Reinforced concrete is the load-bearing backbone of modern structures—from residential buildings and infrastructure to industrial facilities. The composite construction material of concrete and reinforcing steel combines high compressive strength with tensile and flexural capacity. In practice, this composition affects not only design and execution but also controlled demolition and the separation, crushing, and sorting in concrete demolition. Especially where low-emission, low-vibration, and precise methods are required, tool solutions such as concrete pulverizers, rock and concrete splitter systems, as well as supplementary hydraulic cutting and shear tools from Darda GmbH are used across different applications.
Definition: What is reinforced concrete?
Reinforced concrete is a composite construction material made of concrete and reinforcing steel. Concrete carries compressive forces; steel takes up tensile and shear forces. The bond between ribbed reinforcing steel and the cement matrix ensures composite action. With sufficient concrete cover the steel is passivated; concrete carbonation or chloride contamination can reduce this protective effect by inducing reinforcement corrosion. Structural design considers crack widths, ductility, fatigue, and deformations. Typical resulting structural elements are slabs, beams, columns, walls, foundations, frames, and bridge structures.
Material composition and properties of reinforced concrete
Concrete consists of cement paste, aggregates, and water; admixtures and additions can tailor properties (e.g., flowability, early strength, impermeability). Reinforcing steel is installed as bars, mesh reinforcement (fabric), stirrups, or prestressing steel. The bond interface is governed microstructurally by adhesion, friction, and mechanical interlock. This yields characteristic failure modes in deconstruction: the concrete splits, shears, or crushes; the reinforcement remains ductile and must be mechanically separated. High-performance concrete (HPC) and dense matrices increase the crushing energy, whereas damaged zones (cracks, delaminations, spalling) facilitate the attack with concrete pulverizers or splitter cylinders.
Typical structures and components made of reinforced concrete
Reinforced concrete is found in slabs and walls, stair flights, shafts, columns, foundations, bridges, tunnel linings, tanks, silos, and machine foundations. This variety shapes the choice of methods in the following Darda GmbH application areas:
- Concrete demolition and special demolition: selective removal of load-bearing and non-load-bearing structural elements during ongoing operations or in sensitive environments.
- Gutting works and cutting: removal of interior walls, claddings, upstands, and attachments as preparation for the main demolition.
- Rock excavation and tunnel construction: transition zones between excavation and the reinforced concrete shell require controlled, low-vibration separation.
- Natural stone extraction: edge areas of quarries and plant sites with reinforced concrete infrastructure (foundations, pedestals, ramps).
- Special operations: confined spaces, work at height, underwater areas, or zones with elevated protection requirements.
Separation and deconstruction methods for reinforced concrete
The choice of method depends on structural analysis, access, environmental requirements, required accuracy, and the recycling concept. Mechanical methods are particularly established in selective deconstruction.
Controlled splitting with rock and concrete splitters
Rock and concrete splitters work with hydraulic spreading force in drilled boreholes and generate directed tensile stresses. This allows massive structural elements (foundations, walls, abutments) to be broken down into manageable blocks. Especially in areas with vibration or noise restrictions, non-explosive splitting is advantageous. Splitter cylinders are placed in predrilled boreholes; by using defined splitting sequences, the crack path can be controlled and reinforcement can be selectively exposed.
Concrete pulverizers for slabs, walls, and beams
Concrete pulverizers crush the concrete by pressing and crushing forces and expose the reinforcement. They are suitable for gutting works, partial demolition, and removing edges or bearing zones. Controlled crushing keeps connection details visible, which facilitates subsequent steel cutting and improves material sorting.
Combination shears, multi cutters, and steel shears for reinforcement and built-in components
After exposing the steel, combination shears, multi cutters, or steel shears cut reinforcement, sections, lines, and built-in components. This separates the composite material into clean fractions, supporting the recycling of concrete debris and steel scrap.
Hydraulic power packs as the power unit
Hydraulic power units supply splitters, concrete pulverizers, and shears with the required flow rate and pressure. A stable working pressure, a well-controllable oil supply, and tool-matched flow are crucial to ensure consistent cutting and splitting performance.
