sample was poured onto a plate, and was deemed acceptable based on whether or not it spread out far enough.
In 2007, concrete was pumped from the ground to a height of 601 meters, breaking the previous pumping record held by a skyscraper in Taipei, Taiwan. At this level, the pumping pressure was nearly two hundred bars.
Because of the incredible height, concrete was flowing through the pumping lines for extended periods of time, wearing the inside of the pipes. To ensure that the pipes did not have to be replaced during construction, long-life pumps with thick walls of 11mm were used.
The 132,000 square meter curtain wall façade of the Burj Khalifa is made of aluminum, silicone, and glass. It consists of over 24,000 panels specially designed to save energy. Their high-performance reflective glazing greatly reduces heat transmission, which is a critical feature in the extreme heat of Dubai.
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