Promising manufacturers of building products and components faster turnaround times, combined with the possibility of flexible on or offsite manufacturing, while reducing the overall cost of energy consumption and waste, might seem a tall order for some, but not for scientists at Australia's CSIRO, who have developed an innovative clean technology for curing concrete products that is now ready for commercial development.
Developed by a multidisciplinary team led by Dr Swee Liang Mak of CSIRO Sustainable Materials Engineering, the low energy accelerated processing (LEAP) technology uses controllable microwave energy to rapidly set and harden concrete.
'Microwaves have the potential to deeply penetrate a material, which enables heating from within the material; says Dr Mak. 'The current technology is suitable for heating medium-thick products.
CSIRO testing has shown that pre-cast concrete can be cured using LEAP in less than six hours without the use of chemical accelerants. This is almost three times faster than conventional steam and other heating methods, which can take between 12-24 hours.
The technology has already undergone intensive laboratory and pilot scale R&D programmes, including trials on hollow-core products, (see above). In this example, the hollow-core slab was cured with microwaves and stripped of formwork after a processing time of four and half hours. The active microwave heating of the product lasted for only around 10% of the total processing time, using a total energy of 40 MJ per tonne. As well as significantly decreasing curing times, concrete treated with the technology also shows a rapid boost in strength, which continues to develop as the concrete ages.
Initially developed for the rapid curing of long-bed pre-cast concrete such as railway sleepers, hollow-core slabs and wall panels, the technology can be effectively used on a broad range of products, including bricks, paving, blocks, roof tiles, and concrete pipes and poles. Even concrete roads may potentially be a market for this exciting fast curing technology. The flexibility of the technology means it can be used to either complement or effectively replace the use of conventional steam chambers, casting beds heated with water or steam and autoclaves currently used in the pre-cast concrete industry. The use of microwave heating also means heating can take place from a cold start, making pre-heating of casting beds no longer necessary and as such reducing energy consumption.
'We have had interest locally, and from Germany, Singapore and Malaysia; says Dr Mak. 'There is a broad range of potential markets ranging from low-cost housing to high-end, high-performance products. There are a number of countries in Asia and South America that are potentially attractive markets since they have a history of kick-starting their economies after recession by building large numbers of low and medium-cost housing developments, which require huge volumes of precise concrete