Assessing Climate Change Induced Risk to Concrete Structures

Abstract

This thesis evaluates the suitability of current concrete durability design codes against carbonation projections, for 10 nations and 1 region, considering sheltered concrete conditions, encapsulating 11,265 metropolitan areas (44% of global metropolitan areas). The scope incorporated 2020 built infrastructure, projected until 2120, and new buildings built between 2020 to 2050, projected for 50 years.
Further to suficiency at the level of a nation, localisation of code to said areas (via digitisation of codes) was considered as a method of reducing concrete provision volumes at scale. All information has been generated in accordance with a coordinate system obligated by the United Kingdom Government and North Atlantic Treaty Organisation. The Centre National de Recherches Météorologiques climate model-1, high-resolution format, state-of-the-art climate model was used for climate modelling.
Fédération-internationale-du-béton-Guiglia, conceived in 2013, was selected as the carbonation model of choice (from a set of multiple) after verification of accuracy, using 247 real-world carbonation samples from Finland, South Africa and Switzerland. In sheltered form, it was found to have a model fit of R2 = 0.5. This generally underpredicted carbonation in the short-term, suggesting that findings of this thesis are conservative. A modification to this model was developed for use with relative humidities below 62.5%.
Under the nearest carbon dioxide and temperature climate scenario to present, Shared Socioeconomic Pathway 126, cover provision was found to be suficient for buildings and infrastructure in the United Kingdom, Australia, Denmark and the United States. Of these, only the United Kingdom and Australia consistently showed suficient provision (according to current design codes) across all scenarios. This appears to arise from code design philosophy, as opposed to specific environmental factors. Structures employing precasting in Southern France and Northern Italy have been predicted to be under significant risk of both durability and structural failure before the end of design life. Weak reinforced concretes in both Germany and Finland are predicted to have structural failure risk, before the end of design life, for in-situ pours.
Additional concrete cover provision requirements to meet design life, under each Shared Socioeconomic Pathway are presented, as well as the decade when the existing design code is predicted to no longer be suficient, due to potential climate change. Digital maps have been created to show the distribution of carbonation at a national level, through use of geographic information systems, which can be used for policy localisation.
When incorporating design location (specific area increases as opposed to national increases in cover based on predicted requirements), total volume of cover provision for a nation would only reduce below current in Italy and Finland, under low and high carbon dioxide scenarios, respectively.
This work provides new insights into the likely durability performance of reinforced concrete in metropolitan areas, accounting for the higher levels of atmospheric carbon dioxide anticipated under various potential climate change pathways, which is yet to be widely considered in the literature. The findings suggest the need for updated design codes to account for higher carbon dioxide concentrations under the most likely scenario, alongside eforts to reduce carbon emissions to further probabilise less extreme climate scenarios.

Date of Award	21 May 2026
Original language	English
Awarding Institution	University of Portsmouth
Supervisor	Stephanie Barnett (Supervisor), Malcolm Whitworth (Supervisor) & Lee Woods (Supervisor)