NOVEMBER 2010 | VOLUME 13 | NUMBER 1110

RESEARCH NEWS

A new type of concrete for road building

has been developed as an alternative to

asphalt or traditionally made concrete

in pavements. The material is more

energy efficient, means less potholes and

maintenance, is cheaper to make and is

ready for use immediately after it has been

laid, helping to reduce road closure times

and traffic jams. Another key benefit is that,

when it is disused, the material can be taken

away, crushed and recycled for use in a new

pavement.

The new roller-compacted concrete (RCC),

which has been developed by researchers at the

University of Sheffield and EU partners as part of

the EcoLanes project, consists of dry mix concrete

reinforced with recycled steel fibres from waste

tyres, and is 12% cheaper than conventional road

construction. It also reduces construction time by 15%,

bringing a 40% reduction in energy consumption over

its lifetime.

The new concrete material uses a very different

consolidation method, roller compaction, which

means that the dry mix requires less cement than

conventional concrete and is stable enough for light

traffic straight after being laid. Finding a suitable

reinforcement material that is also compatible

with roller compaction technology, such as fibre

reinforcement, was the initial challenge that led to the

Ecolanes project.

The researchers undertook a number of successful

demonstrations in different countries to ensure the

technology could operate under a range of climatic

conditions. Concrete laid with roller compaction

technology utilises a similar technology as

that of asphalt construction, making it ideal

for future construction projects.

The success of the Ecolanes project,

which started in 2006, has meant the

team are developing new guidelines that

assume the benefits of fibre reinforcement

and allow for the design of thinner

pavements. It could also lead to tyre

recycling plants that produce tyre wire

for these new concrete applications,

which would have the advantage of

increasing the profitability of tyre recycling

and helping the industry comply with EU landfill

directives.

However, work still needs to be done to convince

the construction industry to introduce new codes

of practice that accept fibre-reinforced RCC. The

researchers are aware that they need to develop

their guidelines so that they can be used in codes.

The next focus for their research will now move to

recycled aggregates, as they are suitable for fibre

reinforcement and would help reduce costs further.

Laruie Donaldson

Concrete revolutionises road constructionCOMPOSITES

Load testing.

Researchers have developed a method that uses

aluminum and a liquid alloy to extract hydrogen

from seawater to run engines in boats and ships,

representing a potential replacement for gasoline

and diesel fuel in marine applications.

The technique had previously worked only for

freshwater, but a new formulation also enables

the method to generate hydrogen from seawater,

said Jerry Woodall a Purdue Professor of electrical

and computer engineering.

The method makes it unnecessary to store or

transport hydrogen – two major challenges in using

hydrogen for ships and vehicles, Woodall said.

Because waste produced in the process could be

recycled using wind turbines and solar cells, the

technology also represents a new way of storing

energy from solar and wind power, he said.

The researchers led by Woodall have been developing

aluminum-based alloys that generate hydrogen

from water, first reporting on the approach in

2007 [Woodall et al., Nanotechnology International

Conference, ENIC2007]. The Purdue Research

Foundation has filed a separate provisional patent

application on the new process for seawater and also

holds title to the original patent application filed in

2007 for the freshwater process. The researchers also

have presented peer-reviewed papers on the overall

technology.

The aluminum splits water by reacting with the

oxygen atoms in water molecules, liberating

hydrogen in the process. The waste product,

aluminum hydroxide, can be recycled back to

aluminum using existing commercial processes.

The material is made of tiny grains of aluminum

surrounded by an alloy containing gallium, indium

and tin, which is liquid at room temperature. The

liquid alloy dissolves the aluminum, causing it to react

with seawater and release hydrogen, Woodall said.

A key to developing the technology is controlling

the microscopic structure of the solid aluminum

and the gallium-indium-tin alloy mixture.

“This only works because there is liquid gallium

between the grains of aluminum, which dissolves the

aluminum bit by bit,” he said. “The dissolved aluminum

then reacts with water to release hydrogen.”

The formulation contains 90% aluminum and 10% of

the liquid alloy. The reaction also produces heat, which

could be harnessed to generate electricity.

Jonathan Agbenyega

Hydrogen generationENERGY

Hydrogen generation.

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