Energy efficient curing for concrete masonry and clay aggregates blocks
Lignacite Ltd, a manufacturer of concrete masonry and clay lightweight aggregate blocks based in Brandon, UK, has achieved a 44.5% reduction in its carbon dioxide emissions using more efficient curing equipment and alternative aggregates at its Brandon factory, which opened in 2006.
The curing chambers, developed in conjunction with concrete curing systems experts CDS Ltd, based in Stoke on Trent, UK, make full use of the exothermic reaction given off by cement as it dries. Fans are situated throughout the chamber to distribute the heated air at a rate of 1.5-3m/s, providing a more even cure. Composite panels that are 10cm thick improve insulation to help retain heat. These adjustments have helped reduce overall energy usage.
Stephen Hall, Operations Director at Lignacite, adds, ‘The new chambers can cure blocks in 10-12 hours, but because it is an open-loop system with 100% more capacity, we can reduce the heat and leave the blocks in the chamber for a week, rather than remove them after 24 hours. So it gives us the choice of using less time to cure [than previous methods] or of stretching [the process] out to get a more even cure'.
The company has also experimented with a variety of alternative aggregates to stone or sand, such as wood, glass, concrete or brick rubble, and even waste materials like plastic and paper. Its Lignacrete dense blocks, used in some of the residence halls of the University of East London, UK, use crushed glass instead of gravel. Its medium density blocks use a high proportion of recycled wood particles that would otherwise have gone to landfill.
Lignacite has also received a grant from the Home Grown Cereals Association to research the use of straw in concrete.
Lignacite's blocks typically consist of 15-25% alternative aggregate. ‘The benefit over stone and sand is it uses less virgin aggregate, and can usually be sourced locally,' says Hall.
The Brandon factory also operates on water drawn from a borehole on site, rather than from the town's main supply.
In related news, the Carbon Trust has commended Hanson Building Products, based in Somercotes, UK, for its energy management programme. The company is the first heavy building products manufacturer to be awarded Energy Efficiency Accreditation from the national environmental group. All of Hanson's sites across the UK have achieved the Trust's required energy standards.