Composite construction materials have evolved from niche materials into load-bearing solutions in building construction, infrastructure, and industrial plants. Their high specific strength, corrosion resistance, and design freedom offer advantages—in new construction as well as in deconstruction. For the demolition of structures with composite construction material content, for strip-out, or for cutting composite components, the question arises how tools such as concrete pulverizers or hydraulic rock and concrete splitters—supplemented by combination shears, multi cutters, steel shear, tank cutters, and compact hydraulic power units—can be used effectively and safely. This article places the material in a technical context and shows what matters in planning, execution, and quality assurance during deconstruction.
Definition: What is meant by composite construction material
Composite construction material refers to materials consisting of a combination of fibres and a matrix. The fibres carry the load, while the matrix binds the fibres, protects them, and transfers shear stresses. Typical systems are glass-fibre-reinforced polymers (GFRP), carbon-fibre-reinforced polymers (CFRP), as well as basalt- or aramid-fibre-reinforced polymers. In addition, metal and ceramic matrix composites exist for special thermal or mechanical requirements. Composite construction materials are anisotropic: properties depend on fibre type, orientation, fibre volume fraction, and layup. In construction practice they appear as reinforcement (GFRP/CFRP bars, meshes), as lamellar strengthening of concrete, as rock anchors in tunnel construction, in façade and bridge elements, and as tank materials (e.g., GRP tanks).
Structure and materials in composite construction material
The matrix (often epoxy, vinyl ester, or polyester resin) determines chemical resistance, temperature window, and damping. The fibres—glass, carbon, basalt, aramid—provide tensile strength and stiffness. A laminate consists of multiple plies with defined orientations (0°, ±45°, 90°), often combined with stitched or woven fabrics. Properties arise from the interaction: high tensile strength along the fibres, lower transverse and shear strength, potentially sensitive to delamination and notches. Glass fibres act abrasively on tools; carbon fibres are electrically conductive and generate conductive dust—both influence the selection and operation of cutting and crushing equipment.
Mechanical behaviour and failure modes
Composite construction materials fail differently from isotropic materials. Under tension, fibre rupture dominates; under bending, a mixed failure of matrix cracking, interlaminar shear damage, and delamination occurs. Under local bearing/pressing—such as created by concrete pulverizers—plies can shear; scaling cracks, fibre pull-out, and splintering may occur. Temperature and moisture affect the matrix and thus overall behaviour. For deconstruction this means: a clean load-path approach and avoiding uncontrolled peel or delamination modes reduce splinter projection, noise, and residual hazards.
Applications in construction and their relevance for deconstruction
Reinforcement and strengthening
GFRP and CFRP reinforcing bars are used as corrosion-free alternatives to steel; CFRP laminates strengthen concrete members. In concrete demolition and special deconstruction, these reinforcements influence cutting and crushing behaviour: steel magnets do not separate them, cutting forces distribute differently, and fibres may protrude from the composite after fragmentation.
Rock anchors and tunnel construction
Glass-fibre rock anchors are common in rock excavation and tunnel construction because they can later be machined or cut. During removal, stone and concrete splitters can introduce local stresses in a targeted manner without leaving metallic remnants. At the same time, splinter protection must be observed.
Industrial plants and tanks
GRP tanks and pipelines are chemically resistant and lightweight. During strip-out and cutting in plants, tank cutters and multi cutters help open large wall thicknesses with controlled cutting paths. Dust and emissions control is essential, especially with CFRP-containing attachments.
Implications for tool selection and process control
Concrete pulverizers in conjunction with composite construction material content
Concrete pulverizers generate pressure- and shear-dominated loading. With CFRP laminates on concrete, a strategy of pre-scoring and sectional separation is recommended to control delamination. Tough, impact-resistant cutting edges reduce breakout. Contact surfaces should be slip-resistant to minimize peeling forces. Increased wear is to be expected with GFRP reinforcement.
Stone and concrete splitters in environments with composite construction material
Splitters are suitable for introducing cracks into concrete in a defined way and locally unloading composite reinforcements. In members with thick CFRP layers, pre-drilling and the use of stone splitting cylinders are sensible to create brittle fracture surfaces and avoid long fibre bundles. In natural stone extraction and special cases with fibre anchors, splitting helps achieve metal-free separation surfaces.
Combination shears, multi cutters, steel shear, tank cutters
Combination shears and multi cutters are suitable for mixed cross-sections of concrete, steel, and composite construction material—an adapted cutting geometry is important to limit fibre pull-out. Steel shear are used for hybrid systems with steel sections. Tank cutters deliver uniform cut edges on GRP tanks and reduce spark generation; negative-pressure-assisted extraction limits dust.
