SPEEDY CONSTRUCTION
SPEEDY CONSTRUCTION CONSTRUCTION IS OUR TRADITIONAL HEARTLAND AND IS A SECTOR IN WHICH WE HAVE A HUGE AMOUNT OF EXPERIENCE. WE UNDERSTAND THE IMPORTANCE OF CONSISTENT QUALITY, RELIABILITY AND FLEXIBILITY IN MEETING LOGISTICALLY COMPLEX AND TIME CRITICAL BUILD REQUIREMENTS. WE ARE ORGANISED IN A WAY THAT ALLOWS US TO ACT AS A STRATEGIC SUPPLY CHAIN PARTNER, ABLE TO PLAY OUR PART IN THE BUILD PROCESS BY PROVIDING A HIGHLY EFFECTIVE AND INTEGRATED SERVICE. WE ARE EQUALLY ABLE AND PREPARED TO RESPOND QUICKLY AND EFFECTIVELY TO THE INEVITABLE CHANGE OF PLAN, THE UNEXPECTED DEVELOPMENT, OR EVEN THE UNFORESEEN DISASTER. WHETHER YOU ARE AN INTERNATIONAL CONTRACTOR OR LOCAL BUILDER, YOU CAN BE SURE THAT AT SPEEDY YOU WILL WORK WITH PEOPLE WHO KNOW WHAT THEY ARE DOING AND KNOW HOW TO DELIVER WHAT YOU WANT, HOW YOU WANT IT, WHERE YOU WANT IT AND WHEN YOU WANT IT.
SPEEDY CONSTRUCTION
(READY MIXED CONCRETE)
RMC (READY MIXED CONCRETE)
READY MIXED CONCRETE, OR RMX AS IT IS POPULARLY CALLED, REFERS TO CONCRETE THAT IS SPECIFICALLY MANUFACTURED FOR DELIVERY TO THE CUSTOMER'S CONSTRUCTION SITE IN A FRESHLY MIXED AND PLASTIC OR UNHARDENED STATE. CONCRETE ITSELF IS A MIXTURE OF PORTLAND CEMENT, WATER AND AGGREGATES COMPRISING SAND AND GRAVEL OR CRUSHED STONE. IN TRADITIONAL WORK SITES, EACH OF THESE MATERIALS IS PROCURED SEPARATELY AND MIXED IN SPECIFIED PROPORTIONS AT SITE TO MAKE CONCRETE. READY MIXED CONCRETE IS BOUGHT AND SOLD BY VOLUME - USUALLY EXPRESSED IN CUBIC METERS. RMX CAN BE CUSTOMMADE TO SUIT DIFFERENT APPLICATIONS.
SPEEDY CONSTRUCTION
RMX - ADDING VALUE TO CONCRETE READY MIXED CONCRETE IS MANUFACTURED UNDER COMPUTER-CONTROLLED OPERATIONS AND TRANSPORTED AND PLACED AT SITE USING SOPHISTICATED EQUIPMENT AND METHODS. RMX ASSURES ITS CUSTOMERS NUMEROUS BENEFITS: UNIFORM, CONSISTENT AND ASSURED QUALITY OF CONCRETE FLEXIBILITY IN CONCRETE DESIGN MIXES EASIER ADDITION OF ADMIXTURES FASTER AND SPEEDIER CONSTRUCTION REDUCED INVENTORIES, MATERIAL HANDLING AND STORAGE OF RAW MATERIALS AT SITES SAVINGS IN LABOUR REQUIREMENTS, LABOUR COSTS AND SUPERVISION OF LABOUR REDUCED WASTAGE OF MATERIALS
SPEEDY CONSTRUCTION THE USE OF RMX IS AN ENVIRONMENTAL FRIENDLY PRACTICE THAT ENSURES A CLEANER WORK PLACE AND CAUSES MINIMAL DISTURBANCE TO ITS SURROUNDINGS. THIS MAKES ITS UTILITY MORE SIGNIFICANT IN CROWDED CITIES AND SENSITIVE LOCALITIES. IN CONTRAST TO THIS, CONVENTIONAL METHODS OF MAKING TRANSPORTING AND PLACING CONCRETE AT MOST CONSTRUCTION SITES ARE SOMEWHAT LABOUR-INTENSIVE AND SUFFER FROM PRACTICES WHICH MAY BE ERRATIC AND NOT VERY SYSTEMATIC. THEREFORE THE USE OF READY MIXED CONCRETE CAN PROVE TO MORE COST EFFECTIVE IN THE LONGER TERM WHILE ENSURING THAT STRUCTURES ARE BUILT FASTER AND USING CONCRETE THAT COMES WITH HIGHER LEVELS OF QUALITY ASSURANCE.
