Making Concrete Sustainably
This year, around 12 Billion tons of concrete will be made around the world. And this requires around one-and-a-half million tons of cement. But for every ton of cement produced, a ton of carbon dioxide is released into the air. This is partly the result of chemical reactions when key ingredients, like limestone and clay, are heated to 1400-degrees Celsius. The wide-spread use of coal to reach these temperatures is also a culprit. But what if concrete could be made more sustainably?
Sulapha Peethamparan is working on a multi-faceted project that could usher in widespread use of “green” concrete.
“By the year 2050,” she says, “it’s estimated that 18 Billion tons of concrete will be produced annually. We’re conducting research on concrete that uses none of the energy-intensive, traditional cement.”
This is a tall challenge. Concrete is the construction material used most around the world, she says, because its ingredients — cement, water and aggregate — are cheap and readily available. To develop a better option, Peethamparan is using fly ash and slag. These are industrial by-products. Waste, essentially, that can be recycled and re-purposed to make concrete.
But their use poses other challenges, including questions about strength, transportability and durability. And concrete that is completely cement-free must contain an activating agent, like alkali. But using such material raises concerns that concrete can leach harmful chemicals into water.
The National Science Foundation and New York State Pollution Prevention Institute have awarded Peethamparan $500,000 for multi-year research that will put sustainable concrete to the test. This includes nano-scale characterization to learn more about the nature of non-traditional concrete.“Right now,” she says, “cement production is responsible for six percent of the world’s greenhouse gases causing climate change. We can reduce that, possibly to zero. This research can really change things for the better.”