report on precast elements

8/4/2019 Report on Precast Elements

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PRECAST ELEMENTSREPORT

PRADNYA V CHAVAN5TH YEAR ARCHITECTUREBUILDING CONSTUCTION9/6/2011


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A precast concrete structure is an assemblage of precast elements, which when suitablyconnected together, form a 3D framework capable of resisting gravitation and wind (or evenearthquakes) loads. The framework is ideally suited to buildings such as Apartments, ShoppingMalls, Offices, Schools, Studio, etc. each precast panel is independently supported to the buildingstructure using an assemblage of metal components and anchors. Joints around each of theprecast panels are usually filled with sealant. The connections for precast concrete panels are animportant component of the envelope system. Precast manufacturers utilize numerous differenttypes of anchors but they are often characterized as gravity and lateral types of connections.

The primary purposes of the connection are to transfer load to the supporting structure andprovide stability. The criteria used to design precast connections including but not limited to:

Strength

Ductility

Volume change accommodations

Durability

Fire resistance

ConstructabilityBENEFITS OF PRECAST CONSTRUCTION

The use of precast concrete in construction is widely regarded as an economic, durable,structurally and architecturally versatile form of construction.

1. Compared with traditional construction methods and other building materials, precast as a

construction method, has a number of positive features. It is an industrialized way ofconstruction with inherent advantages:

2. Factory-made products meaning rational and efficient manufacturing processes, skilledworkers, repetition of actions, quality surveillance, etc. Reduced traffic handling costs

3. Reduced accident exposure risks4. Shorter construction time - less than half of conventional cast in-situ construction.

5. Contractors benefit from reduced exposure to traffic hazards. More work can beaccomplished in less time, with fewer weather delays.

6. Costs are lower for forms, skilled field labor, scaffolding and shoring, and cranes.Afterfoundations have been completed, scheduling can be controlled by a single contractorworking with a familiar material

7. High capacity enabling the realization of massive projects.8. Factory made products means consistent high quality.9. Structural efficiency with longer spans and shallower construction depths offering both

flexibility and extended lifetime of buildings.10.Opportunities for good architecture as almost every building can be adapted to the

requirement of the Architect or the Builder.11.Fire resistant construction of 60 to 120 minutes and more.12.Healthy Buildings.

13. Energy conservation .Environment friendly buildings, with optimum use of materials, lessnoise, less dust, etc.,

14.Precast concrete wall systems offer a wide variety of shapes, colors, textures, and finishes tothe designer. As a result, the assessment of samples is a key component in the use of precast

concrete. The majority of the review and approval process is conducted at the precast plantprior to precast panel production. This assessment is in addition to the quality control andfield testing that takes place during the production phase.

15.Speed of construction16.Attractive appearance17.Low noise transmission18.Flexibility for expansion19.Durability Precast20.High load capacity21.Low depth-span ratiosMATERIALS USED IN PRECAST STRUCTURE


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CONCRETE: Precast concrete is of the highest possible quality, both in terms of strength anddurability. Concrete is accurately delivered to every part of the mould, ensuring zerosegregation, honeycombing and minimal vibration. Using materials that have passed strictquality control procedures, rapid hardening cement is mixed with excellent quality aggregates ofknown source and purity, in computer controlled Batching and Mixing Plant, to produce concreteof specified workability and strength.STEEL RE-INFORCEMENT: Precast concrete elements are normally heavily reinforced becausethey are cast horizontally.NON-CEMENTITIOUS MATERIAL: Epoxy resins and hardeners are occasionally used for tensilestrength.The product - precast/prestressed concrete building systemsIn conventional method, concrete is mixed on-site or ready mix is placed into forms on-site.Precast is a high quality concrete prepared in a specialized factory, formed using automatedmachinery into predesigned forms. Components are assembled on site, with connections beingmade on site. In the conventional method, steel reinforcement is used to counteract tensile(pulling apart) forces that can damage/destroy concrete. In the prestressed method, high qualitysteel is first pulled apart, placed in concrete, and the stress thereafter is released once theconcrete is set. This procedure is carried out in a factory, automated for higher productivity, withspecialized machinery.

