Literature Review: Construction Waste Management
The two articles being reviewed in this paper are: a) Multi-Attribute Decision Making in Choosing Suitable Construction Waste Management Methods , and b) A Framework for Managing Construction Demolition Waste: Economic determinants of recycling , both addressing the decision making process in construction waste material management.
Zhang and Li primarily address the topic of scientific methods that can be used to measure variables that affect effective decision making in the efficient disposal of construction waste. The authors highlight that as populations and economies grow, a city’s real estate needs expand too. In such cases, construction of buildings and infrastructural facilities also rise in tandem with economic growth. As such, the waste arising from construction and demolition is very high and the limited numbers of landfills available make it imperative that waste be managed efficiently.
There are several variables that need to be taken into consideration when creating a waste disposal model that best suits a city or a particular landfill’s needs. Some of these variables include technological availability and trustworthiness, cost of implementing measures as well as use of energy. While most of these variables can be mathematically measures to derive numerical analysis and comparisons, there are several attributes that can only be measured and analyzed linguistically. This inability to standardize measurement of variables makes it difficult to analyze and select methods on the same plain.
Zhang and Li propose a model, the prioritized Multi-Attribute Decision Making or MADM, that seeks to address the following: a) Reduce, if not eliminate, the gap that currently exists between numerical and linguistic methods of assessing variables, b) standardizing the scales of measurement of variables, and c) arrive at an aggregate of the analysis of different variables based on their relation to each other. Through this method, the authors propose that decisions pertaining to the identification of optimum construction waste management methods can be facilitated.
The authors first overview traditional assessment methods such as the original MADM and the 2 Tuple Fuzzy Linguistic Representation model. Further, they note that, regardless of their geographic location and economic status, the composition of construction waste material in different countries such as the US, Japan and Honk Kong are more or less the same. These materials include: a) Concrete, b) mixed rubble, c) wood, d) drywall, d) asphalt roofing, e) bricks, f) plastics, g) glass and ceramic, h) metal components, and i) inorganic compounds. As the construct waste to be disposed and managed is the similar, so are the methods that are currently in use. These methods include: a) reduce, b) re-use, c) re-cycle, d) compost, e) incinerate, and f) landfill.
Zhang and Li cite the sustainable attributed of waste management as listed by Roussat et al in 2009. These attributes are: a) lost energy, b) global warming, c) discharge of hazardous substances, d) cost benefit analysis, e) quality of life, and f) employment . Further, the authors note that other attributes such as technological accessibility and reliability as well as product quality need to be considered. These attributes, based on their utility, are then ranked in a prioritized MADM model containing three priority levels with three variables being allocated to each.
Zhang and Li propose that using this revised, prioritized MADM model will facilitate better decision making in construction waste management. The 2 Tuple fuzzy linguistic representation model allows for a more accurate recording and analysis of linguistic data preventing crucial information from being lost. They also suggest the use of a utility based prioritized OWA operator to calculate the sum of the degree of satisfaction at each MADM level. Through the integration of these three methods, the gap between linguistic and numerical measurement of variables can be closed, offering a scientific weekly analysis leading to well informed decision making and effective disposal of construction waste material. Furthermore, the proposed method can be utilized by most countries as they have similar conditions to address pertaining to construction waste disposal.
While Zhang and Li mainly referred to construction waste management in developed countries, Srour et al speak of disposal of construction waste in developing countries . Such countries do not have any national standards or set procedures that provide a framework of effective construction waste disposal. As such, illegal dumping and poor waste management are rampant in such geographies. The authors, through their study, attempt to provide a framework on how construction demolition waste or CDW in developing, taking Beirut, Lebanon, as an example. However, their study of data collected from demolition contractors in addition to other sources revealed that the implementation of a new recycling unit greatly relies on conditions such as recycling gate fee, salability of the by-product, regulatory reform to minimize illegal dumping, and landfill tipping fee.
The authors note that efficient waste disposal plans in developed countries provide very specific recycling targets, providing waste disposal education and training in techniques to contractors to raise their awareness, analyzing the amount and quality of waste created, devising a management plan for each waste product, and improving the salability of recycled goods and by-products. However, recycling itself is a major challenge in developing countries such as Lebanon where resources and facilities are scarce and awareness among authorities as well as contractors is low. Economic growth in Beirut has led to a boom in construction activity, with most 2 or 3 storey buildings being demolished to build taller buildings. This in turn has resulted in a drastic increase in construction demolition waste that is in severe need for proper management.
Srour et al. propose a model that can be used to establish a new recycling facility in Beirut or its suburbs. To begin with, they acknowledge that finding a location for the unit will be a major challenge as land has become much more valuable now. Once a location has been finalized, the authors suggest that the aggregate selling price and recycling gate fee be set. This will boost competition among recyclers who will then need to be encouraged to use recycling of products as opposed to dumping waste in landfills. Increasing the landfill tipping fee, as well as the introduction of regulatory control for CDW disposal will allow for improved waste management in developing countries.
While both the articles covered address the same subject - construction waste material disposal and management – the difference in context leads to differences in the suggested methodologies as well. While Zhang and Li focus on providing a well defined, scientific model that help in improving current standards of waste disposal in developed countries, Srour et al focus solely on the introduction and promotion of recycling in developing countries such as Beirut to reduce the impact on landfills. Although Srour et al’s suggestion is valid, their framework is very vague and would need tremendous work to adapt to various geographies. Zhang and Li’s model, on the other hand, although specific to developed countries, is easy to implement and is highly measurable.
Works Cited
Roussat, N., C. Dujet and J. Méhu. "Choosing a sustainable demolition waste management strategy using multicriteria decision analysis." Waste Management 29.1 (2009): 12-20.
Srour, Issam M., et al. "A Framework for Managing Construction Demolition Waste: Economic determinants of recycling." Construction Research Congress (2012): 1631-1640.
Zhang, Xueqing and Yashuai Li. "Multi-Attribute Decision Making in Choosing Suitable Construction waste Management Methods." Construction Research Congress (2012): 1889-1898.
