Author – Goutham V
The need for low-cost houses in India is gigantic in proportion. Exact estimates are still to be worked out but government sources say that two crore dwelling units are required in the country, 90% of which are low-cost houses. Hence, the central government has launched a mission called ‘Housing for All by 2022’ and has also provided incentives to builders in Union Budget 2016-17. As per the provisions, 100% deduction for profits to affordable housing schemes, under which homes will be built up to 30sq m in the four metropolitan cities and 60sq m in other cities.
There have been numerous efforts to build low-cost houses across the country. Most innovative among them is the method created by IIT Madras students, who have built low-cost, eco-friendly houses by using ‘Glass Fibre Reinforced Gypsum’ (GFRG) panels. They have successfully built a housing unit, which was constructed within a month using pre-fabricated GFRG panels made from waste gypsum.
The fertilizer industry produces around 2,000 tonnes of gypsum everyday in the form of waste, which is dumped over a large area. This waste is re-processed by calcining it into gypsum plaster, which forms the raw material for gypsum panels, which are manufactured in Mumbai by Rapidwall Building Systems, Australia.
The manufacture of these boards is done in three stages:
- Firstly, the gypsum plaster is spread on a special table, on which glass fibers are poured.
- Secondly, another layer of gypsum plaster is poured by using specific equipment to leave a gap between the two layers and then it is left for hardening for 30 minutes.
- In the third stage, these boards are removed and dried faster in a special chamber.
These panels are cut into required sizes using a computerized machine at at the factory and brought to the construction site to used for all parts of the building, right from walls to staircases to roofs. Trenches are first dug at the construction site and the bottom surface is plastered with cement.
The foundation is made of conventional fly ash bricks and plinth beams are cast on it. The entire gap is filled with soil and then plastered with cement. This process takes 11 days to complete.
Special structural design
Then walls, staircases and finally the roof are built using gypsum panels. The hollow gaps between two panels of the roof are filled using the concrete mixture and they are also reinforced. Special structural design is prepared for the building to withstand lateral loads such as earthquakes and storms. PhD students from IIT Madras struggled hard to design the structure for seismic loads.
The Building Materials and Technology Promotion Council of India has approved the design. All hollow parts at the joints are filled with concrete and vertical walls are reinforced. These serve the purpose of conventional reinforced concrete columns. Gaps are provided for plumbing and electric works. The conduits are made before concrete is placed on the roof. Care is also taken to drain rainwater by providing a slope.
A multi-storey house can also be built by using gypsum panels as walls in the similar manner done at the ground floor. The joints are filled with concrete.
Cost and disadvantage
Under the pilot project, the low cost house of 500sq.ft costed around INR 575,000. Not only the house can be built with in a month, this construction is eco-friendly as well. Gypsum, which is dumped over a large area as a waste, is being used effectively. The only disadvantage is that these gypsum panels cannot be used to build curved structures, but concrete can be used to accomplish curved structures.
These panels are being manufactured at FACT-RCF Building Products Ltd in Kochi, a joint venture between Fertilizers & Chemicals Travancore Ltd (FACT) and Rashtriya Chemicals and Fertilizers, Mumbai, in collaboration with the Australia’s Rapidwall Building Systems. Proposals are being mooted with the Indian Government to set up manufacturing units to produce GFRG panels across the country to further scale down transportation costs of these panels.