OPTIMERING AV BETONGKONSTRUKTIONER FÖR ATT MINSKA KOLDIOXIDUTSLÄPP I ANLÄGGNINGSPROJEKT

Sammanfattning

The concrete industry accounts for a significant share of carbon dioxide emissions, with the greatest climate impact arising from the production of cement — the primary binder in concrete — which alone contributes up to 90 percent of the material’s total emissions. In response to increasing demands for climate transition, alternative binders and low-carbon concrete have been developed, while standards and guidelines have been introduced to steer usage towards more resource-efficient construction. Anchored in the UN Sustainable Development Goals and Swedish initiatives such as Fossil-Free Sweden and the industry’s own roadmaps — including the Roadmap for Climate-Neutral Concrete — clear targets have been set to significantly reduce concrete’s climate footprint by the year 2045. Against this background, the present study investigates the extent to which the work processes described in the Roadmap for Climate-Neutral Concrete are applied in practice to enable the achievement of climate-neutral concrete by 2045. The study focuses on calculating potential emission reductions through selecting the right concrete for the right application and implementing low-carbon concrete in a case study project. The thesis was conducted in collaboration with Skanska Stora projekt Stockholm and is based on a tunnel project in Anläggningsentreprenad 8716 Nacka where sprayed concrete has been extensively used. The study analyzes how material choices and design strategies affect the project’s total climate impact, as well as the untapped potential for emission reductions through adjusting exposure classes and cement types based on actual environmental conditions.By reviewing project data, technical regulations, available cement types on the market, and current standards, the study demonstrates that several technical and organizational factors hinder effective climate optimization aimed at reducing emissions from infrastructure concrete. These include industry practices such as applying conservatively high exposure classes based on general guidelines rather than project-specific assessments, and how standards and reference documents dictate cement selection, ultimately determining the proportion of alternative binders used in the concrete mix. Climate calculations indicate that carbon emissions could have been reduced by up to 58 percent through a more project-specific and optimized design. A more conservative adjustment still shows a potential reduction of 16 percent, equivalent to approximately 700 tonnes of CO₂e — a significant saving for a project of this scale. As a complement to the main study, factors influencing carbon reduction throughout the construction process — from tender phase to knowledge feedback — were also examined. A key conclusion is that technical specifications in procurement documents and contracts often limit the use of lower-carbon concrete, despite the availability of proven alternatives. At the same time, the case study shows that measures such as deviations from certain BSAB codes in AMA, reassessment of exposure classes, or the implementation of independent verification requirements can open up new possibilities. For such changes to be realized, a proactive attitude and an integrated approach to climate considerations throughout all project phases are essential.