Cost effective construction techniquesPresentation Transcript
The important need and everyones dream to have there own home with individual needs. Since India is a developing country, the economy haves importance. The housing is so impacted with the cost based construction. So, there are various cost effective techniques of construction. Lots of them are also energy efficient and easily adoptable.
Essential requirement to human existence is a HOME next only to food and clothing. A breakthrough for application of sustainable and cost effective technologies for better housing in rural and urban areas is an urgent need considering spiraling construction costs. There is a need for the adoption of strong, durable, environment friendly, ecologically appropriate, energy efficient and yet cost effective materials and appropriate technologies in construction.
ar. Laurie baker is one who worked on cost effective construction techniques as its best. Baker showed, in fact, that sustainable technologies when adopted with care and creativity, could lead to a unique architectural expression, one that moved the expert and the layman alike. Proper materials is the basic need to develop any construction technique. Brick, wood, stone are three major materials which can be used in India for any type of construction.
Building Cost- The building construction cost can be divided into two parts namely: Building material cost : 65 to 70 % Labor cost : 65 to 70 % Size-The smaller the project in terms of scope or the number of square feet, the more it will cost per square foot. Type-Different types of project have different levels of complexity and detail.
Special Construction Complexity can greatly increase the cost of the project. For exp-Renovation, especially if it requires altering or moving structural components, can be costly because it necessitates demolition as well as building. Special construction may also be necessary to shield surrounding spaces from noise, fire and other hazards. Project accessibility Labor Rates Material Costs General Economic Pressures Time of Year
These were the factors affecting the budget of making any structure but we are here to know more about the construction techniques- the techniques which helps us in reducing the cost of structure. So, lets move towards the techniques…
Central Building Research Institute (CBRI), Structural Engineering Research Centre(SERC),Centre for Application of Science andTechnology to Rural Areas (CASTRA),Regional Research Laboratories (RRL),National Environmental EngineeringResearchInstitute (NEERI)
a)Stabilized compressed earth blocks are made of mud stabilized with 5% cement/lime etc. and compacted in block making machine with no burning. A good walling material as burnt bricks and is economical, stronger, energy saving and simple to manufacture. b) Fly ash gypsum stabilized mud blocks are much stronger with less water absorption and cheaper than cement stabilized blocks. With 5 to 10% flyash- G, 30% saving in cement could be achieved in addition to utilization of the waste product like flyash.
c) Flyash- lime gypsum products manufactured by blending flyash lime and calcined gypsum for making a useful product named Fal-G , and can be used a cementations material for mortar/plaster and for masonry blocks of any desired strength. It can also be used for road pavements and plain concrete in the form of Fal-G concrete. d) Clay red mud burnt bricks produced from alumina red mud or bauxite, an industrial waste of aluminium producing plants in combination with clay. Posses all the physical properties of normal clay bricks and solves the problem of disposal of the waste product and environmental pollution. In addition, they have good architectural value as facing bricks due to their pleasing hues of color.
e)Precast stone blocks of larger size than normal bricks are manufactured by using waste stone pieces of various sizes with lean cement concrete and enable a rationalized use of natural locally available materials. Shaping stones in this manner, enables speedy construction saves on cement, reduces thickness of stone walls and effects overall saving by eliminating plasters on internal/external wall surfaces. f) Precast concrete blocks made to similar dimension of stone blocks without large size stone pieces, but using coarse and fine graded cement. They have excellent properties comparable to other masonry blocks, are cheaper and facilitate speedy construction and especially suitable where quality clay for bricks making is not available.
Random rubble masonry in mud/cement mortar placed in excavation over thick sand bed. Rubble pointing above ground level in stabilized cement mortar. Use of lean cement concrete mix 1:8:16 for base with brick masonry in 1:6 cement mortar footings. Use of lean cement concrete mix as above for base and over burned bricks masonry in cement lime mortar (1:2:12) footings. Arch foundations in place of spread foundations
Normally the foundation cost comes to about 10 to 15% of the total building . It is recommended to adopt a foundation depth of 2 ft.(0.6m) for normal soil like gravely soil, red soils etc. It is suggested to adopt arch foundation in ordinary soils. In case of black cotton and other soft soils, it is recommend to use under ream pile foundation which saves about 20 to 25% in cost over the conventional method of construction.
