IN: Inspiration

Volcanoes save the grey

Cement mixed with volcanic ash could save 16% of production energy and reduce carbon emissions.

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In response to climate change, researchers have begun searching for alternatives to a wide range of devices, resources and technologies. Concrete is no exception.

One of the most widely used resources, concrete, is essential to many types of building processes. Yet the production of cement is a multi-step process that requires energy for treatment, grinding and limestone collection.

Production of Portland cement (the most common cement mix) uses a great deal of heat energy and around 5% of the world’s carbon emissions are the result of Portland cement production – a problem that researchers hope to solve by adding volcanic ash to the concrete mix.

Researchers from MIT have partnered with Kuwait scientists to shed light on the immense benefits of adding volcanic ash to a cement mix. What makes volcanic ash preferable is its availability. Ash is readily available around volcanoes, both active and inactive.

By replacing a variable portion of cement with volcanic ash, researchers found that less energy was used in the production of the cement mix. Though the research used ash from Saudi Arabia, many types of volcanic ash bind readily with water to produce concrete paste.

The reduction of carbon emissions, however, comes at a cost to the strength, life-span and durability of the material. On the one hand, researchers found that the production of cement in which 50% was replaced with volcanic ash (with an average particle diameter of 17 micrometers) used 16% less energy than that of traditional Portland cement. On the other hand, at this size, ash particles caused a decrease in the strength and resilience of the concrete.

Smaller particles are likely to cause an increase in the material’s strength. However, the production of small ash particles involves grinding, which uses heat energy. Two variables – strength and carbon footprint – thus need to be weighed in the production of cement using volcanic ash.

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