MODULAR FRAMEWORK IN BUILDING CONSTRUCTION

MODULAR FRAMEWORK IN BUILDNG CONSTRUCTION CONTENT

S.NO CHAPTERS PAGE NO. 1 INTRODUCTION 2 2 WORKFLOW IN MODULAR FRAMEWORK 6 3 COMPONENTS OF PRECASTED WALL 10 4 INTERNAL STRUCTURE OF A PRECAST WALL 16 5 FABRICATION 17 6 BATTERY MOULD PRODUCTION 20 7 STEAM CURING 24 8 STOCK YARD 26 9 ERECTION 27 10 COMPONENTS OF PROCASTING WALL 31 11 ADVANTAGES 43 12 DISADVANTAGES 46 13 CONCLUSION 47 14 REFERENCES 48

CHAPTER 1 INTRODUCTIONAncient Roman builders made use of concrete and soon poured the material into moulds to build their complex network of aqueducts, culverts, and tunnels. Modern uses for pre-cast technology include a variety of architectural and structural applications featuring parts of or an entire building system. In the modern world, pre-cast paneled buildings were pioneered in Liverpool, England in 1905. A process was invented by city engineer John Alexander Brodie, whose inventive genius also had him inventing the football goal net. The tram stables at Walton in Liverpool followed in 1906. The idea was not taken up extensively in Britain. However, it was adopted all over the world, particularly in Eastern Europe. In Finland this process of construction gained much importance compared to other types of construction. This process is now adopted all over the world with its inherent advantages. The reduction of the building cost through modernization of building methods and production of prefabricated components in the factories have received very large attention in all parts of the world, U.S.S.R is the leading to extensively adopt prefabricated construction for a variety of buildings.MODULAR FRAME WORK:Flexible types of structure are a requirement from commercial building developers in an increasingly fluid property market. More and more new buildings need to be designed to be adaptable to changes throughout their lifetime. In high-rise structural engineering, there are essentially three building materials: structural steel, reinforced concrete, and a composite of the two. Within each material, there are a very large number of options that one could choose. This is the latest technology used in the construction for work faster, lighter and good results are obtained at the end of the project. In the highly competitive construction industry, the ability to combine quality, innovation, speed and environmental sustainability in construction will serve as a key differentiator. They are two types of methods to construction of frameworks. Precasting technology Procasting technology

1.1 WHAT IS PRE-CASTING TECHONOLGY?The word Precast Stands for the product which is cast before used in the Construction. Precasting is a construction product produced by casting concrete in a reusable mold or "form" which is then cured in a controlled environment and transported to the construction site and lifted into place. In contrast, standard concrete is poured into site-specific forms and cured on site. Precast stone is distinguished from precast concrete by using a fine aggregate in the mixture, so the final product approaches the appearance of naturally occurring rock or stone. Instead of constructing at the site the walls are constructed at the battery case plant and transported to the site for erection. The Ministry of works, Great Britain defines prefabrication as the formation of buildings or components by the assembly of the materials otherwise than in their final position. The components of a structure are prefabricated and later erected and assembled to create the building then the process may be generally looked upon as prefabricated construction.Structural elements for timber and steel have been fabricated in the workshop for long, but it is precast concrete that is considered as prefabricated structural elements. The development of light weight aggregates, of methods of steam curing and drying of cellular concrete boosted prefabricated construction.

1.1.1 WHY PRE-CASTING?By producing precast concrete in a controlled environment (typically referred to as a precast plant), the precast concrete is afforded the opportunity to properly cure and be closely monitored by plant employees. Utilizing a Precast Concrete system offers many potential advantages over site casting of concrete. The production process for Precast Concrete is performed on ground level, which helps with safety throughout a project. There is a greater control of the quality of materials and workmanship in a precast plant rather than on a construction site. Financially, the forms used in a precast plant may be reused hundreds to thousands of times before they have to be replaced, which allow cost of formwork per unit to be lower than for site-cast production. Mainly in the construction of flyovers and other road works Precasting plays an important role in reducing the traffic obstruction during peak hours and other miscellaneous disturbances. Precasting may be adopted where the roads or site are narrow and construction at site is impossible. Construction has long been perceived as a labour intensive, site based activity that requires a lot of wet works on site, such as concreting, plastering and bricklaying. The industry has also not been associated with high levels of precision as rectification and repair works are normal activities seen as part of "construction tolerance".Prefabrication technology, in particular precast technology, has challenged these mindsets and transformed the industry as the processes involved are more akin to production lineconcepts adopted by the manufacturing industry. Under the controlled factory environment, much lower tolerances and improved quality of surface finish are achieved that eliminate many of the quality problems associated with in-situconstruction. The factory produced precast components are then assembled on site using cranes by skilled precast erection teams. In addition, with the reduction of on-site activities, precast technology provides greater efficiency and increases productivity standards in an industry not traditionally known for its quality and productivity standards.In Singapore, precast technology has been extensively used to replace traditional construction for high rise housing projects, industrial and commercial projects. With India embarking on large scale developments similar to the public housing program in Singapore, precast construction needs to be explored as a viable alternative to existing construction methods. The result would be a total transformation of the construction industry, as has happened in Singapore.