Arch foundation- This type of foundation was used in olden times where in spread foundation is replaced by inverted arch . It reduces the construction cost up to 40% Advantage of this is-In soft soils that the depth of foundation can be greatly reduced; disadvantage is that the end piers have to be specially strengthened by buttresses so as to avoid the thrust to arch action tending to rapture the piers junction.
It is recommended to adopt 1 ft. height above ground level for the plinth and may be constructed with a cement mortar of 1:6. The plinth slab of 4 to 6″ which is normally adopted can be avoided and in its place brick on edge can be used for reducing the cost. By adopting this procedure the cost of plinth foundation can be reduced by about 35 to 50%.
Brick work in 1:6 cement mortar using bricks from black cotton and inferior soil stabilized with fly-ash. Rat-trap bond brick work in 1:2:12 cement lime mortar/1:1.5:3 cement sand mortar. Hollow concrete block masonry in cement mortar. Compressed mud blocks masonry in mud mortar. Stabilized mud blocks masonry (4% cement or lime) in stabilized mud mortar. Sand lime brick walls in 1:6 cement mortar. FAL-G sand block with 1:6 cement mortar.
While laying bricks, the manner in which they overlap is called the bond. The rat-trap bond is laid by placing the bricks on their sides having a cavity of 4? (100 mm), with alternate course of stretchers and headers.The headers and stretchers are staggered in subsequent layers to give more strength to the walls.
This technology has about 25% overall-saving on cost of a building of traditional 9" construction. The structure has proven its strength to go up to three floors with the support of brick columns. With this technique there is reduction in cost of the wall by 25% as with conventional English bond (9’’thk wall) 350 bricks are required per cu. m whereas in Rat-trap bond only 280 bricks are required and also the reduced number of joints reduces the mortar consumption.
THE COMMON BURNT BRICK IS ONE OF MAN‟S GREAT INVENTIONS. ALL OVER THE WORLD, WITH ONLY A FEW EXCEPTIONS, NEARLY ALL BRICKS ARE ROUGHLY THE SAME SHAPE AND SIZE - THAT IS ABOUT 9 X 4.5 X 3 INCHES. IN MANY OF THESE SITUATIONS LISTED ABOVE A “JALI” IS JUST AS EFFECTIVE. FAR FROM BEING A LOT MORE COSTLY THAN THE BASIC WALL, IF MADE OF BRICK IT CAN BE LESS COSTLY THAN THE HOUSE WALL!
Instead of using regular wallingsystem of lintel andwindow system ,jaliwork can help cost estimation.
Soil cement block technology this method of construction of wall is by soil cement blocks in place of burnt bricks masonry. It is an energy efficient method of construction where soil mixed with 5% and above cement and pressed in hand operated machine and cured well and then used in the masonry. The overall economy that could be achieved with the soil cement technology is about 15 to 20% compared to conventional method of construction. Concrete block walling In view of high energy consumption by burnt brick it is suggested to use concrete block (block hollow and solid) which consumes about only 1/3 of the energy of the burnt bricks in its production. Concrete block masonry saves mortar consumption, speedy construction of wall resulting in higher output of labor, plastering can be avoided thereby an overall saving of 10 to 25% can be achieved.
Domes and vaults in brick or stabilized mud block with appropriate mortar. Upgraded thatch roof on appropriate frame work. Pre-cast RCC “L” panel Precast RCC cored units in M15 concrete. Precast RCC channel units in M15 concrete Precast Waffle units in M15 concrete Burnt clay tube roofing in vault form.
Filler slabs Partly precast RCC planks and joist in M15 concrete. Partly precast RCC joist and brick panels Partly precast RCC in hollow concrete blocks Thin RCC ribbed slabs Ferrocement channels Brick funicular shell on edge beam Bamboo reinforced concrete Brick funicular shells with RCC edge beams Brick jack arched over RCC joist Precast RCC cored units in M15 concrete. Precast RCC channel units in M15 concrete
Provide an economicsolution to RCC slab byproviding 30 to 40% costreduction on floor/roofunit over RCC slabswithout compromisingthe strength. These beingprecast, construction isspeedy, economical dueto avoidance ofshuttering and facilitatequality control.
