Identification of non-value adding (NVA) activities in precast concrete installation sites to achieve low-carbon installation

The lean production philosophy has been applied in the construction industry to reduce waste and increase efficiency. It is until recently that the lean philosophy has proven to be effective to meet the challenges of sustainable development. Many studies have shown that lean philosophy can be applied in precast concrete factories to lower inventory, reduce waste and increase efficiency. However, the precast concrete installation cycle should not be overlooked following a life cycle perspective. This study adopts a weighted factor model comprising 30 contractors in the Singapore construction industry and a case study. Construction site layout management practices are investigated using the weighted factor model. Strategies to improve the construction site layout are presented in a case study. The results indicated that there are many non-value adding activities in the site layout management practices that contribute to an increase in the carbon emissions level. Little consideration of green building materials, improper specifications of the precast concrete products, lack of an uninterrupted workflow, and inaccurate estimation of seem to be the most important ones. The results provide good practice guidance and can be used as a checklist for contractors to identify the NVA activities in the installation sites to achieve low-carbon installation. The results will also be useful for regulatory agencies to provide recommendations for contractors to improve the installation procedure and reduce carbon emissions.     

Critical factors for waste management in office building retrofit projects in Australia

Office building retrofit is a sector being highlighted in Australia because of the mature office building market characterised by a large proportion of ageing properties. The increasing number of office building retrofit projects strengthens the need for waste management. Retrofit projects possess unique characteristics in comparison to traditional demolition and new builds such as partial operation of buildings, constrained site spaces and limited access to as-build information. Waste management activities in retrofit projects can be influenced by issues that are different from traditional construction and demolition projects. However, previous research on building retrofit projects has not provided an understanding of the critical issues affecting waste management.This research identifies the critical factors which influence the management of waste in office building retrofit projects through a literature study and a questionnaire survey to industry practitioners. Statistical analysis on a range of potential waste issues reveals the critical factors, as agreed upon by survey respondents in consideration of their different professional responsibilities and work natures. The factors are grouped into five dimensions, comprising industry culture, organisational support and incentive, existing building information, design, and project delivery process. The discussions of the dimensions indicate that the waste management factors of office building retrofit projects are further intensified compared to those for general demolition and construction because retrofit projects involve existing buildings which are partially operating with constrained work space and limited building information. Recommendations for improving waste management in office building retrofit projects are generalised such as waste planning, auditing and assessment in the planning and designing stage, collaboration and coordination of various stakeholders and different specialists, optimised building surveying and BIM technologies for waste analysis, and new design strategies for waste prevention.     

Concrete block production from construction and demolition waste in Tanzania

In Tanzania, construction and demolition (C&D) waste is not recycled and knowledge on how it can be recycled especially into valuable products like building materials are still limited. This study aimed at investigating the possibility of recycling the C&D waste (mainly cementitious rubble) into building material in Tanzania. The building materials produced from C&D waste was concrete blocks. The concrete blocks were required to have a load bearing capacity that meets the building material standards and specifications. Eight C&D waste samples were collected from C&D building sites, transported to the recycling site, crushed, and screened (sieved) to get the required recycled aggregates. Natural aggregates were also used as control. The recycled aggregates were tested in the laboratory following the standard methods as specified in Tanzanian standards. The physical, mechanical and chemical characteristics were determined. The physical and mechanical results showed that recycled aggregates were weaker than natural aggregates. However, chemically they were close to natural aggregates and therefore suitable for use in new concrete block production. In the production process, each experiment utilized 100% recycled aggregates for both fine and coarse portions to replace natural aggregates. The Fuller's maximum density theory was used to determine the mix proportions of materials in which a method that specifies concrete mix by system of proportion or ratio was used. The concrete blocks production processes included batching, mixing (that was done manually to get homogeneous material), compacting and moulding by hand machine and curing in water. After 28 days of curing, the concrete blocks were tested in the laboratory on compressive strength, water absorption ratio and density. The results showed that the blocks produced with 100% recycled aggregates were weaker than those with natural aggregates. However, the results also showed that there is a possibility of recycling the C&D waste into building material because 85% of the tested concrete block specimens from recycled aggregates achieved a compressive strength of 7 N/mm², which is defined as the minimum required load bearing capacity in Tanzania. Therefore, the C&D waste could be a potential resource for building material production for sustainable construction in Tanzania rather than discarding it. Further work should focus on the economic feasibility of production of concrete blocks with recycled aggregates in Tanzania.     