Types of Precast Products

Hollow Core Slabs

Beams

Columns

Outer Wall Panels

Hollow core Inner Wall Inner PanelsApplications of Precast ProductsThe developments in products, materials and techniques have made precast / prestressedconcrete competitive in a variety of residential, commercial, industrial, transportation and manyother types of structures. A few examples of applications to different types of structures are:

Building Structures - Residential Buildings, Office Buildings, Warehouses and IndustrialBuildings and Other Building Structures

Parking Structures Precast Concrete Cladding

Stadiums/Arenas

BridgesPrecast concrete piles

They come in different sizes and shapes, ranging from 10-inch square piles to 66-inch diameterhollow cylinder piles.Pile caps also can be precast concrete, reducing exposure, forming andcuring inthe field. The concept of precast (also known as prefabricated) construction includes thosebuildings where the majority of structural components are standardized and produced in plantsin a location away from the building, and then transported to the site for assembly.

These components are manufactured by industrial methods based on mass production in orderto build a large number of buildings in a short time at low cost. The main features of thisconstruction process are as follows: The division and specialization of the human workforce The use of tools, machinery, and other equipment, usually automated, in the production ofstandard, interchangeable parts and products

This type of construction requires a restructuring of the entire conventional constructionprocess to enable interaction between the design phase and production planning in order toimprove and speed up the construction. One of the key premises for achieving that objectiveis to design buildings with a regular configuration in plan and elevation.


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Depending on the load-bearing structure, precast systems described in the WHE can be dividedinto the following categories: Large-panel systems Frame systems Slab-column systems with walls Mixed systems

The designation large-panel system refers to multistory structures composed of large wall andfloor concrete panels connected in the vertical and horizontal directions so that the wall panelsenclose appropriate spaces for the rooms within a building. These panels form a box-likestructure. Both vertical and horizontal panels resist gravity load. Wall panels are usually onestory high. Horizontal floor and roof panels span either as one-way or two-way slabs. Whenproperly joined together, these horizontal elements act as diaphragms that transfer the lateralloads to the walls.

A large-panel concrete building under constructionDepending on the wall layout, there are three basic configurations of large-panel buildings:

Cross-wall system. The main walls that resist gravity and lateral loads are placed in the shortdirection of the building. Longitudinal-wall system. The walls resisting gravity and lateral loads are placed in thelongitudinal directionPanel connections represent the key structural components in these systems. Based on theirlocation within a building, these connections can be classified into vertical and horizontal joints.Vertical joints connect the vertical faces of adjoining wall panels and primarily resist verticalseismic shear forces. Horizontal joints connect the horizontal faces of the adjoining wall and floorpanels and resist both gravity and seismic loads. Depending on the construction method, these

joints can be classified as wet and dry.Wet joints are constructed with cast-in-place concrete poured between the precast panels. Toensure structural continuity, protruding reinforcing bars from the panels(dowels) are welded,

looped, or otherwise connected in the joint region before the concrete is placed.Dry joints are constructed by bolting or welding together steel plates or other steel inserts castinto the ends of the precast panels for this purpose. Wet joints more closely approximate cast-in-place construction, whereas the force transfer instructures with dry joints is accomplished atdiscrete points. Figure 5 shows a plan of a large-panel building with the connection details. Inthis system, vertical wall panel connections are accomplished by means of groove joints, whichconsist of a continuous void between the panels with lapping horizontal steel and vertical tie-bars. Horizontal joint reinforcement consists of dowels projected from the panels and the hairpinhooks site-welded to the dowels; the welded length of the lapped bars depends on the bar


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diameter and the steel grade. Vertical tie bars are designed for tension forces developed at thepanel intersections. bars placed in vertical and horizontal

joints provide an increase in bearing area for the transfer of tension across the connections

