Chapter two is a review of contemporary literature related to the topic. It will explain how authors perceive Construction waste recycling method for waste minimization purposes. The literature review will also discuss about the underpinning theory, what is known and unknown about the topic. It will also discuss about what various researchers have done in the past, especially in the area of construction waste recycling method for waste minimization purposes.
Much of the waste stream going to landfill consists of solid waste from the construction and demolition of buildings. Waste minimisation strategies have been popular for some time in the construction industry. This paper considers the effect of these strategies on one case study. Sourcing materials with recycled content in terms of embodied energy and cost is suggested as the next phase of environmental management in construction.
Many studies measure waste from construction sites on the basis of either volume or mass, to gauge the effect on disposal costs (Johnston and Minks, 1995; Graham and Smithers, 1996; Faniran and Caban, 1998). This does not give the best appreciation of the problem in terms of the environment. The savings from using materials with recycled content can be best measured in terms of the environment by considering their embodied energy (Thormark, 2000).
Embodied energy represents 10-40 times the annual operational energy of most Australian residential buildings, depending upon building design, climate construction systems, equipment type, fuel sources and building usage patterns. Each year in Australia, the embodied energy used in construction is approximately equal to the annual operational energy of the built stock, and together they make up 30-40 per cent of national energy use and greenhouse gas emissions.
There are several problems with existing embodied energy analysis methods, which include process analysis, input-output analysis and hybrid analysis. Process analysis, while accurate for particular processes, often ignores a large number of small to medium processes. Input-output analysis, despite its many inherent errors, is used because of its unique property of systemic completeness. Errors for process analysis data are approximately 10 per cent (Boustead and Hancock, 1979), and for input-output data errors are approximately 50 per cent (Miller and Blair, 1985). Hybrid analysis methods attempt to reduce the errors inherent in each of the two previous methods. There are two types: one based on the process analysis framework and the other based on the input-output framework. For the hybrid analysis methods, errors vary between these rates, depending upon the mix of process and input-output data.
2.3 Construction Waste
Construction waste can be divided into three principal categories namely material, labour, and machinery waste. However, material wastage is given more concern because most of the raw materials used in construction industry come from non-renewable resources
(Ekanayake and Offori, 2000).
construction waste is defined as: the difference between the value of those materials delivered and accepted on site and those used properly as specified and accurately measured in the work, after deducting the cost saving of substituted materials and those transferred elsewhere (Peng and Tan, 1998).
Similarly, the Building Research Establishment (BRE) has defined building waste as the difference between materials ordered and those placed for fixing on building projects (Skoyles and Skoyles, 1987).
Recently, for the purpose of evaluation of the construction material waste sources, Ekanayake and Offori (2000) have given a broader definition of the construction waste as: any material, apart from earth materials, which need to be transported elsewhere from the construction site or used within the construction site itself for the purpose of land filling, incineration, recycling, reusing or composting, other than the intended specific purpose of the project due to material damage, excess, non-use, or non-compliance with the specifications or being a by-product of the construction process.
2.3.1 Definition of construction waste
Construction waste is anything generated as a result of construction and then abandoned, regardless of whether it has been processed or stockpiled. It comprises surplus materials from site clearance, excavation, construction, refurbishment, renovation, demolition and road works. There are two types of construction waste:
Inert construction waste
Non-inert construction waste
Non-inert construction waste is around 20% of the total and usually comprises bamboo, timber, vegetation, packaging waste and other organic materials. Some of these can be recycled while others are disposed of at landfills. In contrast, inert waste – otherwise known as public fill – mainly includes construction debris, rubble, earth, bitumen and concrete, which can be used for land formation. Materials like concrete and asphalt can also be recovered for construction use.
Wastes can be defined as all wastes in solid form which are discarded as useless or unwanted and in general arise from human activities. Construction wastes are wastes generated from building, demolition and refurbishment works for individual housing, commercial building or other structures. (Peavy et al., 1985)
2.4 Construction waste minimization
Waste minimization is a waste management approach that focuses on reducing the amount and toxicity of hazardous waste that is generated. In addition to hazardous wasted regulated under RCRA, the EPA encourages waste minimization techniques that focus on preventing waste from ever being created, (source reduction) and recycling. there are three general methods of waste minimization: source reduction, recycling, and treatment.
2.4.1 Steps of waste minimization:
Reduce consumption of resources by building smaller houses that are better designed for your needs. This is the most effective way to conserve precious resources for use by future generations and reduce waste. It also lowers costs.
Re-use existing buildings and materials and reduce demand for resources, lower waste volumes and save money. Don’t Demolish – Deconstruct, give old buildings new lives.
