Construction waste is defined as fairly clean, heterogenous building materials which are produced from the various construction activities, as per Tchobanoglous et al., 1993. Construction, renovation and demolition activities lead to the formation of waste.
The construction waste poses great danger to environment. This has put construction industries under pressure to consider suitable methods to protect the environment across all industries including construction.
Quantity and quality of construction waste generated from any specific project would vary depending on the circumstances and types of materials used in the project.
Recycling of construction waste is one way to counter risk to construction wastes. So, the invention of proper technology to recycle these materials is of great importance. For instance, concrete waste can be crushed and used as recycled aggregate.
Sources of Construction Waste Generation
Construction wastes are possibly generated by various sources which are presented below:
- Design source
- Procurement source
- Handling of materials source
- Operation source
- Residual source
- Other sources
Types of Construction Wastes and Recycling Strategies
Brick wastes are generated as a result of demolition, and may be contaminated with mortar and plaster. Brick wastes are sometimes blended with other materials like timber and concrete. Currently, bricks are recycled by crushing and using as filling materials.
Concrete wastes can be generated due to demolition of existing structures and testing of concrete samples etc. commonly recycling measures of concrete wastes are used crushed concrete as aggregate.
The crushed concrete aggregate has been used as a replacement to natural aggregate in new concrete, and it also has been employed in the construction of road base and trenches.
3. Ferrous Metal
Ferrous metal is another type of wastes which not only highly profitable but also can be recycled nearly completely. In addition, ferrous metal can be recycled multiple times.
Masonry waste is produced as a result of demolition of masonry buildings. It can be recycled by crushing the masonry waste and used as recycled masonry aggregate.
A special application of recycled masonry aggregate is to use it as thermal insulating concrete. Another potential application for recycled masonry aggregate is to use it as aggregate in traditional clay bricks.
5. Non-ferrous Metal
Aluminum, copper, lead, and zinc are examples of nonferrous materials wastes produced at construction sites. The majority of these materials can be recycled.
6. Paper and Cardboard
Paper and paper board is another type of waste materials which is estimated to comprise one-third construction and demolition wastes by volume. These waste materials are recycled and reprocessed to produce new paper products.
The plastic wastes are best possible for recycling if these materials are collected separately and cleaned. Recycling is difficult if plastic wastes are mixed with other plastics or contaminants.
Plastic may be recycled and used in products specifically designed for the utilization of recycled plastic, such as street furniture, roof and floor, PVC window noise barrier, cable ducting, panel.
Timber waste from construction and demolition works is produced in large quantity all over the world. Whole timber arising from construction and demolition works can be utilized easily and directly for reused in other construction projects after cleaning, de-nailing and sizing.
Construction Waste Problems
- Waste material is a by-product of human and industrial activity that has no residual value.
- Need for Comprehensive construction waste management in every site.
- Every personnel, from the management to the operational level should work for the goal of construction waste management.
Importance of Recycling
- Reduce the demand for new resources.
- Cuts down the cost and effort of transport and production.
- Use waste which would otherwise be lost to landfill sites.
- Lack of appropriately located recycling facilities.
- Absence of appropriate technology.
- Lack of awareness
Consideration for Construction Waste Recycling
When considering a recyclable material, three major areas need to be taken in to account are:
- Compatibility with other materials
- Material properties