Crafting Concrete: Exploring the Aesthetics

1 May 2019

Published in: Concrete magazine, May 2019

Exposed concrete is often regarded as having an industrial aesthetic: grey, often smooth surfaces that are tough enough for the harshest industrial environments, and commonly associated with the mechanisation of the 20th century. 

But this is only one of concretes guises.  In recent years the trend is towards the expression of what might be called ‘natural concrete’, or concrete that appears hand crafted and ‘of the earth’. This includes concrete that is pigmented to have an earthy tone or with surface texture and colour created by exposing natural fine and coarse aggregate.

The Bruder Klaus Field Chapel in Mechernich, Germany, designed by Swiss architect Peter Zumthor is a widely published example. Completed in 2007 the raw materials for its concrete walls were reportedly sourced from surrounding fields, the concrete rammed into place to create distinct, sand coloured layers with a crumbly texture reminiscent of geological strata.  Zumthor used a similar technique for the construction of Secular Retreat, Devon, the most recent project of the holiday property company Living Architecture, set up by writer and philosopher Alain de Botton. This house displays handcrafted, rammed concrete walls both inside and out and was completed in 2018.  The process of creating rammed concrete is laborious and this, combined with challenges of providing reinforcement potentially limits its wider application. Never the less, it has a has a strong aesthetic appeal.

Recent projects with a layered and geological aesthetic include the Yorkshire Sculpture Park’s new visitors centre and gallery, designed by Feilden Fowles Architects. Here, rather than ramming the concrete, slender, reinforced walls were constructed using shallow layers of site-batched, fluid concrete with different pigment and aggregate combinations to reflect the natural strata and geology of its surrounding area. The surfaces were then shot-blasted to varying depths to add surface texture and enhance horizontality and a natural appearance.  On a larger scale the Forum :terra nova exhibition venue near Elsdorf, Germany by L├╝derwaldt Architekten used ready-mixed concrete supplied with a variety of different earth coloured pigments to create reinforced structural walls two storeys high in layers of varying depth.

Examples of contemporary architecture using cast in situ concrete in earthy colours are numerous. They include Bernardo Bader’s russet coloured Islamic cemetery in Altach, Austria; the red con-crete ‘pyramids’ of Casa das Historias Paula Rego in Cascais, Portugal and the beautifully simple clay coloured temple near Pune, India designed by locally-based Karan Darda Architects. Other favour-ites include the massive concrete facades of the Barcelona’s Ciudad de la Justica and more recent-ly, also by David Chipperfield Architects, the pinkish hues of Inagawa cemetery, near Osaka, Japan.  Here the effect was enhanced by honing the surfaces to reduce its light reflectance to soften the impact.
Closer to home the Respite Pavilion at the North Ayrshire Community Hospital by Graeme Massie architects is constructed using concrete with a soft, brownish hue textured by horizontal timber formwork. And the sculptural cast in situ concrete facades of 168 Upper Street by Amin Taha Architects are terracotta inside and out.  

The use of natural aggregates and pigments to colour architectural precast concrete is not a recent trend with numerous examples in the UK alone. The ground floor facades of the East Village housing by Patel Taylor Architects, for example, where expression was taken further by using a form liner created with a stone texture set out to include fake mortar joints.  At Silverburn Shopping Centre, by BDP large facetted cladding panels replicate a textured rock face around the perimeter, also using flexible form liners.
The textured internal concrete surfaces of Mole Architects’ Houseboat in Dorset for Roger Zogolovitch took another approach. Here the surfaces of the cast in situ structure were heavily shot-blasted, enhancing the natural variation in the concrete surface and revealing the locally sourced coarse aggregate. The concrete is creamier in colour than grey due also, in part to the presence of GGBS. Another example of texture is at 21 Caroline Place, by Aman Taha Architects. Here the ceiling of the new basement was cast using ready-mixed concrete contained 50% GGBS and specially sourced pale aggregate, the entire surface was then point tooled to create a rough texture.

The reasons for any architectural trend will be complex and multi-faceted and deserves far more consideration and space than is available in this short article. In the UK, the good availability of pigmented ready-mixed concrete and the cost-effectiveness of earth-coloured tones (in comparison with blue and green hues for example) will facilitate their use in a wide range of projects. But it not just economics in play, and it is a broader set of considerations that influence design. This includes the need to manage the impact that the built environment on our sense of wellbeing. Arguably of growing importance based on the increase in uptake of environmental assessment standards as the Well Standard (an assessment tool to measure and acknowledge design to support the health and wellbeing of  building occupants) and the growing interest in biophilic design, recognised as part of such standards.

The publication ‘14 patterns of biophilic design – improving health and wellbeing in the built environment’ written by environmental consultants Terrapin Bright Green, is an interesting publication on the topic and contains numerous examples of the use of concrete.  In lives increasingly influenced by virtual reality, and digital technology it is not difficult to understand the appeal of natural materials, of free-flowing patterns and the connection to nature that they offer. In this regard the aesthetic of exposed concrete has a role to play, and even more so for a concrete that takes its references from the earth and the natural aggregates from which it is made.

Written by - Elaine Toogood, senior architect at The Concrete Centre