2 Construction Industry and its Impact to Built Environment
3 Construction Industry account for one-sixth of the world's fresh water withdrawals, one- quarter of its wood harvest. The cement sector alone accounts for 5 % of global man made CO 2 emissions
4 Construction & Demolition (C&D) generate between 10% and 40% of the solid waste stream in most countries (Kibert et al, 2000). C&D wastes can generally be used for low-priority works like footpaths, drains, pavements etc. Most bonding & drying agents in carpets, veneers, particle board, plywood and paint emit volatile organic compounds (VOC’s) which contribute to greenhouse gases and global warming. Pollution and Wast e
Environmental impacts Resource depletion Physical disruption Chemical pollution Other effects; Social disruption, undesirable visual impact. Social impacts Loss of open space & biodiversity Social Isolation Increased car dependency Decreased air quality Unhealthy indoor environment Economic impacts To Builders: Increased compliance costs & waste disposal costs To Owners: Increased utility & maintenance costs To Occupiers: Loss of well being & productivity To Society: Decreased environmental quality
According to the World Watch Institute about 40% of the world's total energy usage is dedicated to the construction and operation of buildings. The building industry consumes 3 billion tons of raw materials annually, 40% of the total material flow in the global economy. Only about 0.003 % of earth's water is readily available as fresh water for human use (Miller, 1992). Building materials manufacturing, construction and operations consumes 16% of available fresh water annually In 1990 the building industry consumed 31% of Global energy and emitted 1900 Megaton's of Carbon.
Towards an innovative & eco-friendly Construction Industry 7
8 ‘Continued ability of a society, an ecosystem, or any such interactive system to function without exhausting key resources and without adversely affecting the Environment’ Principles: 1.Maximizing the use of renewable and natural resources; 2.Minimizing the use of energy and water; GREEN Building
9 Green building materials offer specific benefits to the building owner and building occupants: Reduced maintenance/replacement costs over the life of the building; Energy conservation and reduce harmful emissions; Improved occupant health and productivity; Lower costs associated with changing space configurations; Do not exhaust the existing supplies of finite materials; Green Buildings Materials
10 Underlining Principle: Assuming that all stages in the life of a material right from extraction, manufacture, transportation to the installation, operation, maintenance and the recycling and waste management cause some degree of Environmental impact which needs to be evaluated.- This is called Life Cycle Analysis (LCA) for any material/product. Choosing Building Materials
11 1. CEMENT CONCRETE Energy Intensive industry Depletion of natural resources Green house gas emissions Characteristics of Sustainable Managed Alternatives
12 Recommended Alternatives: 1.Blast furnace Slag Concrete Using Ground Granulated Blast Furnace slag with Cement (from steel plants) in mixes
13 Recommended Alternatives: 2.Using Recycled Aggregates Crushed Concrete, Bricks and other masonry waste
15 2.Lime : rha : Sand (1 : 1 : 1) rha: Rice husk ash - hard protecting coverings of grains of rice (burnt)
16 Our predecessors knew it better……. We were much less resource dependent in the past Looking back to think ahead……………..
17 RAMMED EARTH AND MUD BLOCKS CONSTRUCTION IN BHUTAN
Earthen Construction Technology A brief History Tabo Monastery, HP – India, 996 AD Shey Monastery, Ladakh 17 th Century Ramasseum, Egypt Around 1300BC Our Very Own Auroville-Earth Institute Aman, Gangtey
20 Innovative Building Technologies: Machine that produces HI-CSEB, developed by Auroville Earth Institute, Tamil Nadu, India Aurum Press 3000
21 HI-CSEB Economical/affordable, environmentally friendly, easily available, stronger, energy saving and simple to manufacture Better Thermal Insulation Warm in winter and cool in summer
Technical /Engineering Aspects Block Production Material selection Soil Identification – Top soil and soil with organic matter should not be used. Grain size distribution - more of sandy is preferred. Gravel (mm)Sand(mm)Silt(mm)Clay(mm) 20 to 2mm2 – 0.020.02 – 0.0020.002 - 0
