It’s long been known that cement production creates some of the worst carbon dioxide emissions, but what wasn’t known until recently is that overtime, concrete absorbs carbon dioxide in the air around it, thereby offsetting up to 43% of the emissions created during cement production.
This breakthrough, made by scientists at the California Institute of Technology, subverts the traditional thinking around natural carbon sinks, which are plants, the ocean and soil and has the scientists believing that there may be more to the theory that human systems can also act as carbon absorption.
The rate of absorption may also be increasing, partially due to the current construction booms in nations such as China, as the life expectancy of a building there is shorter than it is in Europe or North America. The increased absorption happens when a building is crushed down, creating an increased surface area for the carbonation process to occur.
There has long been a discrepancy in carbon accounting and the researchers believe that their discovery accounts for this, as in the past only natural carbon sinks have been accounted for. The discovery also shows the importance of looking at the entire lifecycle of materials, especially for those businesses looking to budget and reduce their carbon dioxide outputs and governments trying to better understand where they sit globally in regards to emissions.
More than 69 billion tonnes of cement has been used globally since 1930, creating 38.2 gigatonnes of carbon dioxide, which is about 5 per cent of total carbon emissions.
The scientists involved in the study are hoping that their findings can be used to inform the future of how cement is reused and recycled.