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Top1. Introduction
In the developing countries, demolition wastes range from 20% to 30% of the total annual solid wastes (Al-Ansary, 2002), which can express how big the problem is. Construction and Demolition waste (CDWs) doesn’t contain much hazardous waste compared to what found in municipal solid waste but CDWs still has its own problems. One of the major problems is the huge bulk of CDWs, without regard to the very long lifetime of CDWs which means occupied landfill for extremely long time before moldering of CDWs (Dantata et al., 2004). EPA (2002) has organized a composition for CDWs materials into a list of eight groups. This paper is concerned with only on the first group “concrete, bricks and tiles”.
Peng et al. (1997) presented a hierarchy of CDWs managing options; including reduce, reuse, recycle, compost, incinerate and landfill. Reduce refers to any activity to avoid waste creation, Design stage is considered as the most effective stage in Project Life Cycle to implement waste reduction. At this stage, designer can consider using of re-usable materials or design a building with a long lifespan. Reusing is the next stage of waste management options; it can be described as using the same material more than once without the need for reprocessing. Recycling is the third option, which means the reprocessing of a reclaimed material and converting it into a new material or use. Composting is the next option; the term 'compost' refers to the organic material that can be used as a soil amendment or as a medium to grow plants. Incineration is considered the fifth option of waste management; the CDWs are burned to recover electrical energy or heat. Wood and plastic wastes are considered as the most applicable CDWs in this phase. The last option for CDWs management is a landfill. A landfill is a place where material is dumped as an end-stage.
Choosing the wrong alternative for demolition waste disposal will cause not only high economic losses, but also hazardous environmental and social impacts as well. That’s won’t be an easy task for decision maker, since it's affected by several indicators, for that reason MCDM have been introduced to aid the decision maker to choose the right decision. MCDM is a tool that can be implemented in optimizing the decision-making problems considering a number of criteria (Kahraman 2008). MCDM techniques have been developed long time ago. Nowadays, there is such a wide list of these techniques; each of them has its own features and weakness. Of the many MCDM methods, Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) has been applied in different application areas.
TOPSIS method is a technique to evaluate alternatives’ performance, considering the similarity with the ideal solution (Behzadian et al., 2012, Krohling and Campanharo, 2011). TOPSIS is capable to combine between different indicators with various units simultaneously (Ekmekçioğlu et al., 2010); However, TOPSIS in its standard form is deterministic and doesn’t consider uncertainty which is considered as one of its main weakness (Gavade 2014). This encourages several attempts to introduce the term “Fuzzy/Uncertainty” in TOPSIS technique (Jahanshahloo et al., 2006, Jahanshahloo et al., 2009, Krohling and Campanharo, 2011). Determining the exact value for the elements of decision matrix (weights or performance values) aren’t reachable in many practical cases as they pass through human judgments which could be vague or including fuzzy or interval data.