Analysis of Barriers and the Potential for Exploration of Deconstruction Techniques in Portuguese Construction Sites
Abstract
:1. Introduction
2. Deconstruction: A Tool in Building Rehabilitation
3. Barriers and Advantages of Deconstruction
3.1. Barriers and Opportunities for Deconstruction
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- Lack of information, skills and tools on how to both deconstruct and design for deconstruction.
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- Lack of a large enough established market for deconstructed products.
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- Lack of design. Products are not designed with deconstruction in mind.
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- Reluctance of manufactures, which always prefer to purchase a new product rather than to reuse an existing one.
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- Composite products. Many modern products are composites which can lead to contamination if not properly deconstructed or handled.
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- Joints between components are often designed to be hidden (and therefore inaccessible) and permanent.
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- Deconstruction requires additional time. Time constraints and financial pressure to clear the site quickly, due to lost time resulting from delays in getting a demolition, or removal permit, may detract from the viability of deconstruction as a business alternative.
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- Deconstruction is a labor-intensive effort, using standard hand tools in the majority of cases. Specialized tools designed for deconstructing buildings often do not exist.
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- The proper removal of asbestos-containing materials and lead-based paints, often encountered in older buildings that are candidates for deconstruction, requires special training, handling, and equipment.
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- Re-certification of used materials is not always possible, and building codes often do not address the reuse of building components.
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- The design of joints to facilitate deconstruction.
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- The development of methodologies to assess, test and certify deconstructed elements for strength and durability, etc.
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- The development of techniques for reusing such elements.
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- The identification of demonstration projects to illustrate the potential of the different methods.
3.2. Deconstruction Benefits
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- Reuse and recycle materials: materials salvaged in a deconstruction project can be reused, remanufactured or recycled (turning damaged wood into mulch or mortar and concrete into aggregate for new foundations) [4].
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- Foster the growth of a new market—used materials: recovered materials can be sold to a salving company. The market value for salvaged materials from deconstruction is greater than from demolition due to the care that is taken in removing the materials in the deconstruction process.
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- Environmental benefits: salvaging materials through deconstruction helps reducing the burden on landfills, which have already reached their capacity in many localities. By focusing on the reuse and recycling of existing materials, deconstruction preserves the invested energy embodied in materials, eliminating the need to expend additional energy to process new materials. By reducing the use of new materials, deconstruction also helps reducing the environmental effects, such as air, water and ground pollution resulting from the processes of extracting the raw materials used in those new construction materials. Deconstruction results in much less damage to the local site, including soil and vegetation, and generates less dust and noise than demolition.
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- Create jobs: deconstruction is a labour-intensive process, involving a significant amount of work, removing materials that can be salvaged, taking apart buildings, and preparing, sorting, and hauling the salvaged materials.
3.3. Cost of Deconstruction
4. Guidelines to Design for Deconstruction and Tools to Materials Recovery Analyses
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- To use recycled materials—the incremented usage of recycled materials will encourage both industry and governments to investigate new recycling technologies and the creation of a greater support network for future recycling and reuse.
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- To minimize the number of different types of material—this will simplify the material organization process and reduce transportation.
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- To avoid toxic or potentially harmful materials—this will lessen the contamination potential inherent to materials segregated and will also reduce potential risks to human health during disassembly.
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- To schedule separate assembly of materials with different reuse potential—this will keep large quantities of a given material from being contaminated by small quantities of another that cannot be separated.
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- To avoid secondary finishing and coating whenever possible—these materials may contaminate the underlying material and make recycling less workable. Whenever possible, use of materials that incorporate their own surface coating or finish or use of separate mechanically connected finishing.
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- To provide permanent identification of types of material—many substances, such as plastics, are not easily identified and should have ID tags or marks signalling ‘non-removable’ or ‘non-contaminant’ so as to make them easier to organize in the future.
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- To minimize the number of different types of components—this will simplify the process of sorting on site and make the potential for reprocess more attractive due to the larger quantities of same or similar items.
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- To use a minimum number of wearing parts—this will reduce the number of parts that need to be removed in the remanufacturing process and thereby make reprocessing more efficient.
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- To use mechanical connections rather than chemical ones—this will allow for the easy separation of components and materials without force, and reduce contamination to materials and damage to components.
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- To make chemical bonds weaker than the parts being connected—if chemical bonds are used, they should be weaker than the components so that the bonds will break during disassembly rather than the components; for example, mortar should be significantly weaker than the bricks.
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- To choose an ‘open space’ construction system that allows for changes in the compartmentalization of the building through replacement of components without significant construction work.
