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 towards 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 some £200,000pa on
heating costs alone. Additional benefits would include a safer working
environment and improved quality through a more controllable and uniform heating
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 almost every conceivable 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
This article was written by Dave Parker of The New
Civil Engineer, and appeared in the feature New Concrete Engineering, September