Taking the path towards decarbonisation

Aligned with the global cement sector, Votorantim Cimentos has committed to net zero CO₂ concrete in 2050, while also setting ambitious targets for 2030. One of these is to reduce its CO₂ emissions to a maximum of 475 kg of CO₂ per t of cementitious material, and to have a clinker factor of only 68%. To achieve this value, Votorantim Cimentos must broaden the types of supplementary cementitious materials that can be used to replace clinker, without compromising the performance of the resulting cement products.

The most effective supplementary cementitious materials for reducing the embodied CO₂ of cement are those that do not need any pretreatment, such as the byproducts from other industries, like slags, or natural materials that can be used as extracted, like natural pozzolans or fillers, and those that allow significant levels of clinker replacement. The source of the supplementary cementitious material must also be close to the cement plant to avoid costs and CO₂ emissions related to its transportation.

Because of their local availability, in the South and Southeast of Brazil, Votorantim Cimentos mainly uses fly ash and blast furnace slag, respectively, whereas in the rest of the country, the clinker is mostly replaced by acidic slags, natural pozzolan, calcined clay, and limestone filler.

Traditional pozzolans, like glassy volcanic rocks or volcanic ashes are rare in Brazil. Therefore, in recent years, Votorantim Cimentos has been focusing on reducing its CO₂ footprint by developing cements with natural, unconventional pozzolans. These can be, for example, silica-rich volcanic rocks, such as rhyolite, or metamorphic rocks such as schists and phyllites.

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Read the article online at: https://www.worldcement.com/special-reports/05072023/taking-the-path-towards-decarbonisation/