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The Sustainable Formwork System: Analysis of Sustainable Metrics and Types

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Formwork

The Formwork should have sufficient strength to carry a dead load and live load coming on it during casting operation and after that till concrete gets hard and gain some percentage of design strength. Therefore choosing the best one is almost a necessity for a successful system. Discussed below are some of the popular formwork system available.

The selection of formwork systems is often governed by their competence in optimizing concrete activities in an isolated manner, without relating this choice to the entire construction workflow. Advanced high-rise formwork technologies have an upper hand over the regular ones. The importance of advanced high-rise formwork systems in streamlining the workflow of concrete and other downstream activities allows for a better  structure segmentation further allowing for better resource allocation. Additionally, there is more waste reduction, smaller work batches, less inventory, and safer working environment.

Sustainable Construction

“Sustainable construction means designing, renovating or converting a building in compliance with environmental rules and energy-saving methods.”

to promote environmentally friendly materials and the companies that use them. And therefore greatly contribute to the well-being and “sustainability” of buildings;

to highlight the concept of energy saving, particularly taking on board the typical Brussels context.

  • better insulation,
  • rational use of energy,
  • the use of renewable energies,
  • better mobility,
  • the use of natural or low embodied energy materials, etc.

Sustainable Formwork System

Awareness towards sustainable society has been on the rise lately and this globally wide phenomenon ultimately will provide a safe and healthy environment for the living assurance of the upcoming generations. Construction industry is seen to be able to   play a bigger role into a sustainable society by offering sustainable construction. In this context the study describes in this paper focus on sustainable concrete formwork system which is an important element in the concreting process. Creating sustainable formwork system will move forward the construction industry into sustainable construction initiatives.  The study aims to identify the basic benchmarks for sustainable formwork system. The main specifications of construction sustain-ability which applied to formwork system are also extracted. Through extensive review of literature the sustainable formwork system benchmarks can be  divided into three main categories; environmental such as (Waste generation, Using renewable material, Formwork reusable, and Material efficiency), economical such as (Installation cost, Cost in-use, Life-cycle cost, and Formwork serviceability), and social such as (Safety assessment & safety design of formwork system, Direct employment, and fire resistance), which covers all activities and processes related to formwork system. Identification of the sustainable formwork system elements and properties can assist developers and others stakeholders to evaluate the performance of the system in order to make enhancement to the system.

Sustainable building can be defined as those buildings that have minimum adverse impacts on the built and natural environment, in terms of the buildings themselves, their immediate surroundings and the broader regional and global setting. Sustainable building are considering the entire life cycle of buildings, taking environmental quality, functional quality and future values taken into account.

Formwork system development has grown very fast throughout the twentieth century parallel with the growth reinforced concrete technology. Formwork designers and builders are increasingly aware of the need to keep abreast of technological advancements materials utilization to develop creative innovations and technologies.

In constructing conventional reinforced concrete building, it will involve largest portion of formwork. It accounts for 35 to 60 percent of the cost of the concrete work. Formwork system development has grown very fast throughout the twentieth century parallel with the growth reinforced concrete technology. Formwork designers and builders are increasingly aware of the need to keep abreast of technological advancements materials utilization to develop creative innovations and technologies. In constructing conventional reinforced concrete building, it will involve largest portion of formwork. It accounts for 35 to 60 percent of the cost of the concrete work. The cost is not the only significant factor; however, in the formwork system there are also other aspects include speed, safety, and quality (Kim et. al, 2005). Several materials used for concrete formwork range from traditional materials such as wood, steel, and aluminum or to nontraditional materials such as fiberglass. Wood is the most widely used material for formwork, Formwork system could be classified according to its purpose to mould concrete members such as slabs and beams, walls and columns. There are many types of formwork system according to its method of erection and the materials that had been used. Traditional formwork system which uses timber as the main material is the most common and widely used in building construction. This traditional formwork system involves disadvantages such as labour intensiveness, long cycle period and mass of wastes.

New concrete formwork systems are recently developed from different materials with various methods of installation with intention to achieve sustainable construction. These sustainable formwork includes; Insulated Concrete Formwork, Plastic Formwork System, Aluminum Formwork  System, and Tunnel System.

With the massive developments in construction and construction material industry in India, demand for building materials has witnessed an upsurge. In addition to building materials like timber and steel, the demand for sustainable and environment-friendly products such as aluminium formwork and used materials, has also risen, according to reports. There is a need to meet the growing demands for building and industrial material manufacturers, suppliers and retailers.