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- To use assembly technologies that are compatible with standard building practices—resorting to specific technologies will make disassembly harder and may call for special labour and equipment, turning this into a less attractive option.
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- To separate the structure of inner walls from casements or coatings—so as to allow for parallel disassembly, where some parts of the building may be removed without affecting others.
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- To provide access to all parts of the building and to all components—ease of access will favour disassembly. Whenever possible, to allow that component recovery inside the building is made without specialized equipment.
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- To use components that make handling easier—allowing for handling at every stage; disassembly, transportation, reprocessing and reassembly.
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- To consider the space involved and the means necessary to deal with the many components during disassembly—handling may call for connection points for lifting equipment or temporary support or buttressing mechanisms.
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- To ensure realistic slack among elements so as to allow for all the necessary movements during disassembly.
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- To use the smallest possible diversity of connectors—enforcing standards will make disassembly easier, faster, and demand fewer kinds of tools and equipment. Even if the end result is oversized connections, the time required for assembly-disassembly will surely be enough compensation.
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- To use a disassembly hierarchy connected with the components’ lifespan—using components with shorter life spans where access and disassembly are easier.
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- To provide for permanent identification of component types—using international-standard barcodes may make it easier to divulge deposit banks and the commercialization of materials and components found in different places.
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- To standardize the parts while allowing for an infinite variety of the whole—this will allow minor alterations to the building without major building works.
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- To use a standard structural grid—grid sizes should be related to the materials used such that structural spans are designed to make most efficient use of material type.
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- To use a minimum number of different types of components—fewer types of component means fewer different disassembly operations that need to be known, learned or remembered—it also means more standardization in the reassembly process which will make the option of relocation more attractive.
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- To use lightweight materials and components—this will make handling easier, quicker, and less costly, thereby making reuse a more attractive option.
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- Permanently identify point of disassembly—points of disassembly should be clearly identifiable and not be confused with other design features.
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- To provide spare parts and on site storage for them (especially for custom built components)—both to replace damaged components and to facilitate minor alterations to the building.
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- To sustain all information on the building manufacture and assembly process—measures should be taken to ensure the preservation of information such as ‘as built drawing’, information about disassembly process, material and component life expectancy, and maintenance requirements.
5. Contribution towards Increased Competitiveness of Companies
6. Establishing a Conduct for a Successful Deconstruction Process
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- Conduct a walk-through with the owner’s representative and a deconstruction contractor to determine the feasibility and level of salvage possible. Identify materials and job phases where recovery, recycling and salvage opportunities are the greatest. The walk-through also can identify materials that could be salvaged and reused on-site.
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- To compare costs, require estimates for full deconstruction of the structure, targeted salvage prior to demolition, and traditional demolition.
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- Based on the walk-through and cost comparison, it should be determined if full deconstruction of the structure is an option or if salvage prior to demolition would be more effective.
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- Determine in advance how much time is available to complete the demolition phase of the project. The bid and contract process is the best place to assure that adequate time is available. Contracting mechanisms include decoupling demolition from the design/build phase of construction contracts. The demolition aspect of the project can be delayed while the terms of the larger design/build agreement are worked out, thus allowing time for deconstruction and salvage prior to completing demolition.
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- Other alternatives to ensure enough time to complete deconstruction and salvage include issuing an early notice to proceed for the demolition phase of the project or creating a separate request for proposal or bid and contract for deconstruction and demolition.
7. Suggestions to Impel the Deconstruction Process in Portugal
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- To approve specific legislation.
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- To improve the efficiency of the authority control.
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- Training all construction intervenients.
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- Diffusion of benefits by workshops.
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- To consider environmental factors in contractors selection.
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- To increase the disposal taxes.
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- To increase the penalties for the illegal landfills.
8. Final Comments
References and Notes
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Couto, J.; Couto, A. Analysis of Barriers and the Potential for Exploration of Deconstruction Techniques in Portuguese Construction Sites. Sustainability 2010, 2, 428-442. https://doi.org/10.3390/su2020428
Couto J, Couto A. Analysis of Barriers and the Potential for Exploration of Deconstruction Techniques in Portuguese Construction Sites. Sustainability. 2010; 2(2):428-442. https://doi.org/10.3390/su2020428
Chicago/Turabian StyleCouto, João, and Armanda Couto. 2010. "Analysis of Barriers and the Potential for Exploration of Deconstruction Techniques in Portuguese Construction Sites" Sustainability 2, no. 2: 428-442. https://doi.org/10.3390/su2020428