Advances in sustainable concrete

Currently, between 90 million and 140 million tpa of cement are produced in North America, much of which is made into concrete for real estate projects. Now, those in the industry are becoming increasingly concerned with environmental standards and sustainability.

The cement industry in North America has made a continuous effort over the last few years to become greener. According to the Cement Association of Canada’s 2008 sustainability report, the industry improved its energy efficiency by 11% and reduced greenhouse gas emissions by 6.4% between 1990 and 2006.

To reduce emissions, additives, such as flyash, blastfurnace slag and silica fume are commonly blended with the cement, reducing the carbon footprint of the final product.

Canadian Company Whitemud is pioneering for greener and stronger concrete using metakaolin, made from kaolin ore, as a supplement to cement. The company claims that cement made with metakaolin is more durable than ordinary Portland cement and other widely-used cement substitutes. According to Whitemud, metakaolin cement reduces greenhouse gas emissions, saves time and money on the construction site and will enable buildings to last 100 years instead of just 50 or 60.

The company has a kaolin min at Wood Mountain, about 170 km southwest of Regina, which contains some 160 million t of kaolin ore. It plans to produce 200 000 of metakaolin a year.

In Louisiana, civil engineers are reportedly developing a polymer concrete using flyash. Erez Allouche, Assistant Professor at Louisiana Technical University and colleagues are conducting research on a reduced CO2 emitting geopolymer concrete. The researchers say that using geopolymer concrete instead of concrete made of Ordinary Portland cement could mean reduced CO2 emissions, produce a more durable infrastructure, conserve hundreds of thousands of acres currently used for coal combustion products and protect aquifiers and surface bodies of fresh water by removing flyash from disposal sites.

In addition, new aggregates are being used to create a greener and more durable concrete blocks. Poraver is created by crushing and refining post-consumer glass to create lightweight pellets that expand and generate a fine-pored granulate. Atlas Block Co. Ltd, for example, has created a new lightweight, environmentally friendly concrete block using 30% Poraver. According to the company, the block is non-toxic, chemically stable, mould-proof, odourless and unaffected my moisture.

Atlas has developed a prototype block made with Poraver that is much lighter than the lightest block currently on the market. The block could weigh as little as 10 lb, 20 – 22 lb lighter than the common lightweight block used in the industry.

Although the prototype has received good reviews so far, it must go through further extensive testing before it can receive approval from the CSA.

Read the article online at: https://www.worldcement.com/the-americas/26102009/advances_in_sustainable_concrete/