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Ct formwork presentation
- 2. Compare and contrast FIVE (5) types of materials for formwork. You need to explain the suitability of the material, advantage and disadvantages of the material, cost of the material and the number of re-use of that material.
- 3. What is formwork ? Formwork is a mould with supporting structures used to shape and help support the concrete until it can attain a sufficient strength to support it’s own weight.
- 4. Types of materials used for formwork Timber Fabric Steel Aluminium Plastic
- 5. Compare and Contrast the Type of Materials for Formwork Number of Re-use Disadvantage Cost of Material Suitability of the material for formwork Advantage Materials for Formwork
- 7. Timber -the most common material used for formwork -it is suitable used for irregular-grid podium structure Timber formworks are high adaptability to complicated shape
- 8. Advantages Flexibility -the most flexible type of formwork (can easily be made into any shape or size) Handling -people new to building formwork typically choose timber because it requires no special tools nor a high level of construction experience Light Weight -is light weight compare to the steel or aluminium formwork (easy to fix or remove) Lower Initial Cost -the initial purchase price of a conventional 1820 Ă— 600 mm timber formwork in Taiwan is US$14.00 -compare with the initial purchase price of a plastic formwork of the same scale is US$40.50
- 9. Disadvantages Shrinking&Swelling -timber shrinks, swells and bends over time and different climatic conditions Fungal&Insect Attack -if not properly attended, the fungi and insects may attack timber during the process of seasoning Limited Reuse -can’t be used for long (can only be used about 4-8 times) Hygroscopy -timber has a natural ability to absorb water (if the timber is dry, it will absorb moisture from wet concrete and weaken the concrete)
- 11. Fabric formwork Fabric formwork is a building technology that involves the use of structural membranes as the main facing material for concrete moulds. Unlike traditional formwork, the material is highly flexible and can deflect under the pressure of fresh concrete. The resulting forms exhibit curvature as well as excellent surface finishes that are generally not associated with concrete structures.
- 12. Advantages Disadvantages ● Achieves aesthetic purposes ● Beautiful surface finishes ● Increases concrete strength( it’s permeable nature for water to flow out) ● Light weight (100-300 times lighter) ● Cost saving as fabrics costs lesser than conventional formwork(1/10 of plywood fwk cost per unit area) ● Reusable ● Less waste produced ● Lacks rigidity ● Limited number of fabric formwork manufacturer ● Does not retain moisture well during concreting
- 14. Steel -is an important structural component used in the making of physical structures such as roads, bridges and skyscrapers
- 15. Advantages Complex Designs -the panels can be fabricated in large number in any desired modular shape and size Longer Life Span -stronger, durable and have longer life than timber formwork &their reuses are more in number Non-Absorbent -does not absorb moisture from concrete
- 16. Disadvantages High Maintenance Cost -steel formwork are susceptible to corrosion when exposed to air and water (so they must be painted periodically) Expensive -heavy and thus expensive to transport
- 18. Aluminium Aluminium formwork is getting popular in construction industry. It often used in pre-fabricated formwork, that is put together on site. Aluminum alloy formwork is best apply into the position such fields as wall, horizontal floor, column, beam, stairs, window sills, floating plate etc.
- 19. Mivan Formwork System Mivan is basically an aluminium formwork system used widely in residential unit and mass housing project.It is suitable to constructing large number of houses within short time using room size forms to construct walls and slabs in one continuous pour on concrete Construction Technique 1. Setting up the wall reinforcing steel 2.Placement of aluminium formwork 3.Pouring concrete
- 20. Aluminium Advantages Easy to fix and remove -Doesn’t required skilled labour -increase worker productivity 2.Strong and light -lighter than steel approximately 50% 3.Monolithic crack free structure Disadvantages 1.Corrosion, attacked chemically by wet concrete -aluminum alloys is effective to resisting corrosion 2.No architectural changes possible
- 21. PLASTIC FORMWORK
- 22. Plastic Formwork Plastic Formwork make building concrete walls, storm cellars, basements, and pillars quick and with easiness This formwork used when complicated concrete shapes are required such as waffle floors Example of plastic formwork :Glass reinforced plastics (GRP) and vacuum formed plastics The initial purchase price of plastic formwork is higher than timber however the average usage cost of plastic formworks is no higher than 1/4 that of timber formworks Plastic formwork is getting more popular in construction industry due to the average usage cost and environmental friendly characteristic Waffle slab Glass reinforced plastic
- 23. Different Types of Plastic Formworks Nova Plastic Formwork System It is produced from composite plastic material and it is the only plastic form that can be employed in both salt and fresh water without damage Siscon Plastic Formwork System It is one type of commercially available plastic forms which can be used to construction various structural elements such as walls, columns, and slabs. It provides substantial precision.
- 24. Plastic Advantages Super lightweight -easy to handle and stack increase worker productivity 2.Fungus and termites resistant 3.Chemically resistant 4.Easily cut and nail 5.Easy to clean -Cement does not stick to plastic 6.Can be re-used many times Disadvantages 1.Less durable than metal formwork 2.Expensive in initial cost 3.Load carrying capacity low 4.Damage by heat -form expansion because of exposure to hot sun or heat from hydration of cement(GRP) 5.Attack by alkalies in the concrete(GRP)
- 25. Number of Re-use Plastic formwork systems can be re-utilized around /more than 100 times. Steel can be used upto 100 pours if they are carefully cleaned and stored. Aluminium formwork can be used more than 300 times in a low average use-cost. Aluminium Steel Timber Plastic Fabric More than 300 times 100 times 4-8times More than 100 times Unknown Timber formwork is limited reuse.Hence promoting the use of alternative materials is imperative to reduce the speed of deforestation.
- 26. THE END