Soft rock processing covers the controlled loosening, shaping, and breaking down of naturally formed rocks of low to medium strength such as limestone, sandstone, marl, gypsum rock, tuff, or chalk. In construction, in concrete demolition and special demolition, in natural stone extraction, as well as in rock excavation and tunnel construction, methods with low vibration levels are required that work precisely and gently on the material. Central to this are hydraulic splitting and shear methods, for example the use of hydraulic rock and concrete splitters for crack steering and—depending on the task—of concrete demolition shear for selective separation work on masonry, concrete, and natural-stone-like composites.
Definition: What is meant by soft rock processing
Soft rock processing encompasses all technical processes used to loosen, split, separate, or shape rocks of low to medium compressive strength (typically uniaxial compressive strength in the range of about 5–60 MPa, depending on petrography and moisture content). These include hydraulic splitting via boreholes, crushing with shears, precision cutting at edges, and controlled detachment along natural bedding or joint planes. The objective is reproducible crack guidance with minimal vibrations, noise, and dust generation. In practice, hydraulic splitter and concrete splitter are often powered by hydraulic power units; concrete demolition shear are additionally used when components made of concrete or mixed construction materials with a soft rock share are selectively deconstructed or adjusted.
Material groups and key properties of soft rock
Soft rock is heterogeneous. For planning, geological classification and mechanical properties are decisive: limestone (fine- to coarse-crystalline), sandstone (cemented, varying grain bonding), marl (clayey-calcareous), gypsum/anhydrite, tuff, and chalk differ significantly in strength, abrasivity, moisture uptake, and bedding behavior. Relevant parameters are in particular uniaxial compressive strength, indirect tensile (Brazilian) strength, modulus of elasticity, natural jointing/bedding, porosity, water content, and degree of weathering. For the work strategy it is important whether pronounced bedding planes favor crack propagation, whether zones with higher strength (e.g., siliceous layers) are present, and whether embedded items such as masonry anchor, reinforcement, or utility line occur. These factors determine borehole spacing, required splitting pressure, shear jaw opening, and the sequence of work steps.
Methods and tools: splitting, shear work, and controlled separation
The choice of method depends on rock characteristics, target geometry, space constraints, and emission requirements. Hydraulic hydraulic splitter and concrete splitter generate high radial forces via splitting wedges and reaction shoes in prepared boreholes and open defined cracks in the rock. They are particularly suitable for blockwise release in rock excavation and tunnel construction as well as for precise detachment of façade or foundation areas during building gutting and cutting. Concrete demolition shear grip and crush components through high jaw forces; they are helpful when soft rock occurs in combination with concrete or masonry, for example in plinths, retaining walls, or infills. Hydraulic power pack supply both methods with the necessary pressure and flow rate. For special tasks, an steel shears can additionally be used for metal parts when the soft rock is coupled with technical installations.
Hydraulic power packs and energy supply
For consistent splitting and shear performance, a stable system pressure, sufficient flow rate, and thermal reserves of the unit are essential. Pressure and temperature monitoring, clean hydraulic fluid, and suitable hose cross-sections ensure repeatable crack formation, especially in moist or clayey rock that tends to “lubricate.”
Borehole geometry and splitting strategy
Borehole diameter and depth must match the splitter. Hole spacing is based on strength, jointing, and desired block size: a denser grid for more homogeneous, firmly bonded sandstones; larger spacing for pronounced bedding. Starting at free edges, splitting is performed in sequences to steer crack propagation and avoid overbreak.
Shear kinematics and edge work
When using concrete demolition shear on mixed masonry and weakly bonded natural stones, gripping position, application point, and feed are decisive. Intermittent work with brief holding pressures promotes controlled spalling and prevents unintended indentation into porous structures.
Workflow and best practice
A structured workflow increases quality and efficiency: clarify the geological situation, define safety and emission targets, select the equipment combination, then proceed in a coordinated manner from drilling plan through splitting to edge finishing.
Pre-investigation and documentation
Bedding, weathered zones, and moisture must be recorded. Core drilling or test drilling in critical areas provide indications of bonding and possible inclusions. Documenting strength indices and water inflows facilitates the selection of grid spacing and tools.
Pre-splitting, post-splitting, edge finishing
Pre-splitting creates relief joints and produces predictable fracture faces. Post-splitting reduces block sizes for transport or further processing. With concrete demolition shear, edges are straightened, openings are exposed, or composite stones are selectively released without unnecessarily weakening load-bearing areas.
Handling and logistics
Transport route and lifting points should be planned early. Block sizes are aligned with lifting gear and haulage. In tunnel situations, cyclic work with small splitting sequences minimizes fine dust and noise loads.
Application areas and typical scenarios
In natural stone extraction, splitting along natural bedding enables the recovery of dimensionally accurate raw blocks from limestone or sandstone. In rock excavation and tunnel construction, soft rock is released with low vibration levels at boundaries to protect neighboring structures and linings. In concrete demolition and special demolition, composites of concrete, masonry, and soft rock occur, for example with foundations on limestone beds; here, hydraulic splitter and concrete splitter support targeted opening, while concrete demolition shear selectively crush components. In building gutting and cutting, cutouts, chases, and openings in weakly bonded masonry areas are produced with precision. Special demolition includes work in sensitive environments such as heritage sites, hospitals, or industrial areas where vibrations, dust, and noise are strictly limited.
Quality requirements for fracture faces and dimensional accuracy
The quality of fracture faces influences material yield in natural stone extraction and connection capability in fit-out. Accurate edges result from sequential splitting with adequate free faces and from subsequent edge finishing. In porous rocks, moderate step spacing reduces the tendency to spall. For mating surfaces, uniform splitting energy and a finely tuned borehole rhythm are decisive.
Safety and environmental aspects
Work in soft rock requires prudent dust and water management. Mechanical methods are inherently characterized by low vibration levels; nevertheless, neighboring structures should be monitored. Personal safety equipment, protection against hydraulic pressure, safe routing of the hydraulic hose line, and an orderly drilling pattern reduce risks. Legal requirements regarding noise, dust, and workplaces must be reviewed for the specific project; information provided here is always general and not individual advice.
Maintenance and operation of hydraulic systems
Regular visual inspection of hoses, couplings, and wedge/cylinder components, clean filtration, and oil change intervals ensure consistent splitting and shear forces. Temperature management prevents performance loss under continuous load. Adhering to the system’s specified pressure limits protects the rock and tools from unnecessary stress.
Planning and cost-effectiveness
Productivity results from a coordinated combination of drilling performance, splitting sequence, and material handling. Costs are positively influenced by minimal rework, dimensionally accurate blocks, and reduced emissions. An early decision between splitting, shear work, or a combined approach improves schedule and budget adherence—especially in urban deconstruction projects and demanding building gutting.
Typical error sources and solutions
Frequent causes of quality or schedule issues can be avoided with thoughtful preparation. These include a drilling grid that is not adapted, excessive splitting distances in heterogeneous material, missing free faces for crack propagation, too high a feed rate during shear work in porous stones, or undersized hydraulic power pack. Remedies include a geologically justified grid plan, gradual load increase, setting relief joints, and a coordinated choice of equipment—preferably with hydraulic splitter and concrete splitter for crack steering and concrete demolition shear for precise edge and composite work.