Carbon Capture In Concrete – Offsetting Carbon Emissions

Carbon capture happens to be crucial for decreasing the untoward effects of human carbon dioxide emissions on the environment. Apparently, a researcher’s team from the University of Tokyo and also Nagoya University, Japan, has gone on to successfully come up with a method so as to determine the source of carbon in case of concrete. This method helps to know whether the carbon comes from the raw materials used or if it gets derived from carbon in the air that is trapped during the reaction that it has with the concrete, thereby resulting in the formation of calcium carbonate.

The team successfully cross-checked the occurrence of direct air carbon capture by way of determining the ratio of specific carbon isotopes when it comes to concrete that had been exposed to the air as compared to the concrete that had not been exposed. This method happens to have the capacity to be beneficial for the industrial segment as well as countries that look to mitigate their carbon emissions.

It is well to be noted that 2023 happens to be on track to become the hottest year ever that has ever been recorded. In Japan, the rice crops went on to collapse, while in the U.S., the roads melted. Despite the various international agreements and numerous calls to action that have been made, greenhouse gas emissions from fossil fuels keep rising. In order to safeguard the planet from surpassing the limit of a 2-degree Celsius temperature rise by 2100 as compared to preindustrial levels, it is indeed essential that one take action. As per the Intergovernmental Panel on Climate Change- IPCC of the United Nations, it is insufficient to solely focus on decreasing and preventing additional emissions. To make sure that this goal is accomplished, it is imperative that one also take measures to eliminate carbon dioxide from the atmosphere.

Direct air capture- DAC happens to be a method that involves the extraction of carbon dioxide from the atmosphere by way of using chemicals or physical processes. The International Energy Agency- IEA has proposed a range of methods, including the elevated usage of DAC technologies, as part of their net-zero emissions scenario. This aims at enabling the worldwide energy sector to remove as much CO2 as it releases by 2050. As per the IEA, the industry sector had 25% of the total global energy system CO2 emissions in the year 2022. Cement, which happens to be the second-most widely used industrial product after water, carries a major environmental burden.

Professor Ippei Maruyama, who happens to be from the Department of Architecture at the University of Tokyo Graduate School of Engineering, said that the concrete industry is facing a major issue of reducing emissions. During cement production, as much as 800 kilograms of CO2 are emitted per ton. Concrete has been mostly recognized for its tendency to react with CO2 across the atmosphere, resulting in the formation of calcium carbonate. This phenomenon is indeed undesirable, as it leads to the corrosion of steel bars that happen to be present within concrete structures. However, the concrete industry is at present exploring methods so as to utilize this reaction more efficiently.

The reaction that goes on to lead to the formation of calcium carbonate happens to have the capacity to fix or even trap CO2, thereby effectively removing the gas from the atmosphere. But it can pose challenges in the construction context. It is worth noting that calcium carbonate happens to be a naturally occurring substance found in rocks such as limestone. These rocks are generally used in the manufacturing of concrete. Maruyama remarked that it is challenging to gauge whether the CO2 that is found in concrete is taken recently from the air or if it originates from rocks. Apparently, a method has been developed to ascertain this, which can go on to determine if the concrete produced happens to be eligible for certification as offsetting CO2 emissions.

It is worth noting that the study was conducted by creating hydrated cement paste samples that happened to be replicas of concrete. After making sure that they were sufficiently hydrated, they proceeded to grind the paste sample into a powder. They kept the nonexposed powder contained carefully while leaving the powder that was exposed open to the air. The powder was dissolved in the acid after 7 and 28 days to so as to collect the gas. The researchers thereafter made use of a technique known as accelerator mass spectrometry in order to analyze the ratio of numerous carbon isotopes like carbon-12, 13, and 14. These isotopes had similar chemical properties but did differ when it came to their physical properties, which allowed the team to assess the carbon source as well as determine if it was actually present in the raw materials. The carbon ratios observed in the gas sample completely matched the expected proportions of carbon isotopes in the air when the gas happened to be sealed.

The researchers happen to be interested in applying the lab-based method to real-world locations and look to test how different quantities of raw materials that are used in local concrete production may go on to impact the results. Fixing carbon dioxide from the air happens to be a certified method for offsetting CO2 emissions, making it financially valuable within the emissions trading context. Maruyama emphasized the importance of distinguishing the calcium carbonate extraction process for concrete production. This research can play a significant role when it comes to supporting a thriving market for this purpose. It is believed with conviction that achieving carbon neutrality and also promoting a circular economy in the construction industry happen to be crucial for the future. This is mostly true in Japan, where the construction sector happens to play a vital role in supporting business continuity and also facilitating recovery efforts after natural disasters.