“On the list of materials people use most, concrete may be a runner-up, but it isn’t small potatoes. Second only to water in terms of how much is used across the globe, the ubiquitous construction material is produced in staggering quantities. According to industry analysts, some 30 billion metric tons of concrete is used globally each year to build bridges, roads, highways, high-rise buildings, sewage systems, and more.
Without a doubt, the hard-as-rock material supports much of the modern world. It’s also responsible for a lot of the world’s greenhouse gas emissions. The high-temperature process for manufacturing cement, the all-important glue that binds the components of concrete, accounts for roughly 8% of the world’s anthropogenic carbon dioxide emissions and consumes 2–3% of the global energy supply, according to the International Energy Agency.
‘Concrete is a very useful material, and for that reason, we use a lot of it,” says Kimberly E. Kurtis, a civil engineer and concrete expert at the Georgia Institute of Technology. “We aren’t just using more concrete than ever,’ Kurtis says. ‘We’re using more concrete per capita than ever,’ she emphasizes, noting that global per capita consumption has nearly tripled in the past 40 years.
And the trend isn’t subsiding. As countries in Asia and Africa continue pushing forward with new construction projects, and nations in Europe and the Americas update aging infrastructure, demand for concrete continues to rise. Increased use could go hand in hand with greater environmental impact, unless manufacturers institute changes to the way this vital material is made.
Manufacturers have already implemented a number of changes. For example, as Ian Riley, CEO of the World Cement Association, an industry trade group, points out, by capitalizing on engineering advances, cement manufacturers have steadily improved the energy efficiency of the enormous kilns used for heating and processing the starting materials from which cement is made. Boosting energy efficiency reduces fuel consumption, which lowers CO2 emissions. Trapping those emissions also helps. Some cement makers are reducing net CO2 emissions through carbon-capture technology using solid sorbents or by sequestering the gas directly in concrete before it sets and solidifies.
A different way to tackle concrete’s CO2 problem is to reformulate cement with similar-behaving materials that inherently generate less CO2 than the ones used in traditional manufacturing methods. Another option is finding materials that enable manufacturers to use less of the CO2-generating components.
The push to reformulate cement isn’t new. But because of the growing threat of climate change, interest in the topic has intensified. Scientists in industry and academia are evaluating these alternative materials from top to bottom to determine if they are readily available and cost effective, are compatible with standard equipment and practices, and form products that are strong and durable.”
View the whole story here: https://cen.acs.org/materials/inorganic-chemistry/Alternative-materials-shrink-concretes-giant/98/i45