Concrete Construction: Cemented in the Industry
Date Posted: December 11, 2019
Posted In: Discussion, Ideas,
From KHL Group LLP: Deep set into the industry, you’d be hard pressed to find a technique more widely used in construction than the use of concrete.
The material offers a versatile quality while providing a solid foundation, which is a necessity for many ambitious construction projects. It’s cost-effective, plentiful and has proven to be a tried and tested method, time and again. Structures built using this substance often last for many years too, with a general service life of around 100 years.
Though the principle use of concrete remains the same, the aggregates industry has embarked on a technology revolution of its own. Health concerns surrounding the material, such as respiratory conditions are being tackled head-on, as are wider environmental concerns involving pollution.
One such development has been established by a team at the Massachusetts Institute of Technology (MIT) in the US. The team has created a way to make cement without heating, potentially eliminating the carbon produced in the process.
Portland cement, the most widely used variety, is made by mixing limestone with sand and clay and then fusing them together at temperatures of around 1,450°C. During this process carbon is emitted from the fuel used in the heating process and the limestone itself.
Altogether, it has been estimated that cement production accounts for 8% of global carbon emissions. Therefore, development of low-carbon production is a vital challenge that the industry has a responsibility to tackle.
The process that the team has developed involves the use of electrochemical processes rather than heat. Firstly, limestone is dissolved in acid then placed in a tank with an electric current passing through it.
This splits water molecules into oxygen and hydrogen, creates an acid at the positive electrode and an alkali deposit of calcium hydroxide at the negative. This deposit, which forms in flakes, can then be used to produce Portland cement.
The results were published in the Proceedings of the National Academy of Science, in a paper by Yet-Ming Chiang, professor of materials science, among others.
Chiang said, “About 1kg of carbon dioxide is released for 1kg of cement made. That adds up to 3-4 gigatonnes of cement and of carbon dioxide produced annually, and the number of buildings worldwide is expected to double by 2060, which is equivalent to building New York City every 30 days.”
So far, the team has demonstrated the process at laboratory scale, but the researchers said it could be scaled up to an industrial process. They warned, however, that it would be difficult to change such a basic process in such a large industry as construction.