How is construction and demolition waste generated?

Focus on Demolition Work Construction and demolition waste is generated during the demolition, renovation, and new construction of buildings, as well as during road and bridge construction. The majority of construction and demolition waste comes from building demolition projects.

What is construction and demolition waste?

Construction and demolition waste consists of a wide variety of materials. For example, when a house is demolished, the following are produced: Construction debris Concrete, cement, clinker bricks, sand-lime bricks, bricks, ceramics, plaster, tiles and asphalt Wood Lumber, formwork, doors, window frames, etc. Metals Ferrous and non-ferrous metals such as rebar, steel beams, fittings, pipes, screws, nails, aluminum profiles, cable scraps, etc. Insulation Materials Synthetic and natural insulation materials such as mineral wool, glass wool, rock wool, polystyrene, perlite, etc. plastics Plastics and films of all kinds, PVC pipes, packaging, covers made of hard plastics Other materials Other mixed waste, such as cardboard, paper, glass, carpet materials, construction site waste, dust, contaminants, and other discarded materials

How is construction waste recycled?

The goal of recycling construction and demolition waste and construction debris is to recycle and reuse the individual components and secondary raw materials in an environmentally friendly manner. To this end, the material is first collected and transported to specialized recycling plants. At the start of the Recycling process, a pre-screen can be used for coarse separation and to reduce the load on the subsequent shredder. The shredder then shreds the remaining material that was screened out by the pre-screen. This step helps preserve the shredding equipment, as it keeps components that are too large or mechanically unsuitable for processing by the existing shredder away from the machine. Examples include sections of steel beams, long formwork timbers, or large, heavy concrete pieces. Magnetic technology is also used to recover items such as rebar, angle iron, and sheet metal, as well as iron screws and nails. Typical examples of magnetic technology include overflow and/or lifting magnets (see also Metal Recycling ). Non-ferrous metals are separated from non-metallic materials (e.g., wood, plastic, glass) using non-ferrous separators, also known as eddy current sorters. The shredder breaks down the material that was not sorted out by the pre-screen and any manual sorters. The so-called hand pickers sort through the materials as they move along a conveyor belt in a sorting booth using their hands. This allows them, for example, to “fish out” valuable metals or remove parts that would interfere with further processing (e.g., due to their size or material). The construction and demolition waste is then classified by size using screening machines. SPALECK 3D COMBI screening machines have proven to be very effective for this purpose, as they can classify up to five size fractions and also reliably screen out the fine material. This is important to ensure that the subsequent sorting technologies—such as eddy current separators, air classifiers, and sensor-based sorting devices—function optimally and can sort the individual components into pure material streams. So-called combination sorters use, for example, 3D object recognition, color sorting, induction sorting, as well as NIR sorting technology or XRF and XRT sorting technology to separate materials. For example, a red brick can be reliably identified as a red brick based on its three-dimensional characteristics and color. Recycling helps reduce landfill costs and increase the recycling rates of secondary raw materials.