Heating methods are versatile aids in construction, deconstruction, and extraction technology to deliberately influence material properties. Heat can plasticize metals, release coatings, drive out moisture, or relieve stresses. In combination with hydraulic tools from Darda GmbH—such as concrete pulverizers, concrete splitters, steel shears, hydraulic demolition shears, multi cutters, rock wedge splitters, or tank cutters—sequenced workflows are created that technically and organizationally support precise concrete demolition and deconstruction, rock demolition and tunnel construction, gutting works and cutting tasks, as well as special assignments, without overstating the methods in a promotional way.
Definition: What Is Meant by Heating Methods
Heating methods encompass all technical techniques used to raise the temperature of materials or structural elements in a controlled manner to steer their response to mechanical or chemical processing. These include, for example, flame heating, induction, electrical resistance, hot air, infrared radiation, or microwaves. Thermal influence can temporarily make the concrete structure or steel appear softer (lower yield stress), reduce moisture in concrete, soften adhesives and sealants, melt ice or frost, or alter stress states. In deconstruction and extraction practice, heating is rarely used as a standalone separation technique; it is usually a preparatory step to then work in a controlled and low-vibration manner with hydraulic cutting and splitting tools from Darda GmbH.
Overview of Method Types and Mechanisms
Heating methods use conduction, convection, and radiation. Decisive parameters are temperature, power density, heating duration, and cooling rate. In concrete, moisture migration and thermally induced stresses dominate; in steel, thermal expansion and microstructural changes act. In practice, thermal steps are combined with tools powered by compact hydraulic power units: preheating can ease the cutting process on thick steel cross-sections, help loosen stiff connections, or precondition the lifting of bituminous layers. Subsequently, concrete pulverizers, steel shears, hydraulic demolition shears, multi cutters, tank cutters, or concrete splitters perform the principal material removal or separation.
Physical Fundamentals and Material Behavior
Heat input alters strain, strength, toughness, and moisture balance of a component. What matters is how quickly and how deeply heat penetrates. High gradients promote cracking; uniform heating minimizes damage outside the planned separation zone. Careful selection of the heat source and temperature monitoring protect adjacent components, embedded parts, and surfaces.
Concrete and Reinforced Concrete
Concrete contains bound and free water. Rapid heating raises vapor pressure in capillaries, which can cause spalling. For selective work in concrete demolition and special demolition, heat is therefore used moderately, e.g., to release surface coatings or remove ice. The actual removal is then preferably mechanical, for example with concrete pulverizers or concrete splitters, to handle the concrete structure and the reinforcement in a controlled way and to selectively deconstruct the load-bearing structure.
Steel and Non-Ferrous Metals
Metals expand with temperature; strengths and yield points decrease as heat increases. Preheating can reduce cutting forces and improve the behavior of tough steels. In areas with spark or fire hazards, thermal methods are often used in a limited way; here, cold-working steel shears, hydraulic demolition shears, multi cutters, or the tank cutter are used, driven by hydraulic power packs.
Common Heating Methods in Practice
Depending on material, component geometry, and boundary conditions, the method is selected. Important representatives are:
Flame Heating (Oxy-Fuel, Propane)
An open flame is used for preheating, releasing coatings, or de-icing. Advantages are high power density and mobility. Disadvantages are emissions, sparks, and fire loads. In deconstruction, flame processes are often used only as preparation, while the actual separation is carried out by hydraulic cutting and splitting technology.
Induction Heating
Induction generates eddy currents in conductive materials and heats them without contact. This is well-suited for nuts, bolts, flanges, or compact steel cross-sections. After loosening or reducing the prestress, steel shears or hydraulic demolition shears can perform the cut in a controlled manner.
Electrical Resistance and Heating Mats
Resistance heaters and heating mats warm surfaces uniformly, for example to keep areas frost-free, support drying processes, or soften bitumen layers. After heating, layers can be cleanly lifted or reduced with mechanical tools, for example during gutting works and cutting.
Hot Air and Infrared
Hot-air blowers and infrared emitters are suitable for local heating without an open flame, e.g., when removing coatings, releasing adhesive joints, or drying. The lower-emission application favors work indoors before hydraulic crushers or shears take over.
Microwave and High-Frequency Methods
Microwaves heat dielectric materials volumetrically. Applications include dehumidification and special deconstruction cases where moisture content is deliberately reduced. In practice, these methods are project-specific and are usually combined with mechanical separation technology.
Thermal Lance
The oxygen lance allows separating massive steel or composite cross-sections and drilling into heavily reinforced concrete. Due to high temperatures, sparks, and emissions, it is used with strict protective measures and is often replaced by cold alternatives where possible. Where fire protection and air quality take priority, concrete pulverizers or concrete splitters are preferred.