Some basic test for identifying the suitability of soil 15%gravel, 50%sand, 15% silt, 20%clay Granularity (Grain size distribution test) Compress a moist soil by hand Difficult to compress – gravely soil Very easy to compress – Clayey soil -Compressibility (Ease of the soil to be compressed) Smells Rotten – lot of humus Musty – humus Agreeable smell – no humus - suitable for construction Humus (presence of organic materials0 Difficult to break – clayey soil Breaks easily – gravely soil Plasticity ( Capacity to withstand deformation) Wash the hand on which the soil paste was made Soils grains does not stick on the palm – Gravely soil Thin film of soil stick on the palm – clayey soil. Cohesion(Property of the soil grains to remain together)
Proportions Cement : Soil (1 : 6) Water content = 25 liters for one bag of cement Varying the ratio esp. the cement has the proportionate cost involved The ratio can go up to 1 cement to 10 soil 24
Same basic data on CSEB PropertiesValues Dry Compressive Strength @28days 3 – 6Mpa (N/sqmm) ( +10% after 1 year, 20% after 2years) Wet compressive strength @28days (3days immersion) 2 – 3 Mpa Dry bending Strength @28days0.5 – 1 Mps Dry Shear Strength @28days0.4 – 0.6Mpa Density1700 to 2000kg/cum Water absorption @ 28days after 3 days immersion8 to 12 % by weight Energy Consumption110MJ ( Kiln fired bricks = 539MJ)
Comparison with other building blocks Properties CSEB (HI - 245)Ordinary class III brick Concrete hollow blocks Size245x 245 x 95195 x 95 x 75390 x 190 x 190 Weight8kg3kg16kg Compressive strength (28days) 30 – 60kg/cmsq35kg/cmsq45kg/cmsq(approx) Cost (Nu.)13 per block ( 1:6 mix ratio) 11 per brick @ Thimphu 38.00 per block @ Thimphu For a 250mm thick 1msq wall in a load bearing building @ Thimphu BlockNumbersCost(Nu) HI - CSEB40(Approx)520 Ordinary second class brick166(approx)1496.00 Hollow concrete Block19.5(approx)741
Block production machines Two Machines in the market 1)HI – CSEB Block machine – Habitech centre, Thailand 2) AURUM PRESS 3000 – Auroville,India Designer/ manufacturerAuroville Earth institute/ Aureka, Cost of PressRs 69,800.00 Cost of Mould ( 1 set)Rs 41,500.00 Max Blocks size 245 x 245 x 95 Compression force150KN( 15 tones) Production capacity per day with 7 workers 500 Blocks (average) Designer/ manufacturerHabitat centre, Bangkok Cost of Press 73,500.00 (Nu) 2008 rate Cost of Mould ( 1 set) - Max Blocks size 300 x 150 x 95 Production capacity per day ( 6- 7 workers) 500 average
Pilot House Construction – SQCA using HI – CSEB 245 Two storied load bearing structures - serve as model for the earthquake resistant design features Sample Blocks test results Soil sample sourceAverage Compressive Strength Proposed construction site (1:8 mix ratio 22 kg/cmsq Buddha Dodema site ( 1: 8) 33 kg/cmsq
Advantages 1.Use of cheap & locally available materials 2.Job opportunity for local people 3.Biodegradable materials 4.Energy efficiency and eco friendliness 5 – 15 times less energy consumed than fired brick and around 3 – 8 times less emission 5.Transferable technology 6.Import Reduction
Advantages 7. Cost effectiveness 8. Minimum mortar required 9. Keys that interlock with each other provides better integrity 10. Hollow provisions for laying vertical and horizontal reinforcements to improve the lateral load resisting capacity 11. Ease and Fastness in construction 12. Fire resistant
Limitations Only for low rise structures: maximum 2 storey Strength very much dependant on the properties of soil Too much stabilization(cement) will make no economic sense Interlocking features do not provide air tightness. Minimum gap is formed due to which termite/air current can pass.
Limitations Requires minimum mortar between the blocks to maintain horizontal construction level Too much mortar between the blocks jeopardizes the interlocking feature For frame structures, HI-CSEB can be used as filler materials but the structural members sizes increases due to increase in the block weight
HI-CSEB in Bhutan No of private individuals who procured the machine-2 Commercial basis- Established in Jemina by 2 firms
Way forward 1.Conference on GREEN Construction – Awareness and exchange of knowledge; 2. Sensitization w/shops & trainings in Green building practices; 3.Standards and regulations; R & D required Formulation of standards and guidelines
Conclusion Sustainable /economical/eco friendly building material Easy and simple technology Creates employment opportunities Reduce dependency on import of bricks Making housing affordable Therefore, production and construction with HCSEB is relevant and it is to be adopted where ever possible.