1.2 WHAT IS PROCASTING TECHNOLOGYConstructing at the site the walls are constructed by using panels, this panels are laid in and out of the reinforcement wall. The concrete is poured in the box shaped panels. This type of system was used directly in the site. The word procast Stands for the product which is cast before (Pro) used in the Construction. Procasting is a construction product produced by casting concrete in a reusable mold or "form" which is then cured in a controlled environment. Procasting stone is distinguished from procasting concrete by using a fine aggregate in the mixture, so the final product approaches the appearance of naturally occurring rock or stone. Structural elements for timber and steel have been fabricated in the workshop for long, but it is Procasting concrete that is considered as fabricated structural elements. The development of light weight aggregates, of methods of steam curing and drying of cellular concrete boosted construction. There is a greater control of the quality of materials and workmanship in the construction site. Mainly in the construction of flyovers and other road works procasting plays an important role in reducing the traffic obstruction during peak hours and other miscellaneous disturbances.

2. WORKFLOW IN MODULAR FRAMEWORK

Owner brings the concept

Architect work on this concept and provides initial drawings to the precast engineering firm

Precast engineer completes the design process and forwards the information to the fabrication firm

Based on the piece drawings or called shop ticket, fabricators starts casting these products in the yard

The pieces are shipped at the construction site

Erector bringing his expertise in field follows the erection sequence to complete the project.

Total precast concrete building systems are becoming a popular choice for many construction projects. Architectural and structural precast, prestressed concrete components can be combined to create the entire building Developers who use total precast systems say precast can shorten the project timetable six to eight weeks when compared with steel and even more when compared with cast-in-place concrete construction. That savings can be critical in bringing a new building into a competitive marketplace or in meeting a tenant's need for occupancy on a specific date. A total precast system's speed helps keep projects on track.FIG. 2.1 FLOW CHARTThe precast concrete structural system is rarely adopted in office buildings because of the typical open plan design and long spans which give rise to deep beams and heavy weight of each individual member. The feasibility or constructability of using precast concrete structural system and construction method, especially for office buildings located in high value urban districts usually with highly constrained site areas, is not well ascertained by most designers. As a result, the precast concrete system and method, especially one that involves structural precasting, its merits in minimizing construction waste and environmental impacts. Comparison of different structural construction methods in various categories, items etc. the relative performance had been shown in the next table.Table 2 Comparisons of Different Structural Schemes and Associated Construction MethodsEvaluation on the Relative Performance of Different Structural System and

Associated Construction Method

Aspects of ConcernsRelative Performance of Different Structural

System and Associated Construction Method

CategoriesItemsCastingRCCPrecast

Foundation CostHighMediumHigh

Material CostLowHighLow

Transportation CostMediumHighHigh

CostInstallation CostHighLowMedium

Protection CostLowHighLow

Decoration CostLowHighLow

Maintenance CostLowHighLow

OverallLowHighLow

Design Finalization Lead TimeShortLong(1)Medium

Procurement andProcurement Lead TimeShortLongMedium

Preparation TimeFabrication TimeShortLongMedium

OverallShortLongMedium

Installation TimeLongShortMedium - Short(2)

ConstructionFire Protection Application TimeNilLongNil

TimeFinishes Application TimeMediumLongShort

OverallMediumMediumMedium-Short

Embodied EnergyLowHighLow

Insitu Formwork RequirementsHighLowLow

Noise PollutionLowLowLow

EnvironmentalAir PollutionLowLowLow

ImpactWater RequirementsLow LowMedium

Wastage GenerationsHighLowLow

Difficulties in RecyclingLowMedium(3)High

OverallHighLowLow

Off-Site StorageLowHighHigh

On-Site StorageLowHighHigh

Site Access RequirementsLowHighHigh

LogisticEffect from Site SurroundingsLowHighHigh

RequirementsOff-site TransportationLowHighHigh

Vertical Transportation on siteLowMediumHigh

Just In time RequirementsLowHighHigh

OverallLowHighHigh

Resistance to Design ChangeLowHighMedium

Difficulties in Finishes ApplicationLowHighLow

FlexibilityConstraint on Headroom RequirementsHighLowHigh

Constraint on Column SpacingsHighLowHigh

Constraint on Services PenetrationLowHighLow

CHAPTER 3COMPONENTS OF PRECASTED WALLThe construction of the prefabricated walls involves the following components which are arranged in the shutter plates as per standards. Usually the walls have steel reinforcement besides that it also consists of several other components which completes the construction the skeleton part of the precasted wall. Each component has its own advantage and function to produce the load bearing capacity, ductility, strength, good appearance etc. usually there are seven components which are listed below additional components can also be used to improve the inherent properties. Let us study each of them in detail Spacers Sleeves PVC cover blocks Magnets Dowels Lifting hooks Connecting loops

3.1 SPACERS:These are provided in between the steel reinforcement fabrication during the primary level of pre casting. Basically spacers are provided to overcome the problem of steel reinforcement bulging out the wall during the battery case mould production. Spacers are usually of 90mm in diameter made of strong plastic material which will not melt during the time of hot water curing in battery case. These will allow getting the wall having reinforcement exactly at the centre of the wall after getting the precasted wall. 140mm diameter spacers are used in 150mm walls.

