Climate change is one of the key challenges facing the human race in the 21st century. This phenomenon is primarily attributed to global anthropogenic CO2 emissions, 5% of which come from Portland cement production that is an integral part of the concrete industry. To respond to this challenge new approaches to sustainable development of concrete infrastructure combining both mitigation and adaptation measures are needed. The project contributes to the formulation of such approaches.
The project aims to develop a method for the evaluation of the whole life performance of RC structures subjected to carbonation in conditions of climate change, which takes into account both mitigation and adaptation measures. The method is based on the integration of two techniques: Life Cycle Assessment (LCA), which places emphasis on environmental issues, and Life-Cycle Cost Analysis (LCCA), which concentrates on economics. Since there are numerous uncertainties associated with associated with environmental and mechanical loads, material properties, models, etc. the method uses a probabilistic approach. To achieve this aim the following objectives have been planned:
• Experimentally determine the carbonation rate in traditional and ‘green’ (i.e. with fly ash and blast furnace slag) concretes in unloaded and loaded states;
• Develop a numerical model for predicting carbonation and CO2 uptake of concrete, which accounts for the influence of loads (including caused by them cracks), time-variant ambient CO2 concentration, temperature and relative humidity;
• Develop an integrated probabilistic LCA-LCCA method for evaluating the whole life performance of RC elements subjected to carbonation with particular emphasis on their deterioration and subsequent repairs and associated CO2 emissions;
• Prepare case studies illustrating application of the method.
Results obtained during the project demonstrate a clear influence of loading conditions on the carbonation rate of concretes, especially of ‘green’ concretes. Thus, it has been essential to account for that in the numerical model of concrete carbonation that has been developed. The LCA-LCCA analysis of a case study has shown that the use of ‘green’ concretes in RC structural elements leads to a reduction in carbon dioxide emissions, while the life-cycle cost of the elements remains similar to that of the elements made from Portland cement concrete. However, the use of ‘green’ concretes increases the probability of carbonation-induced corrosion, in particular in conditions of climate change.
