Separation cut

A separation cut is the targeted, controlled separation of construction materials along a defined line. It forms the basis for precise work in concrete demolition, special demolition, building gutting, rock excavation and tunnel construction, as well as in natural stone extraction. Depending on the material and the task, mechanical, hydraulic, or combined methods are used. In practice, separation cuts are often combined with other methods: a pre-marked cut can be produced by cutting tools and then separated in a material-appropriate manner, released, or converted into manageable segments using concrete demolition shears or rock and concrete splitters. Hydraulic power packs provide the required output for mobile tools and shears, while specialized devices such as Multi Cutters, steel shears, or tank cutters are used for metallic components.

Definition: What is meant by a separation cut

A separation cut is understood as producing a separating joint in concrete, stone, masonry, metal, or composite components. The goal is the defined delimitation of a component or segment in order to remove it with low load, low vibration, and in a controlled manner, or to continue processing it. The separation cut differs from non-specific demolition through its planned cut path, clear tolerances, and a tool choice matched to material properties, member thickness, and reinforcement. Typical methods are sawing (e.g., wall saw, wire saw, slab saw), shearing (concrete demolition shears, steel shears, combination shears, Multi Cutters) and—as a complementary technique—hydraulic splitting with rock and concrete splitters or rock splitting cylinders when the cut is to be finished or widened by wedging forces. In the application areas of concrete demolition and special demolition, building gutting and cutting, rock excavation and tunnel construction, natural stone extraction, as well as special operations, the separation cut is used as a central means for crack control, load reduction, and dimensional accuracy.

Fundamentals and mode of operation of the separation cut

A separation cut follows a predefined line coordinated from both a structural and logistical perspective. In concrete construction the cut path is oriented to reinforcement layers, nodes, and load paths. In rock, natural joints, grain fabric, and brittle fracture behavior are considered. Essential parameters are cut depth, kerf width, edge quality, permissible spalling, and the share of inserts such as reinforcing steel or embedded components. For low-vibration working methods, a combination is often chosen: sawing or shearing tools establish the exact course, concrete demolition shears release the remaining residual cross-section, and rock and concrete splitters widen the cut in a defined way. Hydraulic power packs supply the tools with pressure and flow; correct tuning influences cutting speed, heat input, and tool wear. For metallic structures—such as vessels, tanks, or pipelines—steel shears or tank cutters are used, which cut sheet and sections appropriately and create a clean edge for further handling.

Distinguishing the methods: cutting, shearing, splitting

Separation can be performed in different ways. The choice of method depends on material, member geometry, constraints, and the objective.

Cutting

Sawing methods (floor joint cut in slabs, wall saw, wire saw) produce very precise, straight cuts with low roughness. Water-cooled sawing reduces dust and heat input. In heavily reinforced cross-sections, predrilling (core drilling) is often used to relieve reinforcement content or to set lifting points.

Shearing

Hydraulic concrete demolition shears and combination shears fragment the cross-section through cutting and compressive forces. They are particularly suitable when cutting and breaking should occur in a single operation, for example when opening wall or slab openings in a controlled manner. Multi Cutters and steel shears cut sections, reinforcing steels, and sheet; tank cutters are designed for shell plates and ring-shaped cuts.

Splitting

Hydraulic rock and concrete splitters as well as rock splitting cylinders generate splitting forces that act along an existing cut, a row of boreholes, or a natural plane of weakness. This allows massive cross-sections to be released without explosives and with low vibration. Splitting complements the separation cut by tearing open the remaining cross-sections in a defined manner and separating the parts from one another.

Fields of application of the separation cut

Concrete demolition and special demolition

In selective deconstruction, components are segmented to reduce loads, separate arising materials, and optimize transport routes. A separation cut defines segment boundaries; concrete demolition shears release the segments, splitters assist on thick sections or at sensitive objects where vibrations must be avoided. Hydraulic power packs feed mobile tools on confined job sites.

Building gutting and cutting

During conversions and refurbishments, openings for doors, shafts, utilities, or extensions are created. Slab saw cuts in slabs, walls, and floor plates are often followed by concrete demolition shears to separate embeds and residual areas. Steel shears and Multi Cutters cut reinforcement, beams, or girders; tank cutters are used when vessels or metallic enclosures are segmented.

Rock excavation and tunnel construction

In geologically sensitive areas, low-vibration methods are in demand. Preparatory separation cuts along rows of boreholes and subsequent splitting with rock splitting cylinders enable controlled detachment of rock packages without affecting adjacent structures. During enlargement works, concrete demolition shears help to open shotcrete or lining elements.

Natural stone extraction

In quarrying natural stone blocks, separation cuts are guided along natural joints. After initiating by sawing or drilling, splitters are used to gently release the block. The goals are dimensionally accurate edges and high yield with minimal microcracking.

Special operations

In special situations—such as tank deconstruction, emergencies, or contaminated areas—controlled, low-spark, and precise separation cuts are essential. Tank cutters and steel shears cut metallic shells; for composite components, concrete demolition shears follow for residual concrete. The interplay of defined cut guidance, splitting technology, and suitable hydraulic supply increases process safety and traceability.

