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Concrete - Wrap up warm

New Concrete Engineering Inditherm - A thin, tough, flexible 'electric blanket' that provides uniform heat on low voltage power? Is this just what the concrete industry has been waiting for?

Rotherham based Inditherm's flexible carbon based conductive polymer is a solution looking for lots of problems. Sandwiched between a range of protective and insulating materials, the patented polymer is transformed into a heating blanket that can be as little as 6mm thick. Yet it can produce temperatures of up to 120'C on voltages less than 48v and operate on as little as 6v. And because the polymer is present throughout the blanket, the pattern of heat generated is absolutely uniform and free from 'hot spots'.

The Inditherm technology has already been adopted by other industrial sectors for purposes as diverse as keeping football pitches frost free and hospital patients warm. Now, in conjunction with Sheffield Hallam University's Centre for Infrastructure Management, Inditherm is looking to the construction sector for new opportunities.

One obvious niche is precast concrete production, and Inditherm has already carried out trials with at least one producer. In this application a 'unidirectional' sandwich is used, with heavy insulation on the outer face of the blanket to ensure as much of the heat available as possible goes into the concrete rather than the surrounding air.

From these trials Inditherm calculated that switching from steam curing to the polymer blanket would save this particular producer around £200,000pa on heating costs alone. Additional benefits would include a safer working environment and improved quality through a more controllable and uniform heating cycle.

Lateral thinking came up with another precast concept.

Inditherm proposes that the unidirectional polymer sandwiches are actually cast into precast wall panels intended for use in prisons and other similar high security buildings. These panels in effect become structural storage radiators, eliminating the need for hot water radiators and pipework that are prone to vandalisation and conversion into improvised weapons and missiles.

Further down the line is the possibility of using such heating panels in modular construction systems to minimise time on site and the need for specialised trades following on behind erection of the building envelope.

Low temperature concreting on site is another obvious possible application. Low voltage operation and the material's high inherent flexibility make it adaptable to most application on site - and it works in ambient temperatures as low as -40'C.

Less obvious but possibly more important, Inditherm believes, is the use of the polymer sheets as integral heating in concrete bridge decks. This would eliminate the need to use de-icing salts on the structure, reducing the risk of reinforcement attack by chloride ions. Integral Inditherm panels could also keep disabled access ramps clear of ice and, with recent legislation likely to catalyse a major spurt in access ramp construction, this could be a very attractive option for building owners.

Some day we might all be wearing winter clothing with Inditherm heating built in, powered by a miniature fuel cell in a back pocket.

Long before then many in the construction industry will have taken advantage of the Inditherm concept to solve some niggling problems. In the concrete sector alone the possibilities are almost endless.

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