Iconic concrete structures around the world

The world is full of wonderful engineering feats that push the boundaries in creativity. But most of these fascinating structures would not exist were it not for the use of one of the most ubiquitous and versatile building materials. Concrete forms a big part of our surrounding landscapes, whether it be in road surfaces, dams or buildings. Even the architects and builders of the most impressive structures across the globe aren’t shy about its use.

Christ The Redeemer

Location: Rio de Janeiro, Brazil

Construction: 4 April 1922 - 12 October 1931

If you look up at the narrow summit of Mount Corcovado, you’ll see the imposing statue of Christ the Redeemer. The statue, which represents Jesus Christ, is made of reinforced concrete clad in a mosaic of thousands of triangular soapstone tiles, and sits on a square stone pedestal base. It is the largest Art Deco-style sculpture in the world.

Actual onsite construction of the structure didn’t begin until 1926, with the building of the pedestal and chapel. Scaffolding in the shape of the outstretched figure was erected on this base, and workers were transported by rail up the mountain to assemble the steel mesh that would reinforce the concrete.

The statue has braved the elements, including several lightning strikes, since it was completed in 1931. Designers even planned for continued maintenance by creating internal areas with access doors to various parts of the statue.

Amount of concrete: 265 cubic metres (estimated)

Interesting fact: Because of the statue’s mountaintop position, it is prone to lightning strikes and gets hit around three to six times a year. Prior to the Fifa World Cup in 2014, lightning struck and broke one of the statue’s thumbs.

Three Gorges Dam

Location: Hubei, China

Construction: 14 December 1994 - 2006

A straight-crested concrete gravity structure, the Three Gorges Dam is 2,335m long with a maximum height of 185m. The dam allows the navigation of ocean-going cargo vessels and generates hydroelectric power via the dam’s accompanying hydroelectric plant. It was also intended to provide protection from floods, but efficacy on this point is unclear and has been debated.

Adding to the engineering prowess, the dam also has ship lifts and locks to manage all the shipping vessels that use the Yangtze River. Normal cargo goes through the ship locks while passenger ships use the lifts, where the journey takes 36 minutes.

While the construction is indeed an engineering feat, it has also been at the forefront of controversy: construction of the dam caused the displacement of at least 1.3 million people, and the destruction of natural features and countless rare architectural and archaeological sites.

Amount of concrete: 28 million cubic metres

Interesting fact: When the dam was built, 39 trillion kilograms of water from the Yangtze River built up behind it to 175m above sea level. Its sheer size altered the Earth’s moment of inertia, slightly slowing its rotation.

The Pentagon

Location: Virginia, USA

Construction: 11 September 1941 - 15 January 1943

A symbol of military power, the Pentagon is the headquarters of the US Department of Defence and is one of the largest office buildings in the world. It was designed by architect George Bergstrom and built by contractor John McShain.

Bergstrom had to use an asymmetrical five-sided shape for his design because of the position of existing roads on the site. And because the site is on the floodplain of the Potomac River, the ground conditions presented several engineering challenges.

A minimal amount of steel was used in the structure as it was in short supply during World War Two. Instead, the Pentagon was built as a reinforced concrete structure, using 680,000 tons of sand dredged from the river, and a lagoon was created beneath the Pentagon’s river entrance. To minimise steel usage, concrete ramps were built rather than installing elevators.

Architectural and structural design work for the Pentagon proceeded simultaneously with construction, with initial drawings provided in early October 1941, and most of the design work completed by 1 June 1942. The construction work, at times, got ahead of the design, with different materials used from those specified in the plans. Pressure to speed up design and construction intensified after the attack on Pearl Harbour on 7 December 1941.

Amount of concrete: 333,000 cubic metres

Interesting fact: There is enough telephone wire in the Pentagon to wrap around the circumference of the Earth 4.5 times.

Burj Khalifa

Location: Dubai, United Arab Emirates

Construction: 6 January 2004 - 1 October 2009

Towering over the city of Dubai is the Burj Khalifa, the tallest free-standing structure in the world. Described as a ‘Vertical City’, the tower stands at a whopping 828m and has 160 habitable levels, more than any building.

Designed by American architect Adrian Smith and developed by local estates agency Emaar Properties, the tower’s highest reinforced concrete core walls were pumped using high-strength 80MPa concrete from ground level, with a staggering vertical height of 601m. This smashed the previous pumping record on a building of 470m on skyscraper Taipei 101 in Taiwan.

Amount of concrete:  330,000 cubic metres

Interesting fact: The design of the building resembles the Hymenocallis flower, native to Central and South America. The central core emerges at the top and culminates in a sculpted spire.

Lake Pontchartrain Causeway

Location: Louisiana, USA

Construction: 20 January 1955 - 30 August 1956

Lake Ponchartrain is a large saline lake and wetlands area in south-east Louisiana that connects to the Mississippi Sound, with New Orleans on its southern shore. This massive body of water covers 630 square miles (1,600km2). As the region’s population boomed after World War Two, people began considering ways to cross the lake to overcome the lengthy travel time of driving around it. This was when a bridge-building project came to be.

Indeed, the Louisiana Bridge Company built a manufacturing plant near the northern end of the lake, where the bridge would sit. From there, all concrete parts for the causeway were poured, cured, and assembled on-site.

The bridge structure, approximately 38km long, also features extensive parts made of pre-stressed concrete, made by pouring concrete around high-strength steel tendons that have been stretched under tension to increase their resistance, making the finished piece stronger.

Louisiana’s soft soils meant piles had to be driven deep into the ground to provide enough support for the vast structure. The company used hollow, pre-stressed concrete cylinders 1.37m wide, for the pilings – larger and stronger than those used in any past project.

Amount of concrete: 197,140 cubic metres

Interesting fact: Bridge police write about 1,100 citations per month for traffic violations on the causeway, with all the revenue going to St Tammany and Jefferson parishes.

Fernsehturm Berlin

Location: Berlin, Germany

Construction: 1965 - 3 October 1969

The design of the iconic sphere you see at the top of the Fernsehturm Berlin television tower was inspired by the Soviet Sputnik satellite, demonstrating the influence of the Space Age and new technologies, with the cross-section resembling a space rocket.

Work on the foundation began on 4 August 1965 and was finished by the end of 1965. The concreting of the tower foot began on 15 March 1966. The concreting progressed rapidly, so that the 100m mark was exceeded on 4 October 1966. Its shaft reached its final height on 16 June 1967.

Amount of concrete: 7,900 cubic metres for the shaft

Interesting fact: If you dine at the TV tower, you will find yourself in a rotating restaurant. It takes 30 minutes to rotate fully and get a 360-degree view of Berlin. To avoid emergencies, the kitchen is at the bottom of the TV Tower, so every dish travels up a few hundred metres with a special elevator.