High-performance concrete is regarded as a key material of modern structural engineering. Its high compressive strength, density, and durability enable slender cross-sections, long spans, and resilient structures. For planning and execution, but also for deconstruction, building gutting and selective concrete separation/cutting, special requirements arise: the dense matrix, possible fiber reinforcement, and high reinforcement ratios influence the choice of methods and tools. Especially in the context of concrete demolition and special demolition, users benefit from controlled, low-vibration methods, such as hydraulic splitting or targeted crushing with concrete pulverizers in combination with suitable hydraulic power units from Darda GmbH.
Definition: What is meant by high-performance concrete
High-performance concrete refers to concretes with above-average load-bearing and serviceability properties, achieved through an optimized mix design, a low water-to-binder ratio, high-quality aggregates, reactive supplementary cementitious materials (e.g., silica fume), and often fiber reinforcement. Primary targets include high compressive strengths, low porosity and low permeability, increased resistance to freeze–thaw and de-icing salts, as well as improved durability against chloride contamination and CO₂ via reduced concrete carbonation. In practice, high-performance concretes are frequently used in bridge and high-rise construction, for precast elements with slender cross-sections, in tunnels, and in exposed environments. Ultra-high-performance concrete (UHPC) represents a particularly dense and capable variant with very high strengths and frequent fiber reinforcement.
Composition, mix design, and material properties
The mix design of high-performance concrete aims for a densely packed matrix with minimized capillary pores. This includes fine powders (e.g., silica fume, ultrafine cements), effective superplasticizers, an optimized grading curve, and a low water-to-binder ratio. Steel or polymer fibers can influence crack formation and post-cracking load capacity. The dense matrix leads to high compressive strength, increased modulus of elasticity, and reduced water absorption, but requires careful concrete curing to avoid early shrinkage cracking.
Classification and key properties
According to common European standards, high-performance concretes are classified based on characteristic compressive strengths. Typical targets are strengths above the conventional range, high bulk density, low chloride migration, limited carbonation depths, and increased abrasion and freeze–thaw resistance. Tensile strength and brittle fracture behavior are often limiting without fiber reinforcement; with steel fibers, energy absorption improves significantly.
Durability and microstructure
The dense microstructure reduces the ingress of water, de-icing salts, and chlorides. This positively affects corrosion risks of the reinforcement. At the same time, carbonation may proceed more slowly, but must still be considered where matrix alkalinity is lower. In practice, parameters such as water penetration depth, chloride migration coefficient, and abrasion resistance are used to assess suitability in exposed environments.
Influence on deconstruction, separation, and demolition
High-performance concrete poses special challenges for deconstruction: increased compressive and tensile strength, tougher fracture behavior (particularly with fiber concrete), and high reinforcement congestion hinder classical percussive methods. For controlled, low-vibration and noise-reduced operations, hydraulic methods are suitable. Targeted opening along cracks and joints, local weakening of cross-sections, and staged unloading are key strategies in special demolition.
Concrete pulverizers in high-performance concrete
Concrete pulverizers act through concentrated pressure and appropriate jaw geometry. For high-performance concrete, a stepwise approach is recommended: nibble edges, monitor crack formation, and systematically remove member edges. In this way, uncontrolled spalling is limited. High bite force and robust jaws are important with a dense matrix and possible fiber reinforcement. In combination with high-performance hydraulic power packs from Darda GmbH, components can be selectively opened, reinforcement exposed, and sections reduced in size. This approach is particularly relevant in the application areas of concrete demolition and special demolition as well as building gutting and cutting, for example when preparing for subsequent separation of reinforcing steel.
Rock and concrete splitters for non-explosive opening
Hydraulic wedge splitters operate in pre-drilled anchor holes. Defined splitting forces from hydraulic rock and concrete splitters create controlled crack patterns along the drilling grid. In high-performance concrete, smaller hole spacing is often selected to reliably open the tough matrix. Advantages include low vibrations, low noise, and precise crack guidance—suitable for rock excavation and tunnel construction, for selective deconstruction of massive foundations, and for work in sensitive environments. Rock splitting cylinders and matching hydraulic power packs from Darda GmbH enable non-explosive, controlled widening of cracks up to full member separation.
