Master's Thesis : A robust LCA model for Alkali Activated Concrete

Abstract

In this master thesis, the methodology of life cycle assessment has been applied on two concrete systems in order to compare two types of binder. The first system is a regular cement using Portland cement as its main component while the second system is based on an alkali-activated binder tailored for a public infrastructure in Leuven. For the regular cement using mainly Portland cement, the most relevant impact category is the global warming potential without surprise and the most of the impact comes from clinker production and its high demand in energy. In a second place, ozone layer depletion is also highly relevant in this system due to the use of super plasticizers based on a chlorocarbon. Other categories such as eutrophication, acidification, abiotic depletion (fossil fuel) and photochemical oxidation play a role in the environmental impact of concrete but on a lower scale. For the second system based on an alkali-activated binder, the results are different. The most relevant impact category is the ozone layer depletion due to the higher use of superplasticizer in the concrete mix. Global warming potential is only the third most relevant impact category after abiotic depletion (fossil fuel). Comparing both systems, the reduction of CO2 emissions between the first and the second system is around 50%. This can be explained by the decrease of the amount of Portland cement in the second mix. Overall, the alkali-based binder has a better environmental footprint except in the ozone layer depletion impact category. This is explained by the use of the superplasticizer in higher quantity. This specific superplasticizer is used for its very good efficiency but in order to improve even more the environmental footprint of this binder, it would be required to find a better alternative.