Precast concrete and masonry - 40 years on

British Precast annual review 2046-executive summary

Developments in materials

Climate change and sustainable living continue to dictate our construction markets. The UK cement industry is now recovering and storing all its process and energy carbon dioxide (CO2) in empty underground gas

and oil fields. The use of biomass and other waste fuels is now predominant in helping concrete to be seen as the most environmentally friendly construction material. With corrosion problems solved, carbonation is now recognised as a major sustainability benefit, making concrete the only available carbon-positive building product.

New reinforcement materials guarantee no deterioration, even in the most aggressive conditions. Textile reinforcement is commonplace, as is the use of ultra-high-performance concrete - both allowing lightweight, elegant and very slender precast sections. Precast concrete has long since been a totally predictable and reliable material, possessing dial-up qualities such as strength and durability - cement content is now optimised every time with 100% hydration, thanks to the universal use of modern admixtures. Most demolition arisings are used as a concrete aggregate - with pulverised concrete rubble used as a partial feedstock for new cement. Virgin aggregates are increasingly sourced from automated underground mines. There is a total emphasis on local materials - hauling heavy materials like lumber, steel and concrete around the world has been outlawed by the GATT Environmental Pact. The role of trees as carbon sinks makes them too precious to use as a temporary building material.

With constructional steel priced out of the market, precast concrete is now the construction material of choice, minimising waste and optimising sustainability - our markel share is more than double what it was in 2006.

Housing

Zero energy, zero carbon precast and masonry houses are now the norm with no mode of structural deterioration -200-year life structures are the standard legal European requirement for all new houses and buildings. Flexible interiors are possible with concrete, featuring movable masonry and precast panel partitions on tracked systems. The thermal mass benefits of concrete and new ventilation techniques allow houses to be habitable in these much hotter summers without air-conditioning. Lightweight housing continues to be outlawed to conserve energy and reduce emissions and lire risk. Houses and hot water are heated both by geothennal exchange systems and via photovoltaics built into masonry and external panels and fibre-cement weatherboards. Paved surfaces and precast underground water storage are designed in an integrated way to conserve precious water and mitigate against the continuing ferocity of rainstorms and resultant flooding.

Since the ban on the use of timber, all new houses have had precast floors, most now titled with service ducts. Basements and living roof spaces are compulsory as a planning condition. Balconies, usually planted for shade and carbon and fume absorption, are now universally designed into ull homes, offices and apartments. New house roofs feature hinged precast slabs to conserve energy, with concrete tiles fitted featuring 'new generation' affordable photovoltaics. Concrete homes, capable of floating, but anchored, are mandated by law for large swathes of Britain, especially along south-eastern coasts. At the turn of the century, ?60,000 Prescottian housing estates continue to lie empty because, by law, they cannot be recycled or landfilled. With termites endemic for many years, the routine retrofitting of precast floors into masonry houses to replace wooden floors continues.

Commercial and industrial buildings

All precast concrete structures are now capable of being disassembled and reused - and leasing is a common method of procurement. Insurers have long since favoured precast structures to minimise risk. The airtight nature of precast buildings enables minimal outlay on heating and cooling energy. Underground construction has come to the fore in the last 20 years to maximise land use and optimise energy-use. All urban areas are featuring 'sky cities' in the form of precast framed buildings up to 60 storeys high. Exposed precast surfaces are all self-cleaning. White, Mediterranean-style concrete architecture is favoured, as are photo-engraved personalised fa?ades.

Buildings' external finishes now feature less glazing and more solid wall area to restrict solar gain. Intelligent precast has been the structural material of choice for many years, with built-in chips and radio devices functioning as information stores, distress alarms and security devices.

Civil engineering

The exploitation of underground space is now accelerating following successful trials at getting sunlight down to 60 storeys. Concrete pipe systems are now dualled between foul sewage and harvested stormwater systems. The generation of concrete pressure pipes installed over 20 years ago to transport water from the north to the south and east of the country continues to give good service. All estate roads, city streets and many minor roads are permeable and block-paved to match the new generation of electric trams and cars running on precast tracks. The use of lighter-coloured concrete paving and nxriing materials is now mandatory to reduce urban heat island effects in all British towns and cities. All motorways feature parallel and raised road-train systems running on precast viaducts, with elegant slender precast bridges now commonplace. Offshore floating islands constructed from linked sections of aircrete are commonly found at strategic coastal and estuary locations - the first floating aircrete runway and air terminal will open shortly, opening the way to fully sustainable waterworlds.

Factories

Concrete product plants are now all fully automated with laser- and robot-controlled 24-hour operations. Underground and earth-sheltered factories are common. No wastage is allowed to leave the site by law. All operatives are trained right through their careers at the long-established University of Concrete and its local campuses. The use of quiet self-compacting concrete, often provided by specialist on-site, ready-mixed concrete companies, is the norm. Loading and unloading onto 60-tonne road-trains is automatic. Mobile satellite precast factories are operated by several national manufacturers for the largest contracts. For many years precast products have all been made with microdot implants that contain full information on mix contents and details of origin. Structural components now feature intelligent tags with 3D details to facilitate deconstruction and re-erection - these are mandatory to minimise new clement production. These tags can also relay distress to the facilities manager in the event of overloading or damage.

Construction sites

All construction projects are awarded on a whole-life costed basis to the benefit of precast concrete. Smaller, modular products, such as root tiles, masonry and paving, are routinely laid robotically. Extendable booms work with universally used small tower cranes to place precast right next to the point of construction. Communication between architect, engineer, client and supplier is seamless and paperless. All building and engineering projects are designed, procured and managed using 4D systems. No wastage is allowed on site without large fines being incurred - any precast waste is automatically routed back at the contractor's cost to the plant of origin.

Concluding remarks

Some might say that thinking 40 years ahead is an unnecessary diversion. My response is that it has never been so important. Everything that we now build from precast concrete and masonry is likely to have a potential life well in excess of 40 years; in fact, well in excess of 100 years. These homes, buildings and structures will he occupied and giving service in a world that inevitably will be very different from today. By future-proofing what we offer in 2006 -and that means serious thinking and planning - we will significantly improve our competitive edge against other construction materials.

* Authors note:

If any readers agree or disagree with this view of the future, or wish to present an alternative vision, please let me know at martin.clarke@ britishprecast.org - we will publish any interesting views or articles on www.britishprecast.org. If you want to discover what other construction people think might happen by 2030 (not 2046), visit the European Construction Platform at www.ectp.org/documentation. asp For details of the UK National Platform for the Built Environment contact: dhynes@ constructingexcellence.org.uk