SPEEDY CONSTRUCTION TIME IN TRANSPORT (INDIAN STANDARD ) THE GENERAL REQUIREMENT IS THAT CONCRETE SHALL BE DISCHARGED FROM THE TRUCK-MIXER WITHIN 2 H OF THE TIME GF LOADING. HOWEVER, A LONGER PERIOD MAY BE PERMITTED IF RETARDING ADMIXTURES ARE USED OR IN COOL HUMID WEATHER OR WHEN CHILLED CONCRETE IS PRODUCED. THE TIME OF LOADING SHALL START FROM ADDING THE MIXING WATER TO THE DRY MIX OF CEMENT AND AGGREGATE OR OF ADDING THE CEMENT TO THE WET AGGREGATE WHICHEVER IS APPLICABLE.
SPEEDY CONSTRUCTION THE COMPANIES LARSEN & TERBO ACC LTD ADITYA BIRLA GROUP PRIZM JP CEMENT
CROSS WALL CONSTRUCTION • IT IS A FORM OF CONSTRUCTION WHERE LOAD BEARING WALLS ARE PLACED AT RIGHT ANGLES TO THE LATERAL AXIS OF THE BUILDING, • THE FRONT AND REAR WALLS BEING ESSENTIALLY NON-LOAD BEARING CLADDING. • CROSSWALL CONSTRUCTION IS SUITABLE FOR BUILDINGS UP TO 5 STOREYS HIGH WHERE THE FLOORS ARE SIMILAR. • THE INTERMEDIATE FLOORS SPAN LONGITUDINALLY BETWEEN THE CROSSWALLS PROVIDING THE NECESSARY LATERAL RESTRAINT • THE JUNCTIONS BETWEEN THE NON-LOAD BEARING CLADDINGS AND THE CROSSWALLS MUST BE WEATHERTIGHT.
• IF A PITCHED ROOF IS TO BE EMPLOYED WITH THE RIDGE PARALLEL TO THE LATERAL AXIS AN EDGE BEAM WILL BE REQUIRED TO PROVIDE A SEATING FOR THE TRUSSED OR COMMON RAFTERS AND TO TRANSMIT THE ROOF LOADS TO THE CROSSWALLS.
TYPICAL CROSS WALL ARRANGEMENT
ADVANTAGES OF CROSSWALL CONSTRUCTION:• LOAD BEARING AND NON-LOAD BEARING COMPONENTS CAN BE STANDARDISED AND IN SAME CASES PREFABRICATED GIVING FASTER CONSTRUCTION TIMES. • FENESTRATION BETWEEN CROSSWALLS UNRESTRICTED STRUCTURALLY. • CROSSWALLS ALTHOUGH LOAD BEARING NEED NOT BE WEATHER RESISTANT AS IS THE CASE WITH EXTERNAL WALLS.
DISADVANTAGES OF CROSSWALL CONSTRUCTION:• LIMITATIONS OF POSSIBLE PLANS. • NEED FOR ADEQUATE LATERAL TIES BETWEEN CROSSWALLS. • NEED TO WEATHER ADEQUATELY PROJECTING...
2
1
FIG.1: INSITU FIXING SYSTEM FOR THREEWAYJOINT 1. Fixing loops 2. 25mm-diameter rebar tie rod
FORMWORK IS THE TERM GIVEN TO EITHER TEMPORARY OR PERMANENT MOULDS INTO WHICH CONCRETE OR SIMILAR MATERIALS ARE POURED. IN THE CONTEXT OF CONCRETE CONSTRUCTION, THE FALSEWORK SUPPORTS THE SHUTTERING MOULDS.
