Concrete is the most commonly used man-made substance on the planet, second only to water as the most utilised resource.
Cement, a key constituent of concrete and its historic forebear, has been used for thousands of years in various forms, including in Ancient Egypt and Greece.
Almost 2,500 years ago, merchant tribes in the deserts of Arabia were using deposits of silica mixed with lime to create cement to build water channels and cisterns for collecting scarce rainfall.
Over 1,900 years ago, the Romans also employed a type of cement, which included using volcanic ash. They built the colossal 43 metre diameter dome of the Pantheon in Rome, still standing today.
In the modern world, concrete (basically cement and water mixed with aggregates such as gravel and sand) defines much of our landscape: bridges, motorways, tunnels, power stations, office and apartment blocks, airports, underground stations, industrial sites, shopping, leisure and exhibition centres, civic buildings, car parks, hospitals.
But it was the idea of reinforcing concrete, giving it enormous strength and versatility in form, that made such highly complex large-scale structures possible.
In 1892, a French engineer, François Hennebique, patented a pioneering reinforced concrete system: the first to be commercially successful and widely used. He became a key figure in helping revolutionise the entire world-wide construction industry.
The beginnings: Experimenting with cement
There was a long gap between the fall of the Roman Empire in the 5th century and the 18th century before there was a revival of interest in cement. Engineers began experimenting with new compounds.
This resurgence may have been due in part to the 18th century interest in Classical civilisation. Knowledge was bought back from the Grand Tour when aristocratic young men travelled Europe with a tutor, particularly to Italy, to gain an education in Classical culture and architecture.
It has been suggested too that the cost of building in stone was a factor, as was the Industrial Revolution (mid-18th to mid-19th century), when factories, mills and warehouses were often destroyed in fires and there was a demand for economic fire-resistant buildings.
Concrete was one answer, but the first challenge was to make reliable cement, the essential bonding agent for the aggregates. When cement and water are mixed, it triggers a reaction known as hydration, causing the concrete to harden.
Experiments culminated in Portland cement, a generic term for a mix of materials such as limestone, shale or clay, heated to extremely high temperatures and finely ground. The name was derived from its resemblance to Portland stone.
Portland cement was patented by bricklayer Joseph Aspdin in Leeds in 1824. However, the first true commercial Portland cement was manufactured twenty-one years later by rival inventor, Isaac Charles Johnson (1811 to 1911), at his cement plant in Swanscombe, Kent.
Reliable cement meant that the potential of concrete could be realised. But another major challenge remained – its strength. Concrete is hugely strong under compression – good at load bearing like stone, but weak at withstanding stresses – bending and twisting causes it to fail.
Engineers spent the next decades developing how concrete could be reinforced. Key among them was the Frenchman, François Hennebique, whose system was the first to be widely used in Britain.
François Hennebique: Pioneer of reinforced concrete
The success of Hennebique’s system was the use of inexpensive steel rods as reinforcement (rebar) within the concrete, giving it high tensile strength (the maximum stress that a material can withstand before breaking).
But it was also Hennebique’s astute business model that ensured his then dominance.
Hennebique worked only with existing leading contractors, licensing their use of his system providing they followed his strict specifications. This included putting workers he himself had trained technically into the businesses and ensuring stringent supervision of quality.
By the beginning of the 20th century, Hennebique had licensed contractors across Europe. By the end of the first decade, his reinforced concrete system had been used in almost 20,000 structures and his company had more than 60 offices across four continents.
Hennebique buildings in Britain
Weaver’s Mill, Swansea
The first building in Britain to use the Hennebique system was Weaver’s Mill, completed in 1898. The cement, aggregates and steel were all imported from France.
Weavers Mill survived the Luftwaffe bombing of Swansea, February 1941 during the Second World War, only for developers to succeed where the German air force had failed – it was demolished in 1984 to make way for a supermarket.
Jetties, Haslar, Gosport
In the early 20th century, Gosport was chosen as the Royal Navy’s principal submarine depot. On the outbreak of the First World War (1914-1918), the Navy had 80 submarines – the vessels then were cutting edge naval technology.
The pioneering Hennebique system jetties were used as mooring for submarines during the war, and remained in use until 1993 when the last vessels departed. The horizontal and diagonal design of the concrete beams are reminiscent of the traditional timber construction of piers.
In the Second World War, reinforced concrete was widely used to build defensive structures across the country, including anti-aircraft and anti-tank defences, and thousands of pill boxes, as well as airfield runways and hangars and vast pre-fabricated mobile ‘Mulberry Harbours’, towed to France for rapidly offloading supplies onto beaches during the Allied D-Day landings (6 June 1944).
Royal Liver Building, Liverpool
Although the Royal Liver Building has a granite facade, it is a rare early 20th century survivor that used the Hennebique reinforced concrete system for its structural frame.
At the beginning of the century, there were no regulations covering the use of reinforced concrete, with technical specifications only known to a few. However, with the passing of legislation in 1915, technical information became widely available.
Spanish city, Whitley Bay, Tyne & Wear
Pictured is another surviving building constructed using the reinforced concrete Hennebique system. After falling into disrepair, a major regeneration project saw the Spanish City re-open in 2018 as a leisure and event venue.
Reinforced concrete after the First World War
In the early years of the 20th century, reinforced concrete was mostly used for utilitarian buildings and structures, such as warehouses and factories, bridges and roads.
The period between the First World War (1914 to 1918) and the Second World War (1939 to 1945) saw architects embracing the exciting freedoms and design possibilities of the new material, including arches, spiral shapes and curved forms.
Mendelsohn was one of several refugee architects who fled Nazi Germany for Britain in the 1930s bringing new technical knowledge and Modernist ideas with them.