Integrating waste, manufacturing and industrial symbiosis: an analysis of recycling, remanufacturing and waste treatment firms in Texas

The continually increasing volume of the waste stream has led to numerous calls for strategies to close the loop on material use through industrial symbiosis strategies which direct used material and products (wastes) back to production processes. By use of a survey of recycling, remanufacturing and waste treatment firms in Texas, this paper asks if these firms can operate as a bridge between production and consumption/waste to efficiently increase the flow of used materials and products back to production processes at the local level. The results suggest that while most materials and used products are collected locally, only some can be re(consumed) locally. Moreover, the firms face negative perceptions about their activities from industry and the public at large that likely slow both the rate of entry of new firms into these markets and the expansion possibilities of existing firms. In addition, the types of conventions that characterize the interactions of more successful firms are not well developed in this sector(s). It is unlikely that recycling, remanufacturing and waste treatment firms can become central players in the production, consumption and waste cycle loop until society develops production design, marketing and consumption philosophies that include recycling and remanufacturing at a fundamental level.     

Integrating waste,manufacturing and industrial symbiosis: an analysis of recycling,remanufacturing and waste treatment firms in Texas

The continually increasing volume of the waste stream has led to numerous calls for strategies to close the loop on material use through industrial symbiosis strategies which direct used material and products (wastes) back to production processes. By use of a survey of recycling, remanufacturing and waste treatment firms in Texas, this paper asks if these firms can operate as a bridge between production and consumption/waste to efficiently increase the flow of used materials and products back to production processes at the local level. The results suggest that while most materials and used products are collected locally, only some can be re(consumed) locally. Moreover, the firms face negative perceptions about their activities from industry and the public at large that likely slow both the rate of entry of new firms into these markets and the expansion possibilities of existing firms. In addition, the types of conventions that characterize the interactions of more successful firms are not well developed in this sector(s). It is unlikely that recycling, remanufacturing and waste treatment firms can become central players in the production, consumption and waste cycle loop until society develops production design, marketing and consumption philosophies that include recycling and remanufacturing at a fundamental level.     

Analysis of the implementation of effective waste management practices in construction projects and sites

In this paper, the implementation of effective waste management practices in construction projects and sites is analyzed, using data from a survey answered by 74 Spanish construction companies based in Catalonia. Most commonly implemented practices were found to be on-site cleanliness and order, correct storage of raw materials, and prioritization of the nearest authorized waste managers. The least widespread practices were the use of a mobile crusher on site, the creation of individualized drawings for each construction site, and the dissemination of the contents of the waste management plan to all workers, to help them to meet its requirements. Waste regulations for construction and demolition, and the corresponding construction waste management facilities, were designed before the recession in the Spanish construction sector. Current waste generation rates are still below predicted levels, and the infrastructure was designed for five times more waste generation. Even so, the percentage of reused and recycled waste currently amounts to 43%. Survey respondents highlighted various instruments and measures that would make the management of construction and demolition waste more sustainable. Most of the opportunities identified by construction firms are within the scope of government and related to a combined system of bonus and penalties and the establishment of environmental awareness and training programmes for all the stakeholders. Within the scope of authorized waste managers, firms suggested improvements such as the standardization of fees, a reduction of the time until the issue of waste management certificates, a higher number of inspections, and a change in the current model of a few large construction waste management facilities. This research is useful to better understand the current status of construction and demolition waste management in construction projects and sites. Thus, the results of this research will guide policy makers and relevant stakeholders such as contractors, clients, architects and engineers to achieve the EU target of recovering 70% of construction and demolition waste in 2020. In this sense, reliable information can help governments and professional associations to set future C&D waste management regulations, training programmes and dissemination tools, inspections, etc.     