Planning, structural analysis, and safety in reinforced concrete demolition
Deconstruction follows structured planning: analyze load-bearing behavior, secure load paths, define construction stages, and specify measures against uncontrolled fractures. Special attention is paid to prestressing, restraint stresses, redistribution at supports, reinforcement layout, rebar lap splice, and embedment into adjacent components. Occupational and environmental protection consider dust, noise, vibrations, and possible media in cavities. All information is general in nature and does not replace a case-specific professional assessment.
Procedure for selective deconstruction of reinforced concrete
- Investigation: check plans, locate utility lines, record reinforcement and component thicknesses, document damage areas.
- Component securing: provide shoring, plan separation cuts, define drop zones, establish construction logistics.
- Preparation: set drilling patterns for splitter cylinders, mark working joints, determine anchorage points.
- Open the concrete: pre-break edges with the concrete pulverizer, remove cover concrete, expose reinforcement.
- Splitting: deploy rock and concrete splitters to release massive core areas with low vibrations.
- Cut steel: cut reinforcement and built-in components with steel shears, multi cutters, or combination shears.
- Sorting: remove concrete debris, steel, and other materials separately and prepare for recycling.
- Finishing: clean edges, trim remaining reinforcement flush, carry out measurement and quality checks.
Specifics in tunnel construction and rock contact
In tunnels and caverns, the reinforced concrete shell meets rock. Splitters act in a directed manner and transmit minimal vibrations, preserving the surrounding rock mass. Concrete pulverizers can successively remove spalls at the inner shell, while shears cut exposed lattice girders, reinforcement, and anchor heads. A coordinated sequence prevents uncontrolled load redistribution.
Gutting works and cutting in existing structures
During gutting works, non-load-bearing layers, screeds, claddings, and installations are removed. Concrete pulverizers are suitable for nibbling openings, chases, and breakthroughs in slabs and walls. In composite components with steel sheet or built-in components, combination shears and multi cutters help to release the composite in a targeted manner.
Material separation: concrete, steel, and built-in components
Clean separation is essential for recycling. The sequence: crush the concrete in a targeted manner, expose the reinforcement, cut the steel, separate foreign materials. In industrial environments, reinforced concrete often directly interfaces with tanks and pipelines. Cutting torches for tank dismantling are used wherever steel tanks or jackets must be prepared or removed before adjacent reinforced concrete structures are taken down.
Damage patterns and their relevance for deconstruction
Concrete carbonation, chloride contamination, freeze–thaw/de-icing salt damage, and cracks influence demolition. Spalling and delaminations make it easier to bite in with concrete pulverizers; corroded zones can be selectively split with splitters. At the same time, loose areas must be secured to avoid unintended detachment.
Selection criteria for tools in reinforced concrete
- Component thickness and reinforcement ratio: determine crushing force, jaw opening of the concrete pulverizer, and cylinder diameter for splitting.
- Access: tool positioning, installation weight, and hose routing; relevant factors for ceiling heights and shafts.
- Hydraulic parameters: required working pressure and flow rate of the hydraulic power pack; thermal reserve for continuous load.
- Material mix: steel/concrete ratio, inserts, built-in components; combination shears and multi cutters have advantages here.
- Environmental requirements: dust protection and noise control, vibration limits, emission concepts; non-explosive splitting methods are often suitable.
Environment and recycling in reinforced concrete demolition
Source-separated dismantling facilitates recycling: concrete debris can be processed into recycled construction material, reinforcement goes into the scrap cycle. Precise crushing with concrete pulverizers and targeted splitting of large cross-sections reduce fines and improve fraction quality. Clean cut edges on steel parts make bundling and transport easier.
Special applications: confined, sensitive, and specific environments
In hospitals, laboratories, historic buildings, or industrial plants, low-vibration and low-noise methods are required. Rock and concrete splitters as well as concrete pulverizers enable controlled work with minimal secondary impact. Underwater or in zones with special protection requirements, additional safety measures must be observed; such information is generally indicative and does not replace project-specific concepts.
Practical tips for precise results
- Arrange drilling patterns for splitter cylinders symmetrically to steer crack formation.
- Pre-break edges with the concrete pulverizer so reinforcement becomes visible early.
- Plan cutting sequences: cut secondary reinforcement first, then main tension members.
- Check hydraulic power packs for stable working pressure and adequate cooling.
- Continuously consider material separation and transport logistics to reduce travel and waiting times.