Visual concrete: aesthetics and good practice

‘It looks good and it does good’ is a simple explanation for why both designers and clients are increasingly turning to exposed concrete for its visual aesthetic and performance benefits reports Elaine Toogood, architect at The Concrete Centre

Once they remained hidden, but concrete walls, ceilings and columns are now being left exposed as designers rediscover the visual impact of concrete, and clients appreciate the unrivalled energy-saving potential of its thermal mass. For designers the excitement is in turning a building’s structural elements into an artistic statement that, in addition to being a visual backdrop, plays a central role in a building’s performance. For clients, the appeal is not only exciting architecture but also cost and carbon savings.

Exposed visual concrete comes in many guises. It takes the shape and relief of whatever surface it is cast against, offering the potential to create elegant straight lines or complex geometries, while the addition of different coloured pigments or aggregates can add a whole new aesthetic dimension. In conjunction with profiled form-liners or surface finishing techniques, patterns, texture and even photographic images are possible, creating interesting and durable surfaces that can last the lifetime of a building with little need of maintenance.

However, to be successful the specification of visual concrete, and ultimately its construction, requires detailed consideration. The desired finish will be a significant factor in determining the type of facing formwork required, but also potentially whether the concrete is best cast in situ or off-site.

The mix for cast in situ concrete has usually been specified by the structural engineer based on strength and durability requirements, and increasingly sustainability considerations. For visual concrete the mix should also be designed to aid placing and compaction, with sufficient cement content to achieve a quality surface finish. To establish the desired results when designing exposed precast panels, close collaboration with manufacturer and design team is essential. The location of the project can influence visual appearance as the constituents of concrete are locally sourced and vary depending on the local geology.

To aid designers in achieving visual concrete, The Concrete Centre in partnership with The Building Centre, is providing a free inspirational seminar on self-build architecture. The event is free to attend, but registration prior to the event is required at The latest edition of Concrete Quarterly will be available for all attendees, which features the beauty and versatility of concrete in the Glasgow School of Art, East Ham Civic Centre and Stirling Prize 2014 nominee the Everyman Theatre, Liverpool.

Exposed visual concrete provides a robust, low maintenance finish and thermal mass; achieving savings in capital spending in construction and maintenance for clients and reduced operation costs for tenants. Exposed concrete also reduces the building’s lifetime CO2 impact and provides a safe, healthy and inorganic internal and external finish. As the operational CO2 during a building’s life can be far higher than that used for its material production and construction, the use of exposed visual concrete can dramatically reduce a building’s environmental footprint.

Visual concrete provides a winning combination; it marries aesthetic aspiration with prosaic practicality. Designers are offered the opportunity to make an exciting visual statement that earns its keep with a wide range of performance benefits.

Relevant information: