The current focus of the green building community is on recycled materials and energy efficiency at the expense of indoor air quality and source reduction. Two favored recycled materials, expanded polystyrene (EPS) and fly ash, have come under criticism recently for their potentially harmful effects to health and the environment. Recycling is one approach to limiting green house gas emissions. But, isn’t it just a half-hearted attempt to address the environmental problems facing society? Instead of recycling waste, wouldn’t it make more sense to reduce the amount of waste created in the first place? As a building material, cellular lightweight concrete (CLC) (known also as aerated or foamed concrete) delivers a more complete sustainable solution by significantly reducing the amount of raw material needed and the energy required to mold it into a shape for construction. A reduction in material usage is achieved while also providing outstanding energy efficiency and, thanks to the absence of toxic materials or volatile organic compounds (VOCs), excellent air quality.
CLC is produced by combining compressed air with a non-toxic liquid foaming agent. A foam is produced which is introduced into regular concrete (consisting of cement, water and sand) leaving numerous, tiny discrete air pockets within the material. Unlike autoclaved aerated concrete (AAC), no heat is applied in manufacturing. A variety of building products can be produced with CLC including building blocks, panels, and decorative precast fences.
The green credentials of CLC include the following:
- Durable, long lasting material resulting in less waste and less energy cost to society
- Energy efficient with high equivalent R-values and smaller A/C systems typical
- Low density (as low as 1/4 that of regular concrete) means significantly less sand and cement consumed contributing to a lower embodied energy than common building materials
- Does not rot, is not attacked by termites, does not absorb moisture into its core and is mold and mildew resistant resulting in less maintenance and less waste generated through maintenance
- Contains no VOCs or toxic substances. No ozone depleting or hazardous chemicals required for manufacture
- Breathable material that removes toxins from the air and naturally maintains a low relative humidity
- Can be recycled at the end of its life
- Its lightweight means lower freight loads and less energy consumption and pollution during transportation
- Sound absorbing properties lead to significantly reduced indoor noise
The outstanding balance of source reduction, energy efficiency, low embodied energy, absence of toxins and ozone depleting substances, and noise reduction make cellular lightweight concrete the ultimate green building material.
Source by Neil Rock
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