Lightweight Concrete Being Used for Green Roofs

Celcon aircrete, already known for helping to cut carbon emissions because of its excellent thermal insulation properties, is now being put to another ‘green’ use. Waste aircrete which cannot be put back into H+H UK’s manufacturing process is being crushed and used as part of the base material for sedum roofs.

Green roofs, which permit the growth of flowers, grasses and sedum plants, require a combination of organic matter and aggregates to lie on the membrane, to act as a base for plant life to grow and to protect the roof structure. Until recently crushed waste bricks were used as the aggregate, but crushed Celcon aircrete has been found to be better.

Chris Hallas, managing director of Shire Minerals says: “Aircrete blocks are known for their light weight, so crushed aircrete is ideal for use on green roofs because it is so light. This can reduce the strength required in the construction to bear the roof and will reduce costs.”

Architects and planners are being driven by planning constraints to mitigate the environmental damage caused by the erection of new buildings – and this is often the case even when building on industrial waste land. A green roof can support a variety of plant life as well as attracting bird life such as ringed plovers and skylarks.

Apart from creating more natural green spaces in urban and industrial areas, a green roof will provide other benefits such as:

• Better-insulated buildings, so reducing the need for air conditioning
• Improved durability of the roof structure and lower maintenance
• Enhanced air quality through increased greenery consumption of CO2
• Less stormwater run off, so reducing drainage required

Commented Ian Exall, head of marketing for H+H UK: “This is yet a further example of what a sustainable product aircrete is. Already, pulverised fuel ash (PFA), a by product of coal-fired power stations, accounts for nearly 80% of the raw materials we use. We recycle a good proportion of any waste from the manufacturing process and now we have found a productive use for other waste product.”