Collaboration between design and waste management: Can it help close the material loop?

In order to explore the current relationship between industrial design and waste management (WM), a semi-structured interview study was carried out with 25 professionals from WM and designers that have worked with waste. The main aim was to learn about the collaborative work between these two areas and to investigate whether collaboration could help to incorporate material resources into production. The study reveals that designers and WM professionals regard the relation between disciplines in different ways, being more or less centered in their own disciplines. The designers interviewed, however tend to have a wider impression of this relation. This, together with the lack of understanding of the other's role and a fundamental scale difference when dealing with material flows were identified as the main barriers to better and more frequent collaboration. Even though some examples of collaborative work were found, they were not significant enough to have any noticeable effect on the WM system. In order to facilitate future collaboration, the contribution of the presented work is to identify areas for collaboration and suggest initial solutions for overcoming the barriers encountered to help to close the material loop.     

Recycling and householder attitudes: A survey of Norwich

This paper incorporates the results of a survey of recycling activity and attitudes in one UK community, the city of Norwich. The principal aims of the study were to identify the operation of the local market in secondary materials and to assess householder attitudes towards new recycling ventures and the use of recycled paper products. The main findings of the study indicate that a well established secondary paper and metals markets does exist in Norwich. Householder attitudes to recycled products seem, as far as paper is concerned, to depend upon the quality (texture and colour) of the products. As for the collection of secondary materials, better deployment of existing volunteer/charity based groups would appear to be a more ‘economic’ strategy than direct local authority involvement.     

Recycling and consumption in Germany and Japan: a case of toilet paper

This paper compares the recycling attitudes of consumers in Germany and Japan, based on our nationwide questionnaires. We analyzed consumption behavior as well as recycling behavior in narrow sense, because it is important to study the former to see how the supply of recycled materials is balanced with the demand, particularly in Japan which exports little recycled materials. Toilet paper was adopted as a specific good for study, because consumers have options of buying virgin products and recycled products. It was found that German households pay for waste collection specifically and have higher recycling rates than Japanese households. On the other hand, similar figures in German and Japanese consumers were observed with regard to consumption of recycled products. Their purchasing criteria and preference on virgin and recycled products of toilet paper were examined by self-report and blind test with 2×2 experimental design for toilet paper (German versus Japanese, virgin versus recycled). Blind test showed that people prefer domestic and virgin products in both countries. Half of respondents rating virgin products guessed that the products contained recycled material. For Japanese, the material of the sample toilet paper, made from virgin pulp, seems to be a more determining factor than the nationality of products, i.e. made in Japan. On the other hand, for Germans, the domestic nature seems to be a more dominant factor than the material, i.e. made from virgin material. Canonical discriminant analysis in conjunction with logistic regression based on self-reporting data detected the characters ‘multiplied’, ‘appearance’ and ‘brand’ as major factors making the difference in preference between the two countries. The possible reasons causing the similarity and dissimilarity between the two countries are discussed with reference to the background history.     

Some barriers to the use of materials recovered from municipal solid waste

Municipal solid waste (MSW) contains materials which could be put to good use, yet it continues to be discarded, which suggests that it contains little or nothing of value under current conditions. This paper discusses the technical reasons for the lack of commercial interest in recovering materials from MSW. After examining the nature of the salvage industry and trends in the use of materials, the paper considers the characteristics of secondary materials, the properties required of them, and the scope for increased salvage activity. The market prospects are described for waste paper, ferrous and non- ferrous scrap, glass and polymers.     