CONCRETE FORM WORK SERVES AS MOULD TO PRODUCE ELEMENTS OF DESIRED SHAPE AND SIZE
IT IS ERECTED FOR THIS PURPOSE AND THEN REMOVED AFTER CONCRETE IS CURED TO SATISFACTORY LEVEL.
FOR GOOD PERFORMANCE FORMWORK SHOULD BE STRONG AND SHOULD HAVE STRENGTH TO CARRY THE LOADS PRODUCED BY CONCRETE.
SOME OF THE EARLIEST EXAMPLES OF CONCRETE SLABS WERE BUILT BY ROMAN ENGINEERS. BECAUSE CONCRETE IS QUITE STRONG IN RESISTING COMPRESSIVE LOADS, BUT HAS RELATIVELY POOR TENSILE OR TORSIONAL STRENGTH, THESE EARLY STRUCTURES CONSISTED OF ARCHES, VAULTS AND DOMES. THE MOST NOTABLE CONCRETE STRUCTURE FROM THIS PERIOD IS THE PANTHEON IN ROME. THESE BUILDING TECHNIQUES WERE NOT ISOLATED TO POURING CONCRETE, BUT WERE AND ARE WIDELY USED IN MASONRY BECAUSE OF THE COMPLEXITY AND THE LIMITED PRODUCTION CAPACITY OF THE BUILDING MATERIAL, CONCRETE‟S RISE AS A FAVOURED BUILDING MATERIAL
TYPES OF FORMWORK
THE TRADITIONAL SLAB FORMWORK TECHNIQUE CONSISTS OF SUPPORTS OUT OF LUMBER OR YOUNG TREE TRUNKS, THAT SUPPORT ROWS OF STRINGERS ASSEMBLED ROUGHLY 3 TO 6 FEET OR 1 TO 2 METERS APART, DEPENDING ON THICKNESS OF SLAB.
METAL BEAM SLAB FORMWORKSIMILAR TO THE TRADITIONAL METHOD, BUT STRINGERS AND JOIST ARE REPLACED WITH ALUMINIUM FORMING SYSTEMS OR STEEL BEAMS AND SUPPORTS ARE REPLACED WITH METAL PROPS.
MODULAR SLAB FORMWORKTHESE SYSTEMS CONSIST OF PREFABRICATED TIMBER, STEEL OR ALUMINIUM BEAMS AND FORMWORK MODULES. MODULES ARE OFTEN NO LARGER THAN 3 TO 6 FEET OR 1 TO 2 METERS IN SIZE
RE-USABLE PLASTIC FORMWORK. THESE INTERLOCKING AND MODULAR SYSTEMS ARE USED TO BUILD WIDELY VARIABLE, BUT RELATIVELY SIMPLE, CONCRETE STRUCTURES. THE PANELS ARE LIGHTWEIGHT AND VERY ROBUST. THEY ARE ESPECIALLY SUITED FOR LOWCOST, MASS HOUSING SCHEMES
PERMANENT INSULATED FORMWORK. THIS FORMWORK IS ASSEMBLED ON SITE, USUALLY OUT OF INSULATING CONCRETE FORMS (ICF).
ANALYSIS
SUPPORT ALL SUPPORT SYSTEMS HAVE TO BE HEIGHT ADJUSTABLE TO ALLOW THE FORMWORK TO BE PLACED AT THE CORRECT HEIGHT AND TO BE REMOVED AFTER THE CONCRETE IS CURED.
FORMWORK SHOULD HAVE HIGH STRENGTH AND STABILITY SO THAT ANY CONCRETE FORM CAN ACHIEVE ITS REQUIREMENTS.
CONCRETE IS USED BECAUSE IT IS CHEAP AND DURABLE.
AFTER ASSEMBLY ALL LOADS SHOULD BE CALCULATED.
