LIFE CYCLE ASSESSMENT OF A COLUMN SUPPORTED ISOSTATIC BEAM IN HIGH-VOLUME FLY ASH CONCRETE (HVFA CONCRETE) Philip Van den Heede, Elke Gruyaert, Nicolas Robeyst and Nele De Belie (1) (1) Magnel Laboratory for Concrete Research, Ghent University, Ghent, Belgium Abstract Nowadays, a lot of research is being conducted on high-volume fly ash (HVFA) concrete. However, a precise quantification of the environmental benefit is almost never provided. To do this correctly, we adopted a life cycle assessment (LCA) approach. By considering a simple structure and an environment for the material, differences between traditional and HVFA concrete regarding durability and strength were taken into account. This paper presents the LCA results for a column supported isostatic beam made of reinforced HVFA concrete located in a dry environment exposed to carbonation induced corrosion. With a binder content of 425 kg/m³ and a water-to-binder ratio of 0.375, the estimated carbonation depth after 50 years for a 50 % fly ash mixture does not exceed the nominal concrete cover of 20 mm. As a consequence, no additional concrete manufacturing for structure repair needs to be included in the study. Moreover, structure dimensions can be reduced significantly due to a higher strength compared to the reference concrete used in the same environment. In total, about 32 % of cement can be saved this way. The reduction in environmental impact equals 25.8 %, while this is only 11.4 % if the higher material strength is not considered. 1. INTRODUCTION To reduce cement related greenhouse gas emissions, more and more research is being conducted on potential ‘green’ concrete types. Partial replacement of the cement with by- products from other industries, such as fly ash, blast furnace slag and silica fume, makes it possible to contribute to this objective in a significant way. The development of High-Volume Fly Ash concrete (HVFA concrete) by Malhorta is a well-known example [1]. Since it is defined as a concrete in which at least 50 % of the binder material consists of pozzolanic fly ash from coal fired power plants, the environmental benefit of this material seems obvious. However, in very few papers an actual environmental impact score is given for HVFA concrete. Normally, this impact can only be calculated correctly by adopting a life cycle assessment (LCA) approach. According to the applicable standard ISO 14040, the methodology requires a full study of the material consisting of four major steps: definition of goal and scope, inventory analysis, impact analysis and interpretation [2]. As stated in a