建筑垃圾资源化利用项目中特许经营模式的适用和争议——基于江苏省的实践启示

特许经营模式能够较好地发挥市场化、效率化、竞争化导向作用,充分发挥市场机制在资源配置中的决定性作用,在建筑垃圾资源化利用项目中得到了一定的应用。本文在分析江苏省建筑垃圾资源化利用项目中特许经营模式的实践经验和面临问题的基础上,总结了特许经营模式典型的交易结构,从物品属性、市场逻辑、风险分担和垄断之争四个方面对存在的争议问题和观点进行辨析,提出了国家层面制定规则、科学选择运作方式、确保采购充分竞争、合理确定项目补贴、加强政府规制作用和持续优化营商环境等政策建议,以期为未来建筑垃圾资源利用推广采用特许经营模式提供参考和启示。     

Estimation of the recycled content of an existing construction project

The Government's Sustainable Buildings Task Group recently recommended a benchmark requirement for a minimum 10% of reused/reclaimed or recycled content (by material value) in construction projects. The benchmark would be implemented through Building Regulations and public sector procurement. This paper presents the findings of a pilot study to inform decision-making on the feasibility of setting and meeting such a requirement.The project involved determining current levels of recycled content in Defence Estates’ standard design for modern barracks accommodation, and quantifying the scope to increase this content. The existing designs for the new barracks were found to use nearly 20% recycled and recovered materials. The project identified opportunities to increase this proportion to nearly 25% with no increase in cost or risk.     

The work of Envirowise in driving forward UK industrial waste reduction

Envirowise — formerly the Environmental Technology Best Practice Programme — is an UK Government Programme designed to help businesses to improve environmental performance and reduce costs. It works closely with industry bodies to prepare a strategic approach to producing and promoting tools that help companies take action to reduce waste at source. By September 2000, the Programme had helped UK companies to save £125 million per year by reducing the use of raw materials and the production of waste. The Programme produces practical advice based on existing practices in industry. As well as producing published information, Envirowise runs a free telephone helpline for UK companies. Envirowise undertakes a considerable amount of marketing to help companies overcome the barriers to action. The Government has set the objectives for the Programme's managing contractors; these are based on the impact of its activities in terms of reduced waste production.     

Diversion from landfill: quality products from valuable plastics

Mechanical recycling of 100% post-consumer plastic waste into high-quality products has been performed. The chemical and physical properties of these recycled materials have been compared with similar products manufactured from virgin resins. The properties of a blow-moulded bottle prepared from 100% post-consumer high-density polyethylene (HDPE) showed that this recycled polymer exceeded the materials specifications for virgin plastic designs. Similarly, a sample of thermoplastic polyolefin (TPO, 100% polypropylene), obtained entirely from shredder residue (SR) displayed sufficient material strength for future separation and reprocessing.     

Decisions on recycling: Construction stakeholders’ decisions regarding recycled mineral construction materials

Construction and demolition (C&D) waste, being already the largest waste fraction in industrialized countries, is expected to increase in the future. C&D waste recycling has been considered to be a valuable option not only for minimizing C&D waste streams to landfills but also for mitigating primary mineral resource depletion. Even though the use of recycled mineral construction materials (RMCM) is regulated and successful application examples are available, construction stakeholders do not yet broadly apply them. Although various criteria hindering a transition towards a broader application of RMCM have been identified, it is yet unknown how these criteria differ among decisions, stakeholders and applications. We therefore analyze construction stakeholders’ behavior, and decision-making regarding RMCM for the construction material market in Switzerland. Stakeholders’ decision-making was quantified with the analytical hierarchy process (AHP) in a survey in combination with their behavior. The results demonstrate the importance of stakeholder interaction, i.e. most stakeholders decide which material to apply based on interaction with other stakeholders e.g., recommendations and specifications. However, the initial general specification by awarding authorities that construction should be sustainable has little relevance to the subsequent material decisions. On the contrary the role of the recommendation of engineers, have a high impact on the subsequent decisions by the other stakeholders. Results also confirm that RMCM are broadly accepted in civil engineering (CE), whereas in structural engineering (SE) RMCM are still a niche product. The good alignment of the outcome of decision modeling with observed behavior shows the usefulness of analyzing decision-making with AHP.     