EXAMPLES
SPEEDY CONSTRUCTION BOX FRAME CONSTRUCTION Method of building with concrete in which individual cells, or rooms, are set horizontally and vertically together to create an overall structural frame. Because the main weight of the building is carried through the cross walls, they must be sufficiently thick to carry their own weight as well as loads from above, and so the potential height of a structure built in this manner is limited. The most common application is in low apartment flats and similar buildings having walls and floors formed by reinforced concrete slabs. •Type of construction resembling a series of boxes, involving structural walls at right angles to the façade (called cross-walls): its repetitive nature limits its use to hotel-bedrooms, small flats, hostels, etc. • Type of timber-framed structure where rooftrusses are supported on a frame of posts, tiebeams, and wall-plates.
Most buildings of this type have some kind of lateral loadresisting elements, mainly consisting of cast-in-place or precast shear walls, etc. In case lateral load-resisting elements (shear walls, etc.) are not present, the lateral load path depends on the ability of the slab-column connections to transfer bending moments. When the connections this type.
BOX FRAME CONSTRUCTION
A roll formed, aluminum, box frame strut for use in making a panel which includes such struts, which struts are made of roll formed sheet aluminum material of a uniform thickness of between 0.025 inch and 0.032 inch. The struts comprise a hollow body with an elongate socket extending from one edge to receive the marginal edge of a pane with the struts being circumposed about the pane to define a building panel. The struts are of a closed or box frame configuration.
Table Form work
Table formwork is a kind of formwork specializing in floor slab concreting，and it is widely used in highrise buildings, skyscrapers, multi-storey industrial factory buildings, underground structures, etc. Standard as well as nonstandard table formwork can be set up to meet the requirements of slabs in different shapes and dimensions. Advantages of the formwork are easy structure, simple assembly and disassembly, flexible location, and multiple using times. By the specially designed lifting fork, the whole table formwork unit can be lifted and repositioned, thus speeding up the construction cycle and saving much labor cost, too.
• The table form work has simple structure, it is easy to assemble and disassemble and can be reused . • Practical shifting trolley make for virtually fatigue-free operations. Fully assembled units are manoeuvred quickly into place, • Easier to handle and safer than hand-operated formwork, particularly as room heights increases.
Table forms can be relocated by a crane with the help of a carrier called spoon. For security purposes guardrails and similar components are used around the slab.
• Each table provides a large area of slab formwork. Table form system is mostly beneficial for flat slab design. • Supplied with adjustable/telescopic feet, system practical for buildings with variable floor heights • Fast erection & dismantling when compared to scaffold shoring systems Two different models are available with telescopic and shifting trolley designs respectively for different structural features such as slab thickness, span width etc. Plywood faced system can use steel or H20 timber beams as main & secondary girders. When steel secondary girders are used the width of table form becomes adjustable. Beam forms can be used in conjunction with table form to cast the slab and beams together.
W h e n w o o d e n b e a m s a r e u s e d. . .instead of steel I sections :
Formwork H20 Timber Beam, also called H20 Wood beam, I Joist, I beam, Wood H beam or Wood Girder, is widely used in formwork systems, construction systems parts, Falsework systems, timber structures and other bearing structures .
Specification of our H20 prefabricated timber formwork beams: l. Wood Species: pine 2. Flange: solid wood 3. Web: plywood or LVL laminated veneer lumber plywood 4. WBP resin Weather and Boil Proof (the category of glue used to make the most durable plywood, made with melamine or phenolic resin) 5. Coating with painting (yellow color, waterproof, rot-proof, frozen-proof) 6. Standard size: 200mm(height) X 80mm(width) X 40mm(flange thickness) 7. Length:1.8m, 2.9m, 3.0m, 3.3m, 3.9m, 4.9m, 3.9m 8. Thickness of Web: 22mm / 27mm / 28mm / 30mm ( special thickness available on request) 9. Plastic protective cap is available on request
T a b l e F o r m w o r k s. . .types & details :
Assembling on site...
