Characterizing the generation and flows of construction and demolition waste in China
TL;DR: In this article, the authors proposed to increase the recycling rate and reduce landfill rate of C&D waste to improve the potential recycling economic values, but also dramatically reduce land use and potential environmental impacts.
About: This article is published in Construction and Building Materials.The article was published on 2017-04-01 and is currently open access. It has received 273 citations till now. The article focuses on the topics: Demolition & Demolition waste.
Summary (2 min read)
Jump to: [Introduction] – [1. Surveys and interviews] – [2. Methods to quantify the amount of CDW] – [2. Recycling sector in Mongolia] – [3.2. Construction waste quantification] – [3.3. Total CDW in Mongolia] and [Conclusions]
Introduction
- The construction industry generates about 35% of industrial waste in the world (Construction Materials Recycling Association, 2005; Hendriks and Pietersen, 2000) .
- Most of these solutions seek to minimize and regulate Construction and Demolition Waste (CDW).
- In EU, Llatas (2011) and Màlia et al. (2013) carried out studies to propose indicators to estimate the amount of CDW.
- CDW is thus one of the largest waste streams in Mongolia.
- A huge part of the construction and demolition work is done by small and medium-sized contractors and subcontractors.
1. Surveys and interviews
- The 35 construction companies covered almost every Aimag in Mongolia, included the Omnogovi .
- The number of construction companies constitutes the 10% of the total members of Builder Association.
- Recycling industries are most commonly concentrated in capital city along with Mongolia's population and industry.
- For reasons of efficiency, factories tend to locate themselves near the source of materials or end markets, or both.
2. Methods to quantify the amount of CDW
- -Lack of incentives from construction regulatory authorities and low costs of sending materials to landfill.
- -Lack of community attention on CDW management.
- -In the building materials industry in Mongolia processing technology and equipment are often obsolete.
- -Demolition activity is not followed by the separation of CDW because companies have no incentives to perform this task.
2. Recycling sector in Mongolia
- -The recycling sector is often considered along with the waste sector and it is not always possible to isolate the data and information that relates to the recycling sector alone.
- -Recycling sector is not clear belong to which government department collect data information, and strategy.
- One of the purposes of the in-depth interviews conducted for the research was to arrive at an understanding of the effectiveness of current waste management policies and regulations.
- The relevant legislative acts for this sector were started to be developed from 2000.
- Furthermore, the lack of investment constitutes a major problem, most of actual recycling plant's equipment is obsolete and a strong renovation is needed.
3.2. Construction waste quantification
- UB is facing an important transformation in the last years and number of construction sites has started to increase again after a small interruption during 2013-2015.
- Figure 4 shows the number of active construction sites for each district.
- All the waste produced is going to disposal sites and it can be noticed that wooden materials represents the biggest amount mostly because of wooden packing used in the construction site.
3.3. Total CDW in Mongolia
- It is important to notice that Concrete and Bricks account for the large majority of the total amount and as expected, construction waste is marginal compared to demolition activity.
- Statistics show that the amount of CDW is booming every year in months March, September and October.
Conclusions
- In Mongolia, CDW management represents a significant challenge because the performance of SMEs in construction and demolition debris management is still poor.
- The Government agencies lack of the support and human resources to effectively monitor illegal disposals and enforce CDW regulations.
- For that reason, the implementation of a waste management policy with not only economic instruments (taxes on landfill), but legal measures such as: selective demolition obligation, voluntary agreements and responsibilities is needed.
- Looking at concrete as the main waste flow estimated in Ulaanbaatar, EU standards can be applied and adapted.
- In the Netherlands, selective demolition of EOL buildings is one of the common practices in CDW management projects.
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Figures (7)
![Table 4. Rounded average percentage of waste composition by volume in construction (%) [Methods for estimating construction and demolition (C&D) waste, C. Llatas, 2013]](/figures/table-4-rounded-average-percentage-of-waste-composition-by-3ubc4dew.png)
Table 4. Rounded average percentage of waste composition by volume in construction (%) [Methods for estimating construction and demolition (C&D) waste, C. Llatas, 2013] ![Figure 1. CW quantification methodology [Methods for estimating construction and demolition (C&D) waste, C. Llatas, 2013]](/figures/figure-1-cw-quantification-methodology-methods-for-24n3if9g.png)
Figure 1. CW quantification methodology [Methods for estimating construction and demolition (C&D) waste, C. Llatas, 2013] ![Table 3. Average Demolition waste generation rates (kg/m3) [Methods for estimating construction and demolition (C&D) waste, C. Llatas, 2013]](/figures/table-3-average-demolition-waste-generation-rates-kg-m3-3gpptcrh.png)
Table 3. Average Demolition waste generation rates (kg/m3) [Methods for estimating construction and demolition (C&D) waste, C. Llatas, 2013] 
Figure 4. Number of construction sites in each district of UB 
Table 2. Percentages of material-i in each of the building structures in UB 
Table 1. Questionnaires sent to construction companies and to recycling companies in Mongolia. 
Figure 2. CDW disposal in UB during the period 2013 – 2015 divided by the three principal landfills
![Table 4. Rounded average percentage of waste composition by volume in construction (%) [Methods for estimating construction and demolition (C&D) waste, C. Llatas, 2013]](/figures/table-4-rounded-average-percentage-of-waste-composition-by-3ubc4dew.webp)
![Figure 1. CW quantification methodology [Methods for estimating construction and demolition (C&D) waste, C. Llatas, 2013]](/figures/figure-1-cw-quantification-methodology-methods-for-24n3if9g.webp)
![Table 3. Average Demolition waste generation rates (kg/m3) [Methods for estimating construction and demolition (C&D) waste, C. Llatas, 2013]](/figures/table-3-average-demolition-waste-generation-rates-kg-m3-3gpptcrh.webp)
Citations
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TL;DR: Wang et al. as mentioned in this paper conducted the CDW management analysis through 3R principle and investigated existing policies and management situations based on the reduction, reuse and recycle principles, which revealed that primary barriers of reducing CDW in China include lack of building design standard for reducing CDw, low cost for CDW disposal and inappropriate urban planning.