Reuse or Burn? Evaluating the Producer Responsibility of Waste Paper

In 1992, Sweden introduced a producer responsibility ordinance which explicitly states that sorted out, collected waste paper must be material recycled. Another alternative could be to recover energy by incineration. Material recycling was prioritized, although there is no environmental consensus favouring either of the alternatives. By calculating shadow prices of waste paper for the paper industry and for the heating plants, this study tries to determine whether waste paper should be partly incinerated. The study also addresses whether the producer responsibility has contributed to an inefficient allocation of waste paper. The results find no economic support for the producer responsibility.     

The UK Landfill Tax: an analysis of its contribution to sustainable waste management

The UK Government in October 1996 introduced a Landfill Tax to ensure that landfill waste disposal is properly priced so as to reflect its environmental cost and to help promote a more sustainable approach to waste management in which less waste is produced, reused or recycled. The UK Customs and Excise have recently reviewed the tax and the report indicates that there has been a modest reduction in waste going to landfill by industry but not households. It is submitted that for there to be a significant move towards a more sustainable approach to waste management to meet the targets set in the National Strategy the tax should be higher and the money raised by the tax should be invested to make alternatives to landfill cheaper and more readily available. It is also submitted that the Tax Credit Scheme, introduced as a means of enabling some of the tax to be invested to promote better waste management, is inadequately funded and the money is inappropriately focused. Following an examination of the projects and contributions made under the Scheme it is found that most of the contributions are not made towards projects which will fulfil the UK Government's perceived purposes. It is further submitted that there needs to be a more rational approach to waste management and legislation in Philadelphia forms a good case study of such an approach     

Who are our informal recyclers? An inquiry to uncover crisis and potential in Victoria,Canada

What is considered garbage embodies a recoverable economic value, and environmental cost if not recycled. Throughout the world, the often marginalised and impoverished population earns a living through informal recycling. This is also true for Victoria, British Columbia, one of the most affluent cities in Canada. This paper discusses results of a participatory socio-economic survey involving informal recyclers in Victoria, BC to determine their livelihood determinants. The findings reveal that “binning” is an important survival strategy to generate income. A new waste-management model that considers the social and environmental context is needed. Inclusive public policies can respond to the livelihood concerns outlined in this paper by facilitating access to recyclable materials, devising occupational safety improvements and educating about alternative strategies for resource recovery. This model can contribute to the overall sustainability of the community by reducing the waste of resources and people, empowering marginalised populations and reducing the environmental impacts of natural resource use and waste disposal.     

建筑废弃物的回收原理与方法研究

由于社会和经济因素的要求,当今的建筑生命周期要最大程度地完成圆形的循环过程,即重新使用拆建物料制造新产品。循环经济的大背景下,承建商通过坚实的理论基础,采用分层次的方法来进行建筑废弃物的管理。文中总结了两种方法的优点和缺点,进行了混合回收与源头分离两种方法的比较研究。最值得注意的是两个不同的意向方案:绿色星球计划和ICC-ESSAVETM方案。突出的可持续认证和设计方案及绿色星球计划侧重的能源效率模型时常被繁重调试系统的LEED所青睐。一旦被国际编码理事会所批准,这些文件可以在LEED的评分系统下或绿色星球计划中,帮助其寻找资格评分。文章最后分析了建筑废弃物的回收流程,并得出结论:高达95%的建筑和拆迁建筑废弃物都可以回收;回收相比垃圾填埋更节省资金;源头分离较混合回收需要更多的管理和劳动力,但能获得更大的经济利益;承建商应该组织和管理现场的回收工作。