Planning, cut sequence, and work preparation

The quality of a separation cut depends largely on planning. A careful survey prevents unexpected inserts and minimizes risks.

1. Existing-conditions analysis: drawings, rebar locating, material testing, member thicknesses, and load paths.
2. Cut concept: alignment, cut depth, segment sizes, lifting points, shoring.
3. Method selection: sawing, shearing (concrete demolition shears, steel shears), splitting (splitters), combinations.
4. Resources: size hydraulic power packs (pressure/flow), tool selection, wear parts.
5. Site logistics: dust and water management, noise control, transport routes, disposal.
6. Cut sequence: preliminary separations, control cuts, final and relief cuts, rework.

Cut path and fixed points

Markings, scribe lines, and anchor bolts secure dimensional accuracy. For openings in slabs, shoring and suspension points are to be set up in advance to avoid unintended breaks. The cut sequence often begins with relief cuts, followed by main cuts and final separation with concrete demolition shears or splitters.

Material and component specifics

Concrete exhibits different separation behavior depending on strength class, aggregate, aging, and moisture. Reinforcement content, bonding agents, and prestressing influence the required force and tool selection. Natural stone responds according to mineralogy and jointing; for metamorphic rock, anisotropic fracture planes must be considered. Metallic components require shearing tools with sufficient jaw opening and cutting force. Composite materials such as reinforced concrete demand tuned combinations of cutting, shearing, and splitting.

Process parameters and machine characteristics

For reproducible results, parameters must be controlled transparently:

• Hydraulics: system pressure and flow of the hydraulic power packs determine cutting and shearing force as well as working speed.
• Tool geometry: jaw opening and blade geometry on concrete demolition shears/steel shears, wedge angle on splitters, segmenting on saw blades.
• Cooling/dust control: water supply during sawing; extraction or binding of fine dust where required.
• Feed and cycling: adjusted engagement prevents thermal damage and edge chipping.
• Splitting strategy: borehole spacing, wedge positions, and step sequence control crack propagation.

Quality assurance, tolerances, and edge finish

A good edge finish, low spalling, and adherence to dimensional tolerances characterize a high-quality separation cut. Before releasing segments, visual inspections, measurements, and—if necessary—crack indicators check the condition. Edges are reworked, for example with concrete demolition shears to break off loose areas or with a light follow-up cut to correct the edge. Documentation of cutting parameters and tool states supports traceability.

Safety, health, and environment

Safety aspects are an integral part of work preparation. The statements here are always general in nature and do not replace an object-specific assessment:

• Structural stability: define shoring, segment weights, lifting equipment, and exclusion zones.
• Emissions: route dust, noise, and water under control; ensure air changes in interior spaces.
• Energy and hydraulics management: secure hose routing, depressurize before tool changes, avoid drip leaks.
• Sparks and fire loads: when separating metallic components, assess ignition sources; only cut tanks after proper preparation.
• Ergonomics: adapt tool weights, grip positions, and working postures; plan load changes.

Typical failure patterns and countermeasures

• Breakouts at the cut edge: reduce feed, choose suitable blade segmenting, finish with concrete demolition shears.
• Jamming: check kerf widths, set relief cuts, use splitters to widen.
• Insufficient separation of reinforcement: plan steel shears or Multi Cutters, perform rebar locating in advance.
• Excessive tool wear: check hydraulic parameters, optimize cooling, replace cutting edges in time.
• Unexpected crack formation: revise cut sequence, adjust borehole spacing during splitting, improve shoring and unloading.

Economy and sustainability

A coordinated separation concept reduces time, emissions, and rework. The combined use of precise cut guidance and suitable hydraulic tools—such as concrete demolition shears for targeted opening and rock and concrete splitters for low-vibration release—improves the recyclability of materials. Through careful segmentation, transport and sorting can be optimized, which can increase recycling rates.

Practice-oriented process chain: example sequence

1. Locate and mark the cut line; define lifting points and exclusion zones.
2. Create the main cuts (slab saw, wall saw, wire saw) to the defined depth.
3. Separate inserts with steel shears or Multi Cutters; attach rigging.
4. Widen and finalize the separation with concrete demolition shears or—on massive components—with rock and concrete splitters.
5. Safely hoist the segments; check the edge finish; rework only where required.
6. Orderly handover to transport and recovery; site clean-up and documentation of parameters.

Relation to the equipment technology of Darda GmbH

In many applications, cutting and hydraulically separating methods complement each other. Concrete demolition shears enable controlled opening and separation after a prepared slab saw cut. Rock and concrete splitters as well as rock splitting cylinders create low-vibration separations in massive cross-sections, for example in foundations or in rock. Hydraulic power packs provide the necessary energy supply. For metallic components in composite constructions, steel shears, Multi Cutters, and tank cutters are available to separate reinforcement, sections, and shells properly. These combinations enable material-appropriate separation cuts in all the application areas mentioned—from special demolition to building gutting through to tunnel construction and special operations.