Rock tools

Rock tools include all tools and hydraulic attachments used to process, split, separate, or convert natural rock into transportable units in a controlled manner. In practice, the spectrum ranges from non-explosive splitting to cutting and shearing embedded components, up to selective deconstruction at the interface between rock and concrete. Especially in sensitive environments—inner-city settings, existing tunnels, or areas of listed heritage structures—low vibration levels methods are in demand. Here, hydraulic systems from Darda GmbH such as hydraulic rock and concrete splitters or, additionally, concrete pulverizer come into play when concrete components or installations near rock need to be selectively removed.

Definition: What is meant by rock tools

Rock tools are specialized tools and hydraulic attachments for the mechanical processing of rock. They generate controlled stresses in the rock to initiate cracks and release blocks along the desired cutting lines. These include, in particular, rock and concrete hydraulic wedge splitters with rock splitting cylinders, as well as cutting and shearing systems that can be used in mixed construction situations (rock/concrete/steel). The energy supply is typically provided by power unit. Rock tools are used in the fields of rock excavation and tunnel construction, natural stone extraction, concrete demolition and special demolition, strip-out and cutting, and in special applications.

Design and operating principles of rock tools

Rock tools use mechanical lever, wedge, or shear principles to locally exceed the tensile strength of the rock. With hydraulic splitting technology, boreholes are drilled and rock splitting cylinders are inserted. A wedge extends, pushing two counter-bearings apart and generating radially acting forces that open the rock along natural or predefined planes of weakness. Cutting and shearing systems are used in addition where components embedded in the rock—such as reinforcement, anchor heads, or concrete stiffeners—have to be separated. hydraulic power units provide the required pressure and flow; precise matching improves efficiency and reduces thermal and mechanical stress on the system.

Hydraulic splitting technology

The splitting method is based on the wedge principle. The prerequisites are boreholes with suitable diameter and sufficient depth. The splitting wedge generates high radial forces with very low structural vibrations—ideal in vibration-sensitive zones. This method is particularly suitable for rock demolition and tunnel construction, controlled natural stone extraction, and special applications such as rescue operations or work in ATEX zone where non-explosive approaches are preferred.

Cutting and shearing principles

In transition zones from rock to structure, shearing or cutting tools are additionally used. Concrete pulverizer separate concrete components and facilitate exposing the rock when deconstruction is carried out in stages. Combination shears and Multi Cutters are useful when reinforcement, anchors, or other metal parts must be cut. Steel shear and tank cutters primarily belong to the domain of strip-out and cutting but prove relevant whenever metallic installations or tanks in rock-adjacent excavations or drifts have to be removed.

Grabbing, breaking, and secondary breakage

After splitting, controlled secondary breakage is often performed to achieve transportable piece sizes. Through coordinated splitting sequences and, if necessary, reworking in secondary boreholes, block geometry can be purposefully controlled. Where concrete is present, concrete pulverizer support separate removal.

Typical rock tools and applications

• Rock and concrete hydraulic wedge splitters: Non-explosive splitting of granite, gneiss, basalt, limestone, or sandstone. Application in rock excavation and tunnel construction, underpinning, sensitive demolition near infrastructure, as well as in shafts or basements with restricted space.
• Rock splitting cylinders: Core components of the splitters; they transfer the hydraulic energy of the unit directly into splitting force. Different wedge geometries and cylinder sizes allow adaptation to borehole diameter and rock strength.
• Concrete pulverizer: For selective deconstruction of concrete in areas near rock, for example to expose anchor plate, foundation interfaces, or linings in tunnels before splitting the rock itself.
• Combination shears and Multi Cutters: For separating mixed materials (concrete with reinforcement, metal elements) as part of strip-out and cutting or in mixed profiles during special demolition.
• Power unit: Supplies splitting cylinders, shears, and crushers. Key factors are sufficient flow rate, stable system pressure, clean hydraulic oil, and robust filtration.
• Steel shear and tank cutters: For metallic installations, shafts, or containers in rock-adjacent environments; they complete the tool chain in complex deconstruction projects.

Selection criteria: determining the right rock tool

The choice of the right rock tool depends on rock parameters, environmental conditions, and logistical constraints. The goal is a safe, reproducible result with minimal emissions and optimal cycle time.

Geological parameters

• Compressive strength and toughness: Hard, dense rocks require higher splitting forces and adjusted wedge geometries. Softer, bedded rocks are more sensitive to edge loads and benefit from tighter drilling patterns.
• Jointing and strata: Natural fractures, bedding planes, and weathered zones can be used or must be bridged. The orientation of boreholes should consider the rock’s preferred splitting directions.
• Moisture and temperature: Wetness, frost, and temperature gradients influence friction, wedge effect, and crack propagation.

