Low-Cost Semi-Permanent Shelters Construction Methodology Composite materials such as jute-coir composite boards, rice husk particle boards with bamboo mat veneer etc. fixed on MS angles (ISA 40X40X6) & channels (ISMC 75X40) and erected quite quickly @ 8-10 houses per day are an effective low-cost solution for shelters lasting for about 5 years. These natural materials have all the properties required for a general purpose board and can be used in place of wood or MDF synthetic resin boards. The steel channels & angles are erected through proper grouting, bolting & welding to get the shelter dimensions (20 ft x 12 ft x 8 ft high) along with steel purlins on the top to support the roofing sheets. The boards are fastened to this structure allowing the provisions for door & window. The doors & windows are also made of composite boards. The flooring is done by leveling the soil and compacting the debris on it to get the desired height. Finally, cement concrete is applied over the compacted debris to form the permanent floor. Space for washing the utensils is also provided inside the shelter connected with a drain-out pipe. Generally, the dimensions (length & breadth) of the floor are built slightly larger than the inside dimensions of the shelter to protect the foundations of supporting steel structures. As the UV attack of sunrays disintegrates the polymeric resin thus reducing the life of the boards, the outer walls of the shelters are painted with weather coats for improved life span. The roof is covered with terracotta tiles to improve the heat insulation properties as well as to prevent the UV attack on the roofing sheets. Flexible construction using steel frames fixed with nuts & bolts would bear tensile, compression & flexural stresses and allows lateral movements of the structure thus reducing the effect of seismic forces. Lightweight material used for walls & partitioning also absorbs & reduces seismic energy and its impact or effect. The material used for constructing the shelters for earthquake victims is modular in nature and once the rehabilitation work is complete these shelters could be easily be dismantled and transported to different location. The construction details, given in the sketch for the shelters, using the two types of boards are similar. Jute-coir Composite Boards The jute-coir composite boards, as an alternative to wood products, have been developed under a project launched by the Advanced Composites Mission in partnership with M/s Natura Fibretech Pvt. Ltd., Bangalore. Two composite boards namely, coir veneer boards (jute face veneer, alternate coir & rubber wood veneers inside) as plywood substitute and natural fibre reinforced boards (jute face veneer + coir) as MDF substitute have been developed under the project. Natural hard fibres such as coir and jute impregnated with phenolic resins are used for manufacturing these boards. While the MDF substitute boards are made only by jute and coir bonded by phenolic resin, the coir veneer boards are manufactured with jute, coir & rubber wood waste veneers inside. A very thin layer of jute fibres impregnated with phenolic resin is overlayed as face veneer for improved aesthetics and to give a wood like finish. The coir fibre contains 45.84% lignin as against 39% in teakwood. Therefore, it is more resistant than teakwood against rotting under wet and dry conditions and has better tensile strength. Similarly low cellulose content in coir (43%) as against 63% cellulose in wood makes it more durable than teakwood. These jute-coir boards can be used in place of wood or MDF boards for partitioning, false ceiling, surface paneling, roofing, furniture, cupboards, wardrobes etc. These boards have been employed as doors & doorframes as an alternate to conventional material like wood, steel etc. The jute-coir boards conform to IS-12406, the relevant codes for MDF boards and they were tested against the specified values. The properties of jute-coir composite boards are given in following Table : The Bureau of Indian Standards (BIS) has recently brought out the relevant standards (IS 14842 : 2000) for coir veneer boards and the product developed by Natura conforms to the codes. The jute-coir composite boards are made of renewable natural fibres and have attractive natural look with substantial longer life span. The critical advantages of natural fibre based boards are as follows : • Termite/borer Proof • Good insulation properties • Fire retardant • Water resistant • Strong & rigid • Can be nailed, screwed, laminated and cut sharply. Some of the applications of these natural fibre based boards are as follows : • Partitioning • False ceiling & roofing • Surface panelling • Furniture • Cupboards, wardrobes etc. Under the initiatives by the Advanced Composites Mission, 250 nos. shelters (20 ft x 12 ft x 8 ft high) are being constructed using jute-coir composite boards. While walls are constructed with 12-mm thick coir veneer boards, the roof would be constructed using 10-mm thick jute-coir composite boards. Compiled by Sukla Choudhury
