Neel Renne

Considering the emerging need for more sustainable practices, life-extending interventions in the concrete sector are gaining interest. This paper focuses on a life cycle assessment of repair and prevention strategies for corrosion-related damage using a case study. Eleven intervention strategies based on the EN 1504-9 principles, categorized under four methods, are considered to extend the service life of the canopy of a recreational facility in Belgium for 25 and 50 years: (i) PR: patch repair (with surface protection) i.e. local removal of delaminated concrete, (ii) CR: conventional repair (with surface protection) i.e. extensive removal of contaminated concrete, (iii) GCP: galvanic cathodic protection, and (iv) ICCP: impressed current cathodic protection. Overall, the combination of CR at the beams and slabs with PR at the columns can be considered the most optimal intervention strategy based on the single score and three out of six key midpoints: carcinogenic human toxicity, non-carcinogenic human toxicity and fine particulate matter formation. Alternatively, the ICCP scenarios, particularly those with discrete anodes and titanium strips, also perform well, especially in terms of global warming potential, freshwater ecotoxicity, and marine ecotoxicity. Finally, for a 25-year service life extension scenario, the combination of CR and PR achieves the lowest impacts across all dominant midpoint indicators and single score.

Nowadays a vast number of concrete structures are approaching the end of their expected service life. The need for sustainable rehabilitation (maintenance and repair) is urgent and due to the expected deterioration of buildings and civil structures, there will be a great need for preventive and/or curative interventions in the near future. More than 2/3 of the damage to reinforced concrete structures is linked to reinforcement corrosion, which can affect the durability of the structure and the residual load-bearing capacity. With the necessary transition towards a circular economy and the Sustainable Development Goals in mind, it is important to deviate from considering only the technical requirements and initial costs during the design of concrete structures. Hence, the environmental impact over the entire life cycle and the intended service life extension need to be considered as well. A typical residential building in a Belgian coastal environment with damaged reinforced concrete balconies is selected as case study to evaluate different frequently used repair techniques (i.e. patch repair, conventional repair, galvanic cathodic protection, impressed current cathodic protection and total replacement) by means of a life cycle assessment. Several sensitivities are mapped by analysing the influence of the intended service life extension, the volume and configuration of the construction, the repair mortar composition and the application of coating/waterproofing. It was stressed that these uncertainties could have a substantial effect on the environmental impact and highlight the domains where further research is needed (e.g. assumed life span and composition of repairs). Due to this manner, it is not possible to identify one environmental optimal repair method. However, for a short service life extension (e.g. 5y) small interventions like patch repair seem to be more sustainable while methods like cathodic protection and conventional repair are preferable for longer service life extensions (e.g. 40y).

Nowadays, a vast number of concrete structures are approaching the end of their expected service life. The need for maintenance and repair is high due to the continued deterioration of the existing building inventory and infrastructure, resulting in a large need for concrete repair in the near future. Reinforcement corrosion is the most important deterioration mechanism, causing (i) severe concrete damage (cracking along reinforcement and the spalling of the cover concrete) and (ii) loss in steel section. Therefore, appropriate repair techniques for corrosion damage are the main focus of this review paper. With the European transition towards a circular economy and with sustainable development goals in mind, it is also important to consider the environmental impact along with the technical requirements and life cycle cost. In order to improve the sustainability of concrete structures and repairs over their life cycle, life cycle assessment (LCA) and life cycle cost analysis (LCCA) should be applied. However, more research efforts are needed in this field for further development and refinement. This literature review tries to adress this need by compiling existing knowledge and gaps in the state-of-the-art. A comprehensive literature survey about concrete repair assessment through LCA and LCCA is performed and showed a high potential for further investigation. Additionally, it was noticed that many differences are present between the studies considering LCA and/or LCCA, namely, the considered (i) structures, (ii) damage causes, (iii) repair techniques, (iv) estimated and expected life spans, (v) LCCA methods, (vi) life cycle impact assessment (LCIA) methods, etc. Therefore, due to the case specificity, mutual comparison is challenging.