Abstract: Construction and demolition waste (CDW) accounts for 30% to 40% of the total amount of waste in China. CDW is usually randomly dumped or disposed in landfills and the average recycling rate of CDW in China is only about 5%. Considering there is big challenge in adoption of circular economy in CDW industry in China while related research is still limited, we conduct the CDW management analysis through 3R principle. Existing policies and management situations were investigated and analyzed based on the reduction, reuse and recycle principles. Results reveal that primary barriers of reducing CDW in China include lack of building design standard for reducing CDW, low cost for CDW disposal and inappropriate urban planning. Barriers to reuse CDW include lack of guidance for effective CDW collection and sorting, lack of knowledge and standard for reused CDW, and an under-developed market for reused CDW. As for recycling of CDW, key challenges are identified as ineffective management system, immature recycling technology, under-developed market for recycled CDW products and immature recycling market operation. Proposals to improve the current situation based on 3R principle are also proposed, including designing effective circular economy model, reinforcing the source control of CDW, adopting innovative technologies and market models, and implementing targeted economic incentives.
504 citations
TL;DR: In this paper, construction and demolition (CD ineffective CD and using finitely recyclable construction materials) are ranked as three high priority barriers which should be removed before transforming current linear economy to circular economy in C&D waste management.
Abstract: Construction and demolition (CD ineffective CD and using finitely recyclable construction materials are ranked first. Also from an aggregate perspective, agency and ownership issues in C&D waste management, lack of integration of sustainable C&D waste management, and uncertain aftermaths of moving toward circular economy in C&D waste management are three high priority barriers which should be removed before transforming current linear economy to circular economy in C&D waste management.
231 citations
TL;DR: In this article, a theoretical framework for the circular economy in the construction and demolition sector is presented, which is comprised of 14 strategies within the five lifecycle stages of constructing and demolition activities.
216 citations
TL;DR: In this paper, the authors provide a comprehensive review on recycled aggregate (RA) and recycled aggregate concrete (RAC) regarding their history, recycling, reuse and manufacture process, inherent defects (e.g. existing of additional interfacial transition zones in RAC), and materials properties.
Abstract: Using recycled aggregate s from construction and demolition waste can preserve natural aggregate resources, reduce demand of landfill, and contribute to sustainable built environment. This study provides a comprehensive review on recycled aggregate (RA) and recycled aggregate concrete (RAC) regarding their history, recycling, reuse and manufacture process, inherent defects (e.g. existing of additional interfacial transition zones in RAC), and materials properties. Specifically, these properties of RAC include fresh concrete workability, physical and chemical properties (i.e. density, carbonation depth, and chloride ion penetration), mechanical properties (i.e. compressive, flexural, and splitting tensile strength as well as elastic modulus), and long-term performance (i.e. freezing-thawing resistance, alkali-silica reaction resistance, creep, and dry shrinkage). On top of that, methods for improving RAC mechanical properties and long-term performance are summarized and categorized into three groups, i.e. (1) reduction of recycled aggregate porosity, (2) reduction of old mortar layer on recycled aggregate surface, and (3) property improvement without recycled aggregate modification (i.e. different concrete mixing design and addition of fibre reinforcement). Next, current regression-based models and artificial intelligence models on the prediction of compressive strength, modulus, and compressive stress-strain curves of RAC are reviewed and the ir limitations of those models are discussed. Furthermore, the state-of-the-art RAC applications are presented. Additionally, challenges of RAC application are reviewed taking China as an example. The link between material from CDW and EU green policy are discussed by analysing the previous research projects funded by European Commission. Finally, future perspectives of RAC research focus are discussed, i.e. development of “green” treatment methods on recycled aggregate s , further direction on nanoparticle application in RAC, and the establishment of database for RAC strength prediction.
213 citations
TL;DR: In this article, a review of recent literature on the factors, barriers and motivations that influence the generation and management of CDW is presented, and two indicators are calculated for selected countries using the latest available data and an explanatory model is developed with a view to identifying the factors affecting CDW generation.
Abstract: Construction and demolition activities and natural disasters generate vast quantities of waste materials. Globally, it is estimated that about 35% of the quantities of construction and demolition waste (CDW) produced are directed to landfills, without any further treatment, although efforts to recycle and reuse CDW are increasingly being made. This paper, through a review of recent literature, focuses on the factors, barriers and motivations that influence the generation and management of CDW. Based on the analysis, two indicators are calculated for selected countries using the latest available data and an explanatory model is developed with a view to enabling identification of the factors affecting CDW generation. Most importantly, a concept map is created involving thirty-six different nodes that represents existing knowledge with respect to the components of the CDW system, and the positive or negative relationships between them.
205 citations
References
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TL;DR: The findings from this study indicate that survey and case study are major methods for data collection, and the data are mostly processed through descriptive analysis, and C&D waste management will continue to be a hot research topic in the future.
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TL;DR: It is concluded that approximately 13.71 million tons of C&D waste was generated in 2012 in Shanghai, of which more than 80% of this C&d waste was concrete, bricks and blocks.
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