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Filler Slab Roofs


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Many building materials are used for construction and different methods are followed. Each of these building materials has a unique embodied energy. Out of these materials, Roofing material constitute one of the major energy consuming components of the building. Effective utilization of available energy and its conservation is global challenge. For a developing country like India, the increasing demand of energy has created a scope for the study embodied energy of alternative roofing technique and their advantages for the sustainable building construction. The total embodied energy of a building can be reduced significantly by using alternate roofing technique such as RCC Filler slab which has lower embodied energy value.
Filler slab technology is a simple and a very innovative technology for a slab construction. The filler slab is based on the principle that for roofs which are simply supported, the upper part of the slab is subjected to compressive forces and the lower part of the slab experience tensile forces. Concrete is very good in withstanding compressive forces and steel bears the load due to tensile forces. Thus the lower tensile region of the slab does not need any concrete except for holding the steel reinforcements together. Hence concrete in the bottom region of solid RCC slab is replaced by an energy efficient and cost effective material. With reduced consumption of building material for roofing, the cost of the building can be reduced predominantly.

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Filler Slab Roofs

  2. 2. What is EMBODIED ENERGY?  Energy consumed in the production of basic building materials  Energy needed for transportation of the building materials  Energy required for assembling the various materials to form the building Construction sector in India is responsible for major input of energy resulting in the largest share of CO2 emissions (22%) into the atmosphere. The Need for Alternatives
  3. 3. The Concept
  4. 4. Replacing unnecessary concrete in the tension zone with filler material suitably
  5. 5. Filler material selection • Filler material should be inert in nature. It should not react with concrete or steel in RCC slab constructed. • Filler materials water absorption should be checked for as it will soak the hydration water from concrete. • Filler material should be light in weight, so that overall weight of the slab reduces and also the dead load onto the foundations is reduced. • Filler material should be low cost so that it cost is much lesser then the cost of the concrete it replaces. • Filler material should be of a size, cross-section and thickness which can be accommodated within the spacing of the reinforcement and cross section of the slab. • Filler material texture should match with the desired ceiling finish requirements so as not to provide an ugly ceiling pattern.
  6. 6. Installation of Filler material Filler materials should not be installed at the shear zone.  Clear distance of 150 mm from end supports in all directions.  Gap of about 75 mm between each unit of filler material.
  7. 7. Stabilized Mud Filler Blocks as Filler material
  8. 8. Mangalore Tiles as Filler Material
  9. 9. Laying Earthen Pots as Filler material
  10. 10. Ceiling when Earthen Pots used as Filler material
  11. 11. Terracotta Roofing tile as Filler material
  12. 12. Plan and Section of RCC Filler Slab
  13. 13. Sl. No Material Embodied Energy (MJ) Conventional Roof Filler slab roof Quantity consumed Total Embodied energy (MJ) Quantity consumed Total Embodied energy (MJ) 1 Concrete Cement (kg) 5.85 8453 49452 6847 40055 Coarse aggregate (m3) 108 19.15 2068 15.51 1675 Fine aggregate (m3) 87.5 10 837 7.76 679 2 Reinforcing Steel (Kg) 42 564 23689 349.58 14682 3 Mangalore Tile 5 0 0 1469 7345 Total Embodied energy (MJ) 76047 64436 Difference of energy (MJ) 11611 Percentage saving of energy 15 % ILLUSTRATION Embodied energy calculations for a 200 sq.m slab of 100 mm thick.
  14. 14. 76047 MJ 64435 MJ 58000 60000 62000 64000 66000 68000 70000 72000 74000 76000 78000 RCC Slab Filler Slab Energy(MJ) Embodied Energy for a 200 sq.m slab RCC Slab Filler Slab Now 1 kw = 3.6 MJ  Therefore a saving of 3220 kwH of electricity equivalent is achieved  This is equivalent to 0.28 tonnes of oil saving  This is equivalent to 3.22 tonnes of CO2 gas released to atmosphere  This is equivalent saving of 4800 hours of AC electricity consumption or 200 days
  15. 15.  Consumes less concrete and steel due to reduced weight of slab by the introduction of a less heavy, low cost filler material.  Filler slab technology can also be applied to mass housing projects and township projects to gain high cost saving and also saving in high energy consuming materials.  This can be of a better thermal comfort if a cavity is kept between the filler material or the filler material itself has a cavity.  Filler slabs can be kept exposed (with proper workmanship) to create aesthetically pleasing ceiling with a view of filler material from below and thus the cost of plastering and/or painting also can be avoided.  Reduction in concrete quantity compared to conventional slab construction, adds this technology to the list of sustainable and environment friendly technologies and with green building features. ADVAVNTAGES
  16. 16. CONCLUSION It is possible to save on approximately 19% of the total concrete and including the cost of filler material and around 5-10% of your concrete cost If the filler material is just a waste material, it saves upon nearly 15% on roof concrete construction cost. The total embodied energy of the can be significantly reduced by about 15% when compared with solid RCC slab thus conserving the energy.
  17. 17. THANK YOU