Lime Based Construction Materials as a Carbon Sink

Lime is used in a variety of industrial sectors (e.g. construction materials, iron and steel industry, flue gas cleaning, etc.). By the thermal decomposition of limestone (CaCO3), known as calcination, two products are obtained: CO2 and quicklime, i.e. calcium oxide (CaO). There is a growing interest in quantifying and improving the potential of CO2 absorption of lime containing products during their operational life. The carbonation occurs during the lifetime of the lime application and it consists in the absorption of atmospheric CO2 that closes the loop by forming calcium carbonate back. Thus, a portion of the CO2 emitted during calcination is reabsorbed and stored in a permanent stable form. A literature review was carried out on the Carbonation Rate (CR) of lime used in three different construction materials: air-lime mortars, mixed air-lime mortars and hemplime. Out of 205 scientific publications reviewed, only 57 provide information about CR, specifically 21 for air-lime mortars, 27 for mixed air-lime mortars and 9 for hemplime. CR is 80-92% for pure air-lime mortars, 20-23% for mixed ones and 55% for hemplime. For all the materials, the CR trend over time was also assessed, according to the Fick’s law.