CO2 Utilization in Concrete using CO2-Loaded Aqueous Ionic Liquid

By: Benjamin Opuni

Studies on various means of reducing CO2 emission or on the capture, storage and sequestration of emitted CO2 have been conducted to provide mitigation measures for greenhouse-induced temperature increases from a medium-and long-term perspective (Jang et al., 2016). The majority of currently available technologies include the utilization of CO2 in the manufacturing of chemicals, fuels, and fire extinguishers, as well as the injection of CO2 into oil reservoirs to improve oil recovery (CO2-EOR) (IEA 2019). Henceforth, utilizing captured CO2 in a process that yields valuable materials has consequently recently attracted a lot of attention. One of the prime examples is the sequestration of CO2 by mineral carbonation and transformation into an industrially useful product. (Jang et al., 2016).

CO2 can be utilized as an input in concrete making process. CO2-derived concrete could be used for the same applications as conventional concrete, provided the material properties are similar or better. Concrete is made by combining cement, water, and various types of solid aggregates (such as sand, gravel, and crushed stone) in a mixing container. CO2 can be utilized a s a component of the filler (aggregate), as a feedstock in the production of the binding material (cement), and as an input for the curing of concrete. The formation of carbonates, which are the type of carbon that is found in concrete, is the result of the reaction of CO2 with certain minerals, such as calcium oxide or magnesium oxide. (ICEF 2017_roadmap1, n.d.).

The term “curing” refers to a series of processes that take place in concrete after it has been mixed with water, cement, and aggregates. Cement is transformed into crystals that interlock with one another and bind the components of concrete together during this process. This gives the material the its strength. By injecting CO2 as part of the concrete mixing process, water is replaced by CO2 to produce calcium carbonate. In point of fact, this process takes place naturally in regular concrete, but at a very slow rate. This is because the CO2 in the air only penetrates the concrete at a rate of a couple of millimeters per year (Ecofys, 2017).

In order to solve this problem of inefficient CO2 uptake by concrete, the CO2-rich aqueous ionic liquid will then be utilized directly in a cement-based material such as concrete. This could reduce the amount of cement needed in the concrete mixture, thus leading to reduced energy consumption and CO2 emission from the production of cement. Other potential benefits are shorter curing time, less water consumption and a higher strength of concrete compared to conventional concrete.