Plan of a large-panel building showing vertical connection detailsFrame SystemsPrecast frames can be constructed using either linear elements or spatial beam-column subassemblages. Precast beam-column sub assemblages have the advantage that the connectingfaces between the sub assemblages can be placed away from the critical frame regions;however, linear elements are generally preferred because of the difficulties associated withforming, handling, and erecting spatial elements. The use of linear elements generally meansplacing the connecting faces at the beam-column junctions. The beams can be seated on corbelsat the columns, for ease of construction and to and to aid the shear transfer from the beam to

the column. The beam-column joints accomplished in this way are hinged. However, rigid beam-column connections are used in some cases, when the continuity of longitudinal reinforcementthrough the beam-column joint needs to be ensured. The components of a precast reinforcedconcrete frame are shown in Figure


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Slab-Column Systems with Shear WallsThese systems rely on shear walls to sustain lateral load effects, whereas the slab-columnstructure resists mainly gravity loads. There are two main systems in this category: Lift-slab system with walls Prestressed slab-column systemPrecast columns are usually two stories high. All precast structural elements are assembled bymeans of special joints. Reinforced concrete slabs are poured on the ground in forms, one on topof the other, as shown in Figure Precast concrete floor slabs are lifted from the ground up to thefinal height by lifting cranes.The slab panels are lifted to the top of the column and then moveddownwards to the final position. Temporary supports are used to keep the slabs in the positionuntil the connection with the columns has been achieved. In the connections, the steel bars(dowels) that project from the edges of the slabs are welded to the dowels of the adjacent

components and transverse reinforcement bars are installed in place. The connections are thenfilled with concrete that is poured at the site. Most buildings of this type have some kind oflateral load-resisting elements, mainly consisting of cast-in-place or precast shear walls, etc. Incase lateral load-resisting elements (shear walls, etc.) are not present, the lateral load pathdepends on the ability of the slab-column connections to transfer bending moments. When theconnections have been poorly constructed, this is not possible, and the lateral load path may beincomplete.


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Another type of precast system is a slab-column system that uses horizontal prestressing in twoorthogonal directions to achieve continuity. The precast concrete column elements are 1 to 3

stories high. The reinforcedconcrete floor slabs fit the clear span between columns.Hollow-core precast slabAfter erecting the slabs and columns of a story, the columns and floor slabs are prestressed bymeans of prestressing tendons that pass through ducts in the columns at the floor level and

along the gaps left between adjacent slabs After prestressing, the gaps between the slabs arefilled with in situ concrete and the tendons then become bonded with the spans. Seismic loadsare resisted mainly by the shear walls (precast or cast-in-place) positioned between the columnsat appropriate locations. A typical building under construction is shown in Figure

Post-tensioned slab-column connectionPrecast Panel Types for Building EnvelopesThere are generally four types of precast panels used as part of building envelopes:

Cladding or curtain walls

Load-bearing wall units

Shear walls

Formwork for cast-in-place concrete

Precast cladding or curtain wallsPrecast cladding or curtain walls are the most common use of precast concrete for buildingenvelopes. These types of precast concrete panels do not transfer vertical loads but simplyenclose the space. They are only designed to resist wind, seismic forces generated by their ownweight, and forces required to transfer the weight of the panel to the support. Common cladding

units include wall panels, window wall units, spandrels, mullions, and column covers. These unitscan usually be removed individually if necessary.Load-bearing wall units resist and transfer loads from other elements and cannot be removedwithout affecting the strength or stability of the building. Typical load-bearing wall units includesolid wall panels, and window wall and spandrel panels.Precast concrete shear wall panels are used to provide lateral load resisting system whencombined with diaphragm action of the floor construction. The effectiveness of precast shearwalls is largely dependent upon the panel-to-panel connections. Precast panels are used asformwork for cast-in-place concrete. The precast panels act as a form, providing the visible


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aesthetics of the system, while the cast-in-place portion provides the structural component ofthe system.

