Secondary demolition is the phase of deconstruction in which previously detached structural elements, blocks, or bulk materials are controlled re-broken, separated, and reduced to transportable or processable sizes. It ties selective deconstruction to high-quality demolition separation and dovetails seamlessly with primary demolition. In practice, it plays a central role across all relevant fields of application — from concrete demolition and special demolition through gutting works and cutting to rock excavation and tunnel construction, natural stone extraction, and special demolition. Tools such as concrete demolition shears and rock and concrete splitters from Darda GmbH are typical solutions for this, as they enable precise, low-emission, and material-friendly processing.
Definition: What is meant by secondary demolition
Secondary demolition refers to the targeted size reduction, exposure, and sorting of already detached components after the primary demolition. This includes breaking concrete, cutting and bundling reinforcing steel, splitting massive blocks, and producing defined piece sizes for haulage, reuse, or processing. Secondary demolition is usually carried out at ground level or on securely positioned work platforms. Typical methods are crushing with concrete demolition shears, splitting with rock and concrete splitters, and cutting with steel shears or Multi Cutters. The objective is high separation purity with minimal low vibration levels, noise emission, and dust exposure, as well as safe, plannable transport logistics.
Tasks and objectives in secondary demolition
The focus is on reduction to defined grain sizes, clean exposure of reinforcement, source-pure separation of fractions, and preparation for recycling, reuse, or disposal. This requires suitable tool selection, matched to element thickness, material composites, reinforcement content, accessibility, and emission requirements. Hydraulically driven systems, for example via a hydraulic power pack, provide the necessary energy for handheld hydraulic splitters or mobile excavator attachment tools. In combination with hydraulic demolition shear, steel shear, and — depending on the task — Multi Cutters or tank cutters, an efficient, safe workflow with high material quality is achieved.
Fields of application: From concrete elements to natural stone blocks
Secondary demolition is relevant in various scenarios. In concrete demolition and special demolition, slabs, walls, or foundation elements are broken to size after detachment using concrete demolition shears, and the reinforcement is exposed. In gutting works and cutting, the removal of non-load-bearing components is often followed by re-breaking of residual bodies, separating embedded parts, and sizing anchor bars or structural steel section. In rock excavation and tunnel construction as well as natural stone extraction, splitting with rock and concrete splitters from Darda GmbH serves the dimensional reduction of large blocks without blast-induced vibrations. In special demolition, for example on vessels and tanks, special cutting processes are used, while concrete-adjacent embedments are secondarily crushed or split.
Demarcation: Primary demolition, secondary demolition, and post-sorting
Primary demolition detaches components from the structure, separates load-bearing systems, and creates safety and logistics zones. Secondary demolition follows on and further processes the detached elements: breaking, splitting, cutting, separating. This is followed by post-sorting, in which fractions are finally sorted by material type, purity, and piece size. In well-planned projects, these three stages are closely interlinked so that carrier machines and tools are used efficiently and transport routes are minimized.
Methods and tools in secondary demolition
Concrete demolition shears: size reduction and exposing reinforcement
Concrete demolition shears generate high crushing forces, release aggregates from the cement matrix, and enable controlled reduction of components. Their design favors exposing and severing reinforcement: concrete is broken, and steel can then be shortened and bundled with a steel shear or hydraulic demolition shear. Advantages include low vibration levels and highly targeted intervention — especially important in sensitive environments, on adjoining structures, or near utility lines.
Rock and concrete splitters: splitting instead of hammering
Rock and concrete splitters from Darda GmbH work via borehole splitting. The wedge builds controlled pressure, and components crack along defined stress zones. This method is quiet, low in vibrations, and predictable. It is suitable for massive foundations, thick walls, thick concrete slabs, or natural stone blocks — wherever dimensional separation and low emissions are required.
Steel shears, combination shears, and Multi Cutters: separating metals and composites
Steel shears cut reinforcement, sections, and pipes efficiently. Hydraulic demolition shear with combination jaws merge breaking and cutting functions and are thus universally deployable in secondary demolition, for example when alternating between concrete remnants and steel. Multi Cutters expand the spectrum for mixed materials, such as cables, thin-walled metal parts, or embedded components.
