Tag Archives: concrete

What can be done about the global sand shortage?

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It may come as a surprise to learn that sand is the most exploited resource after water. Globally, we extract around 50 billion tonnes of sand and gravel every year and the United Nations is calling for increased monitoring of extraction and supply chains. We use sand in a very wide range of products, from toothpaste to paint, cosmetics to ceramics. Even in the glass in the screen you reading this on. In particular, huge quantities of sand are used in the construction industry, most commonly in the production of concrete.

Global sand crisis RISE Design Studio

Powering our infrastructure

Sand extraction is predominantly driven by demand for building and infrastructure projects. The industry generally requires river sand, which retains its sharper edges – beach and desert sand is of no use as it has been worn by the sea or wind, which makes it too smooth to function as an aggregate.

Building a single home can require around 200 tonnes of sand to manufacture the required concrete. With increasing global demand for housing, it is therefore unsurprising that several countries have significantly reduced the available supply of river sand. This has sparked a concerning new geopolitical situation, whereby there is substantial illegal trade of river sand. This is underpinned by dredging or mining for sand from poorer countries and then illegally selling this to countries with a shortage of supply.

What can be done?

A recent United Nations report calls for an international standard on extraction. With the global population predicted to reach nearly 10 billion by 2050, and 70% of people expected to live in urban areas, the demand for sand is not likely to slow down. Countries need to wake up to the negative impacts sand extraction has on biodiversity, which means a fundamental shift in how we think about and value sand.

Making changes will be particularly challenging in the context of construction-led post-Covid recovery, which is a driving rhetoric in many countries. There are calls to implement wide-reaching standards that are enforced by agencies. These will require supply chain monitoring and scrutiny of links between governments, industry and other interests. Countries can also try to avoid surplus construction projects, plan more compact urban growth, employ green infrastructure, and design policy to make it easier for buildings to be retrofitted.

What role do architects have to play?

Making these wide-reaching changes will not be easy but architects have a role to play in helping to raise awareness and shift the mindset. First and foremost, they can demand that building materials can either be replaced or reused. In practice, this might mean greater use of materials such as wood, or exploring options like recycled steel or other elements that make up the circular economy. A focus on retrofitting existing buildings, rather than demolishing and rebuilding, would also have a significant impact on the amount of sand required in the overall material input.

 

Spotlight on Ricardo Bofill as we set up our new studio in Barcelona

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Later this year, we will be opening a RISE Design Studio in Barcelona. We are excited about this, not least because we take a lot of inspiration from Spanish architecture in our work. Last month, we were very sad to hear the news that renowned Catalonian architect, Ricardo Bofill, had passed away at the age of 82. Bofill’s wide range of impressive buildings have influenced our projects and those of many others. He leaves a lasting legacy for us all.

RISE Design Studio Ricardo Bofill

Early influences and approaches

After an education in Spain and Switzerland, Bofill and a group of friends created ‘Ricardo Bofill Taller de Arquitectura’ in 1963 in the centre of Barcelona. From the outset, he worked in a multi-disciplinary environment, collaborating not only with engineers and other architects, but also artists and writers. This approach later developed into the holistic urban planning/design method that we are more familiar with today. His early projects were seen as exemplars of critical regionalism, with several viewed as a political reaction against the Francoist dictatorship in Spain at the time and a ‘shunning’ of architectural modernism.

In the 1970s, Bofill relocated to France, where his work echoed French traditions of classical architecture. His work in France culminated with the design of the new Antigone district in Montpellier, which combined large-scale industrialisation in precast concrete with classical forms. Described by Bofill himself as modern classicism, his projects like this led to his being referred to as one of the most significant postmodern architects in Europe.

Modular geometry

One of the best-known projects delivered by Bofill and his firm is Walden 7, a modular block of 450 apartments built on the outskirts of Barcelona in 1975. Located on the site of a former cement factory, the modules of the 14-storey building are linked by footbridges and arranged around courtyards. The intention of this design was that the building serves the evolving needs of its residents. On the same site, Bofill built his family home and office, within the original cement factory (see the image above). His stylish and innovative renovation of the factory included a large, central meeting room and exhibition space (the Cathedral), with 10-metre high ceilings and features of the original factory intact in the surrounding décor.

A similarly innovative and impressive project is the ‘monumental’ apartment block Les Espaces d’Abraxas in eastern Paris. Featuring prefabricated stone, cement facades and reference to baroque architecture, one building includes a semi-circular structure that encloses an amphitheatre (that was used as a filming location in The Hunger Games).

From concrete to other materials

Bofill increasingly moved from working with concrete to glass and steel, while still featuring classical elements like columns in his projects. Notable projects from the 1980s include the extension of Barcelona airport before the 1992 Olympics and the National Theatre of Catalonia. His designs gradually lost the classical aspects yet retained his love of a highly formal sense of geometry such as in the Mohammed VI Polytechnic University in Morocco.

A lasting legacy

Over his lifetime, Bofill’s portfolio spanned a wide range of settings, from public buildings to transport infrastructure and urban design. Although Bofill has passed away, his firm in Barcelona continues under the co-leadership of his two sons and we will continue to take inspiration from his work while we establish our new studio in the city.

History of a building: foundations

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Constructing foundations is one of the oldest of human activities. Foundations provide support for structures by transferring their load to layers of soil or rock beneath them. Over 12,000 years ago, neolithic inhabitants of Switzerland built houses on long, wooden piles that were driven into the soft beds of shallow lakes, keeping people high up above dangerous animals and hostile neighbours. A few thousand years later, the Babylonians raised their monuments on mats made from reed, and the ancient Egyptians supported the pyramids on stone blocks which rested on the bedrock. It was in ancient Rome that foundation engineering really leapt forwards, with rules created and concrete used. In the first of a series of posts that chart the history of modern building elements in the UK, we look at how foundation engineering has changed over the past century or so.

Foundations building Muhlhofen

Byelaws for healthy buildings

The Public Health Act, introduced in 1875, was the first legislation that required byelaws to be set by the authorities. These byelaws were focussed on the development of new streets, ensuring the structural stability of houses, preventing fires, providing adequate and efficient drainage, and ensuring air space around buildings.

In 1878, the Building Act provided more detail regarding house foundations and wall types. For foundations, the byelaws stated that walls should have stepped footings (twice the width of the wall) and that nine inch (225mm) thick concrete should be placed under the footings unless the building sat on gravel or rock sub-soil (‘solid ground’). At that time, Portland cement was seen as making the best concrete, with hydraulic lime as ‘the next best thing’. Common (hydrated) lime was seen as inferior.

It is not known how many authorities adopted these byelaws outside London – many produced their own, less onerous rules. This meant that the nature and quality of foundations varied somewhat (concrete foundation, brick footings, rubble/flagstone)  with depths varying according to circumstances and, in general, shallower than modern foundations.

Raft vs strip foundations

Raft foundations are created from reinforced concrete slabs of uniform thickness, covering a wide area. They spread the load over the whole area of the foundation, in effect ‘floating’ on the ground. In the 1920s and 1930s, this type of foundation was common, with brick footings also permitted.

In the late 1940s and throughout the 1950s, most new houses were built on strip foundations, although raft foundations remained popular. Strip foundations are particularly suited to light structural loadings, such as those found in many low-to-medium rise domestic buildings, with minimum strip widths applying to different ground types and total load. These regulations were set out in the National Building Regulations in 1965 and applied generally throughout England and Wales, with the exception of London which had its own Building Acts.

Today, raft foundations are quite rare, except in former mining areas. An overview of modern types of foundations can be found here.