CENTRAL BUILDING RESEACH BUILDINGConstruction TechnologiesPre cast stone-blocks and solid concrete blocks for masonry. Pre cast concrete cored units andchannel units for flooring and roofing

ProductsBrick Extrusion machine for clay bricks. (Indian Patent no 118570)Energy efficient gypsum calcinator for making plaster of paris. (NRDC REPUBLIC DAY AWARD1989)

Mini climbing crane for material handling for construction of muli-tistoreyed buildings (IndianPatent no. 172047, NRDC Republic Day Award-1994)Concrete block making machines (Indian Patent No. 2266/DEL/97)Automatic free fall hammer for sub soil investigations (Indian Patent no. 172108)CBRICK machine for production of flyash bricks.Boring and skirting machine for making bored piles and skirted granular pile foundation. (IndianPatent no. 159540)Plant for production of coir-cement board as wood substituteAccelerated electrical curing for precast RCC and prestressed concrete components.Underground Horizontal Boring Machine for making bores under the ground.

Gypsum Calcinator CONCRETE BLOCK MAKING MACHINE CBRICKMACHINE


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BRICK MAKING MACHINEMAJOR AREAS OF R&D ACTIVITYUtilisation of agro-industrial by-product wastes in making burnt clay bricks & tilesImproved brick production and commercialization of process technologies

Technical appraisal, characterisation of raw material resources and suitability assessment forbrick & tile productionManual and mechanised production of bricks and tilesConversation of natural raw material resources and energy through innovative techniques

Design and development of thermally efficient fixed chimney brick kilnUtilization of low grade bio-mass in burning of bricks and tilesLime based building bricks / blocks through pressing and autoclaving/ atmospheric steamcuring/ moist curingPre-design cost estimate, plant lay out, productivity and maintenance for brick and tile units.Durability appraisal of building productsRURAL BUILDINGS & ENVIRONMENT

Rural Buildings & Environment Division has been conducting studies on rural housing and isengaged in the development of appropriate construction technologies, to improve traditionalhouses, new technologies for low cost houses and other buildings and environmental

improvements. Disaster mitigation for housing in cyclone affected areas including relief andrehabilitation and training to various organisations involved in rural development are some otherareas of work.Major Areas of R&D Activities

Technologies for improvement in the performance of traditional houses made of locally availablematerials like mud and thatchNew technologies for constructing houses using durable materials like brick, cement concrete,steel , stone and timberConstruction technologies for disaster (cyclone/flood) mitigation and relief and rehabilitationwork


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Low cost sanitation and waste water disposal systemsDevelopment and design of houses for economically weaker section for different regionsHouses for hilly areas

Highlights of R & DImprovement on Traditional MaterialsSoil stabilized bricks using cement, bitumen, molasses, limeNon-erodable mud plasterPlinth protection of mud wallsImproved method of making fire-retardent thatch roofFerro cement plaster for mud wallsFerro-cement plaster for fire-retardant thatch roofFrameless doors and window fixturesNew Construction Techniques

Pedestal piles for foundationPrecast concrete panelPrecast concrete joistsFerro concrete arched panels for roofsPyramidal roof with triangular precast concrete panels &

beamsUnreinforced pyramidal brick roofHouses for cyclone prone areasInstant shelter for disaster reliefManually pressed thatch panelsUltra low cost houseDoubly curved tilesHouses for rural poor in different regionsHouses for hilly areasHouses for economically weaker section

Demonstration house usingrural technologies

Fire retardent thatch roof

Highlights of R & DImprovement on Traditional MaterialsSoil stabilized bricks using cement, bitumen,molasses, lime

Non-erodable mud plasterPlinth protection of mud wallsImproved method of making fire-retardent thatchroofFerro cement plaster for mud wallsFerro-cement plaster for fire-retardant thatch roofFrameless doors and window fixturesNew Construction Techniques