Recycle resources that are left over or have reached the end of their useful life. This will reduce demand for new materials and lower the volume of waste going to landfill. sending building material to landfill is like throwing money in the bin.
Use renewable resources like sustainably managed forests. This creates a sustainable economy and helps conserve non-renewable resources use materials with high recycled content to create a market for recycled resources. It will raise the price paid by recyclers for recovered resources and increase the viability of recycling.
Our traditional means of waste disposal (landfill) is uneconomic. Costs to communities for operating and maintaining landfill sites are high and availability of suitable land is limited.
Re-use options for landfill sites are extremely limited due to potential health hazards. Remedial action is often prohibitively expensive.
Emissions and leachate from landfill sites can be highly toxic due to concentrations of heavy metals and toxic chemicals. These toxins find their way into the water table and/or waterways, often with disastrous consequences.
We must reduce waste volumes going to landfill and remove toxic content from materials before disposal. Using other option then sending to landfill. .
2.4.3 Why prevent waste and recycle?
126.96.36.199 Reduce Costs
Recycling, reusing salvaged building materials and minimizing materials and packaging reduces waste disposal costs and material expenses.
188.8.131.52 Marketing Opportunity
The companyâ€™s experience in waste prevention and recycling can be an essential marketing
Tool to the growing number of potential clients interested in participating in the Leed and
Build green building programs.
184.108.40.206 Tax Deduction
When you hire a deconstruction service to remove reusable building materials, the client can
Take a tax deduction when they donate the materials to a nonprofit organization.
2.5 Construction Waste Management
Construction Waste Management is the practice of reducing the actual waste that go to the dump site. Waste reduction is best met by recycling and construction wastes do offer a lot of opportunities for recycling. In fact, 80% of the wastes found in construction trash heaps are recyclable, one way or another. Wood, asphalt, concrete, bricks, metals, glass and even paint do offer several options for recycling.There are three basic steps for construction waste management. They are Reduce, Reuse, and Recycle. Reduce is basically preventing waste from appearing. So it helps if those building materials come in with preplanned sizes.
2.5.1 Construction waste management strategies
Four main construction waste management strategies were identified from the literature (Gavilan and Bernold, 1994; Peng et al., 1997; Faniran and Caban, 1998). They were:
avoid or reduction;
Among these three strategies, avoiding waste which infers elimination or minimization of waste, has been given the highest priority as it requires the least resources other than planning and designing skills. Developing a waste minimization culture in the construction industry may be the initial process of a minimization strategy (Teo and Loosemore, 2001; McDonald and Smithers, 1998). Reuse refers to simply moving materials from one application to another. The third option is recycling and construction waste recycling is a process of separation and recycling of recoverable waste materials generated during construction and remodelling. Composting has also begun to emerge as a new application of an ancient technology, where organic land-clearing debris is processed to produce humus for soil treatment (Ekanayake, 2000). Further, incineration is another process of destroying waste material by burning it and, while once regarded as a practical method of disposing of hazardous waste materials, it has of late, become controversial for many reasons such as the fact that it creates toxic gas and ash, which can harm local populations and pollute groundwater. Disposal or land filling is the lowest in the hierarchy.
Since reduction was identified as the most effective strategy for waste management, several techniques used in construction can be recommended as waste reduction initiatives. Off-site construction technology (dry construction) was highlighted in the literature. For instance, using pre-cast elements one could eliminate 30 per cent to 40 per cent of wastage on building construction sites (Poon et al., 2004b). In addition, there are many advantages of pre-cast element manufacturing such as saving time and overall cost, due to enabling concurrent different production lines; increasing constructability and reducing congestion on site due to changing from an uncontrollable work environment on site to a controllable one in factories (Benjaoran and Dawood, 2004). Therefore, the present paper attempts to identify how effective the use of pre-cast elements in building projects are in construction to minimize construction waste.
2.5.2 Insufficient regulations
The importance of complete governmental regulations for supporting construction and demolition waste management has been extensively investigated. For example, although the Hong Kong government has implemented various types of regulations to minimize construction and demolition waste production, it is found by Tam (2008a) that the mandatory system in implementing the waste management plan for all construction projects would significantly affect the productivity of companies. This is echoed by the study from Shen and Tam (2002), suggesting that legal measures are not effective for implementing environmental management in Hong Kong construction. In all the regulations in Bulgaria, construction and demolition waste is mentioned jointly with municipal waste and the majority of measures envisaged are aimed at the improvement of municipal waste management (Hadjieva-Zaharieva et al., 2003). It is also reported by Kartam et al. (2004) that clear regulations and rules from Kuwait Municipality are lacking for allowing and persuading contractors to use recycled products made from construction and demolition waste.