Jacob Wolff, Daniel Willis, Tom Tang
i. Introduction to formwork • Importance of formwork: Economical considerations – Definition of formwork – Quality of formwork – Formwork Life Cycle
i. Introduction to formwork • Importance of formwork: Economical considerations – Formwork, also called “moulds” or “shuttering” – Formwork, – Reasons – Reasons why concrete structures are generally avoided – Formwork – Formwork greatly affects the final appearance of the finished structure – Formwork – Formwork is a large proportion of the total cost of a structure – The – The ultimate economical success of formwork lies in the ease with which it can be stripped – Formwork – Formwork should be designed in the office and not on the construction site.
ii. Traditional and common formwork • Wood formwork – Wood formwork is the most traditional formwork – Wood – System – System is generally built of lumber or a combination of lumber and plywood system is generally built of lumber or a combination of lumber and plywood – Common – Common and easily obtained timber for formwork is pine (Norway or American American Southern Southern Pine). Its easily worked worked and cheap when compared to other woods – The – The strongest timber formwork is American pitch pine or Southern long leaf pine – Wood – Wood products are the most widely used material for formwork
ii. Traditional and common formwork • Wood formwork – Wood – Wood formwork is the most traditional formwork » Disadvantages of wood formwork: 1. High labor costs: labor costs 2. High waste 3. Limited number of reuses 4. Require high quality labor force and adequate supervision 5. Limited spans (Hanna 33-34) » Advantages of wood formwork: flexibility, economy, and availability
ii. Traditional and common formwork • Steel and aluminum formwork – Steel – Steel & Aluminum Formwork: are often favored over wood formwork because of the greater speed of stripping the formwork, the forms may be reused many times over, and because less physical material is required because of its greater strength. – Steel formwork span longer and are more durable than wood – aluminum – aluminum and steel forming systems are more expensive, but safer, than the old system of plywood and three by fours.
iii. Innovations in concrete formwork • Glass reinforced plastic formwork – Glass-reinforced – Glass-reinforced plastic formwork may be used for complex shapes and special surface sur face features. – Found – Found increasing use because of their strength, light weight, and high number of re-uses. re-u ses. – Produces – Produces high quality concrete finishes (Hanna, 23). – Problems – Problems include attack by alkalies alka lies in the concrete and form expansion because of exposure exp osure to hot sun
iii. Innovations in concrete formwork • Flying formwork – Called – Called “flying” because they are flown from story to story by a crane. – They – They are built in "typical" span lengths l engths in order to provide continual reuse in a variety of jobs. jo bs. – Advantages: – Advantages: Fabrication on the ground for higher productivity, stripping as one integral int egral unit reduces stripping costs, They allow for plenty p lenty of working space below the trusses, Costs are lower low er when 10 + reuses are available, They reduce floor cycle cyc le and construction time – Limitations: – Limitations: Difficult to handle on o n windy days, not used on flat slab with drop panels around aro und columns, building must have an open façade.
iii. Innovations in concrete formwork • Slip Formwork – Slip – Slip forms are another type of early removal system using materials, which are continuously conti nuously re-employed. – Three – Three types of jacks--hollow screw scr ew jack, hydraulic jack and pneumatic jack--are used worldwide w orldwide to "slip" formwork for a wall section to higher hi gher levels as the concrete cures. – The – The screw jack is manually operated oper ated and used in areas of the world where mechanization mechanizatio n is limited. – The – The hydraulic and pneumatic jacks ja cks are fully automated moving continuously as concrete concret e is pumped into place.
iii. Innovations in concrete formwork • Jump Formwork – Jump – Jump forms are another type of concrete formwork, which moves as concrete cures to create a reusable, economic system. – Used – Used when no floor is available to support wall formwork – Consist – Consist of 2+ strongbacks – Jump – Jump forms also have a lifting mechanism m echanism but it is used differently from that of the continuous contin uous pours made with slip-forming. – These – These are designed to swing away aw ay from the structure (like a door opening) for cleaning cleanin g and oiling with subsequent reattaching to the wall w all as it increases in height.
iii. Innovations in concrete formwork • Shotcrete – a process in which compressed air forces mortar or concrete through a hose and nozzle nozzle onto a surface at a high velocity and forms structural or nonstructural structural components of buildings. – Shotcrete Shotcrete may be applied to surfaces using a dry-mix or wet-mix method. – No forms forms or one sided forms are used. – Because Because forms are not always required, shotcreting shotcreting is a cost-effective method for repairing repairing vertical and overhead surfaces. Advances Advances in equipment and materials have made made wet-mix shotcreting a practical repair option
iii. Innovations in concrete formwork
iii. Innovations in concrete formwork
iii. Innovations in concrete formwork • Cobiax (Bubble Deck) – Biaxial system that employs hollow rubber spheres to displace the concrete that has no structural benefit. – The result result is a floor that weighs up to 35% less less than an equivalent solid floor. – Being a modular system, cobiax can be assembled assembled on site or produced and bought as a semi-precast slab. – When integrated integrated into the whole structural frame solution, solution, cobiax delivers many benefits structural benefits and saves money.