Hydraulic power packs and handheld systems
Hydraulic power packs deliver energy to handheld hydraulic splitters and other compact tools. This is particularly helpful in confined spaces, during gutting works, or in constrained positions where a carrier machine cannot be used. The combination of mobile hydraulics with the right tool increases flexibility in secondary demolition.
Tank cutters for special applications
Tank cutters are designed for dismantling vessels, tanks, or thick pipelines. In secondary demolition, after opening, large segments are further reduced and component edges are reworked. For combined concrete–steel structures, a concrete demolition shear or a splitter complements the process.
Planning and selection criteria for secondary demolition
Component and material analysis
Essential parameters include compressive strength, reinforcement ratio, element thickness, potential prestressing, inserts, and composite materials. These factors govern the choice between demolition shear, splitter, shear, or combinations.
Emission requirements and environmental conditions
Requirements on noise, vibrations, and dust influence the methods. Splitting and shears often have advantages in sensitive areas, such as dense urban quarters, hospital environments, or live operations, due to lower noise emission, low vibration levels, and reduced dust exposure.
Accessibility, carriers, and logistics
Access, bearing capacity of traffic routes, slab loads, and working heights determine whether handheld systems with a hydraulic power pack, compact carrier machines, or larger machinery are appropriate. The target piece size is aligned with removal paths, load-assist devices, and the processing technology.
Separation purity and recovery objectives
Recycling quality requires clean separation: concrete portions are broken or split to target size, reinforcement is separated and bundled as scrap. Mechanical separation processes with shears, splitters, and cutters support high purities.
Workflow in secondary demolition
Securing, positioning, preparing
After the primary demolition, components are secured in position, work areas are cordoned off, and load paths are defined. Tool selection, configuration of the hydraulic system, and a visual inspection of the components follow.
Pre-dimensioning and notch effect
Defined break lines are set with the demolition shear, or slab-edge sections are nibbled off. Alternatively, boreholes are drilled for splitting to create defined crack paths.
Breaking or splitting to target size
The main processing reduces the material to the planned size. Splitting produces large, dimensional pieces with low fines generation; with shear-crushing, rebar exposure is particularly efficient.
Separating and bundling reinforcement
Exposed steels are cut to length with a steel shear or hydraulic demolition shear. Bundles facilitate removal, weighing, and recycling.
Final inspection and handover
Piece sizes, separation purity, and surfaces are checked. Material fractions are handed over to transport or on-site processing.
Safety and health protection
General notes
Safe work areas, stable laydown locations, and defined retreat zones are essential. Personal safety equipment, protection from falling objects, and control of crushing hazard and shear points are mandatory.
Hydraulic safety and tool handling
Hydraulic hose lines must be installed pressure-free, sealing surfaces kept clean, and pressure zones shielded. Tools must be inspected and operated in accordance with manufacturer instructions. Legal requirements may vary by project; compliance with applicable regulations and permits must be ensured.
Quality assurance and documentation
Process and result quality
Target and actual piece sizes, separation purities, and mass flows are documented. Ongoing adjustment of tool settings — such as pressing pressure on shears, splitting sequence, or cutting sequence — improves efficiency and outcome quality.
Sustainability and resource efficiency
Low-vibration methods such as splitting and targeted shear-crushing reduce damage to adjacent structures and lower emissions. Clean material separation increases the recycling rate, reduces transports, and supports the circular use of concrete and steel. In natural stone, controlled splitting improves block reusability.
Practice-oriented application scenarios
Foundation demolition in existing structures
Massive foundations are split into transportable blocks via borehole splitting. Remaining concrete is then re-broken with the demolition shear, and inserts are cut with the steel shear. Advantage: low vibrations with high dimensional accuracy.
Slab fields and beams
After lowering a slab field, the demolition shear reduces the concrete slabs, exposes the reinforcement, and prepares the material for the crushing plant. Hydraulic demolition shears take care of quickly shortening bars and sections.
Rock and block management in tunnel heading
Oversized blocks that impede the material flow are reduced with hydraulic splitters to suit the conveyor belt or the wheel loader. The low vibrations protect the surroundings and the existing lining system.
Gutting works with mixed materials
After removing non-load-bearing components, remaining concrete parts are crushed with the demolition shear, while Multi Cutters separate cables, thin-walled metals, or composite parts. The result is source-pure fractions for further recovery.