A novel technology for industrial production of Precast Ferrocement Toilet Core (TOCO) units at affordable cost has been developed at Structural Engineering Research Centre (SERC) of Council of Scientific and Industrial Research (CSIR). This technology is developed for mass production of high quality toilet core units to cater to the needs of the people. Precast concrete technology is used in combination and ferrocement technology in this development. Both the technologies are well established technologies and are in practice. These technologies are different from the conventional construction and has several advantages. Thin ferrocement is used along with mildly reinforced concrete ribs for strength and stability to produce precast panels. The toilet core units can be produced through small scale or large scale industries. A brief summary of the technology, salient features and advantages are given in this paper.
National priorities focus on developing technologies for improving quality of life through mission mode activities. Swachh Bharat mission aims at promoting cleanliness and sanitation coverage for improving the quality of life. CSIR 800 program also aims at improving the quality of life with the help of science and technology. Sustainable sanitation practices can be inculcated through awareness and providing necessary sanitation facilities. Sanitation facility includes building of community and public toilets. Mass requirement for affordable quality toilets exists in the country to fulfil the Swachh Bharat Mission. Number of schools, hospitals, railway stations, public places and rural areas need quality toilet facility. Conventional method of construction can hardly satisfy the massive requirement. Hence, there is a clear requirement of technology for mass production of toilet core units to meet the demand.
The conventional method of toilet construction with brick masonry is laborious, time consuming and labour intensive. It has inherent drawbacks such as poor quality and availability of skilled labour as the quality of the work depends on the skills of the manpower. On many occasions, the poor quality of the masonry toilets for usage is attributed to various economic measures taken to reduce the cost. The walls are not plastered in some cases. Even the plastered wall surfaces are not smooth. It absorbs water and produce dampness. The dampness causes damage to the wall and makes the toilet, less durable. Sometimes the wall dampness produces foul smell and unhygienic environment. Asbestos or metal sheets used for economical roof for the toilet makes the structure flimsy and are vulnerable for damage due to heavy wind. The toilet become unusable after some period of time. On the other hand, Plastic or PVC toilet units small, cramped and costlier. Plastic units are less environmental friendly. Hi-tech E-toilets and stainless steel toilets are very expensive. Natural ventilation and lighting are not sufficient enough in these toilets to make user friendly.
Precast Ferrocement Technology
The two technologies involved in this product are: (i) Precast concrete technology (ii) Ferrocement technology. Both the technologies are well established in general. Precast concrete technology is the alternate method of construction to the conventional method. Precast concrete technology includes casting of components of the structure in a manufacturing or production site other than final location, transporting and assembling the components at the site where the structure is to be located. It combines good design with modern high performance components and quality controlled manufacturing procedures. High quality and speed of construction are advantages of any precast technology. Ferrocement is another technology which can make the scheme affordable as the quantity of materials used is considerably reduced. Apart from cost effectiveness, the technology can be used to produce thin members which are durable. This makes the components lighter than conventional brick masonry and can be transported and erected at site. The components can sustain the normal service load coming on these structures. Hence precast technology combined with ferrocement technology has been adopted in this project.
The development has two models viz.
- Single Toilet Core Unit
- Multiple Toilet Core Units
Single Toilet Core Unit
The single core unit consists of eight panels, of which three are identical. The precast panels were designed for proper strength and dimension. Six different panels viz. wall panel, door panel, roof panel, floor support panel, floor panel and closet support panels moulds were cast with moulds designed and fabricated for each type of panel. The precast ferrocement panels were cast separately and connected together by means bolts and nuts. A new type of connector has been fabricated and used in the dry connections. The connector ensures perfect alignment between the panels to accommodate the bolt and nut connection. This also eliminates drilling of holes or chipping of concrete and provides fixity of the connector in the concrete.
An aesthetically designed cylindrical shell has been designed to provide roof for the Precast Ferrocement single toilet core unit. Truncated four sided inverted pyramid type column heads that merge with the top curved surface have been designed to support the shell on the wall panel ribs. This roof provides sun shade, good ventilation and rain water drain without any stagnation. Provision for placing water tank has been provided on the shell roof top as additional feature for the toilet core unit as a variant where piped water supply is not available. The roof panel has been tested for a superimposed load of 1500 kg as given in Fig. 1. for one month and found to sustain the load without any distress.
All the panels were assembled to ascertain the alignment, erection sequence and stability of the panels. A demonstrative single toilet core unit has been assembled and the unit is shown in Fig. 2.