Formwork  Assessment

A technology evaluation framework developed by Nelms et. al. (2005) in order to help design professionals, regulators, and government entities evaluate a technology’s performance over the life of a project. Underlying the framework are three constructs: (i) a three dimensional structure that treats the physical systems components that make up a building project (the x axis), major phases that make up the life cycle of a project (the y axis), and the spectrum of quantitative and qualitative performance measures, grouped by class, that describe how a project or component of a project will behave (the z axis); (ii) a hierarchical structure of performance measures that corresponds to the z axis in (i), which captures the behaviour of the technology directly within the context of the individual project, plus its impact on the surrounding environment, and a value system in terms of the weights accorded to the various performance measures, including the decision makers aversion to risk; and (iii) a cash-flow model that treats all incremental benefits and expenditures over the project’s life cycle or time frame of interest of the decision maker. Complementing these constructs are the normal design and analysis tools used to forecast performance parameters (e.g., computation of energy consumption, sizing of components, and estimation of costs) (Nelms et. al, 2005). Shen et. al (2007) also developed a checklist for assessing sustainability performance of construction projects deal with factors  affecting the construction project sustainability performance among the project life cycle stages and define according to the sustainability development main categories; economic, social, and environmental.

Formwork System Benchmarks

Three main categories refer to sustainable principles main aspects i.e. economical, social, and environmental.

Environmental Benchmarks

This aspect concern about the construction process affects on the local and global environment, which includes;   Waste generation  Energy & resource consumption Noise pollution Using renewable material Structural operation Formwork reusable Waste efficiency Material efficiency  Impact on local environmental  Air quality.

Economic Benchmarks

The economic aspect of sustainable construction focuses on the importance of stable economic growth. The capacities of the natural environment are considered by adopting measures from fair and rewarding employment through to competitiveness and trade (OGC, 2007). The economic indicators for sustainable formwork system include;  Labour cost  Material & equipment cost  Installation cost  Cost in-use  Life-cycle cost  Formwork serviceability   Simplicity of technology use  Duration of phases  Overlap of phases.

Social Benchmarks

Social sustainability concentrates at responding to the needs of people which providing high customer satisfaction and working closely with clients, suppliers, employees, and local communities (Cooper and Stewart, 2006). Social measures include;  Safety assessment & safety design of formwork system  Direct employment Safety measures Fire safety Fire resistance  .

Available Formwork System

With the current thrust of the government on construction and infrastructural development, the building material industry is booming opportunities. However, time and cost constraints remain a challenge. Another nagging concern is the requirement of trained professionals in the field. Increasing demand in the wake of ongoing and future projects, formwork manufacturers are keeping pace with the construction industry. Further, project requirements have changed at last, wherein they have started accepting innovated products, which reduce human effort providing better quality.

Sustainable Formwork systems

Insulating concrete form or insulated concrete form (ICF) is a system of formwork for reinforced concrete usually made with a rigid thermal insulation that stays in place as a permanent interior and exterior substrate for walls, floors, and roofs. The forms are interlocking modular units that are dry-stacked (without mortar) and filled with concrete. The units lock together somewhat like Lego bricks and create a form for the structural walls or floors of a building. ICF construction has become commonplace for both low rise commercial and high performance residential construction as more stringent energy efficiency and natural disaster resistant building codes are adopted. ICFs may be used with frost protected shallow foundations (FPSF). ICF construction is less demanding, owing to its modularity. Less-skilled labor can be employed to lay the ICF forms, though careful consideration must be made when pouring the concrete to make sure it consolidates fully and cures evenly without cracking. Unlike traditional wood beam construction, no additional structural support other than temporary scaffolding is required for openings, doors, windows, or utilities, though modifying the structure after the concrete cures requires special concrete cutting tools. When designing a building to be constructed with ICF walls, consideration must be given to supporting the weight of any walls not resting directly on other walls or the building’s foundation. Consideration must also be given to the understanding that the load-bearing part of an ICF wall is the concrete, which, without special preparations, does not extend in any direction to the edge of the form. For grid and post & lintel systems, the placement of vertical members of the concrete must be organized in such a fashion (e.g., starting at opposite corners or breaks (e.g. doorways) and working to meet in unbroken wall) as to properly transfer load from the lintel (or bond beam) to the surface supporting the wall.

Characteristics-Energy efficiency, Strength, Sound absorption, Fire protection, Indoor air quality, Environmental sensitivity.

Plastic Formwork

Plastic Formwork make building concrete walls, storm cellars, basements, and pillars quick and with easiness. The plastic formwork come in different sizes that interlock by means of nylon handles to make up the wall. The speed and simplicity of setup make it much handier and practical than conventional wood or steel frameworks. Wall thickness ranges from 10-40 cm in view of various blends of the different elements.

Considering the labour problem and the cost of formwork system at Desire Construction Systems thought to develop an alternative formwork system which could help the industry to not only  reduce construction cost  but also a  system that is  easy to install, dismantle and handle. The system has following Advantages: Cost Effective, Labour Friendly Eco Friendly,  Low in Maintenance  and Versatile.

