Materials used for frameworks Timber replayed Plastic Forms Aluminum forms Steel frameworks TIMBER It should The timber FORMS bearing durable used and for framework treatable must satisfy the following requirements Advantages of using timber forms: It is economical for small construction jobs It is design flexible and easy to erect It can easily be made into any shape or size ALUMINUM The framework turns out to As the strength of aluminum be economical if large in handling, tension and numbers of reuses are made compression is less than the in construction. Renege of steel, it is necessary to use large sections. Their lower density, aluminum The major disadvantage of aluminum forms is that no forms are lighter than steel forms, changes can be made once and this is their primary the framework is fabricated. Advantage when compared to steel Forms made from aluminum are in many respects similar to those made of steel Plastic Frameworks These forms have become increasingly popular for casting unique shapes and patterns being designed in concrete because of the excellent finish obtained requiring minimum or no surface treatment and repairs.
Different types of plastic forms are available like glass reinforced plastic, fiber reinforced plastic and thermoplastics etc Fiberglass-reinforced plastic is has several advantages such as sections can be joined on the job site in such a way so as to eliminate joints, there is no size limitation ;The material allows greater freedom of design ;Unusual textures and designs can be molded into the form lightweight and easily stripped The disadvantage Of using plastic forms is that it does not lend itself to field fabrication Hence, the design and planning of this form must be carefully aired out.
Also care must take not to damage the plastic by the heat applied for accelerated curing of the concrete. Trough and waffle units in fiberglass are used in construction of large floor areas and multistoried office buildings. STEEL FRAMEWORK Mostly used in large construction projects or in situations where large number of re-uses of the same shuttering is possible. Suitable for circular or curved shaped structures such as tanks, columns, chimneys. Etc. & for structures like sewer tunnel and retaining wall.
Strong, durable & have longer life Reuses can be assumed o vary from 100 to 120 and timber varies from 10th 12. Steel can be installed & dismantled with greater ease & speed resulting in saving in labor cost No danger of framework absorbing water from the con. & hence minimizing honeycombing TYPES OF FRAMEWORK TRADITIONAL FRAMEWORK This usually consists of standard framed panels tied together over their backs with horizontal members called waling. C] One side of the wall framework is first assembled ensuring that it is correctly aligned, plumbed and strutted.
C] The steel reinforcement cage is then placed and positioned before the there side of the framework is erected and fixed. [Plywood sheet in combination with timber is the most common material used for wall framework. 0 The usual method is to make up wall forms as framed panels with the ply. Nod facing sheet screwed on to studs on a timber frame. This allows for the plywood to be easily removed and reversed and used on both sides so as to increase the number of reuses..
CLIMBING FRAMEWORK Method of casting walls consists of a climbing framework, the climbing of which may be manual or crane assisted. These forms are widely used in the construction of industrial chimneys, silos, gig rise towers & building cores, bridge piers & pylons, airport control towers, telecommunication, towers etc. Advantages: 0 Staged construction process allows balance of site resources. 0 Anchor accessories can be reused after each pour, reducing material costs on current and future construction programs.
L] In case of trolley mounted framework, the panel retracts from the face, providing space for cleaning and fixing of concrete. C] Framework & access platforms lifted as one, minimizing crane support, reducing labor and material costs. C] & laterally. SLIDING FRAMEWORK OR CHLOROFORMING Slip form means a continuously moving form, moving with such a speed that concrete when exposed has already achieved enough strength to support the vertical pressure from concrete still in the form as well as to withstand lateral pressure caused by wind Etc Advantages .
C] Minimum consumption of timber and steel plates. L] Total elimination of traditional scaffolding CLC Minimum requirements of carpenters for assembling. C] The concrete surfaces can be treated and finished while concrete is green, O The procedure of continuous slipping is applied to making both inner and utter walls as well as columns Of a building. PERMANENT FRAMEWORK Permanent form or stay-in-place framework is one in which the form is left as an integral part of the structure: CLC Utilized as the facing materials of in situ reinforced concrete.