Applications of high-performance concrete in construction
High-performance concrete is found in bridges, highly stressed columns and walls, slender façade elements, tunnel linings, offshore and hydraulic structures, and industrial floors. Over the life cycle, this means long service life, but in deconstruction higher demands on separation and size reduction. Selective methods with concrete pulverizers and hydraulic splitting help to deconstruct components section by section, expose reinforcement, and separate materials by type for construction waste separation. In natural stone extraction and rock excavation, similar principles of controlled splitting are relevant, which can be transferred to handling dense, high-strength rocks and also to high-performance concrete.
Special reinforcement situations
High-performance concrete members often have high reinforcement ratios or prestressing. With steel fiber concrete, after biting away the matrix, a dense fiber network remains that must be cut in a targeted manner. After exposing the steels, depending on the cross-section, hydraulic shears or Multi Cutters are used. Combination shears can be useful when residual concrete and steel must be handled in a single work step. For special plant or vessel deconstruction, tank cutters are tools for special assignments when, for structural reasons, both concrete and steel components must be safely separated.
Planning and execution: Practical notes
Solid planning begins with material and component analysis. Strength class, reinforcement layout, fiber content, prestressing, member thickness, and boundary conditions (e.g., vibration limits, noise control) determine the choice of method. Trial openings and preliminary tests help calibrate the workflow. Hydraulic systems must be matched to sufficient flow rate and pressure; this includes sizing the hydraulic power packs and selecting the tool bits.
Step sequence for selective deconstruction
- Component analysis: review drawings, site inspections, material sampling if required.
- Crack and separation concept: drilling grid for splitters, starting points for concrete pulverizers, shoring and securing.
- Preparation: drilling, installing catch and fall protection, dust protection and noise control.
- Pre-reduction: open edges with concrete pulverizers, control crack formation, detach sections.
- Splitting: apply hydraulic wedge splitters, systematically widen and separate the member.
- Cut reinforcement: expose steel and cut with hydraulic shears or Multi Cutters.
- Unloading and logistics: secure, lift, and transport partial pieces; record materials separately.
Occupational safety, emissions, and environment
Dust and noise reduction are central topics. Wet-cutting and dust extraction methods, localized protective enclosures, and orderly cutting sequences reduce emissions. When drilling in dense high-performance concrete, cooling and coordinated core drills increase tool life. Structural sequence and residual load-bearing capacity must be continuously monitored. Legal requirements regarding occupational safety, construction waste separation, and emission control are project-specific; the following notes are of a general nature.
Quality assurance and testing methods in the deconstruction context
To estimate in-situ member properties, low-destructive methods (e.g., rebound, ultrasonic) as well as core sampling are suitable. During deconstruction, measurements of crack widths, deformations, and vibrations support process control, e.g., via crack monitoring and ground vibration monitoring. Tool condition, hydraulic parameters, and cut quality are documented to ensure repeatability and safety.
Typical challenges and solution approaches
- Dense matrix and high strength: smaller step increments, higher local pressures, adapted jaw geometry for concrete pulverizers.
- Steel fiber concrete: after size reduction, cut fibers in a targeted way with hydraulic shears; consider sparks and splinters.
- Prestressing: plan the load release sequence, identify anchorage zones, avoid percussive interventions.
- Heavy reinforcement congestion: edge “nibbling,” exposing steels, and sectional cutting with Multi Cutters.
- Drilling for splitters: robust core drills, cooling, possibly pilot boreholes and graded spacing in high-strength zones.
Role of Darda GmbH products in the application areas
In concrete demolition and special demolition, concrete pulverizers and hydraulic wedge splitters form a complementary set: pulverizers for controlled removal, splitters for non-explosive opening of massive cross-sections. Hydraulic power packs supply the tools with the required pressure and flow. In building gutting and concrete cutting, concrete pulverizers assist in exposing steel, which is then cut with hydraulic shears or Multi Cutters. In rock excavation and tunnel construction, hydraulic splitting methods are established due to low vibrations and precise crack guidance. In natural stone extraction, the principles of controlled splitting can be transferred to dense rock. For special demolition tasks, in addition to combination shears, tank cutters are available when complex components made of concrete and steel must be safely separated.
Limitations and risks
Thermal methods can lead to undesirable spalling and increased cracking in high-performance concrete. Shock-like loads promote uncontrolled fractures. A controlled, hydraulic approach with adjusted forces, careful sequencing, and continuous monitoring minimizes risks. The selection of methods and tools should always be matched to the member properties and the boundary conditions of the project.