The future of infrastructure is pivoted on sustainability. To enhance sustainability in building systems, adopting sustainable building roofs technology would play a crucial role. Development Alternatives (DA) a social enterprise dedicated to sustainable development, has made tremendous progress in roof technology which integrates developing environmentally appropriate products, conserving energy, and extending roof system life spans. The technology also supports localized masonry techniques which help generate employment in the local area. DA has developed, Ferrocement Channel Roof, TARA Micron and Planks and Joists. Suvankar Bose, Assistant Programme Director, writes about DA’s roofing innovations.
Ferrocement Channel Roof
Ferrocement roofing technology offers a viable alternative to conventional flat roofing systems such as reinforced cement concrete, reinforced brick cement, sand stone, etc. in both rural and urban areas of the country. The technology package for roofing uses state of-the-art design principles to manufacture reinforced shells. It is a viable alternative to steel reinforcement conventionally used in building systems to support the roof, and its strength is as good as steel or reinforced cement. The production process could be useful in developing micro level enterprises supporting the local economy.
The building system uses pre-cast Ferrocement roofing channels of a segmental arch profile which are placed adjacent to each other and spanning over two supports. After partly filling the valley between channels with concrete, the channels form an idealized T-beam and are able to carry the load of a roof / floor. Ferrocement comprises of a uniform distribution of reinforcement by use of chicken wire mesh and welded mesh encapsulated in rich cement mortar, thereby achieving significant reduction in both steel reinforcement and dead weight of roof. This composition provides a more uniform distribution of strength as compared to RCC.
The channels are produced on specially designed vibrating tables and profiled moulds. The production system is uniquely tailored to provide special end details, consistent shape and thickness; all crucial for high performance the channels made with an optimized proportion of cement, sand and water. They have a very high are impervious to penetration of water and provide high structural strength. Ferrocement roofing channels are manufactured using designed mix of cement, sand and water to give high strength mortar that is reinforced with a layer of galvanised iron chicken wire mesh of 22 gauge and tor steel bars of 8-12 mm diameter provided in the bottom nibs of the channel. Ferrocement roofing channels can be safely transported for the application after a curing period of 14 days.