The deformation modulus is a central parameter when components made of concrete, masonry, natural stone, or metal are separated, split, or crushed. It describes how stiff a material behaves under load—and thus largely determines how cracks form, how much stroke a tool requires, and what hydraulic drive power is appropriate. For planners and contractors in concrete demolition, special demolition, natural stone extraction, and rock excavation, the deformation modulus influences the judicious selection and use of concrete demolition shear, concrete splitter, hydraulic wedge splitter, hydraulic demolition shear, Multi Cutters, steel shear or tank cutters (e.g., Tank Cutter) by Darda GmbH.
Definition: What is meant by deformation modulus
The deformation modulus describes the relationship between applied stress and the resulting strain of a material in the (nearly) elastic range. In practice, the elastic modulus (E‑modulus, Young’s modulus) is often intended: the stiffness of a material in tension or compression. In geotechnics and for rock, the term deformation modulus is also used for test-derived, component-oriented parameters that capture overall system behavior (for example, results from load plate test or triaxial tests). The larger the deformation modulus, the stiffer the response: small strains at high stresses. A smaller deformation modulus means higher compliance and larger deformations before crack formation or damage occurs.
Influence of the deformation modulus on the selection and application of cutting and splitting technology
Concrete splitter as well as hydraulic wedge splitter, including hydraulic rock and concrete splitters, generate local tensile stresses that, in stiff, brittle materials (high E‑modulus, e.g., granite or high-strength concrete), quickly turn into cracks. Crack propagation is directional and controllable, the required stroke is smaller, but the necessary peak force is high. In softer or tougher materials (lower E‑modulus, e.g., mixed masonry, young or lightweight concrete), energy is initially stored in deformation; crack initiation succeeds, but requires more opening travel, an adjusted drilling pattern, and potentially multiple application points.
Concrete demolition shear transfer compressive and bending actions via the jaws. In components with a high deformation modulus and low toughness, separation cracks form quickly; in more ductile systems (e.g., reinforced concrete) the bite is deeper and repeated application is advisable. The choice of jaw profile, rotational positioning, and the hydraulic pressure of the hydraulic power pack are aligned with component thickness, reinforcement ratio, and the expected stiffness level. In metal applications—e.g., with steel shear, hydraulic demolition shear, or in tank dismantling—shearing dominates; the deformation modulus influences spring‑back, kerf, and edge quality, which dictate positioning and the required cutting stroke.
Test methods and parameters in concrete, masonry, rock, and steel
Determination of the deformation modulus depends on material and objective. In practice, indicative values are useful and should be verified with site-specific tests.
Typical magnitudes
- Normal to high-performance concrete: about 25–45 GPa (depending on strength, aggregates, and moisture)
- Shotcrete, lightweight concrete: about 10–30 GPa
- Masonry (clay brick, calcium silicate brick, natural-stone masonry): about 1–25 GPa (strongly dependent on unit and mortar)
- Granite, gneiss: about 50–70 GPa; limestone: about 30–60 GPa; sandstone: about 5–25 GPa
- Structural steel: about 200–210 GPa (elastic range)
These ranges are guideline values. Age, moisture, temperature, microstructure, crack state, and reinforcement can significantly alter the measured deformation modulus.
Static and dynamic deformation modulus
Static tests (slow load increase) provide parameters that are usually more relevant for demolition and splitting processes. Dynamic procedures (vibration, ultrasound) often yield higher values because they activate microcracks less. For planning splitter and shear applications, orientation to static behavior is recommended.
Secant and tangent modulus
Materials such as concrete do not exhibit strictly linear behavior. The secant modulus refers to a defined stress–strain interval and is practical for load-bearing and cracking behavior. The tangent modulus describes the slope at a point and is sensitive to crack formation. For estimating stroke lengths, jaw opening, or the advance of a splitting wedge, the secant approach is suitable.
Temperature and moisture dependence
Increased moisture and higher temperatures reduce the E‑modulus of many mineral construction materials. Wet components or freshly cast concrete are more compliant; splitters may require more opening travel, while concrete demolition shear penetrate deeper. Deep-cold materials respond more brittlely; crack formation begins at smaller strains.
Material- and structure-related influences
Concrete and reinforced concrete
As strength class increases, the deformation modulus generally rises. Higher fractions of hard aggregates increase stiffness; high porosity reduces it. Reinforcement increases the overall stiffness of the component and influences crack pattern and spacing: concrete demolition shear must perform rebar cutting or expose bars; a splitting wedge can run up against rebars. For controlled separation, a coordinated approach is sensible: a preliminary bite to break the cover layer, then splitting or another bite, depending on the required separation cut.