COLUMN FORMWORK SYSTEMS The column formwork systems now available are normally modular in nature and allow quick assembly and erection on-site while minimizing labor and crane time. They are available in steel, aluminum and even cardboard (not reusable but recycled) and have a variety of internal face surfaces depending on the concrete finish required. Innovations have led to adjustable, reusable column forms which can be clamped on-site to give different column sizes.
The basic construction sequence using this type of formwork is as follows: • The column forms are assembled and positioned over or enclosing the reinforcing bar cage. • The forms are positively restrained and braced using props. • Concrete is poured. • Once the concrete has hardened sufficiently the formwork is stripped and moved to the next position. • manually or by crane. Disposable forms may be left in place for an extended period to aid curing and strength gain of the concrete before removal.
Raking column forms
ADVANTAGES • The metal column forms are easy to clean and reuse with little waste generated compared to traditional formwork.
• Increased speed and efficiency in construction. • The simplicity of assembly and disassembly reduces the requirement for skilled labor. • Disposable forms that are stripped and discarded after one use can often be recycled. • simplicity of the assembly process ensures that site operatives can quickly become familiar with health and safety aspects of their job. • High quality surface finishes are
WALL FORMWORK
We use vertical panel system for wall form work for high Rise construction in modern concrete structures. Crane-lifted panel systems are commonly used on building sites in wall form work and usually consist of a steel frame with plywood, steel, plastic or composite facing material. The systems are normally modular in nature, assembly times and labour costs are considerably lower than traditional formwork methods with far fewer components required. They offer greater opportunities for reuse for different applications on site. Panel systems are extremely flexible and the larger crane-lifted versions can be used for constructing standard concrete walls, perimeter basement walls, columns and in conjunction with jump form climbing systems.
WALL FORMWORK The basic construction sequence using this type of Wall formwork is as follows:
Panels are connected together flat on the ground to form larger individual crane-lifted units. After assembly of the units one face of the formwork is erected vertically in position and restrained/plumbed using props. Reinforcement is fixed against the erected formwork. The opposing face of the formwork is positioned and both form units are tied together. Concrete is poured.Once the concrete has hardened sufficiently the formwork is stripped and moved to the next position.
WALL FORMWORK
Process efficiency
Assembly is very simple with panels connected and fixed using wedge clamps and hammers, reducing the requirement for skilled labour. Easily adaptable to varying structural geometries, wall heights, etc. Increased speed in construction, compared to traditional wooden formwork. The engineered nature of the panel formwork systems allows quick adjustment of the formwork.
Safety
Working platforms, guard rails and ladders can be built into the completed units of formwork. The simplicity of the assembly process and repetitive nature of the work in certain types of structure ensure that site operatives can quickly become familiar with health and safety aspects of their job. Normally these formwork systems require minimal use of power tools.
Vertically stacked wall form 22.5m high
WALL FORMWORK Other considerations The panel systems are designed for specific maximum concrete pressures. The concrete placement rates have to be adjusted accordingly to keep the concrete pressure within the specified limits. Lightweight manhandled systems are available with steel or aluminium frames and plywood facing. These are commonly used in groundworks construction where a site crane is not always available. This can still be more economical than traditional formwork, especially where the formwork needs to be adapted to varying site uses. For concrete where enhanced durability is required, controlled permeability formwork (normally in the form of a formwork liner) may be used. The formed concrete normally has a regular (textured) surface so can also be specified for architectural reasons.
WALL FORMWORK PRE-ASSEMBLED FORMWORK
Concrete elements are sometimes specified to a high specification with a fair-faced or special finish. With this type of work and where unusual or complex structural geometries are encountered it is not always possible to use modular formwork systems. Various formwork suppliers are able to offer custom-built formwork preassembled in their factories. Where wall construction is repetitive and has many reuses it can be cost effective to use traditional formwork. Pre-assembled formwork can reduce the requirement for space on-site.
