Raw material

Raw material refers to the untreated or only lightly processed feedstocks used in construction, deconstruction, extraction and processing. In the context of concrete demolition, rock excavation, tunnel construction, building gutting and natural stone extraction this includes mineral construction materials such as concrete, masonry and natural stone as well as metals and composite materials. For working with concrete pulverizers (or Concrete Crushers), and hydraulic rock and concrete splitters and other hydraulic tools, a precise understanding of material properties is crucial, because strength, microstructure, moisture and reinforcement content determine the choice of method, the equipment configuration and operational safety.

Definition: What is meant by raw material

Raw materials are natural or industrially manufactured substances that, without further processing, serve as the basis for construction processes, extraction, repair or deconstruction. These include rocks (e.g., granite, limestone, sandstone), binder-bound materials (concrete, reinforced concrete, prestressed concrete, masonry), metals (structural steel, stainless steel, cast iron), plastics and composite materials. In deconstruction, the existing structure itself—such as a concrete wall—is often regarded as raw material that is converted into reusable fractions by targeted separation, crushing or splitting.

The properties of a raw material arise from its composition (e.g., cement paste and aggregate in concrete), its microstructure (fabric, porosity, cracks), its age, and its manufacturing or storage history. These factors largely govern how efficiently concrete pulverizers grip, how stone and concrete hydraulic splitters initiate cracks, or how shears can start separation cuts.

Material classes in the construction and deconstruction context

Raw materials in the construction environment can be classified by origin, microstructure and mechanical behavior. This categorization helps with the methodical planning of demolition, deconstruction or extraction and with matching tools and parameters.

• Mineral-bound: Concrete, reinforced concrete, prestressed concrete, masonry (brick, calcium silicate brick, autoclaved aerated concrete). Typical are high compressive strength, brittle fracture behavior, pronounced microstructure dependencies (grain, pores, moisture) and—where reinforced concrete is concerned—superimposed reinforcement.
• Natural rocks: Granite, diorite, gneiss (hard, brittle), limestone and dolomite (medium strength), sandstone and slate (layer-dependent). Splittability often follows natural joints and bedding planes.
• Metals: Structural steel, reinforcing steel, sections, sheets, tanks. Ductile materials with high tensile strength and toughness; separation is achieved by shearing or cutting.
• Composite materials: Steel–concrete composite, fibre-reinforced concrete, bituminous composites. The combined material behavior requires coordinated separation sequences (e.g., mineral first, then metallic).

Key properties and parameters

For selecting and applying concrete pulverizers, stone and concrete hydraulic splitters and shears, the following parameters are especially relevant:

Compressive and tensile strength

Compressive strength governs resistance to compressive loads (concrete: typically C20/25 to C50/60; natural stone across wide ranges). Tensile strength is significantly lower in brittle raw materials. Splitting methods exploit this difference by generating controlled tensile stresses.

Modulus of elasticity and toughness

A high modulus of elasticity leads to stiffer behavior; brittle materials fail abruptly. Ductile materials such as steel deform before separating. This influences whether splitting, clamping force or shearing forces are effective.

Microstructure, porosity and moisture

Pores, capillaries and cracks steer stresses and can predetermine fracture paths. Moisture and temperature influence energy absorption. Freeze–thaw cycles and alkali–silica reaction alter the raw material over time.

Degree of reinforcement and inserts

Reinforcement, prestressing steel or embedded sections influence the choice of method: concrete pulverizers to expose and separate mineral components, followed by steel shear or Multi Cutters for the metallic fraction.

Layering and jointing

In natural stone, bedding planes, joints and faults define the orientation of splitting and cutting lines. Hydraulic splitters work efficiently along natural planes of weakness.

Raw material and tool selection

The raw material directs the approach and the combination of hydraulic tools. Careful matching increases efficiency, precision and safety.

• Concrete, reinforced concrete: Concrete pulverizers for selectively separating component layers, opening cross-sections and controlled size reduction; after exposing the reinforcement, use steel shear. Stone and concrete hydraulic splitters enable low-noise, low vibration levels separations in massive members.
• Rock and natural stone: Hydraulic splitters generate split-oriented cracks along the borehole axis; in bedded rock they benefit from natural bedding planes. In confined areas, combining with Multi Cutters supports removing residual webs.
• Metallic raw materials: Sections, beams, tanks and sheets are separated with steel shear. Concrete pulverizers are used here mainly to expose adjacent mineral areas.
• Composite sections: Sequential approach: first mineral (pulverizer/splitting), then metallic (steel shear). The hydraulic power pack supplies the required drive for changing tool operations.

Fields of application: From planning to execution

In concrete demolition and special demolition, controllable separation is paramount: controlled opening of components, preservation of adjacent structures, minimization of vibrations. Concrete pulverizers and stone and concrete hydraulic splitters complement each other in sequence and detail work.

In building gutting and cutting, the focus is selective work: separating low-contaminant areas, exposing built-in components, guiding separation cuts. Shears and pulverizers support material-pure separation.

In rock excavation and tunnel construction, hydraulic splitters benefit from orientation along joints. They reduce noise and vibration emissions and allow controlled faces or breakout edges.

