Material thickness

Material thickness – often also referred to as wall thickness, plate thickness, or component thickness – is a fundamental parameter in demolition, strip-out, cutting, and splitting processes. It influences the force required, the choice of tool, the number of work steps, and emissions such as noise and vibrations. In fields such as concrete demolition and special demolition, rock excavation and tunnel construction, natural stone extraction, as well as special operations, material thickness directly governs whether, for example, concrete demolition shears or rock and concrete splitters are appropriate, how hydraulic power units are sized, and which work sequence is sensible.

It also affects cut quality, crack control, productivity, and compliance with limits for vibration and airborne dust in sensitive environments. A consistent approach to determining thickness enables predictable results and reduces rework.

Definition: What is meant by material thickness?

Material thickness is the perpendicular distance between two opposite surfaces of a component or workpiece. For concrete elements this is the wall or slab thickness; for steel components the plate thickness; for natural stone blocks the block or layer thickness. Material thickness affects load-bearing behavior, crack formation, and fracture mechanics, and determines the required intervention: thinner structures can often be separated with cutting or jaw-type tools, while massive cross-sections require splitting methods or multi-stage segmentation. For Darda GmbH’s tool selection – such as concrete demolition shears, steel shears, Multi Cutters, combination shears, stone splitting cylinders, tank cutters, as well as the matching hydraulic power packs – reliably determined material thickness is a central criterion.

In practice, thickness must be distinguished from depth, cover layers, or laminate build-ups. When composite elements are present, the decisive thickness is the effective section to be cut or split, not merely the visible surface layer.

Influence of material thickness on methods and tool selection

Material thickness determines whether cutting, crushing, or splitting methods are economical and technically appropriate. Thin-walled components favor shearing tools, while large cross-sections, due to the nonlinear increase in force demand (higher required energy density), favor splitting strategies. In practice, this leads to the following tendencies:

• Concrete and reinforced concrete up to medium thicknesses: separation with concrete demolition shears or combination shears, possibly in several bites, with attention to reinforcement content and edge guidance.
• Massive concrete cross-sections and natural stone: splitting with rock and concrete splitters or stone splitting cylinders, often combined with pre-drilling and a segmented approach.
• Steel components and tanks: use steel shears or tank cutters, depending on plate thickness, material toughness, and required cut quality.
• Special materials or composite constructions: Multi Cutters and combination shears when varying thicknesses and materials need to be handled in one pass.

Additional selection criteria include access constraints (overhead or confined spaces), permissible vibrations, and handling weight of the segmented pieces. These boundary conditions frequently decide between a pure cutting strategy and a combined cut-and-split approach.

Material thickness in concrete and reinforced concrete

In concrete and reinforced concrete, thickness interacts with concrete strength, reinforcement ratio, and member geometry. Thinner components (e.g., façade panels, balcony parapets) can often be cut or crushed directly with concrete demolition shears. As thickness increases, the required jaw forces grow; additionally, reinforcement diameter and layout influence the cutting line. From a certain thickness and mass, a splitting approach – for example with rock and concrete splitters – is advantageous because it deliberately initiates cracks and converts the member in a controlled way into smaller segments.

Relevant parameters in concrete demolition

• Component thickness and cross-sectional shape: influence gripping position, jaw opening range, stroke lengths, and wedge geometry.
• Reinforcement content: acts as tough inlay material and alters peak loads; the thicker the cross-section, the more relevant the steel alignment becomes.
• Support by hydraulic power packs: greater material thicknesses require sufficient pressure and flow to secure cycle times and force reserves.
• Edge distances, anchors, and inserts: maintain safe clearances to avoid spalling and tool jamming.

Material thickness in natural stone and rock

In rock excavation and tunnel construction, layer thickness, jointing, and local tensile splitting strength determine the approach. Greater thicknesses are preferably processed with splitting cylinders; borehole spacing and diameters are set according to thickness and rock type. In natural stone extraction, block thickness is chosen so that it can be efficiently divided into transportable pieces with rock and concrete splitters, without unnecessary over-drilling and without uncontrolled crack propagation.

Drilling and splitting concept

• Borehole depth approximately equal to the planned splitting depth; greater material thickness requires higher energy density per borehole.
• Spacing between boreholes is moderately increased with growing thickness, but always adjusted to rock anisotropy.
• Pre- and post-splitting in sections to relieve stresses in a controlled manner.
• Staggered patterns (row or chevron) help steer crack paths in thick or heterogeneous strata.

Measurement and documentation of material thickness

Reliable determination of material thickness is a prerequisite for planning, tool selection, and safety. Depending on the material, different methods are available:

• Direct measurement: capture visible edges with a caliper or gauge wedges; for concrete, core drilling and measuring the core.
• Indirect methods: ultrasonic thickness measurement, remote inspection with endoscopy in cavities, magnetic methods for steels.
• Documents and drawings: use as-built documentation and validate with spot checks on the existing structure; log deviations.

Documentation includes not only the thickness but also material class, reinforcement layout, installation situation, and access conditions. This facilitates correct sizing of concrete demolition shears, splitting cylinders, and hydraulic power packs.

