Prof. Devdas Menon, Department of Civil Engineering, IIT Madras, believes that the technology proposed by IIT Madras and demonstrated recently by the construction of a ‘GFRG demo building’ has the potential to meet the challenge of providing affordable housing to the masses.
India has a severe housing shortage problem, which is well known. In particular, there is a need to address the shelter needs of the lower income groups and their aspirations. The challenge is to make these aspirations a reality, by providing for an affordable solution. Ideally, the solution should be scalable, to reach the masses, and should be quickly built, and at the same time addresses issues of sustainability and quality. Clearly, we need a ‘game changer’ in the housing industry.
We believe that the technology proposed by IIT Madras and demonstrated recently by the construction of the ‘GFRG demo building’ has the potential to meet this challenge of providing rapid affordable mass housing.
Advantages over conventional
- High speed of construction: GFRG demo building with four flats in two storeys (total 1,981 sq. ft) built within a month!
- Less built-up area for the same carpet area: wall panels are only 124mm thick.
- Less embodied energy and carbon footprint: significant reduction in use of cement, sand, steel and water; recycling of industrial waste gypsum.
- Lower cost of structure: savings in materials; no plastering.
- Lower building weight (panels weigh only 43 kg/m2), contributing to savings in foundation and reduction in design for earthquake forces, particularly in multi-storeyed construction.
- Buildings up to 8-10 storeys can be designed using this load-bearing system, without the need for beams and columns.
- Excellent finishes of prefabricated GFRG panels: used for all the walls, floors and staircases, with minimal embedded concrete: no need for additional plastering.
The ‘model housing apartment,’ comprising four flats in a two-storeyed building, has been constructed inside the IIT-M campus within a month at a finished cost that works out to Rs.1,250 per sq. ft (including excellent finishes). The ‘GFRG demo building’ was inaugurated by T.K.A. Nair, Advisor to Prime Minister of India, in the presence of Prof. BhaskarRamamurthi, Director, IIT Madras.
Since 2003, the IIT-M research team had conducted extensive studies on the use of these panels as structural members for all components of the building, including earthquake resistant design. These panels, originally developed by RBS Australia, were intended as wall panels (Rapidwall) suitable for rapid erection of walls in buildings to carry gravity loads. The panels are made of calcined gypsum plaster, combined with special additives and glass fibres, to produce GFRG panels — 12m long, 3m high and 124mm thick (with hollow cavities). The IIT-M research group extended the application of this product for the entire building system – including floors, roofs, and staircases, thus significantly reducing the consumption of reinforced cement concrete. The team also collaborated in the indigenous development of an excellent waterproofing material, which is essential for prolonged durability of the GFRG panels, especially in the case of roofs and toilets.
The GFRG panels for the ‘demo building’ at IIT Madras have come from the plant of FACT-RCF Building Products Ltd, Kochi, using reprocessed gypsum from FACT. The building has four units, making up a total built-up area of 1981 sq. ft — two flats with a carpet area of 269 sq. ft each, intended for the economically weaker section, and another two, with a carpet area of 497 sq. ft each, intended for the low-income group. The plans can be replicated horizontally (in plan) and vertically (in elevation) in mass housing projects. This demonstration building will also be used by another research group at IIT-M working on decentralised solar photovoltaic systems with DC appliances, to demonstrate savings in electrical energy consumption. The panels are prefabricated and cut to desired sizes based on room dimensions with openings for doors and windows, thus making rapid construction possible. A panel has two skins of 15 mm thickness that are interconnected at regular intervals (250 mm) with 20 mm thick ribs. The cavities formed by these interconnections can be used for several purposes, filling with concrete, and laying electrical conduits and plumbing pipes.
Filling the cavities with concrete increases the vertical load-carrying capacity almost tenfold, and inserting vertical steel bars in these cavities, contributes to their earthquake resistance. In a multi-storeyed building, the number of concrete-filled cavities and steel bars can be reduced at the higher floor levels. When used as floor slabs, reinforced concrete beams can be embedded and hidden in some of the cavities, as per the design. The overall weight of the structure and consumption of concrete comes down significantly. Conventional plastering is eliminated.
The research work has resulted in two PhD theses, and two PhD scholars are currently continuing the R&D efforts. The Department of Science and Technology, Government of India, had awarded a research grant of Rs.1.32 crore to complete the research work and bring it to a stage of technology transfer.
The panels may be unfilled, partially filled or fully filled with reinforced concrete, as per the structural requirement. Experimental studies and research have shown that GFRG panels, suitably filled with reinforced concrete, possess substantial strength to act not only as load-bearing elements, but also as shear walls, capable of resisting lateral loads due to earthquake and wind. It is possible to design such buildings up to ten storeys in low seismic zones (and to lesser height in high seismic zones). However, such construction needs to be properly designed by a qualified structural engineer.
The GFRG demo building also demonstrates the use of an innovative waterproofing treatment using a nanotechnology based solution, developed by Zydex Industries, Vadodara, for the specifications evolved by IIT Madras.
Based on the research work carried out at IIT Madras, and the research reported elsewhere (Australia and China), Building Materials & Technology Promotion Council, Government of India, has accorded approval of GFRG panels for construction in India.