Aluminium  Formwork

The Aluminium Formwork panels can be designed for any condition / component of buildings and special architectural features. This system is unique as all the components in a building, starting from slabs to floors. The periphery of resulting structure is concrete therefore we can control the concrete quality, the durability of the structure increases. The formwork system gives form to finish, eliminates the need for external and internal plaster and through the system, the walls can be directly painted with a minimal skim coat. Aluminium Formwork System is the aptest to load bearing wall construction. This type of formwork is also being used for the creation of nuclear plants.

The implementation of this formwork in load bearing design is highly cost saving. Moreover, results in savings on overhead expenses. There is an availability of Monolithic crack free structures and casting of walls and slabs possible simultaneously.

Advantages of this system are- Speed , Cost ,Durability, High Labour Productivity , Quality High salvage value.

 

 

Form Work Management Based On Ubiquitous Computing

Form work significantly influences successful project completion in high-rise / mid-rise building construction with reinforced concrete structures. One of the effective ways for reducing the form work duration is to strip the forms without delay when concrete placed in the form is sufficiently cured to stand by itself. In order to strip the forms at the appropriate time, it is important to estimate the concrete strength development at the early stage of the curing process. The concrete maturity method can determine the concrete strength more accurately and consistently than other conventional methods such as using test cylinders or a Schmidt hammer. A ubiquitous computing environment can facilitate the application of the concrete maturity method on the construction site, and a wireless temperature monitoring system has been recently developed in Korea.

Wireless Temperature Monitoring System

The constitution of the wireless temperature monitoring system developed in Korea. The system transmits the temperature data measured from the sensors wirelessly in real-time into the personal computer in the site office, and estimates the maturity and concrete strength. The data are also stored in the computer server, and information is shared with related experts for technical support. However, there are some limitations on the application for form work management in a structural framework in high rise building projects as follows:

Time for installing the sensors and connecting wires with recording devices

Identification of the data into the PC in the site office, and

Gap between the time when the estimated strength of concrete reaches the required standard and form stripping time due to a planned schedule in structural framework

However research have been carried out and the above bottlenecks were overcomes. The research proposes a method which integrates a sensor and recording device with a form, and the sensor and recording device can be separated from the form in the case of a problem such as failure in the sensor or discharge in the recording device. The installing time may then be reduced considerably. Next, the construction manager can identify acquired data and estimated strength on the PC in the site office. However, this could cause proper and timely actions to be delayed according to the changes in the site condition, even though the system has the function of sending the warning message to the managers. Mobile devices, such as smart phones and web pads, can be offered as useful tools for timely management. Form stripping work could be delayed at the time when the required concrete strength is gained. This is because the time of resources input needs to be adjusted if the time taken to reach the required strength for form stripping is inconsistent with the time planned in advance. Thus, daily work management needs to be managed effectively through predicting the concrete strength development and form stripping time.

System  Formwork

The System formwork has the standard prefabricated modular components along with casting panel. The system formwork can suit the required shape of concrete structures. The System form-work has good casting quality, speedier erection and more recycle times compared to the traditional formwork. The initial investment of system formwork is higher than the conventional one. The main components of the system formwork include plywood, beam, waler, false work, joint parts, bracing and operation platform. System formwork is applied in a specialized kind of job. It supports the in-situ RC contractors by providing services of design, delivery, site support and buy-back after job completion.

Jump Formwork System

Jump Form is the type of the system formwork that is used for vertical structures that require the cranage to lift it up for each cycle. Jump Form systems comprise the formwork and working platforms for cleaning/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 wall,  Lift shafts, Stair shaft and Bridge pylons.

Form Work Management Based On Ubiquitous Computing

Form work significantly influences successful project completion in high-rise / mid-rise building construction with reinforced concrete structures. One of the effective ways for reducing the form work duration is to strip the forms without delay when concrete placed in the form is sufficiently cured to stand by itself. In order to strip the forms at the appropriate time, it is important to estimate the concrete strength development at the early stage of the curing process. The concrete maturity method can determine the concrete strength more accurately and consistently than other conventional methods such as using test cylinders or a Schmidt hammer. A ubiquitous computing environment can facilitate the application of the concrete maturity method on the construction site, and a wireless temperature monitoring system has been recently developed in Korea. The system is discussed below.