In natural stone extraction, splitting enables the production of defined raw blocks. The course follows the rock texture; follow-up work is mechanical.

Special deployments include confined spaces, sensitive environments or demanding composite structures. Here, knowledge of the raw material determines sequence, tool changes and borehole-layout-based splitting plans.

On-site inspection and assessment of raw materials

Careful preliminary investigation reduces risks and rework. Proven practical steps include:

1. Inspection and documentation: Construction age, drawings, visible cracks, moisture marks, coatings, installations, anchors.
2. Indicative tests: Rebound hammer for concrete surfaces, simple scratch and impact tests on natural stone, test drilling to determine reinforcement layout.
3. Microstructure and joint analysis: Use visible joint systems and layering to align split lines.
4. Material samples: Cores and chip samples enable petrographic assessment and grain-size evaluation.
5. Detection of inserts: Reinforcement search, locating utility lines and voids; observe electrical safety.

Planning drilling and splitting patterns

An aligned borehole layout is crucial for efficient use of stone and concrete hydraulic splitters. It depends on member thickness, material strength, the desired fracture line and existing inserts.

• Borehole diameter and depth: Match to the splitting system in use; aim for uniform depth along the intended separation joint.
• Borehole grid: Increase density for high strength or unfavorable microstructure; adapt the grid where joints exist.
• Edge distances: Leave sufficient material to guide the crack; use lower splitting energy at edges.
• Sequence: Work from lower-stress zones to critical areas; selectively remove remaining webs.

Typical challenges and material-appropriate solutions

Heterogeneous concretes and composites

Irregular aggregate distribution, very hard inclusions or subsequent grouts lead to inhomogeneous behavior. Approach: first selectively open weak zones with the concrete pulverizer, then locally densify the borehole grid and split.

High degree of reinforcement

Dense reinforcement increases the risk of unwanted load redistribution. Approach: use the concrete pulverizer to expose, then steel shear or Multi Cutters for metallic separation; concentrate splitting operations on zones with low reinforcement.

Prestressed concrete

Caution with prestressing systems: prestressing forces can be released suddenly. Separate only with suitable procedures and in a coordinated sequence; secure and relieve prestressing steel in a targeted manner.

Abrasive or highly jointed natural stones

Change drilling tools more frequently with abrasive rocks; in strongly jointed rock, plan split lines along existing joints and treat edge sections with moderate energy.

Moisture, frost and temperature

Increased moisture reduces tensile strength and influences friction. In frost, brittle behavior can increase. Adjust parameters, remove surface water, minimize slip hazard.

Safety, environmental and permitting aspects

Work on raw material requires a protection strategy tailored to the material. This includes dust suppression, noise control and vibration management, separation of fractions, and the protection of adjacent structures. Permitting and notification requirements can vary by region and must be clarified in advance. Personal protective equipment, safe setup of the hydraulic power pack and checking hydraulic connections are mandatory.

Material separation, recycling and circular economy

In deconstruction, raw material should ideally be separated cleanly: concrete into recycled aggregates, steel into metal fractions, natural stone as quarry run or raw block. Material-pure separation begins at the fracture line: splitting and pulverizers support clean boundaries, shears take over metallic separation. In this way, defined fractions suitable for reuse are produced.

Guideline values for key figures and their significance

Without binding commitments, typical ranges can be stated as orientation:

• Concrete (C20/25–C50/60): Compressive strength about 25–60 MPa; tensile strength about 2–5 MPa; the large difference favors splitting methods.
• Granite/gneiss: Compressive strength often 100–250 MPa; brittle behavior, clearly defined split paths with correct alignment.
• Limestone: Typically 50–150 MPa; bedding planes influence splittability.
• Sandstone: 20–80 MPa; anisotropic, prefer splitting along bedding.
• Structural steel: Tensile strength approx. 400–600 MPa; ductile, separated with shears.

Note: Project- and site-specific tests are decisive; guideline values do not replace investigation of the specific raw material.

Process planning: From idea to execution

A structured plan improves result quality and cost-effectiveness:

1. Material investigation: Stocktaking, sampling, locating inserts, joint mapping.
2. Method selection: Concrete pulverizers for selective removal and opening, stone and concrete hydraulic splitters for controlled separation of massive cross-sections, shears for metal.
3. Parameters and sequence: Borehole layout, starting points, mineral–metal sequence, support by the hydraulic power units.
4. Emission control: Dust, noise, vibrations, splash protection; construction logistics and fraction separation.
5. Documentation: Evidence of material flows, quality of separation edges, adaptations in case of deviations.

Raw material in focus across application areas

In the application areas of Darda GmbH, the raw material dictates the approach. In concrete demolition and special demolition, knowledge of concrete grade and reinforcement is central for choosing between concrete pulverizers or hydraulic splitters. In rock excavation and tunnel construction, stone hydraulic splitters follow natural planes of weakness. In natural stone extraction, the raw material is shaped into raw blocks by its texture. In building gutting, lightweight layers, composites and built-in components are separated in a material-appropriate, sequential manner. Special deployments require a combination of tools tailored to the material variety of the existing structure.