Sustainable concrete bridges : An investigation of possible measures to reduce the climate impact

Sammanfattning: The need of building new bridges is always existing in relation with the increase of infrastructureand transport needs. Bridge constructions have traditionally been associated with highconsumption of resources and large greenhouse gas emissions. Involved parts (clients, designers,contractors and material suppliers) see the need for sustainable solutions and the respective partsare searching for means to get there.The large emission of carbon dioxide (CO2) comes from the production of concrete/cementand steel reinforcement bars. Studies in 2017 measured climate gas emissions in the constructingand infrastructure sector, which showed that concrete and reinforcement steel stood for 8 % ofthe CO2 emissions each. The large climate emission from these products led to climate goals forsustainable development, both global and local, with purpose to reduce the climate emissionregulated by the United Nations (U.N) and applied by the Swedish transport administration(Trafikverket).The purpose of this master’s thesis was to identify possible measures that will have positiveimpact on the climate goals. The possible measures could contribute to future guidelines forhow a bridge designer should work to reduce the climate emissions.The master’s thesis is divided into two main parts: Literature study and case study. The literaturestudy identifies the different materials and their climate impact with focus on the materialsconcrete, cement and reinforcement. It also identifies how a bridge designer can affect theclimate impact in a positive way. The case study implements the measures from the literaturestudy that are applicable. The literature study is implemented on a real bridge that is locatedover road E4 in Kalix. Calculations is performed during the case study to measure the climateimpact from the bridge construction process, in terms of CO2, which is compared to differentmeasures found in the literature study.The results from the literature study shows that the largest climate savings can be achieved byreplacing as much Portland cement as possible. Portland cement is replaced by mixing thecement with supplementary cementing materials such as fly ash, granulated blast furnace slag orcalcined clay. Smaller climate saving was identified by comparing different reinforcementsuppliers and compare their respective environmental product declarations. Finally, recyclingcrushed concrete as coarse aggregates presented possible climate savings along with reducedamounts of waste disposal.Conclusions and results from the studied research are that the largest climate savings can beachieved from the actions made by the material manufacturers. A bridge designer can affect theenvironment by optimizing the bridge structure with the help of suitable bridge types or crosssections.The most effective optimization is achieved through iterative calculations of thedifferent bridge types and cross-sections.