Rock and natural stone
Rocks with a high deformation modulus and brittle behavior (e.g., granites) can be split directionally using hydraulic wedge splitter; cracks propagate along joint systems or weaknesses. In anisotropic layering (slate, bedded sandstones), borehole orientation is critical so that the wedge activates the desired crack path. With lower moduli or weathered zones, a tighter drilling pattern and multi-stage wedge advance may be required.
Masonry and composite systems
Masonry behaves heterogeneously: units and mortar possess different deformation moduli. When using concrete demolition shear, localized pre-cracking along bed or head joints is common. A lower overall modulus leads to larger local deformations, so the separating tool must bite deeper. In composite layers (e.g., concrete with applied protective layers), stiffness varies over the section depth; a stepwise approach is advantageous.
Metals in deconstruction
Steel has a high deformation modulus yet remains ductile up to the yield point. When working with steel shear, hydraulic demolition shear, or in tank dismantling, stiffness influences spring-back and thus the optimal kerf and the required hydraulic pressure. For reproducible cuts, a stable hold, a suitable jaw profile, and sufficient flow rate from the hydraulic power pack are decisive.
Practical guide: implementation on site
- Survey: material, age, moisture, reinforcement, microstructure. If no test values are available, assume conservative deformation moduli.
- Pilot action: a short trial bite with the concrete demolition shear or a first wedge setting at the borehole to assess stroke demand and crack response (e.g., a test cut).
- Tool selection: stiff, brittle components favor concrete splitter; tough composite sections suggest the use of concrete demolition shear with optional follow-up using Multi Cutters.
- Match hydraulic power units: derive required peak forces and stroke speeds from component thickness, expected stiffness, and procedure; choose hydraulic pressure and flow rate accordingly.
- Drilling pattern and application points: larger spacings suffice at higher deformation modulus; at lower modulus, use a tighter pattern to guide cracks purposefully.
- Monitoring: observe crack advance, deformations, and any stress redistributions; gently adjust parameters if behavior is unexpected.
- Safety: assess load-bearing functions, provide shoring, and secure hazard zones. Observe general safety rules.
Calculation and estimation in advance
When splitting wedges or shear jaws are opened, local strain increases. Materials with a high deformation modulus reach crack-initiating tensile stress at a small opening stroke; materials with a lower modulus require larger openings and multiple steps. The required hydraulic performance results from a combination of peak force (pressure × effective area) and work (flow rate × stroke). In reinforced concrete, the steel content and bond increase effective stiffness; the transition from elastic behavior to crack formation occurs segment-wise. In practice, this leads to several application points with moderate strokes rather than a single large one.
Application areas: effects of the deformation modulus
- Concrete demolition and special demolition: stiff, high-strength concretes allow precise splitting with concrete splitter; in ductile composite sections with dense reinforcement, concrete demolition shear with a matched jaw profile prove effective.
- Building gutting and cutting: in heterogeneous layers (screed, leveling compounds, lightweight concretes) the modulus varies; Multi Cutters and hydraulic demolition shear are supplemented by targeted wedge applications at load-bearing cores.
- Rock excavation and tunnel construction: the steerability of splitting depends on stiffness and jointing; hydraulic wedge splitter work particularly efficiently in brittle rocks with a high deformation modulus.
- Natural stone extraction: for dimensionally accurate blocks, controlling the crack path is crucial; in anisotropic settings, a high deformation modulus with pronounced brittleness facilitates straight separation.
- Special deployments: in confined, vibration-sensitive areas, understanding local stiffness enables choosing low-emission methods with adapted strokes and forces.
Distinction from related parameters
The term deformation modulus is often equated with the elastic modulus. Related quantities are the shear modulus (for shear deformations) and the compression or uniaxial compression modulus (constrained or volumetric compaction). Poisson’s ratio describes lateral strain under longitudinal loading and influences crack opening. In geotechnical practice, system-based deformation moduli from field or laboratory tests take center stage; in steel and concrete construction, the E‑modulus as a material property dominates. For the application of concrete demolition shear and concrete splitter, the functional question is decisive: How much force and how much stroke are needed to reach the local crack‑initiating strain and to steer crack propagation in a controlled way?