FIG.3.1 SPACERS3.2 SLEEVES:Sleeves impart the internal strength of the wall during the time of erection. The entire load of the wall is imparted on the sleeves they give the correct shape for the house. Sleeves are called as FEMALES where as the 25mm steel bars are called as MALES. The two ends of the sleeves are open for the insertion of the 25mm diameter steel bars. Therefore these play a vital role in the precast terminology. These are made of light weight steel of 25mm diameter and 25 meters height. The diameter of the sleeves depends upon the load bearing of the wall. External wall sleeves have greater diameter and height compared to internal wall sleevesWALL THICKNESSDIAMETERLENGTH

100mm50mm550mm

150mm65mm550mm

TABLE.3.2 MEASURES

FIG.3.2 SLEEVE3.3 PVC COVER BLOCKS:PVC cover blocks are used in the internal walls and they serve the same purpose like spacers. The main difference between ties and spacers is, spacers are used in the external walls because of large thickness of walls where as ties are used in the internal walls because of small thickness of walls. Ties are tied at the joints with the help of iron wires used to tie the steel bars. Usually 25mm and 15mm cover blocks are used.

FIG.3.3 PVC COVER BLOCK3.4 MAGNETS:Magnets are used to keep the wall in stiff position due to the external disturbances during the fabrication. Usually magnets are kept inside the frame of on opening, door or a window because when the wall in ready these magnets are removed and used for another wall. Care should be taken while placing the magnets during the fabrication at joints or openings. Once the magnet is placed at a joint I should not be removed under any circumstances till concrete wall is obtained, removing or disturbing the place of the magnet disturbs the whole fabrication work.

FIG.3.4 MAGNETS3.5 DOWELS:Dowels are usually called as males. There role is during erection and joining of the walls. They are of 650mm height made of iron bars of 25mm and 16mm diameter during the time of erection the walls are placed such the Dowel of the lower wall should be inserted in the sleeve of the upper wall therefore sleeve and Dowels rods are made with same diameter and height. These components make the whole structure look like one. Total load on the structure is equally distributed through these Dowels therefore based upon the load falling on the structure dowels are designed

FIG-3.5.1 DOWELS3.6 LIFTING HOOKS:Lifting hooks are provided to lift the walls during the battery molding, transportation of walls to site are during the erection of walls at site. The diameters of the lifting hooks are 16mm, 20mm, 25mm depending upon walls. These are inserted 10mm deep inside the wall. They are attached to steel reinforcement already provided to the wall therefore limiting values are not disturbed by fixing the lifting hooks. For internal walls 16mm diameter hooks are provided and for external walls 20 or 25mm are provided based upon the external wall thickness.

FIG.3.6 INVERTED U SHAPED HOOKS3.7 CONNECTING LOOPS:Loops are provided at the sides of the walls for joining at the time of erection. Two to three loops are provided vertically for a wall. If the walls are not provided with loops then it becomes difficult to join the walls at the time of erection. Specification of connecting loops is PVL 80.

FIG.3.7 CONNECTING LOOPSWhen natural calamities like earth quakes occur the connecting loops are disjoined without affecting the structure. This is the advantage available with the connecting loops these are also responsible for distributing the load applied by the Dowels and other miscellaneous components.

CHAPTER 4 INTERNAL STRUCTURE OF A PRECAST WALL

FIG.4.1 INTERNAL STRUCTURE WALL

CHAPTER 5FABRICATION5.1 GENERAL:Before placing the wall in the battery mould fabrication should be done using cold shutter plates. The process of providing steel reinforcement and other provisions such as doors, windows, ventilators, water piping, and electric circuits is called as fabrication. Fabrication must be done very carefully and systematically as this plays an important role. If once any of the single provision is not made and the wall is precasted then it becomes impossible to provide after the recasting process.5.2 PROCEDURE:Usually fabrication is done with the help of wall panels of different sizes according to requirement; walls panels mostly used are 4, 6. 4 cold shutter plates are used for manufacturing the internal walls where as 6 walls are used to manufacture external walls due to large thickness.