Pedestal piles for foundation

Demonstration house usingrural technologies


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Precast concrete panelPrecast concrete joistsFerro concrete arched panels for roofsPyramidal roof with triangular precast concretepanels & beamsUnreinforced pyramidal brick roofHouses for cyclone prone areasInstant shelter for disaster reliefManually pressed thatch panelsUltra low cost houseDoubly curved tilesHouses for rural poor in different regionsHouses for hilly areasHouses for economically weaker sectionBuilding Systems

Prefab brick panel systemPrefab concrete panel systemPrefab jack-arch panel systemIntegrated thin wall and column system

Brick skeleton systemConcrete skeleton systemTimber skeleton systemBrick panels & concrete joists systemsPrecast concrete system for cyclone resistant housesHeat reflective & water proofing treatment forroofs.Sanitation & EnvironmentalImprovement

Low cost latrinesLow cost latrines for high water table areaWaste water disposal system

Ferro Cement unit for waste water disposal system

Fire retardent thatch roof

Disaster relief ultra low

cost house

Prefab brick panel system

Lowcost latrine

Waste water disposal


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system

TECHNOLOGY SHOWCASE

C BRICK

A technological approach for employment generation in areas near flyash ponds.Quality bricks from flyash.Compressive strength 40 to 80 kg/sq. cm.Water absorption less than 20%.Efflorescence free product3000 Bricks per day production requires:Manpower: 10 personsLand: 700 Sq.m.

Power requirement: 10 KWSuited to small scale industryValue addition to flyash30% saving in fuel in firing as compared to traditional clay brick technology.Suitable for manual and semi-mechanised productionRaw materials : Moderately plastic clay mass, flyash and fuel.Plant requirements : ConventionalCLAY FLYASH BRICKSValue addition to flyash30% saving in fuel in firing as compared to traditional clay brick technology.Suitable for manual and semi-mechanised productionRaw materials : Moderately plastic clay mass, flyash and fuel.

Plant requirements : ConventionalPOLYTILESHigh mechanical strengthExcellent chemical and wear resistanceVery low porosityDecorative and durableSuitable for floors and walls to residential, commercial and industrial buildings.

COIP CNSL BOARDSingle layer flat pressed medium density fiber board.Low water absorptionWorkable with normal wood working toolsPaint-able, nail-able and screw-ablePhysico-mechanical properties as per IS: 3087100% wood replacementLab scale technology ready for transfer


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SISLANA PANELSRaw materials: Sisal fiber and polyester resin.Alternative to single walled press boards.Light weight, rigid and weather resistant.Screw-able and nail-able.Adequate thermal insulation and sound absorption.Panel meets IS: 12406-88 requirements.Suitable for walling, door paneling and roofing applications

GYPSUM BINDERWater resistant gypsum binder.Properties :Color: Grayish whiteBulk density:1000-1200 kg/m3Compressive strength:20-30 MPa (28 days)Water absorption: 5-10% (28 days)Performance in water:No leachingSuitable for exterior applications for blocks and masonry mortars, low and highdensity glass fiber reinforced gypsum boards and for commercial gypsum plasters.ELECTRIC CURING OF CONCRETEConsistent quality product.

Low voltage (around 60V) to reduce electrical hazards.Power consumption: 70 Kwh/m3 of concrete.

55-60% of 28-days strength attained within 24 hours.Especially useful in low temperature regions.Suitable for PCC poles, PSC railway sleepers and PCC rafters.ENVIRONMENT FRIENDLY MATERIALS AND TECHNIQUES

By and large, conventional building technologies like burnt bricks,steel and cement are high in cost, utilise large amount of non-renewable natural resources like energy, minerals, top-soil, forestcover etc. These increase dependence on external materials and

manpower, harm the local economy and are generally polluting innature.

