Editor’s Desk: Sustainable Cement
Adapting & Redesigning the Cement Industry to Combat Climate Change
Aside from water, concrete is the most ubiquitous material used today, and over 10 billion tons of it are produced annually by an industry that is worth over $37 billion. Portland cement, the most commonly used cement, has been around for a couple centuries and is a basic ingredient in a variety of cement products, including mortar and stucco. In concrete, cement is the durable, waterproof glue, or binder, that gives the material its strength and durability. It’s also one of the reasons that the concrete industry produces 8% of the world’s carbon dioxide emissions.
You see, making cement isn’t exactly eco-friendly. The chemical reactions inherent in the production of cement result in an immense amount of CO2 emissions. This includes the collection of sand for aggregate, burning high-temperature kilns, and grinding. The process of making Portland cement hasn’t evolved much over the last couple of centuries, and it still incorporates the mixing of limestone, clay, and gypsum.
That’s the bad news. The good news is that there are better, more sustainable materials that can be used to make cement, including coal fly ash, calcined clays, and other industrial by-products looking for a second use. Kilns, too, can be redesigned to be less energy intensive, ultimately decreasing the amount of CO2 released into the air. You might be wondering why we use so much cement in construction when it is such an aggressive component of climate change. There is a case to be made for the hardiness and longevity of concrete and cement offsetting its greenhouse gas emissions. Concrete structures have a long lifespan, a low life cycle cost, and are resilient against rust and other types of damage.
In 2016, nearly 200 countries came together to negotiate and sign the Paris Agreement, which has a long-term goal of limiting the global temperature increase in order to reduce the risks and impacts of climate change. The Paris Agreement also encourages countries to increase their ability to adapt to the adverse impacts of climate change and foster climate resilience and low greenhouse gas emissions development. What better way to start than with the behemoth cement industry?
To be fair, there have been recent changes in cement production. According to the Portland Cement Association, alternative fuels, such as industrial byproducts that otherwise would end up in landfills, represent more than 15% of total cement plant energy consumption in the United States. Portland-limestone cement, which is relatively new to America, is a blended cement that incorporates between 5%-15% limestone as an ingredient, which lowers its environmental footprint by about 10%.
These low-CO2 options are popular amongst a small, yet steadily growing market. However, in order to keep up with the rapid urbanization of the United States and the world, cement production needs to take a giant leap towards reusing industrial wastes. Not only will this decrease CO2 emissions, but it will also help to encourage and sustain a circular economy, one that is regenerative of natural systems and rejects the consumption of finite resources.
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