Concrete cancer: not pretty. Sarang/Wikimedia Commons 

By itself, concrete is a very durable construction material. The magnificent Pantheon in Rome, world’s largest unreinforced concrete dome, is in excellent condition after nearly 1,900 years. .. repair and rebuilding costs of concrete infrastructure, just in United States.. trillions of dollars …Steel reinforcement was a dramatic innovation of the 19th century. Steel bars add strength, allowing creation of long, cantilevered structures and thinner, less-supported slabs. It speeds up construction times, because less concrete is required to pour such slabs. Concrete is 3rd-largest contributor CO2 emissions, after automobiles and coal-fuelled power plants.

Moisture entering tiny cracks creates electrochemical reaction. One end of rebar  anode other  cathode, forming  “battery” that powers transformation of iron into rust. Rust can expand rebar up to four times its size, enlarging cracks and forcing concrete to fracture apart in a process called spalling, more widely known as “concrete cancer”.. ..collapsed civilisations of the past show us consequences of short-term thinking. We should focus on building structures that stand the test of time – lest we end up with hulking, derelict artefacts that are no more fit for their original purpose than the statues of Easter Island.

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