The role of concrete after the Second World War
In Britain during the Second World War, an estimated two million homes – as well as schools, hospitals, infrastructure, transport systems, civic, cultural, commercial and industrial buildings – were severely damaged or destroyed by bombing.
The country had to be rebuilt fast. But there was a shortage of traditional materials, including bricks and wood, as well as skilled labour. Low cost, relatively quick to construct, reinforced concrete was the answer, especially in urban areas.
In Britain, the vast reconstruction programme (which included the razing of slums, the building of public housing and pre-fabs, and the establishment of new towns) was state-controlled, led by national and local government. Building styles were generally plain and functional. Policies were in the context of the welfare state which had come into being post-war, based on the principles of equal opportunity for all.
Brutalist Britain: Concrete in the 1960s and 1970s
The 1960s was a socially progressive decade of rapid change; a time of strong economic growth after the austerity of the 1950s; of idealism; of optimism that a better future lay ahead.
A distinctive type of architecture emerged in the 1960s and 1970s; the clearest visual manifestation of the design possibilities of concrete.
Monumental buildings (high rise flats, multi-storey car parks, universities, schools, leisure and shopping complexes, often with extensive road schemes) were constructed. This uncompromising dramatic style was versatile and cheap, changing the face of urban Britain.
Brutalism, as certain types of this new radical architecture came to be known, was first associated with internationally-acclaimed architect, Le Corbusier (1887 to 1965), a Swiss-French Modernist pioneer who, in 1952, celebrated the unfinished surfaces and the texture of raw concrete (Béton Brut).
His ideas on urban planning and the aesthetics of concrete inspired a new generation of architects and planners who embraced them as an exciting social and visual break from the past.
Brutalism eventually fell out of favour after it became associated with urban decay and social problems. It had generally been reviled by the public.
Many important concrete Brutalist buildings were demolished (see ‘Those We Have Lost’ later). In recent years, however, there has been a critical reappraisal and a growing appreciation of the style, with some buildings now listed.
Parkhill is a survivor. The estate was saved and refurbished by developers Urban Splash, beginning in 2004.
Many high rise buildings at the time were system-built – constructed using standardised factory-made pre-cast concrete panels, assembled on site. Public confidence in these estates – already at a low – was seriously undermined by the Ronan Point disaster of 1968, where the entire corner of a 22-storey block of flats progressively collapsed downwards after a gas explosion, killing four residents and injuring 17.
The disaster was a shock to the construction industry and led to major changes in building regulations. Within 20 years, many local council tower blocks were demolished across the country, including those where it was found that metal reinforcement within the concrete had corroded, compromising structural integrity.
Concrete in the modern world
Reinforced concrete can be designed to create extraordinary forms, as well as taking on different textures and colours.
The pictured interior shows the Marshall Building’s extensive exposed concrete, and tree-like structure of vaulting.
Mass-produced reinforced concrete in many different guises is a crucial material used in virtually all construction projects across the globe today, from modest houses to the tallest towers.
In Britain, concrete is being used for the immense tunnels of London’s new sewerage system, still under construction: Thames Tideway. Likewise, the 118 kilometre mainly underground Elizabeth Line (Crossrail) from Reading, Berkshire to Abbey Wood on the far south-east reaches of Greater London. HS2 (the high speed rail link being built between London and the major cities of the Midlands and the North of England) is pioneering the use of low carbon concrete for its more than 500 bridges and tunnels.
This extraordinary material has produced some of the world’s greatest architecture, including the Sydney Opera House (Jørn Utzon with Ove Arup, 1973) and the Fallingwater house, Pennsylvania, USA (Frank Lloyd Wright, 1935), along with spectacular structures such as the Panama Canal (1914), the colossal Christ the Redeemer statue, Rio de Janeiro (1931), and the controversial Three Gorges Dam, China (completed 2012).
The downside is that the manufacture of concrete’s key ingredient, cement, creates a massive carbon footprint, the source of around eight per cent of the world’s carbon dioxide (CO2) emissions.
With well over 20 billion tons of concrete poured annually and, taking into account the CO2, the miles covered to transport the raw materials and the fact that it uses around 10% of the world’s industrial water supplies, concrete’s environmental impact today is huge.
Architects, designers and researchers worldwide are working on alternatives to cement, and on eliminating its CO2 emissions. Zaha Hadid’s glass-fibre cement Heydar Aliyev Centre (pictured above) is one example.
Areas of research have included making low carbon concrete mixes that use waste materials, such as recycled plastic, ash from coal-fired power stations or blast furnace slag; bio-concrete using CO2-absorbing moss and lichen; capturing CO2 and injecting it into concrete mixes, permanently locking it in.
Progress is being made, including the concrete industry burning waste materials rather than fossil fuels and improving the energy-efficiency of its plants.
As the search goes on for more sustainable concrete, the world’s most vital building material continues to be used in vast quantities and for the foreseeable future.
Lost buildings: Demolished concrete landmarks
Old Wembley Stadium, London. Demolished in 2003.
Tricorn Centre, Portsmouth, Hampshire. Demolished in 2004.
Pimlico Comprehensive School, London. Demolished in 2008.
Birmingham Central Library, West Midlands. Demolished in 2016.
Welbeck Street Car Park, London, demolished 2019.
Written by Nicky Hughes.
Reusing our buildings is one of the most effective ways to reduce carbon emissions and eliminate unnecessary waste. By adapting our historic buildings appropriately, we can reduce carbon emissions, improve quality of life and nurture the skills needed for a green economy. Read our Climate Change Strategy.
- ‘Concrete Architecture’, Catherine Croft. Published by Laurence King Publishing.
- ‘Space, Hope and Brutalism’, Elain Harwood. Published by Yale University Press.