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 | | CONCRETE BLOCKS – THE TRUE MEASURE OF SUSTAINABILITY | | | Lignacite Ltd | | 11/06/2008 | | | Putting the words ‘concrete’ and ‘design’ in the same sentence might once have seemed something only the most ardent, some might say blinkered, PR company would have suggested. When blocks were predominantly commodity products, it would have been considered inconceivable to think that awareness of the diversity of concrete block design would have failed to keep pace with manufacturing developments or the degree to which sustainability might affect it. An array of colours, textures, shapes and finishes now provides the architect with undeniable scope to produce the look and feel of traditional natural materials at far lower cost. Less evident are the changes in raw material usage, manufacturing methods and environmental factors which provide tangible evidence of how products of greater sustainability are being developed.
Companies such as Lignacite understandably use modern manufacturing methods, but how does this translate into meaningful evidence of block sustainability for the specifier? Eradication of wastage by recycling damaged blocks rather than send them to landfill is the first stage of the process, but the less obvious areas of recycling efficiency make more interesting reading. The unique, medium density 'Lignacite' block, for example, uses graded wood particles, a selected waste product from the timber industry, as an aggregate. The Ashlite lightweight block now contains more than 50% of waste fly ash from power stations and is compliant with the BREEAM standard. Recycled glass which has no other immediate recycling purpose is also used as a substitute for stone in Lignacrete blocks. Even facing masonry product manufacture helps reduce waste and pressure on natural resources by using sand which is a bi-product of the china clay industry. These blocks, designed for internal or external use, combine an inherently smooth, close textured, decorative finish with strength and durability. Available in an extensive range of thicknesses and strengths and in solid, hollow and cellular forms there is now a choice of seven subtle shades. In all instances, there is no compromise in appearance or durability.
From an energy saving perspective, manufacturing efficiency may be taken for granted, but curing chambers now conserve energy by using the natural heat given off by the exothermic reaction between cement and water. Fuel emissions are pumped into the kilns where the carbon dioxide is absorbed by the blocks. This not only reduces the amount of carbon released into the atmosphere but improves block quality by sealing in the lime to eliminate damage by weathering. Water too, is recycled throughout the manufacturing process in addition to being taken from a borehole on site, rather than from the local mains system. Sand and aggregate being quarried adjacent to Lignacite’s plant will save an estimated equivalent of 30,000 lorries delivering to the plant over the period of agreed extraction, after which the area will be returned to wildlife conservation.
Technical development is progressing in rather more unusual ways too. Creation of phosphorescent blocks is achieved through use of carefully graded particles of glass which absorb light. These provide a colourful luminous blue or green effect when natural light is restricted. Product development has even evaluated use of waste straw as a raw material. With an over-supply of 6-8 million tonnes in the EC, the source is entirely replenishable, the intention being that local, rural economies should benefit as the supply source. Straw is carbon neutral, has low thermal conductivity, reduces unit weight and, in its mixed and cured state is not flammable. Trials have already shown the finished product to have improved crushing strength.
Past block manufacture was based on the use of non-replenishable materials. Products such as Lignacite’s Polished Facing Masonry, which provide designers with the opportunity to draw inspiration from the use of concrete, combine the best of traditional building design within current energy and thermal performance requirements. Better acoustic performance, inherent decorative appeal, durability and precision of surface finish are all factors encouraging a fresh approach to use of concrete blocks for the design of mainstream rather than just specialist projects. Whatever the type or scale of project, however, it has never been easier to create a contemporary appearance using products which make a tangible contribution to building sustainability. | |
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