Application Fields and Coupling with Hydraulic Technology
Heating unfolds its benefits primarily in process chains that combine thermal and mechanical steps. Typical application fields in the environment of Darda GmbH are:
Concrete Demolition and Special Demolition
During selective removal, moderate heating can release coatings, paints, or waterproofing. Afterwards, concrete pulverizers enable material-friendly deconstruction of slabs, walls, and ceilings. For thick, crack-resistant components, concrete splitters are suitable to introduce splitting forces in a targeted manner.
Gutting Works and Cutting
In gutting works, heating helps loosen screwed and press-fitted connections, separate installations, and remove brittle sealants. For the actual cut on structural steel sections, pipes, or tanks, steel shears, hydraulic demolition shears, multi cutters, or the tank cutter are used.
Rock Excavation and Tunnel Construction
Thermal rock removal is rare for environmental and safety reasons. In enclosed spaces with limited ventilation, mechanical methods predominate. rock wedge splitters as well as concrete splitters apply controlled splitting forces and avoid additional thermal loads. Heating may at most be used at the edges for de-icing or drying.
Natural Stone Extraction
Historic thermal wedging is hardly used today for quality reasons, as it can create microcracks. Extraction is predominantly performed using splitting technology and controlled mechanical separation to ensure fracture-surface quality and raw block yield.
Special Operations
Under special conditions—such as contaminated sites or an ATEX zone—heating methods are used very cautiously and only after a hazard assessment. Cold-working, hydraulic tools from Darda GmbH reduce spark production and thermal impact on the surroundings.
Process Planning, Parameters, and Sequence
Successful heating requires coordinated process control. Key points are:
- Definition of target temperature, heating rate, and maximum exposure time
- Shielding of adjacent components and a work setup with low fire load
- Selection of the downstream separation tool (e.g., concrete pulverizer, steel shears) depending on the desired cut finish
- Sequence planning: heat – separate – secure – cool
- Provision of suitable hydraulic power packs for consistent tool performance
Temperature Measurement and Monitoring
Contactless measurement methods and surface indicators are used for control. The goal is to avoid overheating, maintain temperature windows, and limit thermal effects on reinforcement, bearings, and embedded parts.
Influence on Tool Loading
Moderate preheating can reduce cutting forces on steel. At the same time, the heating level must not be so high that coatings transfer onto tools or components become uncontrollably soft. For concrete pulverizers, heating serves more as edge preparation; core separation remains mechanical to ensure dimensional accuracy and surface finish.
Occupational Safety, Fire Protection, and Environmental Aspects
Heating methods generate heat, gases, and potentially vapors. Protective measures are mandatory and depend on the conditions on site. The statements are general in nature and do not replace a project-specific assessment.
Fire Protection and Explosion Protection
Open flames and sparks require fire watches, appropriate extinguishing agents, and permits. In areas with flammable media or dust atmospheres, use may be limited or impermissible. Cold-working, hydraulic alternatives reduce risk.
Emissions and Health Protection
Flame, lance, and hot-air processes generate exhaust gases, aerosols, and odors. Suitable extraction and respiratory protection may be required. Extra caution is necessary when thermally processing coated metals or concrete-based building materials.
Quality Assurance and Documentation
For reproducible results, temperature histories, exposure times, heat sources used, and the downstream processing must be documented. Component samples and visual inspections verify whether thermal effects—such as cracks or strength reductions—remain within the tolerated range.
Alternatives and Supplements to Heating
Depending on project goals, mechanical methods can replace or complement heating:
- concrete splitters for low-vibration removal of massive components
- concrete pulverizers for precise biting and separation of concrete on sensitive structures
- steel shears, hydraulic demolition shears, multi cutters, or tank cutters for cold cutting of steel beams, pipes, and tanks
- Waterjet cutting and sawing technology as additional non-thermal options
Typical Sources of Error and Avoidance
Common issues include non-uniform heating, excessive temperatures, lack of shielding of sensitive areas, and unclear process sequences. Remedies include clearly defined temperature windows, stepwise heating, suitable protective devices, and rapid changeover to the appropriate hydraulic separation tool.
Practice-Oriented Sequences in Deconstruction
A proven approach is gradual heating for preparation, followed by mechanical separation and controlled removal. Examples include removing heated coatings with subsequent processing by concrete pulverizers or loosening heated bolted connections before cutting with steel shears or hydraulic demolition shears.
Technical Rules and Demarcation
For the use of thermal methods and their combination with hydraulic tools, the relevant technical rules, building code requirements, and in-house work and fire protection concepts are decisive. Specific requirements must be verified on a project- and site-specific basis.