Construction industry includes massive works that produce a significant amount of wastes. In general, the construction waste can be defined as the waste products or the unwanted materials obtained directly from the construction activities or indirectly obtained as a result of the construction works.
According to Tchobanoglous et al., 1993, construction waste is defined as “a fairly clean, heterogeneous building materials which are produced from the various construction activities.” In addition to the construction activities; the demolition, rehabilitation and renovation activities also produce considerable construction wastes. Some of the examples of such construction wastes include various building materials such as nails, electrical wiring, shingle, insulations, dredging materials, tree stumps, rubble etc.
In case of building construction, the construction wastes mostly include the leftover or the damaged building materials such as bricks, concrete, wood etc. According to the statistical data, the construction waste generated from a building construction can be as high as 10 to 15% of the materials utilized for the construction of the building. However, the quantity of the waste produced usually depends upon the specific type of the project, the materials used, the workmanship and the techniques of construction used.
As per the reports of Technology Strategy Board, 2% of the landfill waste comes from the construction and demolition of buildings and 13% of the products delivered to construction sites are sent directly to the landfill without having being used. These construction wastes may even include hazardous materials such as lead, asbestos etc. Thus, the safe disposal of the construction wastes is a challenging issue of the construction industry.
Some of the typical examples of the construction wastes can be listed as follows:
1. Bricks, Concrete, tiles and ceramics.
2. Wood, glass and plastic.
3. Insulation and electrical wiring.
4. Bituminous mixtures, tar and coal tar.
5. Metallic wastes, cables and pipes.
6. Soil, contaminated soil, stones and dredging spoil.
7. Cement, cementation materials and gypsum.
8. Paints and varnishes.
9. Adhesives and sealants.
Sources of Construction Wastes
1. Design Source:
Various types of wastes are generated due to the design error.
2. Procurement Source:
Various type of wastes are generated on account of the ordering error, supplier’s error etc during the procurement of the materials at the site.
3. Material Handling:
Various types of wastes are generated during the handling of materials due to careless transporting and loading of materials, inappropriate storage etc.
4. Operational Sources:
Various types of wastes result during the operation phase of the construction due to various reasons such as the installation of wrong materials.
5. Residual and Other Sources:
Various types of waste are generated by the cutting, moulding of materials etc.
Types of Construction Wastes
The various types of the construction wastes can be described as follows:
1. Brick Wastes
Brick wastes are the common type of wastes that are generated particularly during the construction, renovation or demolition of buildings. Brick wastes may also be in combination with concrete, timber, mortar etc. Such construction wastes are mostly recycled by crushing and using as filling materials.
2. Concrete Wastes
Concrete wastes are mostly generated due to the demolition of existing concrete structures as well as during the testing of concrete samples. In common practice, such wastes are crushed and used as aggregate. The recycled concrete aggregate is used as aggregate in road pavements, new concrete constructions etc
3. Masonry Wastes
Masonry wastes are the type of wastes that are commonly generated from the demolition of masonry buildings and structures. These wastes can be recycled like the concrete wastes and can be used as aggregates. The recycled masonry aggregates can be used in the construction of thermal insulating concrete as well as in traditional clay bricks.
4. Ferrous Metal Waste
Ferrous metal wastes are the type of construction wastes that are usually generated from the piping and sanitary fitting works. These are the most profitable type of wastes as they can be almost completely recycled. The recycling of such wastes can even be done several times.
5. Non-Ferrous Metal Wastes
The non-ferrous metal wastes mostly include copper, aluminium, lead, zinc etc. The non-ferrous metal wastes can also be recycled.
6. Plastic Wastes
The plastic wastes are also generated significantly during the construction activities. These wastes can also be recycled but it must be taken care that the plastic wastes are collected and cleaned separately. The wastes thus collected and cleaned can be recycled and duly used as street furniture, roof and floor, PVC window, noise barrier, cable ducting, panelling etc.
7. Timber Wastes
A large amount of the timber wastes are generated every year from the construction and demolition works all over the world. Such timber wastes can be used directly for other constructions as well as can be recycled and used. It must be noted that the timber is cleaned, de-nailed, and sized properly before it is recycled or reused.
Negative Impacts of Construction Waste
Some of the adverse impacts of the construction wastes can be listed as follows:
1. Some of the construction wastes are difficult to dispose and have no residual value.
2. Some construction wastes are disposed of by landfill which highly affects the quality of the soil and also decreases the land availability for agricultural and other use.
3. Some of the construction wastes can be hazardous such as lead.
4. The construction wastes may harm the environment.
Construction Waste Management
The efficient management of the construction wastes is an essential aspect of the sustainable construction. Some of the key points that must be utilized for the efficient management of the construction wastes can be listed as follows:
1. Minimizing the wastes:
As far as possible, recyclable materials must be used for the construction activities so that the waste produced can be minimized.
2. Segregation of the construction wastes.
3. Reusing and Recycling:
As far as possible, the wastes produced during a particular construction activity must be reused or recycled and used for some other task in the same project.