What are the most common demolition material streams suitable for recycling operations?
The components of C&D generated in demolition works vary depending on the activity type of the construction demolished and its structural components. However, broadly, the C&D stream is comprised of concrete, masonry, wood, metal, asphalt pavement, drywall, and a variety of other minor constituents.
The following table shows the most common demolition debris suitable for recycling operations and briefly outlines their main characteristics.
The materials must, however, be checked for contaminants before recycling, even if they are a priori recyclable. In this case, it will generally be ineligible for recycling and will have to be treated as waste. However, it may sometimes be possible to decontaminate and then recycle the material without contaminants.
COMMON MATERIALS PRESENT IN DEMOLITION WASTE | ||
| Concrete | Consists of a mixture of cement paste and aggregates. The paste, composed of Portland cement and water, coats the surface of the fine and coarse aggregates which then forms the mixture into a rock-like mass. | |
| Recycled concrete can be used in many of the same ways as new materials would be used, such as gravel, paving materials, and aggregates. | ||
| Reinforced concrete | It is the concrete in which steel is embedded in such a manner that the two materials act together in resisting forces. | |
| The way to recycle this type of concrete is based on separating the concrete itself from the rebar and then processing them separately. | ||
| Ceramic | A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, non-metallic material, such as clay, at a high temperature. | |
| Used ceramics from the construction and demolition industry can be crushed and resold to tile manufacturers or have another end use as a range of products such as drainage material or rock base for driveways. | ||
| Asphalt Pavement | Also called bituminous concrete or asphalt pavement, this material is a mixture of fine and coarse aggregate with the asphalt (approximately 6% by mass) serving as the binder | |
| Recycled asphalt replaces the need for virgin (or new) asphalt in any project or roadway. | ||
| Wood | Construction products manufactured from wood include dimensional lumber, plywood, oriented strand board (OSB), fiberboard, posts, and poles. | |
| Wood can be reused as a building material, recycled into mulch for landscaping or pulp for paper production and used beneficially as a fuel. | ||
| Plaster / Gypsum | Plaster is a manufactured building product in the form of a panel that is used for interior wall and ceiling surfaces in buildings, primarily composed of gypsum (~90%) and paper surfacing and backing. | |
| Gypsum recycling is the process of converting gypsum waste into recycled gypsum, thus generating a raw material that can replace virgin gypsum raw materials in the manufacture of new products. | ||
| Metal | Numerous construction materials manufactured of metal are encountered in demolition waste. These include steel in structural supports, joint and cladding systems, and as part of the plumbing and electrical utilities. | |
| Recycled metal can be melted and sold to manufacturers to be used as a raw material. | ||
| Bricks | A brick is a type of block used to build walls, pavements and other elements in masonry construction. Properly, the term brick denotes a block composed of dried clay but is now also used informally to denote other chemically cured construction blocks. | |
| Bricks and blocks can be recycled to make aggregate for use as general fill or highway sub-base, in landscaping, to produce new bricks and blocks, to make sports surfaces such as tennis courts and athletics tracks or as plant substrates. | ||
| Tiles | Tiles are usually thin, square or rectangular coverings manufactured from hard-wearing material such as ceramic, stone, metal, baked clay, or even glass. They are generally fixed in place in an array to cover roofs, floors, walls, edges, or other objects such as tabletops. | |
| Old tiles will get thrown in with other building rubble and either crushed and turned into concrete or possibly sold as materials for building roads. | ||
| Glass | Glass is a solid substance that’s made by heating normal sand until it turns into a liquid and then left to cool. It may be transparent or translucent and brittle. However, it isn’t just a material that let light into an area, but there are actually several types of glass used in the construction industry. | |
| Glass can be recycled into fiberglass products or glass packaging. Furthermore, recycled glass is increasingly being used in the manufacture of construction-related products. It is important to note, however, that in any case, glass can only be recycled off-site. | ||
| Mineral wool | Mineral wool is a non-metallic, inorganic product manufactured from a carefully controlled mix of raw materials, mainly comprising either stone or silica which are heated to a high temperature until molten. The molten glass or stone is then spun and formed into a flexible, fibrous mat for further processing into finished products. It is used for thermal and acoustic insulation in buildings. | |
| Recycled mineral wool is usually used to manufacture new insulation material. | ||
| Plastic | The most common plastics used in construction are polyvinyl chloride (PVC), high-density polyethylene (HDPE), and expanded polystyrene (EPS). Plastic is used for various applications such as seals, windows and doors, pipes, cables, floor coverings, and insulation. Moreover, it is increasingly common the use of FRPs (Fibre Reinforced Plastic) in various types and forms to improve mechanical properties and reduce shrinkage. | |
| Recycled plastics are usually used in the manufacturing of new building and construction products. | ||
All these materials are generated in varying amounts based on factors such as project type, project size, age of the structure, condition of the structure, and geographic location.
Additionally, it must be noted that not all materials can be recycled on-site. Demolition must be preceded by an inventory. Some materials can be recycled on-site, while others must be transported off-site.
However, it must be said that although the majority of the recycling tasks will be carried out on-site, some jobs need to be done. Deconstruction must be assessed and prepared beforehand, for example, by removing windows, piping, etc. In most cases, this sorting will take place on-site.
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