JUMP FORM Generally, jump form systems comprise the formwork and working platforms for leaning/fixing of the formwork, steel fixing and concreting. The formwork supports itself on the concrete cast earlier so does not rely on support or access from other parts of the building or permanent works. Jump form, here taken to include systems often described as climbing form, is suitable for construction of multi-storey vertical concrete elements in high-rise structures, such as shear walls, core walls, lift shafts, stair shafts and bridge pylons. These are constructed in a staged process. It is a highly productive system designed to increase speed and efficiency while minimizing labor and crane time. Systems are normally modular and can be joined to form long lengths to suit varying construction geometries. Guided climbing formwork for the core of Riverside Quarter residential development Wandsworth, London
Why choose jump forming?
Jump forms can be designed to suit inclusions such as floors and beams by adjusting the size of the forms. There is no need to worry about collapse of thin walls. Friction is not a problem so thick walls can be constructed more easily. Tapered walls are easily catered for in the design of the form. Pouring of concrete is not continuous so it can be arranged at convenient times to fit in with other activities such as stripping another section, or shiftwork. The off-form finish of the work may not need to be touched.
TYPES OF JUMP FORM
Normal jump/climbing form – units are individually lifted off the structure and relocated at the next construction level using a crane. Guided-climbing jump form – also uses a crane but offers greater safety and control during lifting as units remain anchored/guided by the structure. Self-climbing jump form – does not require a crane as it climbs on rails up the building by means of hydraulic jacks, or by jacking the platforms off internal recesses in the structure. It is possible to link the hydraulic jacks and lift multiple units in a single operation.
basic construction sequence The formwork and the access platform are assembled on the ground. This combined formwork and access platform assembly is lifted using a crane and fixed to „cast-in‟ anchors or tracks (climbing brackets) bolted to the wall elements below. Once the poured concrete is strong enough, the assembly is struck from the new/current concrete lift, and raised by crane to the next position. For selfclimbing systems this is done using the hydraulic jacks. This whole cycle can be completed within a short time; the actual time depending on the size and complexity of the construction.
CONSIDERATIONS
Jump form is typically used on buildings of five storey's or more; fully selfclimbing systems are generally used on structures with more than 20 floor levels. However, a combination of crane-handled and self-climbing platforms can be viable on lower structures.
Before placement
Make test batches to check the hardening time of the concrete to be used. It's no good having the concrete soft on exit from the form because it may fall away. Also it's no good having the concrete become so hard in the form that it creates too much friction.
Friction might cause the concrete to stick to the form and be pulled up with it, leaving unfilled spaces.
Make sure that the position, vertical alignment and level of the formwork is correct.
Prepare lights and covers for night work and bad weather.
Erect safety net.
Make sure that work platforms and rails are in place and that they are secure.
Make sure that standby equipment is on hand in case of breakdowns.
If the formwork is aligned with nibs or kickers, make sure that the form is firmly supported at the joint.
During placement
Keep work deck clear of debris and concrete which could fall into the formwork. Watch for bleeding of water out of the concrete. This changes the composition of the concrete. Vibrate the freshly poured concrete only; the concrete at the bottom of the form may vibrate out. Check for correct alignment, plumb and level as the form is jacked up. Make sure that the form is jacked up at constant rate change the speed of slip if necessary. Check for 'blowouts' - soft concrete falling out of the bottom of the form, or 'lifts' - concrete that has stuck to the form and has been lifted away from the concrete below, leaving a space. Fix them. Make sure that all blockouts and penetrations are correctly placed and tied down. Make sure they do not float. Make sure that the jacking mechanism is working correctly. Make sure that steel reinforcement does not protrude into the unfilled form face space. Bend it so that it does not foul the form as it passes.
After placement
Vibrate the top layer of concrete. Remove and clean the formwork while the concrete is still green. Insert next layer of reinforcement. Finish the surface of the concrete. Near the end of the slipping process, rods must be set into the concrete at the right height so that they will take the weight of the formwork and the yokes can be removed. The rest of the formwork can then be removed.
Completed jump form core and table form for a residential development, Manchester courtesy Doka)
Make test batches to check the hardening time of the concrete to be used. It's no good having the concrete soft on exit from the form because it may fall away. Also it's no good having the concrete become so hard in the form that it creates too much friction. Friction might cause the concrete to stick to the form and be pulled up with it, leaving unfilled spaces. Make sure that the position, vertical alignment and level of the formwork is correct. Prepare lights and covers for night work and bad weather. Erect safety net. Make sure that work platforms and hand-rails are in place and that they are secure. Make sure that standby equipment is on hand in case of breakdowns. If the formwork is aligned with nibs or kickers, make sure that the form is firmly supported at the joint.