iii. Innovations in concrete formwork • Cobiax (Bubble Deck) – Advantages biaxial structure longer span- no beams weight savings-fewer supportssupports- high earthquake resistance retrofit-change of use reduction in construction construction time Actual benefit in % savings savings when compared to solid flat slab. Concrete in floors 32% Floor reinforcing steel 20% Concrete in foundation 20% Columns 40% Beams and Joists 100% Deck construction time 35%
iii. Innovations in concrete formwork • Cobiax (Bubble Deck)
iii. Innovations in concrete formwork • Cobiax (Bubble Deck)
iii. Innovations in concrete formwork • Insulated Concrete Forms (ICF) – Insulating concrete formwork (ICF) otherwise known as permanently insulated formwork (PIF) is an insulated in-situ concrete system of building that is quick to construct and offers levels of performance significantly better than that available from slower, more traditional approaches to building. – ICF are based on large, hollow lightweight block components that lock together without intermediate bedding materials, such as mortar, to provide a formwork system into which concrete is poured.
iii. Innovations in concrete formwork • Insulated Concrete Forms (ICF) •
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Building with Insulating Concrete Forms is gaining momentum because of its unparalleled comfort, energy efficiency, and safety ratings at comparable costs. ICF building materials can achieve an R-Value of up to 40 and save 80% on heating and cooling costs.
iii. Innovations in concrete formwork • Insulated Concrete Forms (ICF) •Insulating Concrete Forms are infinitely versatile, allowing design and construction flexibility •ICF forms are manufactured from high density, biologically safe, fire retardant, type II/III expanded polystyrene. The Quad-Lock Building System will not support combustion. The fire resistance of a 6" thick finished Quad-Lock wall is 4 hours.
iii. Innovations in concrete formwork • Tilt-Up Concrete Forms – Wall sections are cast on site and tilted up into place. – In this case the tilt up wall is also an ICF product by Quad-Lock Concrete Building Solutions
vi. Fabric Formwork
iii. Fabric Formwork History – – –
Erosion Control and pond liners – initial practical uses for fabric formwork in the 70s Geotextiles – some of the first patents for fabric formwork Miguel Fisac – used formwork for textured walls.
vi. Fabric Formwork
iii. Fabric Formwork The 80’s and the 90’s – – –
Kenzo Unno – in-situ cast concrete walls Rick Fearn – Canadian inventor of fabric formwork techniques which was sold to Fastfood Industries. Mark West – artist, architectural educator, and builder invented a series of techniques for constructing fabricformed walls, walls, beams, columns, slabs, and panels. Now the director of C.A.S.T. at University of Manitoba’s Faculty of Architecture.
vi. Fabric Formwork
iii. Fabric Formwork
vi. Fabric Formwork
iii. Fabric Formwork •
Characteristics –
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Surface – permeable membrane allows air bubbles and excess water to bleed out, leaving a cement-rich paste at the surface of the the form. Eliminates the need need for additional additional treatment such as sand blasting, acid etching, veneers… Loss of excess water through the permeable fabric produces a stronger and more durable “case hardening” of the concrete through a significant improvement in its compaction and water-cement ratio near the surface. Geometry and Structure – Textiles resists only tension while concrete resists compression. The structural opposites work together to make an efficient formwork for concrete. Lightweight Formwork – 100 to 300 times lighter l ighter than conventional wooden wooden forms. Best formwork formwork fabrics are are also 1/10th the cost of formwork formwork plywood per unit area. Increases in material and structural efficiency are the result of a fundamental paradigm shift in formwork structural strategy. First major advancement in concrete formwork technology since plywood after WWII
vi. Fabric Formwork
iii. Fabric Formwork •
Sustainability (construction) –
The Cost for fabric formwork is 1/10th the cost of plywood formwork. This lowers the Embodied Embodied Energy of the building. Embodied energy energy is the energy energy consumed consumed by all of the processes associated with the production of a building, from the acquisition of natural resources to product delivery. This includes the mining and manufacturing of materials and equipment, the transport of the materials and the administrative functions. Embodied energy is a significant component of the lifecycle impact of a home.
vi. Fabric Formwork
iii. Fabric Formwork •
Sustainability (structure) –
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Remarkable structural advantages are obtained by the use of flexible textile formwork and its structurally opposite capacities to concrete: The fundamental physical law that tension and compression forces exist as geometric inversions of each other. The natural natural gravity laden deflections produced by textile formworks can be used to produce sophisticated three dimensional compression shell and vault structures through the simple act of inversion – a process inherent to precast production. Even when geometric inversion is not possible such as cast-in-place members, structurally efficient variable section members can be easily formed using fabric formwork. Structural members with a lower lower dead weight weight (higher efficiency) are produced by varying the crosssection of a structural member to follow the path and distribution of the forces inside it. This is notoriously notoriously difficult to do using traditional panelized, rectangular “box” mold, and relatively simple to do using flexible formworks.
vi. Fabric Formwork
iii. Fabric Formwork
vi. Fabric Formwork
iii. Fabric Formwork •
Future Projections –
New ways to think about concrete • Construction – lightweight concrete lends itself to different construction methods • Form – more efficient forms mean lighter structures and a move away from prismatic or rectilinear design • Industry – These efficiencies could alter the industry of concrete design. Integration with existing projects could yield significant gains.