FIG.5.2 COLD SHUTTER PLATE5.3 FIGURES OF COLD SHUTTER PLATES

FIG.5.3 6 EXTERNAL COLD SHUTTER PLATE

FIG.5.3 4 INTERNAL COLD SHUTTER PLATE 5.4 WALL PLANS FOR PREFABRICATIONIn Precasting the walls are designed in software called PRESTRO which is the advanced version of the staad pro. An architect designs the walls as per requirements and wall plans are sent to engineer for fabrication process which reduces the time and work power as the walls are designed in the software. The role of the structural engineer is to see whether the reinforcement is placed properly or not.Precast wall components are arranged during the fabrication of walls.

CHAPTER 6BATTERY MOULD PRODUCTION6.1 GENERAL:Battery mould production consists of vertical spaces where precast Cold shutter plates are placed after the fabrication process is completed. Wall panels are moved with the help of gantry cranes which are manually operated with the help of remotes. Dimensions of the wall, and all the connections such as electric power points, water pipe fittings should be checked thoroughly before placing a wall in the battery mould care should be taken while lifting the wall such that the wall should not get disturbed due to improper handling by crane.

FIG. 6.1 BATTERY MOULD PRODUCTION EQUIPMENTAfter placing the wall in the mould concrete is poured with the help of pumping. Pumping of concrete should be done very carefully to prevent the humps and air voids. Self compacted concrete is used to fill the battery mould so that the concrete freely flows through the empty spaces in the form of liquids. While filling offsets are provided for slab arrangement. When the filling process completes the walls are left free for nearly 45min and then boilers are switched on for hot curing of walls at 60-80 degrees temperature. Hot curing imparts greater strength compared to the general CIS walls, this process continues for 12 hours and then the walls are taken out from the battery mould with the help of gantry cranes. While placing the walls single crane is used and while removing two cranes are used to balance the loads.

FIG-6.2 PRECAST WALL AFTER REMOVING FROM BATTERY MOULD PRODUCTION

FIG.6.3 PLACING OF WALL IN BATTERY MOULD PRODUCTION

FIG.6.4 GANTRY CRANE FOR LIFTING THE WALLSCHAPTER 7STEAM CURING7.1 GENERAL:Hot weather may be defined as any period of high temperature in which special precautions need to be taken to ensure proper handling, placing, finishing and curing of concrete. Hot weather problems are most frequently encountered in the summer, but the associated climatic factors of high winds and dry air can occur at any time, especially in arid or tropical climates. Hot weather conditions can produce a rapid rate of evaporation of moisture from the surface of the concrete and accelerated setting time, among other problems. Generally high relative humidity tends to reduce the effects of high temperature.7.2 WHY TO CONSIDER HOT WEATHER?It is important that hot weather be taken into account when planning concrete projects because of the potential effects on fresh and recently placed concrete. High temperatures alone cause increased water demand, which in turn will raise the water-cement ratio and yield lower potential strength. Higher temperatures tend to accelerate slump loss and can cause loss of entrained air. Temperature also has a major effect on the setting time of concrete; concrete placed under high temperatures will set quicker and can therefore require more rapid finishing. Concrete that is cured at high temperatures early will not be as strong at 28 days as the same concrete cured at more moderate (70F) temperatures.High temperatures, high wind velocity, and low relative humidity can affect fresh concrete in tow important ways; the high rate of evaporation may induce early plastic shrinkage or drying shrinkage cracking, and the evaporation rate can remove surface water necessary for hydration unless proper curing methods are employed. Thermal cracking may result from rapid drops in the temperature of the concrete, such as when concrete slabs or walls are placed on a hot day followed by a cool night. High temperature also accelerates cement hydration and contributes to the potential for cracking in massive concrete structures.7.3 HOW TO CONCRETE IN HOT WEATHER:The key to successful hot weather concreting is recognition of the factors that affect concrete and planning to minimize their effects. Use proven, local recommendations for adjusting concrete proportions, such as use of water reducing, set retarding admixtures. Perhaps a moderate heat of hydration cement (ASTM Type II moderate heat) or puzzalonic admixture (fly ash) can reduce the effects of high temperatures.Advance timing and scheduling to avoid delays in delivery, placing and finishing is a must; trucks should be able to discharge immediately and adequate personnel should be available to place and handle the concrete. When possible, deliveries should be scheduled to avoid the hottest part of the day.In the case of extreme temperature conditions or with mass concrete, the concrete temperature can be lowered by using chilled water or ice as part of the mixing water.Other measures such as sprinkling and shading the aggregate prior to mixing can be used to help lower the temperature of the concrete. If low humidity and high winds are predicted, then windbreaks, sunscreens or mist fogging may be needed to avoid plastic shrinkage cracking in slabs.7.4 ADVANTAGES OF STEAM CURING:High pressure steam cured concrete develops in one day or less the strength as much as the 28 days strength of normally cured concrete, the strength developed does not show retrogression.High pressure steam cured concrete exhibits higher resistance to sulphur attack freezing and thawing action and chemical action. It also shows less efflorescenceHigh pressure steam cured concrete exhibits lower drying shrinkage and moisture movement.CHAPTER 8STOCK YARDAfter battery cases molding the walls obtained are placed in the store house constructed near the batching plant. The store house consists of various groups of walls which are divided as per requirement. The information regarding the walls that is date of manufacturing, wall number in the plan etc. the entire information regarding the walls is stored in the data base of a computer so that while transporting walls of required house or villa can be transported.

