Can We Make Concrete Low-Carbon?

Written By Teacher: Teresa Pettitt-Kenney

Hi there! My name is Teresa and I just finished my Bachelor's degree in Environmental Science and am excited to pursue environmental education in the future! I am extremely passionate about climate change, equitable climate action, and how education can work to address these issues. 

Concrete is everywhere in our lives, but learning about its environmental impacts can be eye-opening. Because we use concrete so extensively, a significant amount of energy goes into creating it, increasing greenhouse gases in our atmosphere. However, it doesn’t have to be this way, as many options are being discovered to make concrete more sustainable. Explore these exciting innovations with your students through this TED talk on making carbon-negative concrete or this article on the invention of eco-friendly concrete. Seeing innovative solutions to this real-world issue can inspire students to come up with their own ideas to fight climate change.

Written By: MIT Environmental Solutions Initiative

The MIT Climate Change Engagement Program, a part of MIT Climate HQ, provides the public with nonpartisan, easy-to-understand, and scientifically-grounded information on climate change and its solutions.

Concrete is among the world’s most consumed materials—second only to water. That’s because its durability, affordability, and availability make it essential to countless construction projects, from bridges, to roads, to buildings.

Since concrete is used on such a large scale, it also produces large amounts of heat-trapping greenhouse gases, mostly from a manufacturing process that emits carbon dioxide (CO2). Yet, the world will need concrete to build infrastructure that can cope with climate change and population growth. So the question is: how do we lower concrete’s environmental impacts even as we continue to rely heavily upon it?

Concrete: its ingredients and impacts

Concrete is a mix of several different materials: water, fine aggregates (or sand), coarse aggregates (or gravel), chemical additives, and, most importantly, cement. Cement is what binds all of these ingredients together to give concrete its durability and distinctive, grey appearance. Cement production, however, also generates most of concrete’s emissions: in fact, a 2016 study found that cement accounts for around 7% of all greenhouse gas emissions worldwide.

Cement begins as crushed minerals that are heated in a kiln to make what is called “clinker.” Clinker is ground into a powder, mixed with a few additives, and then blended with some other minerals to create cement.

This process creates CO2 in two main ways. The first is the chemical reaction that occurs as clinker forms. The second is heating the kiln to temperatures above 2600°F, which must be done using fossil fuels.

To make low-carbon concrete a reality, manufacturers, engineers, and scientists are working to lower the CO2 emissions of cement production and change the ingredients used in concrete.