Innovative materials developed for construction industry

Concrete printing sounds like something from the realms of science fiction, but it’s very much today’s innovation rather than tomorrow’s world.

A research group at Loughborough University, led by Dr Sungwoo Lim, has developed a 3-D printer that is able to build physical objects directly from computer-generated instructions.

Known as additive manufacturing, concrete printing is one such example whereby a specific type of concrete, which has been developed for the process, is deposited in layers very precisely under computer control.

To date, a one-tonne reinforced concrete bench and a two-metre square ‘curvy’ panel have been printed.

Richard Buswell, senior lecturer at Loughborough University, and a principal investigator on the project, called Freeform, said, “Anything is possible. We are working with a prototype, but within five years – with money and desire – there’s no limit to what could be printed.”

In theory, a skyscraper could be printed, however Buswell believes it’s more likely that the machine will be used to build components rather than a whole structure. “I expect it will be used in high end construction, special buildings or parts of them,” he said.

The benefit to industry is greater precision and therefore reduced waste, and less gross CO2 emissions compared to a conventional concrete form building. Embodied energy, via transportation miles, would be lessened as printing could be undertaken in an onsite factory.

The commercial viability of the concrete printing process will be evaluated with three industrial partners: Hyundai Engineering and Construction, Foster and Partners and Buro Happold.

If printed concrete strikes you as futuristic building material and process, rammed earth as a construction matter sounds positively pre-historic – but utilising 21st century engineering know-how it’s very much a material of our time.

Natasha Watson, a research engineer at Buro Happold, said, “The material’s qualities for use in living spaces include heat and moisture regulation, and it’s breathable which provides better indoor air quality. It’s a natural material that can be made weather-resistant using lime render.”

Compressed in layers and allowed to air dry, rammed earth is a low impact material. Onsite construction reduces the embodied energy impacts. Barriers to more wide-scale adoption include warranty and insurance issues.

Rammed earth has the capacity to be load bearing. A 7.2metre high, circular rammed earth construction, the WISE building, has been constructed at the Centre for Alternative Technology in Wales.

Rammed earth techniques have been a mainstay of construction in Africa for millennia. In high impact areas – such as roads that are not laid using tarmac, and therefore prone to constant deterioration – strengthening materials are necessary and vital to keep communication routes open.

AggreBind is a new to market, water-based, cross-linking styrene acrylic polymer that increases the strength of a wide range of soils. Non-toxic – treated soils have been tested and later flora grown in it – the polymer is effective with cohesive and non-cohesive materials and can be applied to strengthen adobe buildings.

Materials that mimic nature, known as biomimics, are a keen area of research development. VELCRO, a fabric hook-and-loop fastener, is one of the best-known biomimics. In 1948, Swiss engineer Georges de Mestral created a prototype, inspired by the burrs of the burdock plan that attached themselves to his clothes and his dog’s fur while out walking in woods.

Andrew Mellor, partner at PRP Architects, said, “Advances in biotechnology and materials science have opened up a range of materials that are not only biomimics but are biological by their very nature – self-healing bio-concrete that grows back over its cracks using encapsulated bacteria, or mortarless self-fusing ‘bio-manufactured’ bricks made out of bacteria, sand, calcium chloride, and urea.”

Last week, at Insite11 at the BRE’s Garston headquarters, contractor Willmott Dixonunveiled transparent photovoltaic architectural roof glazing at its Community Healthcare Campus at the BRE Innovation Park.

The new generation photovoltaic roof glazing, developed by Polysolar, delivers shading, aesthetic appeal as well as generating 3,000kWh of free electricity each year (enough to power a domestic house).

Polysolar is also developing transparent photovoltaic window glazing. Based on innovative organic polymers, the material and technology aims to provide a low cost replacement for standard window glass that will generate electricity and offer solar control.

Willmott Dixon is also constructing the new £6.2 million St Agnes primary school in Longsight, Manchester, with a state-of-the-art, prefabricated timber system using off-cuts from the sawmilling industry.

In a departure from traditional steel or concrete frame systems, the off-cuts are specially fabricated into load-bearing timber components. They will arrive at Longsight in large sections and be assembled to create the school’s structure.

The system, manufactured by Eurban, has key environmental benefits. The manufacture of timber building systems creates no waste in the factory, and has less embodied energy impact. The solution is more economical than steel frame and block.

George Martin, Head of Sustainable Development at Willmott Dixon Re-Thinking, said: “We set up the Re-Thinking division, in 2006, solely as an internal consultancy to push our boundaries. Innovation in materials, technologies and practices is core to our business strategy at board level.”

Gordon Miller is the co-founder and sustainability & communications director of membership organisation Sustain Worldwide. He is a licensed BREEAM International Assessor and consults to housebuilders and developers on sustainability.