FIG.8.1 STOCK YARD FOR PRECAST WALLS

When the walls are shifted to the Stock yard checking is done by the engineer such that all the measurement is provided correctly or not. Provisions for the water and electric circuits are also checked and then passed on to Stock yard. If any corrections are to be done they are made manually.CHAPTER 9ERECTIONThe erection of precast walls generally involves the following steps: Moving the precast wall panels from delivery truck or site stock yard to the designated locations for Installation; Raising the precast panels to the required elevation (and rotating to correct orientation if necessary); Fixing the precast panels in position; and Casting the wet joints and/or grouting and applying sealant.Firstly, the walls taken are taken out from the stock yard and placed in the truck for the transportation of walls to the site with the help of gantry cranes.

FIG.9.1 PRECASTED WALL LIFTED FOR TRANSPORTATIONDuring the lifting care should be taken by the Operator so that accidents should not take place due to mishandling. Lifting process should be done as slow as possible. Four to five or eight walls can be transported at a time to the site depending upon the size of the wall.

FIG.9.2 WALLS PLACED IN TRUCK FOR TRANSPORTATION

Then at the site the walls of selected flat or room are lifted up and placed. Before placing the wall markings are done for the correct position for the wall to be placed. While lifting the wall for erection care should be taken such that wall edges should not be tampered

FIG.9.3 WALL LIFTED FROM TRUCK FOR ERECTIONAt last the walls are joined together with the help of iron rods which are drilled into the slab for joining of two precasted walls. The walls can be joined by cement mortar, but this method is adopted for internal walls external walls are joined with the help of rods and loops.

FIG.9.4 JOINING OF TWO PRECAST WALLSOffsets are provided for the walls during the time of battery case molding such that slabs can be easily fixed between two precasted walls. Usually CIS walls are prepared at the site and precasted walls are joined to them. Therefore the structure consists of both precasted walls and CS walls

FIG.9.5 PRECAST WALL HELD BY SUPPORTS

FIG.9.6 CONSTRUCTION OF CIS WALLSAfter erection the walls are kept under support such that they should not fall under their own weight. When the walls are tightly joined the supports are removed.

CHAPTER 10COMPONENTS OF PROCASTING WALL10.1 INTRODUCTION:The construction of the walls involves the following components which are arranged in the shutter plates as per standards. Usually the walls have steel reinforcement besides that it also consists of several other components which completes the construction the skeleton part of the procasted wall. Each component has its own advantage and function to produce the load bearing capacity, ductility, strength, good appearance etc. usually there are seven components which are listed below additional components can also be used to improve the inherent properties. Let us study each of them in detail Formwork girders Wall formwork Column formwork Slab formwork Bridge and tunnel form work Peri clean Transportation process Form works panels/ plywoodBy this components are used in the site for the construction of the building. Every component has its own important play in the construction. All been used in systematic way for the building construction.

10.2 FORMWORK GIRDERS10.2.1 GT 24The versatile girder The girder is a central component for slab and wall formwork system and choosing the right one is crucial in achieving the highest possible level of cost-effectiveness. The decisive factors are the durability and handling costs not the original investment.

FIG.10.2.1 GT 24Through the high load-bearing capacity and rigidity of the GT 24 compared to other 20-cm high formwork girders, fewer girders, steel walers or props are required for both wall and slab formwork.10.2.2 VT 20K The 20 girder with steel end capDue to the high proportion of synthetic resin in the high grade timber. The peri VT girder is able to maintain its high level of dimensional stability and robustness. Steel caps, secured with side to side rivets, provide strong impact and edge protection and extend the service life of the girder. The VT 20Khas been specially developed for use with slab formwork and is the low price option for thinner slabs.

FIG NO-10.2.2 GT2410.3 WALL FORMWORK10.3.1 MAXIMO Panel Wall Formwork

FIG.10.3.1 MAXIMO PANEL WALL FORMWORKFOR FAST FORMING AND NEAT JOINT AND TIE ARRANGEMENTThe MAXIMO panel formwork succeeds in minimizing imperfections in the concrete finish and creates a neat joint and ties arrangement.By means of a newly developed conical tie system, the wall formwork system does not require any spacer tubes and work takes place from only one side. This means maximum reductions in expense and considerable savings of time and resources. Apart from the advantages of a panel formwork regarding flexibility and fast shuttering times, MAXIMO opens up new possibilities of fashioning visible concrete surfaces through a particular arrangement of individual elements. The uniform tie arrangement continues to underline the very achievable results even more.