Hydraulic power packs and pressure management
Constant flow rates and finely metered pressure promote controlled separation in anisotropic composites. Pressure spikes can encourage delamination and splinter throw; gentle ramp-up and load changes with short hold phases improve result quality.
Occupational safety, emissions, and health protection
- Dust: GFRP produces abrasive dusts, CFRP conductive particles. Wet separation/cutting, extraction with a suitable filter class, and low-dust crushing are recommended.
- Splinters: Cutting and splitting processes can release long fibre fragments. Guards, covers, and adequate cordoning reduce risks.
- Electrical conductivity: CFRP dust can disturb electrical contacts. Protect work areas and clean equipment regularly.
- Noise and vibration: Choose process parameters to avoid resonances and chatter.
Legal requirements for dust and emissions control, waste handling, and occupational safety depend on location. Adherence to the applicable rules of the art and regulatory requirements is generally required.
Recycling and disposal
Composite construction material waste is mechanically shredded, or treated thermally (pyrolysis) or chemically (solvolysis). Recovered fibres are increasingly used as short-fibre reinforcement. Relevant for deconstruction: early separation of concrete, steel, and composite construction material facilitates subsequent reuse. Magnetic separators do not capture GFRP/CFRP portions; visual and sensor-based identification (colour, density, conductivity) supports sorting. Disposal routes should be planned before demolition begins.
Tool wear and maintenance
- Glass fibres are highly abrasive: carbide or hard-coated cutting edges improve tool service life.
- Carbon fibres can promote micro-chipping of cutting edges: a micro-bevel and polished contact surfaces reduce notch effects.
- Regular visual inspection at defined intervals prevents quality losses at cut edges and splinter formation.
- Keep hydraulic systems clean to keep CFRP fine particles out.
Practical guide: procedure for structures with composite construction material content
- Investigation: review drawings, reports, and material samples. Record fibre type, layup, matrix type, and member thickness.
- Select separation strategy: cutting, splitting, or combining—depending on fibre orientation, access, and protection requirements.
- Define tools: concrete pulverizers for concrete-bound CFRP/GFRP reinforcements; stone and concrete splitters for controlled crack formation; for tanks and panels, tank cutters or multi cutters.
- Trial cut/trial split: validate parameters for pressure, feed, bite sequence, and hold times.
- Protective measures: shielding, extraction/wetting, personal protective equipment, defined cutting direction to control delamination.
- Execution with cadence: work in segments, chase edges, control fibre pull-out immediately.
- Rework and sorting: trim fibre remnants, smooth edges, fractionate material.
- Documentation: record parameters, observations, photos, and disposal routes.
Quality assurance and documentation
For composite construction material, cut quality, delamination width, freedom from splinters, and residual load-bearing capacity are key criteria. Simple on-site checks—visual inspection, measuring fraying, pull tests on small fibre bundles—provide quick feedback. Deviations are addressed by adjusting the bite sequence with concrete pulverizers, the wedge alignment with stone and concrete splitters, or the cutting geometry with combination shears.
Particularities in the application areas
Concrete demolition and special deconstruction
CFRP laminates and GFRP reinforcements change fracture patterns. Alternating between splitting (crack guiding) and targeted pulverizer bites (separation) reduces uncontrolled fibre bundles. Hydraulic power packs should be operated to avoid pressure spikes.
Strip-out and cutting
For sandwich panels with GFRP face sheets, near-edge opening and subsequent core removal are recommended. Tank cutters facilitate openings in GRP tanks; multi cutters handle cuts on internal components.
Rock excavation and tunnel construction
Glass-fibre anchors can be split or cut without sparks and metal abrasion. Stone and concrete splitters set predetermined fracture lines; concrete pulverizers remove remaining composites on linings.
Natural stone extraction
In contexts with fibre-reinforced fixings and consolidations, a combination of drilling, splitting, and local cutting is expedient to preserve stone surfaces and minimize fibre remnants.
Special operations
With mixed composites (CFRP/metal/concrete), staged procedures help: first split to relieve, then separate the remaining plies. The sequence choice significantly influences safety and cost-effectiveness.
Planning notes for structures with composite construction material content
- Consider deconstruction early: document location, quantity, and type of composite construction material components.
- Define separation joints: consider layup to control delamination.
- Mark cutting paths: consider fibre direction; across the fibre creates different load paths than along it.
- Material logistics: plan separate collection of concrete, steel, GFRP/CFRP, and composite residues.
This shortens deconstruction times, limits emissions, and improves reuse—without compromising occupational safety.