Accuracy and tolerances

• Specify measuring accuracy (e.g., ±2 mm for plates, ±5 mm for in-place concrete) and record uncertainty for each method.
• Cross-check at edges, penetrations, and transitions where thickness can vary significantly.
• For layered or composite elements, record layer sequence and individual layer thicknesses separately.

Force demand and process parameters

As material thickness increases, cutting and splitting forces do not grow linearly, because additional factors such as friction, notch effects, reinforcement content, and crack deflection come into play. In practice, this means:

• Cutting processes: required jaw force increases with thickness and toughness; larger jaw openings and robust cutting-edge geometry become relevant.
• Splitting processes: with thickness, the splitting pressure required per borehole rises; arranging multiple splitting points reduces individual peaks.
• Hydraulic supply: higher pressures and sufficient flow from the hydraulic power pack ensure constant working speed at high load.
• Temperature and oil condition: viscosity and heat management influence attainable force and cycle stability in thick sections.

Consequence: Thicker components are often processed in sequences – pre-cutting, widening, post-splitting – to smooth force peaks and keep component reactions controllable.

Work preparation depending on material thickness

A robust method is to segment the component according to the determined material thicknesses. In strip-out and cutting, it is advisable to release thinner zones first with jaw-type tools, then split massive sections afterward.

Recommended sequence

1. Record thickness ranges and mark the cutting lines.
2. Pre-cut thinner sections with concrete demolition shears or combination shears.
3. Pre-drill in areas of greater thickness; deploy rock and concrete splitters.
4. Finish edges and residual webs with Multi Cutters or suitable shears.
5. Remove segmented pieces in planned lift weights and verify interim stability before proceeding.

Safety, emissions, and control

The thicker the component, the higher the stored stresses and potential fracture energies. Risk mitigation measures include exclusion zones, controlled sequencing, dust suppression, and monitoring of component movement. In steel and tank work, material thickness influences sparking and heat input; tank cutters are selected according to wall thickness and the medium. Notes on protective measures must always be evaluated project-specifically and should follow recognized rules of the art.

• Define trigger thresholds for vibrations and displacements, and establish stop criteria for unexpected crack propagation.
• Plan noise and dust control proportional to the process energy; combine extraction, wetting, and local enclosures.
• For hot work on thicker steels, implement gas monitoring and continuous ventilation where applicable.

Typical mistakes when dealing with material thickness

• Confusing nominal and in-place thickness: coverings, coatings, and infills are not accounted for.
• Underestimating reinforcement: thicker cross-sections often contain larger or double layers that affect shear performance.
• Splitting spacing too large: in massive components this leads to uncontrolled crack patterns; closer staggering is necessary.
• Under-dimensioned hydraulic power packs: with great thicknesses cycle times drop and process quality suffers.
• Ignoring access and lifting limits: segments sized by thickness but not by handling capacity.

Guideline values for tool selection by material thickness

The following information provides non-binding, practice-oriented guidance and does not replace project-specific design:

• Concrete up to approx. 150 mm: separation and nibbling with concrete demolition shears; spot re-cutting at reinforcement.
• Concrete approx. 150-400 mm: combination of pre-cutting (shear) and segmented splitting with rock and concrete splitters.
• Concrete over approx. 400 mm and massive natural stone: drilling and splitting with stone splitting cylinders; tight splitting spacing.
• Steel plates up to medium thicknesses: steel shears or combination shears; for large plate thicknesses, matched blades and higher hydraulic power.
• Tanks and vessels: select the tank cutter based on wall thickness, material, and the medium’s safety requirements.

Actual limits depend on concrete strength, reinforcement, steel grade, and machine class. Trial cuts or test splits on non-critical sections are recommended where uncertainty exists.

Special operations and varying thicknesses

For special operations – such as complex composite cross-sections, retrofitted components, or local thickening – an adaptive method with Multi Cutters and combination shears is recommended for thinner layers, and splitting devices for the load-bearing core zones. By switching between cutting and splitting principles, the intervention remains controlled and adapted to the actual material thickness.

Sequencing should be reversible where possible, allowing a return to a previous stage if crack paths or forces deviate from expectations.

Hydraulic power packs matched to material thickness

The sizing of the hydraulic power pack follows the required tool force and cycle frequency. Greater material thicknesses typically require higher system pressures and sufficient flow so that concrete demolition shears can develop their full potential and splitting cylinders can build the necessary spreading force. A balanced ratio of pressure, flow, and hose lengths reduces energy losses and stabilizes working speed.

• Dimension hose diameters and lengths to minimize pressure drop at peak demand.
• Provide oil cooling and filtration sized for continuous high-load operation in thick sections.
• Use quick couplers and manifolds configured to the anticipated tool changes within the chosen sequence.

Documentation and follow-up

The final documentation of the material thicknesses actually encountered – including deviations from drawings – provides a solid basis for subsequent deconstruction steps, the selection of subsequent tools from Darda GmbH, and the optimization of future projects. Systematically recording thicknesses, reinforcement layouts, and applied parameters (jaw forces, splitting pressures, borehole spacing) increases the reproducibility and predictability of similar measures.

• Attach measurement logs, photos with scale references, and marked-up plans.
• Record tool settings and hydraulic parameters used for each thickness range.
• Note lessons learned on segmentation, emissions control, and cycle times for benchmarking.