10.3.2 TRIO Panel Wall FormworkHigh labour costs on construction sites increasingly require easier and faster formwork systems. Without exception, the number of components to be moved determines the shuttering times and ultimately the cost of construction. During the development of the TRIO system, PERI engineers placed great importance on reducing shuttering times.Thus a very versatile formwork system was created with a minimum of different components which meets and exceeds the demands of the modern-day job site in a simple way.Fewerindividual components for faster forming.

TRIO is the versatile panel formwork for all projects, on small building sites as well as for large-scale projects

FIG.10.3.2 TRIO PANEL WALL FORMWORKTRIO The versatile panel formwork system TRIO-L Alu the light aluminum system supplementing steel PERI TRIOTRIO 330 Panel formwork for industrial constructionTRIO Structure the TRIO variation for special fairfaced concrete finishesTRIO Housing the fastest TRIO versionTRIO PlatformThe TRIO version providing the highest level of safety.TRIO is the versatile panel formwork for all projects, on small building sites as well as for large-scale projects10.3.3 DOMINO Panel Wall Formwork

FIG.10.3.3 DOMINO PANEL WALL FORMWORKFor housing and civil engineering PERI DOMINO is a lightweight panelized formwork system with elements made of steel or aluminium for housing and civil engineeringprojects.With only four panel widths and structure can be formed. The 0.75 m wide element is also available for use as a multi-purpose panel. Permissible fresh concrete pressure: With concreting heights of up to 2.50 m, the system has been designed for the full hydrostatic pressure according to DIN 18202, Table 3, Line 7 (steel elements). For larger heights, 60 KN.10.3.4 HANDSET Panel Wall Formwork

FIG.10.3.4 HANDSET Panel Wall FormworkPERI HANDSET is a formwork system specially developed for work on a small scale, and cuts the high costs of shuttering with the old system of timbers, boards and nails.Few panel sizes ensure a high level for utilisation for each element. All components are light enough to be handled by just one person.The HANDSET has been designed for a fresh concrete pressure of 40 kN/m.10.3.5 VARIO GT 24 Girder Wall Formwork

FIG.10.3.5 VARIO GT 24 Girder Wall FormworkVariable for all designs and applicationsVARIO GT 24 is the wall formwork with continuously adjustable element connections for all designs and applications. PERI VARIO is an ideal choice as project formwork, with the VARIO standard as a rentable option. Regardless whether it is industrial or housing construction, bridge abutments or retaining walls, any ground plan and all heights can be formed using PERI VARIO.Using VARIO GT 24 as project formwork, elements are optimized accordingly. This means the following points can be freely selected: - type and size of plywood as well as the fixings- element widths and heights- vertical or horizontal tie arrangement- permissible fresh concrete pressureThe formwork is extended by means of the VARIO extension splice 24 in 30 cm increments up to a maximum of 8.10 m. Quickly and easily fitted through the latticework of the GT 24, without having to drill the girders. Only two splicing components which are quickly connected using triple-wing nuts. The flexurally stiff connection also aligns the girders.

10.4 Column FormworkThis type of formworks is used in the construction for columns. There are different types of column formwork for the construction.10.4.1 RAPID Column formwork

FIG.10.4 RAPID Column formworkFor flawless fairfaced concrete Perfect concrete surfaces can be achieved using RAPID column formwork. Through the unique, patented clamping principle, the plywood is simply clamped to the frame. This results in high quality concrete surfaces without any unsightly nail or screw indentations. The chamfer strips effectively seal the corner areas. Using the RAPID system, rectangular or square column cross-sections up to 60 x 60 cm can be continuously constructed without requiring any additional anchors in the concrete. Columns with sharp edges are also possible.

10.4.2 RS Push-Pull-Props

FIG.10.4 RS Push-Pull-PropsA complete range up to 14.00 m.With the development of the new PERI RS 210, RS 300, RS 450 and RS 650 push-pull-props, particularly importance was placed on ensuring a long service life, low maintenance costs and fast handling.Therefore, all PERI push-pull props are now galvanized and with the exception of the RS 210 telescopic. The available lengths in the push-pull prop programme are complemented by the RS 1000 and RS 1400 props which are already manufactured in the same way.For use with prefabricated concrete elementsSafe installation of push-pull props on prefabricated concrete elements from the ground is possible by means of the new PERI Push-Pull Prop adapter RS together with the Quick Connector Head RS. As a result, working operations become considerably faster because no ladders etc. are required. Everything is safely assembled fromthe erection area.Important for construction crews: All work is carried out safely from the ground and without ladders, working scaffold or work platforms.