They are easy to construct, save on cement and steel, are more appropriate in hot climates. These can be constructed using compressed earth blocks also as alternative to bricks for further economy.
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. Therefore in a conventional RCC slab lot of concrete is wasted and it needs extra reinforcement due to added load of the concrete which can otherwise be replaced by low-cost and light weight filler materials, which will reduce the dead weight as well as the cost of the slab to 25% (as 40% less steel is used and 30% less concrete)
The filler slab is a mechanism to replace the concrete in the tension zone. The filler material, thus, is not a structural part of the slab. By reducing the quantity and weight of material, the roof become less expensive, yet retains the strength of the conventional slab. The most popular filler material is the roofing tile. Mangalore tiles are placed between steel ribs and concrete is poured into the gap to make a filler slab. The structure requires less steel and cement and it is also a good heat insulator. Conventional tests by different institutions and laboratories has proved the load bearing capacity of filler slab and found it no less in performance from the conventional R.C.C. slab. Since filler roof tiles are firmly bonded to and covered by concrete, it does not collapse under the impact of say, a coconut falling on the roof.
Saving on cost The savings on cost can be from 15 per cent to 25 per cent. But designing a filler slab requires a structural engineer to determine the spacing between the reinforcement bars. Thermal insulation The air pocket formed by the contours of the tiles makes an excellent thermal insulation layer. The design integrity of a filler slab involves careful planning taking into account the negative zones and reinforcement areas.
Filler slabs provide aestheticallypleasing patterned ceilings. Inmost houses, the filler materialis left open without plasteringto form aesthetic designsymmetry but some residentsprefer to cover the space withPlaster of Paris coating.
Brick arches : Flat, semi circular and segmented Precast thin lintel and lintel cum chajja Brick arch with sand stone chajja Ferro cement chajjas Precast RCC frames with wood insert Resin bonded saw dust frame Polyvinyl chloride frame Fiber reinforced plastic frame
Doors and windows It is suggested not to use wood for doors and windows and in its place concrete or steel section frames shall be used for achieving saving in cost up to 30 to 40%.Similiarly for shutters commercially available block boards, fibre or wooden practical boards etc., shall be used for reducing the cost by about 25. Lintels and Chajjas The traditional R.C.C. lintels which are costly can be replaced by brick arches for small spans and save construction cost up to 30 to 40% over the traditional method of construction.
Arches are an economical and aesthetic means of spanning openings. Arches can be a cost effective alternative to the lintels. The traditional RCC lintels which are costly can be replaced by brick arches for small spans and save construction cost up to 30–40% over the traditional method of construction.
Plantation timber styles with particle board inserts. Medium density fiber board doors. Cement bonded particle board Plantation timber style with rice husk board inserts Red mud polymer panel doors. Ferrocement doors Polyvinyl chloride doors panels.
The cost offinishing itemslikesanitary, electricity, paintingetc., variesdependingupon the typeand quality ofproducts used inthe building andits costreduction is leftto the individualchoice andliking.
Is the circulation space economical & functional & not wasteful? (i.e. passages, corridors, stairs, access verandas & so on). Study local climate & make use of wind directions (to reduce power consumption) & aspect(To prevent unnecessary heat absorption). Make proper use of land gradients contours, natural existing features.
As much as possible use energy free, or energy-less materials, that is, material, for which very little energy is used in their manufacture (e.g. cement & lime are made from the same basic materials but cement uses 100 times more energy) .The result for mortars & plasters is equal. Remember that what is „good‟ for Kerala is not necessarily good for Kashmir. What works well in Bihar may be disastrous in Rajasthan etc. Study local indigenous architecture & use its principles even when using modern materials indigenous architecture represents thousands of years of R&D.
Avoid currently fashionable gimmicks. They are almost always an addition that may be eye-catching but are invariably an extra expense and unjustifiable. Use local plentifully available inexpensive (comparatively) materials .Avoid importing (from other districts) much as possible. Insist on accurate mixes & mixing of plasters, mortars, concretes. Don‟t use over rich mixtures Don‟t forget to apply common sense to all you design & do.
http://www.gharexpert.com http://www.fs.fed.us http://www.greenstone.org http://manajemenproyekindonesia.com/ http://sepindia.org/ http://lauriebaker.net/ Low cost housing- an analogical study of the current practices & technologies by- vastu shilpa foundation