The concrete demolition shear is a hydraulically powered attachment or handheld tool for low-vibration fragmentation of concrete components. It is used in a wide variety of concrete demolition and special demolition situations, such as interior demolition, strip-out and cutting, as well as in areas with strict requirements on noise, vibration, and dust. In practice, the concrete demolition shear is often combined with complementary tools such as hydraulic rock and concrete splitters, combination shears, multi cutters, steel shears, or tank cutters to separate components selectively and keep recycling streams clean. Darda GmbH’s know-how focuses on the precise application of such tools and safe, efficient working practices on the construction site.
Definition: What is a concrete demolition shear
A concrete demolition shear is a hydraulic crushing tool with two opposing jaws that mechanically break concrete and often feature an integrated cutting edge for severing reinforcing steel. The shear is either operated as an attachment on carrier machines (e.g., excavators, demolition robot) or—in compact versions—manually via external hydraulic power packs. In primary demolition, large jaw openings open up massive components; in secondary demolition, debris is processed into defined sizes and reinforcing bars are separated. Unlike impact tools, the concrete demolition shear produces its effect impact-free through high pressing forces; compared to rock and concrete splitters, it does not work with spreading wedges but with shearing or crushing jaw geometries.
Design and operating principle of the concrete demolition shear
Structurally, the concrete demolition shear consists of a main body, hydraulic cylinder, bearings, and jaws with wear teeth. Hydraulic pressure—provided by the carrier machine or a separate hydraulic power pack—moves the cylinder and generates the required pressing force at the jaw tip. Depending on the design, the jaws are equipped with replaceable tooth inserts that increase contact stress in the concrete and promote controlled crack formation. Rotation modules (often 360°) support precise alignment on the component. Variants with an integrated rebar cutter allow the reinforcement to be cut directly after breaking.
Applications and working methods
The concrete demolition shear covers a wide spectrum. In concrete demolition and special demolition it is suitable for load-bearing and non-load-bearing components. During strip-out and cutting it is valued for its low vibration and noise emissions. In tunnel-adjacent areas and other sensitive zones, the shear can be combined with rock and concrete splitters to enable a controlled sequence of opening. For exceptional tasks in special operations, combining with combination shears, multi cutters, steel shears, or tank cutters offers high methodological flexibility.
Primary demolition: controlled opening of massive components
In primary demolition, walls, slabs, and foundations are first pre-weakened and then broken in segments. The concrete demolition shear engages at edges, recesses, or boreholes. Where a defined crack path is required, preparatory work with rock splitting cylinders or rock and concrete splitters can reduce peak loads.
Secondary demolition: processing and material purity
After detaching components, the shear reduces the material to sizes suitable for transport and processing. Reinforcing steel is exposed, severed with the integrated cutter, and bundled for removal. This selective approach supports high recycling rates and reduces the effort of downstream crushing and screening processes.
Interior demolition and urban jobsites
In buildings with ongoing operations or in densely built-up areas, a low-vibration and low-noise method is crucial. In such cases, compact shears powered by hydraulic power units are often the first choice. They reduce vibrations transmitted to the structure and protect adjacent components.
Tunnel construction and adjacent rock areas
In tunnels and shafts, the concrete demolition shear can work on concrete linings, invert sections, and outfitting. For rock itself, rock and concrete splitters or rock splitting cylinders are typically used, while the shear breaks the concrete elements of the lining and foundations in a controlled manner.
Selection criteria and sizing
The right concrete demolition shear is selected based on the task, the carrier machine, and the material properties. Key criteria include:
- Jaw opening and insertion depth relative to component thickness
- Crushing and cutting force at the jaw tip
- Self-weight and permissible carrier machine class
- Hydraulic parameters: working pressure, flow rate, return line
- Jaw geometry and tooth concept (e.g., for heavily reinforced concrete)
- Rotation (fixed or rotatable) for better positioning
- Wear protection, replaceability of teeth and blades
For tasks with a high steel content, steel shears can complement the concrete demolition shear. Where sheets, pipes, or tanks are involved, tank cutters and multi cutters support clean separation. If blasting or impact work is to be avoided, rock and concrete splitters are an alternative for low-stress opening before the shear finally breaks the concrete.
Workflow and process planning
A structured sequence increases safety and efficiency. Typical steps:
- Component analysis: structural analysis, reinforcement ratio, concrete strength class, embedded items
- Clarify accessibility: pick-up points, edges, pre-drilled holes
- Equipment selection: shear and jaw type, if applicable splitters or combination shears
- Sequencing: primary demolition, secondary demolition, sorting
- Logistics: haul routes, intermediate storage, recycling fractions
- Dust and noise reduction: water spray system, shielding
Safety and health protection
Working with concrete demolition shears requires competent operation. Principles include:
- Barricade hazard zones; ensure safe standing and working positions
- Operate the carrier machine according to the manufacturer’s instructions; secure hydraulic lines
- Consider load cases and residual stresses in the component
- Personal protective equipment, dust minimization, and adequate ventilation
- Regular functional checks of the shear, particularly of locks and pins
Legal requirements and recognized rules of practice depend on the country of use and the project. Information on limits and inspection intervals should always be considered in general and assessed for the specific project.
Environmental and resource aspects
Concrete demolition shears enable selective separation of concrete and reinforcement. This facilitates the reuse of aggregates and the return of steel to the metal cycle. The low-vibration working method protects neighboring buildings and reduces secondary damage. Combined with forward-looking site logistics, transport distances and processing effort can be minimized.
Maintenance, wear, and operation
Planned maintenance is required for high availability. Focus areas:
- Check jaw teeth and cutters; replace in good time
- Lubricate bearings and inspect pins
- Tightness of cylinder, hoses, and couplings
- Play and wear in the rotation bearing
- Hydraulic oil quality and cleanliness of couplings
A coordinated operating method—do not run continuously on the pressure relief valve, position the jaws correctly, break material with as few load cycles as possible—reduces wear and increases service life.
Technical parameters and assessment
The performance of a concrete demolition shear is described by parameters such as jaw force, jaw opening, cycle time, and energy efficiency. In practice, the effective force at the tooth tip and the geometry in the contact area are decisive. Normative requirements and test procedures can vary by device type; relevant references usually include manufacturer data, recognized rules of practice, and project-specific specifications. During bid and method planning, the shear is assessed in combination with complementary tools such as rock and concrete splitters, combination shears, and steel shears.
Method combinations with products from Darda GmbH
In demanding deconstruction projects, concrete demolition shears are often embedded in methodological chains:
- Rock and concrete splitters open components with low stress; the shear then crushes and separates the reinforcement.
- Combination shears and multi cutters handle mixed tasks of breaking and cutting, for example with light reinforcement, embedded items, or thin-walled elements.
- Steel shears cut massive steel profiles before the concrete demolition shear breaks adjacent concrete sections.
- Tank cutters are used for vessels and hollow bodies; the shear then detaches foundations and connections.
- Hydraulic power packs supply compact shear solutions in interior demolition with the required energy, independent of a carrier machine’s onboard hydraulics.