Life cycle assessment and hot spot analysis of concrete repair principles and application on life cycle intervention strategies

Abstract

The combination of continually deteriorating reinforced concrete structures and environmental objectives calls for sustainable repair and maintenance interventions. To respond to this need, the environmental impact of life cycle intervention strategies of reinforced concrete structures to restore and prevent corrosion damage is analysed through a life cycle assessment (LCA). First, the dominant midpoint impact categories, related to these interventions, are identified as (1) carcinogenic human toxicity, (2) global warming potential (3) fine particulate matter formation, (4) freshwater ecotoxicity, (5) non-carcinogenic human toxicity and (6) marine ecotoxicity. Secondly, a comprehensive assessment is performed for reference flow activities related to the EN1504–9 principles in order to get more insight into this data before case dependencies are applied. Based on this, the hotspots per category and even per activity could be determined. In general, the production and gross End-of-Life (EoL)-phase are the important life cycle phases. Finally, the activities and principles are combined to achieve actual intervention strategies applied on a case study of a reinforced concrete bridge. The outcomes show the dominance of carcinogenic human toxicity resulting in a high impact for demolishing and rebuilding. Although this scenario scores well for other midpoints, alternative interventions like impressed current cathodic protection score well in general. So, the interventions patch repair, conventional repair, galvanic cathodic protection, chloride extraction and realkalisation perform less well on average. Nevertheless, for specific midpoints or service life extensions they could still have a lower impact, like patch repair for a 20-year service life. In addition, the production and gross EoL-phase are also the most important for the case study. Secondly, when looking at the type of work, the main intervention but also the reinforcement preparation, concrete preparation and concrete surface protection are dominant.