{"id":20096,"date":"2026-01-19T13:32:19","date_gmt":"2026-01-19T12:32:19","guid":{"rendered":"https:\/\/www.darda.de\/?page_id=20096"},"modified":"2026-01-19T13:32:19","modified_gmt":"2026-01-19T12:32:19","slug":"deformation","status":"publish","type":"page","link":"https:\/\/www.darda.de\/en\/knowledge\/deformation","title":{"rendered":"Deformation"},"content":{"rendered":"
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Deformation describes the change in shape and length of materials under load. In concrete demolition, rock excavation, interior demolition, and when separating steel and sheet-metal components, deformation behavior determines whether components crack, cut, split as planned, or break unexpectedly. Those who understand the interaction of material, load type, and tool can use deformation deliberately: concrete structures can be opened in a controlled manner, rock blocks split along existing planes of weakness, and steel sections cut cleanly. Products such as concrete pulverizers, hydraulic rock and concrete splitters<\/a>, hydraulic power units, steel shears, or tank cutters intervene in the deformation mechanisms in different ways\u2014always with the goal of working the existing structure with minimal secondary breakage and precise force application.<\/p>\n

Definition: What is meant by deformation<\/h2>\n

Deformation is the reversible or irreversible change in the geometry of a body as a result of external actions. A distinction is made between elastic<\/em> deformation (fully reversible after unloading) and plastic<\/em> deformation (permanent change in shape). If the demand exceeds load-bearing capacity, fracture occurs, often initiated by crack formation. Concrete exhibits brittle behavior under tension and shear; under compression it shows combined crushing and shear yielding with wedge cracks. Steel behaves ductilely: after reaching the yield strength, the material continues to flow plastically. Rock and natural stone usually deform in a brittle manner, depending on joints, stratification, and water content. Time-dependent effects such as creep and shrinkage (concrete) as well as temperature- and rate-dependent effects additionally influence deformation behavior.<\/p>\n

Deformation mechanisms in concrete, steel, and rock<\/h2>\n

The governing mechanisms are compressive, tensile, and shear deformation, often superimposed by bending and torsion. In concrete, microcracks under tension quickly evolve into macrocracks; under compression, shear-tension cracks and crushing zones form. Reinforcing steel takes tensile forces and enables ductile load-bearing but can locally buckle or yield. Rock shows preferred fracture planes along joints; compression dominates in the core, while edge zones go into tension and open up. In steel structures, yield strength and toughness indicate how far plastic deformation is possible before separation (shear or tensile fracture) occurs. Tools target these mechanisms: concrete pulverizers combine compression and shear; stone and concrete splitters induce controlled tension transverse to the borehole axis; steel shears separate by concentrated shear stresses; tank cutters must account for locally confined heat- and deformation zones with springback.<\/p>\n

Load types and their influence on the demolition process<\/h2>\n

The type of loading determines which deformation dominates and how a component responds.<\/p>\n

Compressive deformation<\/h3>\n

Compression is the dominant load in concrete. Local crushing zones and shear wedges govern the fracture pattern with concrete pulverizers. A stable compression chain<\/strong> reduces secondary breakage, for example through aligned bearing surfaces and coordinated stroke movements. In rock, compression in combination with existing weaknesses leads to split-like openings.<\/p>\n

Tensile deformation<\/h3>\n

Tension causes early cracking in concrete. Stone and concrete splitters exploit this by inducing transverse tension in the borehole field with wedges to create a defined crack plane. In steel, tension leads to reaching the yield point; with thin sheet, springback<\/em> is to be expected.<\/p>\n

Shear deformation<\/h3>\n

Shear is the principle of steel shears and concrete pulverizers when severing overlays and reinforcing bars. In concrete, combined shear and tensile cracks form; crack propagation is influenced by the geometry of the blades and the support of the component.<\/p>\n

Bending and torsion<\/h3>\n

Bending superimposes tension and compression. In cantilevers during deconstruction it leads to crack openings on the tension side. Torsion is relevant for hollow sections and tanks: unplanned twisting can cause buckling and local instability if cuts are placed asymmetrically.<\/p>\n

Deformation of concrete: understanding and using crack formation<\/h2>\n

Crack formation can be controlled when material, geometry, and load path are known. The goal is directed crack propagation<\/strong> with minimal spalling.<\/p>\n

From microcrack to fracture cone<\/h3>\n

Under tension, microcracks grow along the interfacial transition zone between cement paste and aggregate. Concrete pulverizers generate local fracture cones through concentrated compressive and shear stresses; targeted gripping positions can stabilize the crack trajectory. In splitting processes, microcracks link to form a planar split plane between chains of boreholes.<\/p>\n

Reinforcement and ductility<\/h3>\n

Reinforcement bridges cracks and allows plastic redistribution. During size reduction, residual elongation and the catenary action<\/em> of bars must be anticipated. Steels can flow locally; a clean cut with steel shears prevents uncontrolled springback when releasing the last ligaments.<\/p>\n

Influencing factors<\/h3>\n