Construction-related framework conditions

• Vibration and noise control: In sensitive areas, hydraulic splitters offer advantages over percussive methods, with effective noise reduction measures.
• Accessibility: Tool dimensions, hose routing, and lift loads must fit the site conditions—from narrow shafts to large tunnel cross-sections.
• Media management: Plan for dust reduction (e.g., via water mist while drilling), safe oil handling, and suitable ventilation.

Performance indicators and system matching

• Splitting force and wedge stroke: Size according to rock strength and desired block size.
• Hydraulic pressure and flow rate: The power unit must deliver stable pressure; avoid pressure spikes and pressure losses.
• Borehole specification: Diameter and depth influence effectiveness and takt. Precise drilling patterns reduce tool wear.

Workflow in rock breaking: step by step

1. Investigation and planning: Survey geology, joint systems, connections to structures, and transport routes.
2. Define drilling pattern: Set grid, edge distance, and staggering to achieve the desired contours.
3. Drilling: Accurate, cleaned boreholes are critical for splitting performance.
4. Insert splitting cylinders: Position, pre-tension, and carry out the splitting sequence in a controlled manner.
5. Reworking and sequences: Work in multiple cycles along the planned line to avoid uncontrolled cracking.
6. Secondary breakage and removal: Release, sort, and load blocks; where concrete is present, complement selectively with concrete pulverizer.
7. Documentation: As-planned vs. as-built comparison, emissions and quality control.

Tips for precise drilling patterns

Arrange boreholes perpendicular to the intended splitting direction, maintain edge distance, and avoid intersections. Use a tighter grid in irregular zones and adjust the sequence for changing rock layers.

Safety, health, and environment

Working in rock entails stringent requirements for occupational safety and environmental protection. Personal protective equipment, safe setup areas, barriers, and well-planned hose and load management are fundamental. Hydraulic systems operate at high pressure; tightness, couplings, and hoses must be checked regularly. Emissions such as dust and noise should be reduced with suitable measures depending on the environment. Compared to percussive methods, splitting technology typically causes lower vibrations and is therefore suitable for work on sensitive structures.

Low-emission methods in existing structures

In existing buildings, tunnels, or production facilities, hydraulic splitting devices stand out for their low vibration levels. In combination with dust extraction or a water spray system, dust generation can be further reduced. Ensure orderly oil handling and leak prevention to protect soil and water.

Maintenance, operation, and service life

Regular visual inspections and preventive maintenance ensure availability. Wedges and counter-bearings are wear parts; they should be kept clean and replaced in good time. Power unit benefit from correct oil level, suitable viscosity, and effective filtration. Pressure settings must comply with the technical specifications; deviations increase wear and may reduce splitting performance.

Systematic troubleshooting

• Incomplete splitting: Check borehole diameter, inspect wedge condition, clean the borehole, and adjust the sequence.
• Pressure drop: Check filter condition, hose connections, and the unit’s pump; avoid unnecessary hose lengths.
• Uncontrolled crack propagation: Densify the drilling pattern, increase edge distance, and align the splitting sequence with the rock’s bedding.

Standards, guidelines, and good practice

Depending on the region, there are requirements for occupational safety, noise, dust, vibrations, and environmental protection. The selection and operation of rock tools should follow recognized rules of technology. Observe the manufacturers’ safety information; project-specific permits and coordination with authorities may be required. The notes are general in nature and do not replace a case-by-case assessment.

Delimitation and interplay with other methods

Hydraulic splitting technology complements or replaces conventional methods such as blasting, hydraulic breaker (rock hammer), or the wire sawing method—depending on geology, environmental requirements, and schedule. Where concrete and rock zones interlock, concrete pulverizer facilitate selective deconstruction, while rock and concrete hydraulic wedge splitters enable the actual rock removal to be non-explosive and controlled. Shearing tools such as combination shears, Multi Cutters, or steel shear complete the ensemble when metallic installations must be separated.

Application areas of rock tools in practice

In rock excavation and tunnel construction, splitting devices are used for contouring, removing overbreak, and block division. In natural stone extraction, they enable the gentle recovery of raw blocks with defined edge quality. In concrete demolition and special demolition, they support underpinning and the removal of rock-adjacent reinforcements, often in conjunction with concrete pulverizer. In strip-out and cutting, shear and cutter systems complement the tool chain, while in special applications, non-explosive, low-vibration methods support safe progress under difficult boundary conditions.