10.5 Slab FormworkThis type of formworks is used in the construction for slabs. There are different types of slab formwork for the construction.10.5.1 SKYDECK Aluminium Panel Slab Formwork

FIG.10.5.1 SKYDECK Aluminium Panel Slab FormworkFor slab thicknesses up to 95 cm. With the SKYDECK drop head system, striking can be carried out after only one day (depending on the slab thickness and strength of the concrete). The drop head is released with a hammer blow which causes the formwork to drop 60 mm (panels and main beams). The panels can be separated easily from the concrete and immediately used for the next cycle. Furthermore, on-site material requirements are reduced. The SKYDECK main beam reduces the number of props needed only one prop is required per slab area of 3.45 m for thicknesses up to 40 cm. This saves time and simplifies the transportation of formworkmaterials across the site.SKYDECK panels as well as main beams are equipped with self-draining edges. The edges of the panels are undercut which ensures cleaning is kept to a minimum and thus shorter shutteringtimes.

The SKYDECK guarantees a straight support line at the end of the formwork. With system parts, these infill areas can be quickly formed with system components. Systematic assembly and a high degree of safety for standard bays as well as the slab edge are achieved using SKYDECK platforms. The SLT 375 main beam provides a cantilever of approx. 1.30 m. The GS-approved SKYDECK SDB platform together with a foldable handrail frame is safely positioned by means of the SSH shuttering aid. The SKYDECK platform has a safe working load of 150 kg/m.10.5.2 GRIDFLEX Aluminium Grid Slab Formwork

FIG.10.5.2 Grid Slab FormworkThe slab formwork with a completely new safety concept. PERI GRIDFLEX is the flexible slab formwork system complete with accessible girder grids. Due to the lightweight aluminum components and pre-determined assembly sequence, very short shuttering times are achieved. Telescopic filler elements ensure maximum flexibility. The panel grid system allows safe access for laying the free choice of formlining.10.5.3 BEAMDECK Aluminium Beam Slab Formwork

FIG.10.5.3 Beam Slab Formwork

PERI BEAMDECK is the beam slab formwork made of aluminium with integrated drop head to allow early striking. This reduces on-site material requirements. Very few different individual parts with only three system components ensure fast forming as well as easy handling and logistical operations. Depending on concrete surface requirements, the form lining can be freely selected.PERI BEAMDECK combines the advantages of low individual weights with a systematic and fast assembly sequence. For BEAMDECK an efficient range of accessories for edge and filler areas, cantilevers and inclined slabs is available.10.5.4 Table Modules

FIG.10.5.4 Table ModulesCompletely pre-assembled tableform for hire: As rentable standard equipment, PERI modular tables are pre-assembled and ready for immediate use. Fall protection on cantilevered slab edges is already mounted on to the table. Especially for projects with a small number of applications, using modular tables is very cost-effective. There are four standard sizes available. For horizontal and vertical moving of the slab tables, PERI offers an appropriate range of accessories.10.5.5 SKYTABLE TABLE FORMS

FIG. 10.5.5 SKYTABLE TableformsFast and safe moving process. The SKYTABLE can be used, for example, for the complete width of the building. Requiring only two trusses, the SKYTABLE can be assembled up to a size of 24.4 m x 6.10 m. The actual SKYTABLE moving procedure offers more safety as site personnel work from the secured slab edges. During the entire moving process, workers do not have to stand on the SKYTABLE itself.10.6 BRIDGE AND TUNNEL FORMWORKThe Variokit Concept

FIG.10.6 VariokitSystem solutions for bridge, tunnel and civil engineering construction. With standardized, rentable PERI system components and construction-compliant connecting means, supporting structures can be cost-effectively erected and adapted geometrically to the respective structure. Engineering services and materials from one source. PERI not only supplies the required materials. Experienced engineers develop customized formwork solutions. They combine load optimization, flexibility and functionality for a very wide range of construction site requirements.Included in the PERI comprehensive solution is all technical documentation such as static calculations, assembly drawings and instructions for use as well as assembly support and continuous support throughout the project. VARIOKIT consists mainly of rentable standard components which remain unchanged but nevertheless are highly versatile in their use.

CHAPTERS 11ADVANTAGESFollowing are the advantages of precast concrete technology:11.1 QUALITY CONTROL: Because precast concrete products typically are produced in a controlled environment, they exhibit high quality and uniformity. Variables affecting quality typically found on a jobsite temperature, humidity, material quality, craftsmanship are nearly eliminated in a plant environment.

11.2 US SENSITYVITY: Unlike some other materials, precast concrete does not degrade from exposure to sunlight. This is extremely beneficial for above-ground applications.

11.3 ENVIRONMENT FRIENDLY: After water, concrete is the most frequently used material on earth. It is nontoxic, environmentally safe and composed of natural materials. Buried throughout the world, precast concrete products help convey water without contributing to poor water quality.

11.4 WEATHER RESISTANT: Precast concrete is well suited for exposure to all types of weather conditions. In regions experiencing regular freeze-thaw cycles, the concrete mix can be designed to properly withstand damage.11.5 REDUCED WATER DEPENDENCY: Precast concrete increases efficiency because weather will not delay production. In addition, weather conditions at the jobsite do not significantly affect the schedule. This is because it requires less time to install precast compared with other construction methods, such as cast-in-place concrete. Precast concrete can be easily installed on demand and immediately backfilled there is no need to wait for it to cure.