The materials and technologies chosen for construction must, inaddition to functional efficiency, fulfil some or more of the following

criterion, for the cause of sustainability and a better quality environment:non endanger bio-reserves and be non-polluting;be self-sustaining and promote self-reliance.recycle polluting waste into usable materialsutilise locally available materialsutilise local skills, manpower and management systemsbenefit local economy by being income generatingutilise renewable energy sources

be accessible to the peoplebe low in monetary cost

Environment-Friendly, Energy Efficient,Cost-Effective Composite Materials/Productsfor Low Cost Housing


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Product:Raw Material Source :Materials for production :

Applications :

BAMBOO MAT BOARDBamboo grass (Plant), species (Meleannca baccifera)Bamboo, polymeric resin, chlorinated hydrocarbons and boron and cashell liquid Flooring, walling, structural membrane, false ceiling, door/


Applications :

BAMBOO MAT VENEER COMPOSITEPlantation wood, bamboo plant,Plantation wood veneer, bamboo mat, polymeric resin, chlorinated hy

boron, cashew nut shell liquid,Door skin in flush doors, structural use as roofing, web construction, pshelters, packing, modular partitions, furniture.


Applications :

PHOSPHOGYPSUM PANELHydrofluoric and phosphoric acid industry and fertilizer industries.By-product phosphogypsum/flouro-gypsum, water, hot aqueous ammsulphate and sulphuric acid silica mixture etc.Gypsum plaster and plaster products: Plaster boards, blocks, bricks, tand walling panels, false ceiling tiles.

Product:

Raw Material Source :Materials for production :

Applications :

BAMBOO CORRUGATED ROOFING SHEET

Bamboo grass (Plant), Species (Meleannca baccifera)Bamboo, polymeric resin, chlorinated hydrocarbons, boron, cashew ncoating for UV protection and to improve impermeability to water.Roofing sheets as substitute to corrugated Asbestos Cement sheets, Iron sheets, Aluminum sheets and Fibre-reinforced Plastic (FRP) sheet


Applications :

BAGASSE COMPOSITE PANEL/BOARDSugar industryGeneral purpose, polyester resin, methyl ethyl ketone and cobalt napFor variety of building and furniture applications. Properties closelyresemble with the wood but lighter in weight. Stackable and can be echiselled and sawed.


Applications :

JUTE POLYESTER COMPOSITEJute industry (Jute plant is grown in several developing countries)Woven jute fibres, and polyester amide polyol as interfacing agentChip boards, roofing sheets, door shutters, partition panels and door/


Applications :

COIR COMPOSITE BOARDCoconut Plantation in Coastal RegionsCore fibres, mineralized water, cashew nut shell liquid, para formaldeMedium Density Fibre boards, can be used as wood substitute for pansurfacing and partitioning and door/window shutters.


Applications :

BAMBOO-RICE HUSK COMPOSITERice mills, bamboo plants (grass)Rice husk, bamboo mat, cashew nut shell liquid and phenolic resin

Temporary shelters, warehouses, false ceilings, Insulation, partition aindustrial and domestic floorings.


RED-MUD POLYMER JUTE COMPOSITEAluminium extraction plant and Jute IndustryRed-mud, jute fabric, polymeric binder


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Applications : Partitions, door shutters, roofing sheets.


Applications :

RED-MUD-JUTE DOOR SHUTTERAluminium extraction plant and Jute IndustryRed-mud, jute fabric, polymeric binderDoor shutters.

Product:Raw Material Source :Materials for production :Applications :

CELLULAR LIGHT WEIGHT CONCRETE BLOCKFly Ash from coal based power generating plantsFly Ash, cement, sand, water and foaming agentConcrete blocks, densities ranging from 400 kg/m3 to 1800 kg/m3. FiIn-situ cellular walls & partitions. Very good insulation at roof tops forreduction of heat load in buildings.


Applications :

FLY ASH POLYMER COMPOSITEAsh from coal-based power generating plantsFly ash, polymeric materialPartitions, door shutters, roofing sheets.