Wireless Temperature Monitoring System

The constitution of the wireless temperature monitoring system developed in Korea. The system transmits the temperature data measured from the sensors wirelessly in real-time into the personal computer in the site office, and estimates the maturity and concrete strength. The data are also stored in the computer server, and information is shared with related experts for technical support. However, there are some limitations on the application for form work management in a structural framework in high rise building projects as follows:

Time for installing the sensors and connecting wires with recording devices

Identification of the data into the PC in the site office, and

Gap between the time when the estimated strength of concrete reaches the required standard and form stripping time due to a planned schedule in structural framework

However research have been carried out and the above bottlenecks were overcomes. The research proposes a method which integrates a sensor and recording device with a form, and the sensor and recording device can be separated from the form in the case of a problem such as failure in the sensor or discharge in the recording device. The installing time may then be reduced considerably. Next, the construction manager can identify acquired data and estimated strength on the PC in the site office. However, this could cause proper and timely actions to be delayed according to the changes in the site condition, even though the system has the function of sending the warning message to the managers. Mobile devices, such as smart phones and web pads, can be offered as useful tools for timely management. Form stripping work could be delayed at the time when the required concrete strength is gained. This is because the time of resources input needs to be adjusted if the time taken to reach the required strength for form stripping is inconsistent with the time planned in advance. Thus, daily work management needs to be managed effectively through predicting the concrete strength development and form stripping time.

Fibreglass  Formwork

The use of fiberglass as a material to make forms for concrete work has increased rapidly. One advantage of fiberglass forms is it is possible to eliminate the joints or seams. Also when special conditions dictate building a form in sections, it is possible to join the units in such a manner that the several sections may later be sealed together with additional applications of resin and fiberglass to produce a seamless mold. Versatility is another advantage. Fiberglass panels can be 100 percent reversible in any situation. Fiberglass is also an excellent insulating material and is impervious to moisture; thus fiberglass forms provide built-in protection against temperature extremes. Although the first cost of fiberglass forms are relatively high, the durability of the material permits almost unlimited reuses. Consequently, wherever it is possible to make repeated use of the same form, the cost may be reduced substantially to a point that the material becomes the lowest cost per use of any form.

Concrete  Canvas (CC)

CC consists of a 3-dimensional fibre matrix containing a specially formulated dry concrete mix. A PVC backing on one surface of the Canvas ensures the material is completely water proof. The material can be hydrated either by spraying or by being fully immersed in water. Once set, the fibres reinforce the concrete, preventing crack propagation and providing a safe plastic failure mode. CC is available in 3 thicknesses: CC5, CC8 and CC13, which are 5, 8 and 13mm thick respectively.

CC is a low mass, low carbon technology which uses up to 95% less material than conventional concrete for many applications. It has minimal impact on the local ecology due to its limited alkaline reserve and very low wash rate. The impact on the environment is further decreased by reducing the need for plant equipment.

Concrete Canvas Shelters (CCS)

Extension of Concrete Canvas technology resulted in Concrete Canvas Shelters which are are rapidly deployable hardened shelters that require only water and air for construction. The key to CCS is the use of inflation to create a surface that is optimised for compressive loading. This allows thin walled concrete structures to be formed which are both robust and lightweight. A 25sqm CCS can be deployed by 2 people in less than 1 hour and is ready to use in only 24 hours.

Concrete Canvas (CC) is fire-safe, does not contribute to the surface spread of flames, and has a low level of smoke development and minimal hazardous gas emissions. Each shelter is lined with a flame retardant fiber reinforced polyethylene inner with a B1 (DIN 4102-01 05/98) fire rating.

CCS can be fitted with a ventilation system along with security door. CCS provides all the benefits of a permanent structure without the associated cost and time delays.

Com-shells

A Comshell roof is a steel-concrete composite shell roof formed by pouring concrete on a thin stiffened steel base shell which serves as both the permanent formwork and the tensile steel reinforcement. The steel base shell is constructed by bolting together modular steel units in the form of an open-topped box consisting of a flat or slightly curved base plate surrounded by edge plates. The edge plates may have lip stiffeners for enhanced local buckling resistance.

Architectural Forms

Architectural concrete differs from structural concrete in that sense the appearance or color of the exposed surfaces of the forms may be more important than the strength of the members. The properties of fresh concrete are such that it may be cast or molded to produce any shape that forms can be made. A variety of colors may also be obtained by adding a color admixture to the concrete mix or by adding a surface coating after the concrete has hardened.

The surfaces may be extremely smooth or they may be quite rough, depending on the desired effects. The appearances of large and possibly drab areas can be improved greatly by the use of recessed or raised panels, rustications, ornaments, and other designs. Metal molds can produce concrete having extremely smooth surfaces. A variety of surface patterns can be obtained using form liners that are placed on the inside of plywood sheathing. A large variety of shapes is available from companies that supply formwork accessories.

Because the quality of the finished concrete is limited by the quality of the forms, it is necessary to exercise care in selecting the materials for the forms. Also, high-quality craftsmanship is required in building and stripping the forms of architectural concrete if the desired effects are to be achieved with a satisfactory degree of perfection.

Info and source

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