Recycling processes shape today’s circular economy in construction and industry. Especially during the deconstruction of structures, in rock excavation, or the building gutting of complex facilities, the quality of processing determines whether waste can become secondary raw materials again. Tools and systems from Darda GmbH are often used in preparatory and separating work steps: for example, when massive concrete structures are opened in a controlled manner using hydraulic rock and concrete splitters, reinforcing steel is exposed, or natural stone blocks are gently separated. The aim is always to keep material flows as single-grade as possible, minimize emissions, and facilitate downstream recovery.
Definition: What is meant by recycling processes
Recycling processes are the technical and organizational sequences used to recover reusable materials or products from waste. In the construction and demolition sector, this includes collection, selective dismantling, pre-crushing and secondary crushing, removal of contaminants, separation of metals, and processing into quality-assured fractions. Reuse (components remain intact) and disposal (landfilling or energy recovery without material recycling) are to be distinguished. In practice, mechanical methods dominate for mineral construction materials, such as crushing, screening, and splitting; for metals, cutting and shearing. Tools like concrete demolition shear or stone and concrete splitter deliver precise preparatory work by separating components so that reinforcing steel and concrete are cleanly divided and material qualities are preserved.
Process steps in construction and demolition recycling
Efficient recycling processes follow a clear sequence. Careful planning and selective deconstruction reduce losses and increase the quality of secondary raw materials.
- Survey and planning: building material inventory, screening for contaminants and hazardous substances, haulage logistics
- Selective deconstruction and building gutting: removal of technical systems, lines, and built-ins; separation cut and sorting at the source
- Pre-crushing: opening, splitting, and cutting of components into manageable piece sizes
- Metals exposure and separation: targeted severance of reinforcing steel, sections, beams
- Secondary crushing and classification: crushing, screening, air separation, magnets, sensor systems
- Quality assurance: testing for particle size distribution, foreign substance content, strength, and suitability
- Recovery: use as recycled construction material, metal recycling, specialized recovery routes
Methods and tools in the context of material separation
Mechanical recycling of mineral construction materials
For concrete, masonry, and natural stone, processing is predominantly mechanical. concrete demolition shear break open concrete structures and expose reinforcing steel; stone and concrete splitter separate massive components along defined lines with low vibration levels. These interventions facilitate subsequent crushing and the removal of steel with magnets. The result is aggregates that, as recycled construction material, can be used in base layers, backfill, or—depending on the suitability class—in new concrete mixes.
Metal recycling from structures
Steel beams, reinforcement, lines, and vessels are separated by cutting processes. Hydraulic shear and Multi Cutters reduce cross-sections so that the fractions are suitable for transport and steelworks. In the deconstruction of tanks and vessels, tank cutters are used in controlled procedures. The gain: high purity of scrap, short loops into the steel cycle, and minimized mixing with mineral materials.
Thermal and chemical special processes
For certain composite materials and bituminous construction materials, thermal processes (for example, hot processing of reclaimed asphalt) complement mechanics. Chemical approaches—such as selective treatment of fine concrete fractions or recarbonation of cement paste—are under development and being tested in projects. Such processes aim to make binder content more usable and further reduce the carbon footprint (CO₂ balance).
Material flows and typical fractions in recycling
Recycling processes bundle materials into defined fractions. The purer the separation, the higher the recovery quality and market value of the secondary raw materials.
- Concrete and reinforced concrete: recycled aggregates, reinforcing steel
- Masonry: mixed mineral fractions or single-grade brick aggregates
- Natural stone: reusable blocks, crushed stone, crusher fines
- Asphalt: reclaimed asphalt for new mixes
- Metals: steel, stainless steel, and non-ferrous metal fractions
- Wood and plastics: material or energy recovery depending on quality
Targeted processing of concrete and reinforced concrete
For reinforced concrete, combining concrete demolition shear to open the component with downstream magnetic separation improves the separation precision between steel and aggregates. This reduces the foreign substance content; at the same time, particle shape and grading remain more favorable, which facilitates later use as recycled construction material. For thick components, prior splitting provides controlled fracture patterns and reduces the crushers’ energy demand.
Using natural stone and excavated rock
In rock excavation and tunnel construction, excavated material accumulates in large volumes. stone and concrete splitter enable blockwise release with low vibration levels, which is advantageous in built-up or sensitive areas. Suitable fractions are further used as crushed stone, backfill, or in natural stone extraction. Early classification by petrographic properties and particle-size fractions is decisive.
Planning and execution in deconstruction
Recycling starts with planning. Selective deconstruction, orderly building gutting, and clean interfaces between trades are key success factors. In practice, in concrete demolition and special demolition—see concrete demolition – deconstruction—components are segmented so that load-bearing structures are relieved in a controlled manner. During building gutting and cutting, clear procedures for dismantling, intermediate storage, and transport are necessary to avoid mixing. For special demolition—for example, in sensitive zones—hydraulic splitting and shearing processes offer advantages through low emissions.
Sustainability, emissions, and occupational safety
Minimizing dust, noise, and vibrations
A water spray system, enclosures, and adapted cutting speeds reduce dust and noise emissions. Splitting methods produce low vibration levels, which is relevant in inner-city locations, on existing buildings, or near infrastructure. The choice between splitting, shears, and cutters depends on the material, accessibility, and permissible immissions.
Hazardous substances, tanks, and media lines
With vessels, pipelines, and tanks, safe separation takes priority. Tank cutters are used only after complete emptying, cleaning, and proof of sufficient gas-free condition. Such work is carried out with proven procedures, coordinated protective measures, and documented releases.
Quality assurance and the use of recycled construction material
Recycling processes deliver high-quality secondary raw materials only when quality assurance is an integral part of processing. This regularly includes:
- Continuous monitoring of the grading curve and particle shape
- Foreign substance checks (metals, wood, plastics, gypsum)
- Documentation of origin, processing steps, and test values
- Alignment of the fraction with the intended use
The result is recycled construction material that—depending on suitability and requirements—is used in sub-bases, base layers, or as aggregate in new construction materials. Consistent separation with concrete demolition shear and splitting methods supports low contaminant levels and reproducible quality.
Practical relevance: Darda GmbH products and applications in the recycling context
Recycling processes achieve their impact when separating and size-reduction steps interlock precisely. In concrete demolition and special demolition, concrete demolition shear open components so that reinforcing steel can be recovered on the steel side. In building gutting and cutting, shears and Multi Cutters support clean separation of sections, lines, and built-ins. In rock excavation and tunnel construction as well as in natural stone extraction, stone and concrete splitter enable low-vibration separations for high-quality subsequent use of rock fractions. In special demolition, for example in sensitive areas or with complex geometries, controlled splitting and cutting facilitate single-grade material flows.
Targeted avoidance of error sources in recycling processes
Typical quality losses arise from mixing on the construction site, insufficient pre-separation, ragged cut edges, or excessive comminution that raises fines content. Remedies include clear material flows, defined separation cuts, sufficiently large pre-crushed pieces, and the targeted exposure of reinforcement before crushing. Where possible, components should be split with low emission rather than broken by blasting techniques to minimize environmental impacts.
Classification within the circular economy
Recycling processes close material loops and conserve primary resources. Alongside material recycling, the reuse of entire components is gaining importance. Downcycling can be reduced through single-grade separation and high-quality processing; upcycling requires defined qualities that can only be achieved with consistent process control. Good documentation and traceable material passports facilitate later use and increase the predictable quality of secondary raw materials.