Applications :

COTTON STALK COMPOSITEWaste from cotton plantsCotton plant waste, cashew nut shell liquid, para formaldehydeMedium Density Fibre boards, partitions, door shutters and furniture.


Applications :

BLAST FURNACE SLAG COMPOSITEWaste from steel plantsBlast furnace slag, polymeric resin, laminating materialPartitions and interior finishing on walls.


Applications :

BAMBOO LAMINATED COMPOSITEBamboo plant, woodBamboo mat, waste wood chips, polymeric resinFlooring, walling and partitions.


Applications :

FIBRE REINFORCED BAMBOO COMPOSITESynthetic fibre, bambooSynthetic fibre, polymeric resin, bambooPartitions, false ceilings and interior finishing on walls.


Applications :

JUTE LAMINATED COMPOSITEJute plants, woodJute fibres and wood chipsFlooring, walling and partitions.


Applications :

CEMENT BONDED PARTICLE BOARDCement and woodCement, waste wood chipsRoofing, flooring, walling and door shutters.


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Applications :

BANANA COMPOSITE BOARDBanana plantBanana plant sheath, methyl ethyl ketone and cobalt napthenatePartition panels and panels for door shutters.


Applications :

SANDWITCHED FLY ASH PANELAsh from coal-based power generating plantsFly Ash, cement, sand, foaming agent.

Partitions and walling panels.


Applications :

JUTE/COIR COMPOSITESJute plant, coconut treeJute fibres, coir fibres, polyester amide polyol as interfacing agent.For making chip boards, roofing sheets, door shutters, partitions and


Applications :

PINE NEEDLES BOARDPine treeNeedles from pine tree, polymeric resin, methyl ethyl ketoneFlooring, walling, structural membrane, boxes and interior finishing o


Applications :

WHEAT STRAW BOARDWaste from wheat cropWheat straw/husk, cashew nut shell liquid, polymeric resinPartitions, false ceilings, insulation and interior finishing on walls.


Applications :

PLANTATION TIMBER DOORS/WINDOWSQuick growing plant-wood from rubber wood plants, poplar wood andRubber wood and poplar wood plants. Thermoplastic and thermosettDoors and window frames, flush and panelled door shutters.

OPEN PREFAB SYSTEMS & SMALL BUILDING COMPONENTS

Partial PrefabricationOpen prefab systems based on an appropriate production level andsmall, easily to handle elements with rationalised production methodshave attracted the attention of housing experts as an important optionfor arresting the rapidly rising escalation in the costs of material andlabour. Building Centers in different regions of India have beeninstrumental in propagating several of these prefab systems at thegrass-root level.Partial prefabrication can be usefully employed for practically every part of a building - foundations,walling systems, doors and windows, roofing systems, lintels and staircase elements. Costs of a roof beingone of the major components of the construction outlay in any building project, one of the thrust areas hasbeen the prefabrication of roofing elements

CELLULAR LIGHTWEIGHT CONCRETE

Cellular Lightweight Concrete (CLC) has been used in over 40 countries over thepast 25 years to produce over hundred thousand houses and apartments, apartfrom schools, hospitals, industrial and commercial buildings. CLC is an air-curedlightweight concrete with flyash as a major ingredient, that can be produced atlarge project sites just like traditional concrete, utilising equipment and mouldsnormally used for traditional concreting. It is especiallysuitable in India for low-rise loadbearing constructions and forpartitioning work in multistorey blocks.Benefits of CLC Blocks/Panels:

Tremendous weight reduction


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High thermal insulationOptimal fire ratingSubstantial material saving:No gravel usedLittle cementLess steel in structure and foundationEasy and fast productionNo primary energy and reduced transportation costsBoon for remote areas with only sand availability.In view the use of flyash (33%) in CLC and this being a good substitute of ordinary clay bricks ( which usehigh energy and precious agricultural topsoil) the Govt. of India has given special import duty concessionsfor specialised equipment.

report on precast elements

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