11.6 WATER TIGHTNESS: Precast concrete products produced in a quality-controlled environment and used with high-quality sealants offer a superior solution to water tightness requirements. Standard watertight sealants are specially formulated to adhere to precast concrete, making watertight multiple-seam precast concrete structures possible.

11.7 EASE OF INSTALLATION: Although precast concrete is quite heavy, nearly all other competing materials require machinery for handling and installation as well. Besides, speed of installation is more dependent on excavation than product handling and placement. Precast does not require the use of special rigging (such as fabric slings) which must be used in order to avoid structural damage while handling materials such as fiberglass. Additionally, because precast products are designed and manufactured for simple connection, many components can be installed in a short time.

11.8 MODULARITY: Because of the modular nature of many precast concrete products, structures or systems of nearly any size can be accommodated.

11.9 AVAILABILITY: With thousands of manufacturers throughout North America, precast concrete products can be ordered from plants in most cities or regions. Since precast structures are manufactured in advance and stored at the plant, they are readily available when needed at the job site. This ensures competitive pricing and a ready supply, which can save days, weeks or even months on a project over cast-in-place concrete.

11.10 EFFICIENCY: Precast concrete products arrive at the jobsite ready to install. There is no need to order raw materials such as reinforcing steel and concrete, and there is no need to expend time setting up forms, placing concrete or waiting for the concrete to cure.

11.11 AESTHETICS: Precast concrete products are both functional and decorative. They can be shaped and molded into an endless array of sizes and configurations. Precast concrete can also be produced in virtually any color and a wide variety of finishes (acid-etched, sandblasted,smooth-as-cast, exposed-aggregate) to achieve the desired appearance for building and site applications.

11.12 LOW MAINTAINANCE: Precast concrete requires little or no maintenance, which makes it an ideal choice for nearly any design solution.

CHAPTER 12DISADVANTAGES

1) Handling and transport may cause breakage of members during transit and extra design provision is to be made.2) Difficulty in connecting precast units so as to produce frame effect as monolithic. As it requires skilled supervision.3) They are to be exactly placed in position, otherwise the loads coming on them are likely to get changed and the member may be affected.4) A little amount of eccentricity may change the nature of stresses from compressive to tension or vice versa.5) If the precast beam is wrongly placed in position (i.e., tension and compression interchanged) the member may fail.

CHAPTER 13CONCLUSION

PRECAST THE NEXT FRONTIER IN CONSTRUCTION

Precasting makes the construction work lighter and good results are obtained at the end of the project. Total cost of the project is increased due to pre production of walls and transportation of walls form battery mould to site. Walls produced by Precasting have best properties when compared to CIS walls. Reduction in the noise makes the working environment free from sound pollution. Fly ash used as admixture makes the walls stronger and fire resistant and eco friendly. Plinth area can be increased because thickness of the walls is very much smaller compared to CIS walls. In the highly competitive construction industry, the ability to combine quality, innovation, speed and environmental sustainability in construction will serve as a key differentiator. With growing affluence, consumers will seek increasingly better quality finishes, concealed service conduits, better durability and aesthetically pleasing exteriors. Architects would want to differentiate their projects by combining aesthetics with cost efficiency through structures that will challenge the abilities of builders. Technologies that transfer activities off site, save materials and protect the environment will be preferred by Governments. Precast technology will thus become the system of choice and as more innovations occur and the supply chain of supporting infrastructure is formed it will truly revolutionize the construction industry.

CHAPTERS 14REFERENCES

1. Poon CS, Yu TWA, Jaillon L. Reducing building waste on construction sites in Hong Kong. Construction Management and Economics June 2004;22:46170.2. Alarcon LF, editor. Lean construction. Rotterdam: Balkema; 1997.3. Coventry S, Shorter B, Kingsly M. Demonstrating waste minimization benefits. CIRIA report 536. London: CIRIA; 2001. 086017 5367.4. Construction Industry Review Committee. Construction for excellence the Report of the Construction Review Committee. HKSAR Government; 2001.5. Afshin Mansouri, S. (2005). Coordination of set-ups between two stages of a supply chain using multi-objective genetic algorithms. International Journal Of Production Research, 43, 31633180.6. Aly, A. H., & Peralta, R. C. (1999). Optimal design of aquifer cleanup systems under uncertainty using a neural network and a genetic algorithm. Water Resources Research, 35(8), 25232532.7. Augusto, O. B., Rabeau, S., Depince, P. H., & Bennis, F. (2006). Multi-objective genetic algorithms: A way to improve the convergence rate. Engineering Applications ofArtificial Intelligence, 19, 501510

WEB REFRENCES:1. www.precastdesign.com2. www.solutions.precast.org3. www.janapriya.com4. www.patentstorm.us5. www.peri.com2