Climbing formwork system for the core of Royex House, Aldermanbury Square, London (courtesy Peri)
Slip form work
Slip form is similar in nature and application to jump form, but the formwork is raised vertically in a continuous process. It is a method of vertically extruding a reinforced concrete section and is suitable for construction of core walls in high-rise structures – lift shafts, stair shafts, towers, etc. It is a self-contained formwork system and can require little crane time during construction. This is a formwork system that can be used to form any regular shape of core. The formwork rises continuously, at a rate of about 300 mm per hour, supporting itself on the core and not relying on support or access from other parts of the building or permanent works. Commonly, the formwork system has three platforms.
oThe upper platform acts as a storage and distribution area while the middle platform, which is the main working platform, is at the top of the poured concrete level. oThe lower platform provides access for concrete finishing. oThe basic construction sequence using this formwork is as follows: oThe formwork and the access platform are assembled on the ground. oThe assembly is raised using hydraulic jacks. oAs the formwork rises continuously, continuous concrete and rebar supply are needed until the operation is finished. oAt the end of the operation the formwork is removed using a crane. oThe entire process is thoroughly inspected and highly controlled.
Before choosing slip forming some of the things to consider are:
The concreting will take place in a very short time. The initial setting up time inset will be longer than for conventional forms but can be reduced by construction of the forms in large slabs off site. The cost per square meter of the equipment will be more than for conventional forms. Labor costs will be higher due to shift work but productivity will be good. There are no construction joints. The process is less weather sensitive than other methods. Working platforms can be covered from the weather and the surface of the concrete can be protected. Standby plant and workers are needed. It is easy to obtain a good key for subsequent finishes. The final tolerance for the completed work is about same as that for other methods. Spiraling and non verticality have almost been eliminated. Economizing on the design of the slip form may lead to major and expensive problems.
Safety
Working platforms, guard rails, ladders and wind shields are normally built into the completed system. Reduced use of scaffolding and temporary work platforms results in a less congested construction site. The completed formwork assembly is robust and provides a stable working platform. The strength of the concrete in the wall below must be closely controlled to achieve stability during operation. The uniform and continuous nature of the work ensures that site operatives can quickly become familiar with health and safety aspects of their job. Formwork suppliers provide materials and resources to help train the labor force. High levels of planning and control mean that health and safety are normally addressed from the beginning of the work.
Other considerations
This formwork is more likely to be economical for buildings more than seven storey's high. Extensive planning and special detailing are needed as the process has little flexibility for change once continuous concreting has begun. Standby plant and equipment should be available though cold jointing may occasionally be necessary. The structure being slip formed should have significant dimensions in both major axes to ensure stability of the system. The setting rate of the concrete has to be constantly monitored to ensure that it is matched with the speed at which the forms are raised. Assembly and operations require personnel to be comprehensively trained to ensure competence. It is necessary to understand and comply with suppliers‟ method statements at all times.
The main advantages can be listed as:
Quicker construction; Less formwork; Less scaffolding; Easier working conditions; Greater salvage; Better concrete; A joint1ess, watertight structure.
TUNNEL FORM WORK
The forms are simply two upside-down steel “L” shaped pieces that join together at the top to form a long tunnel. Tunnels can be as long as 40 feet and from 12 to 22 feet wide. With the addition of a “table,” the deck width can extend to 26 feet. A diagonal brace is positioned from the bottom of the wall extending to the end of the deck
TUNNEL FORM WORK
TUNNEL FORM WORK IN ACTION
BENEFITS: • •
There are cost benefits. Within a couple days the shell and the primary interior walls, the rough electrical, the insulation, and block-outs for plumbing and HVAC are complete. Construction cycles are therefore much shorter than with other building systems so the duration of construction loans is shorter.