Multiple Toilet Core Unit
Multiple Toilet core unit is developed for community toilets where more number of toilets are required in cluster such as schools, public places, hospitals, railway stations, bus stand etc. In this model the units are assembled in a line with common partition wall panel. The roof panels are overlapped at one edge over the other to protect from rain water entering at joint. All panels except floor support panel, floor panel and closet support panel are different from the single core unit wall panels. A demonstrative multiple toilet core unit with two toilets has been assembled and the same is shown in Fig. 3.
TOCO unit provides best solution for the basic sanitation need of the people. TOCO units are made of Ferrocement concrete panels assembled at site. These panels are produced manually (or) at precast factories located at a convenient place and transported to the site.
Speedy construction is obtained by TOCO units as these can be assembled very quickly within few hours and made ready for use in a day. The panels are precisely precast with specially designed dry joints connected through bolts and nuts. Site labour and site construction is very minimal.
Strong and Durable structure is provided by the reinforced concrete ribs and high quality ferrocement concrete mix. This makes the toilet core unit usable for longer life period.
Natural Ventilation and Day lighting are provided sufficiently and is the highlight of TOCO units.
Aesthetic appearance is provided by the Shell Roof of TOCO. The curved surface of the shell roof panel drain rain water faster and prevents dust accumulation on roof top. This makes the roof, free from maintenance.
Spacious inner dimension of TOCO unit 1.22 m × 1.22 m (4′ × 4′) provides better comfort than the normal cramped PVC toilets.
No plastering is required as the inner and outer surfaces are with smooth concrete finish. Variant with ceramic interior is available as optional feature. This ensures easy cleaning and hygienic interior.
No foundation is required for TOCO units and can be erected on any plain surface of 1.52 m x 1.52 m (5′ × 5′) over a levelling course. The minimum Safe Bearing Capacity (SBC) required for erecting TOCO is 4 tonnes / m2. The SBC generally available in most of the soil conditions are higher than this and hence there is no need for any foundation other than levelling course.
Light Weight Structure is provided by the TOCO wall panels as these panels are made of ferrocement and the skin thickness is as thin as 25 mm. The weight of a ferrocement wall panel is comparatively one third of a 150 mm (6”) masonry wall.
Easy erection is enabled by the precast technology and a small crane is sufficient to assemble the units. The weight of panels ranges from 100 kg to 440 kg which can be handled with light lifting machineries.
Dampness free surface is provided by the smooth surface and rich mix of the fer-rocement concrete used in TOCO panels.
Corrosion free galvanized wire mesh used in the ferrocement concrete panels gives durable and high quality structure.
Safety and security are provided in TOCO by various features. Concealed dry joints provide tamper free connection and safety against mischief. Shell action of the roof panel gives strength to support water tank load. The wall panel bottom ribs provide ground support and stability against outward leaning. Floor support panel provides stability against inward leaning and the unit is self-supported without foundation. The vertical ribs provide support to the roof panel and water tank loads. The top rib provides edge stiffening and ventilation opening.
Dimensional Specification of the unit is 1.52 m x 1.52 m (5′ ×5′) outer dimension, 1.22 m × 1.22 m (4′ × 4′) inner dimension and the height of the unit is 2.8 m. Skin thickness of wall panels is 2.5 mm and size of reinforced rib is 100 mm × 50 mm.
Water Tank: Precast Ferrocement water tank of 400 litre capacity is available as an additional feature for placing above the toilet roof, wherever piped water supply is not available. PVC Water tank of capacity 500 litres can also be placed as an alternate.
Septic Tank: Precast Ferrocement septic tank panels are also available as additional feature for the construction of septic tank. The septic tank panels are placed one above the other in two rows interlinked properly below ground level to form conventional septic tank chambers.
Durable high quality
Modular multiple units
Precise technology for factory production
Suitable for industrialised mass production
Cost effective, durable, high quality
Strong, Sustainable, Speedy Construction
Reduction in site labour and site construction
Ease of Installation with minimal lifting equipment
Modularity and Portability
Summary And Conclusion
The development of a novel technology for industrialised production of precast ferrocement toilet core units, its features and advantages are explained. The technology is suitable for mass production of durable and quality toilet core units through small scale or large scale industries. This technology can satisfy the massive requirement of the nation in solving the sanitation problem. This technology can contribute towards the objectives of SWACHH BHARAT for improving the quality of life.