Anyone involved in the conservation of twentieth-century buildings and structures will inevitably come across concrete in some form or another. The development of concrete and the rapid industrialization of its production in the late-nineteenth century means it is an ever-present part of the built environment in most parts of the world.
Advances in reinforced concrete in the twentieth century captured the imagination of architects and engineers, resulting in some spectacular structures that are now being recognized for their cultural significance. Many modern building materials pose specific conservation challenges and concrete is no exception. There is a burgeoning level of knowledge and experience with the conservation of concrete, but there is still much work to be done to secure better conservation outcomes that are more compatible with accepted practice.
Historic concrete includes reinforced concrete and bulk (non-reinforced) concrete. Reinforced concrete generally suffers from deterioration (mainly carbonation and chloride attack) of the concrete which subsequently allows the steel reinforcements to corrode; this results in cracking and delamination of the concrete ‘cover’. Both types of concrete suffer from weathering by pollutants in combination with rain and mould/algal growth which mar their appearance.
The number of listed iconic concrete buildings and structures of architectural, heritage, or historic importance is increasing rapidly, thanks to the hard work and perseverance of the C20 Society, and as they age the need for conservation, preservation and repairs will continue to grow.
Such buildings typically require sympathetic repairs (in-line with Historic England’s conservation principles and philosophy) to ensure that their original appearance is not compromised. This has sparked some lively debates recently which has led to numerous papers being written on the subject. The need for a structurally sound and long lasting repair must be balanced against the need for the repairs to be on a ‘like for like’ basis which also ensures an ‘invisible mend’.
CRL Restoration are at the forefront of this debate. If you need advice, a survey, or a repair carried out, please give us a call.