2021

Mäkikouri, Sampo; Vares, Sirje; Korpijärvi, Kirsi; Papakonstantinou, Nikolaos

Climate change has been identified as one of the biggest issues plaguing human life at present. Hence, immense attention is being paid to developing methods that can potentially reduce carbon dioxide emission. With the help of carbon-negative concrete, manufactured from alternative binders and cured with waste carbon dioxide, a major part of the manufacturing industries that emit carbon dioxide can be potentially turned into a carbon sink. In this study, the waste material streams in Finland, suitable for disposing carbon-dioxide-cured concrete, were mapped. Mine tailings, blast furnace and steel slags, recycled concrete, biomass, coal and municipal waste incineration ashes, green liquor dregs, and foundry sands were studied. It was found that there were sufficient amounts of potential secondary raw materials (about 27 Mt/a) for the preparation of Finnish cement and the production of concrete (requirement: approximately 1.4 Mt/a and 11.2 Mt/a, respectively). The total carbon dioxide uptake potential was estimated to be approximately 1.9 Mt/a (vs. emissions from the cement industry in Finland, 0.84 Mt/a). In addition, the carbon footprints of the conventionally manufactured concrete block were compared with the carbon footprint produced by a modeled carbon-dioxide-cured blast furnace slag block. If such novel concrete were used to produce all the concrete-based substances, it would bring down the emission of carbon dioxide from 1.9% to negative 1.3% in Finland.