Blasting concrete refers to concrete that has been loosened, opened, or had its structure altered by blasting. It primarily arises in concrete demolition, in special demolition, as well as in rock excavation and tunnel construction when explosive charges are used for separation, pre-relieving loads, or creating openings. For subsequent processing, controlled, low-vibration methods such as size reduction with concrete pulverizers or hydraulic splitting with stone and concrete hydraulic splitters are crucial to ensure safety, precision, and clean material separation.
Definition: What is meant by blasting concrete
Blasting concrete is understood as blasted or blast-loosened concrete whose concrete structure has been altered by compressive and tensile waves, microcracks, and separation joints. After the blasting measure, it occurs in blocks, slabs, or fragments and often contains exposed reinforcement. Blasting concrete is generated both during demolition blasting of components and in the course of drill-and-blast advance with concrete linings or anchor and leveling layers. For further processing, hydraulic tools adapted to the irregular fracture surfaces, varying piece sizes, and exposed steel content are required.
Formation and properties of blast-loosened concrete
Blasting concrete forms when detonations send pressure peaks and shear waves through a component. This creates targeted crack networks, but also uncontrolled microcracks. The result is heterogeneous separation surfaces, irregular block sizes, and partially twisted or protruding rebar. Compared to sawn or drilled separation joints, blasting concrete therefore exhibits greater variability in particle size distribution and a more complex residual stress state. For downstream processing, a combination of concrete pulverizers for controlled breaking and hydraulic splitters for targeted, low-load separations along existing crack zones is recommended.
Challenges when handling blasting concrete
- Irregular fracture geometry: slab-like components with varying thickness and edge formation.
- Exposed reinforcement: bent or stress-loaded bars, mesh, and possibly tendon ducts.
- Residual stresses and microcracks: risk of secondary breakage during rehandling and size reduction.
- Material composites: concrete with adhesions from masonry, asphalt, shotcrete, or grout.
- Immission control: dust, noise, and vibrations must be minimized during post-processing.
Process sequence after blasting: Work safely, separate cleanly
- Secure and clear: secure the area against secondary breakage, remove loose parts, visually inspect crack zones.
- Pre-size reduction: open large blocks with concrete pulverizers, follow crack lines, mitigate sharp edges.
- Targeted splitting: apply hydraulic splitters at natural weak zones, define piece sizes.
- Separate reinforcement: cut steel content in a controlled manner using steel shears or combination shears.
- Separate by type: provide concrete and steel separately, adapt piece sizes to the processing line.
- Transport and documentation: record material flows and prepare the further recycling path.
Tools and equipment in the context of blasting concrete
Concrete pulverizers
Concrete pulverizers enable precise, low-vibration breaking along the crack lines produced by blasting. They grip massive components safely, open composites, and reduce piece sizes to a transport- and processing-friendly scale. In sensitive environments or in special demolition, they are the preferred choice for the controlled post-processing of blasting concrete.
Stone and concrete hydraulic splitters
Stone and concrete hydraulic splitters work with high, locally confined splitting forces. In existing drill holes or naturally formed separation joints, split cylinders produce defined separation cracks. In this way, blocks can be divided without additional vibrations or sparking. In combination with suitable hydraulic power packs, a calm, plannable method is available immediately after blasting to make piece sizes predictable.
Combination shears and multi cutters
Combination shears and multi cutters combine crushing and cutting functions. They are suitable for rounding concrete edges, cutting reinforcement to length, and opening composite components in a single operation. Especially with blasting concrete featuring alternating material zones, the combined approach enables rapid progress.
Steel shears and tank cutters
Exposed reinforcement, beams, or built-in steel components can be separated in a controlled manner with steel shears. For exceptionally thick walls or special missions, focused cutting tools such as tank cutters are considered, particularly when ductile, tough steels must be separated reliably and with low sparking.
Application areas related to blasting concrete
- Concrete demolition and special demolition: targeted blasting followed by size reduction using concrete pulverizers and hydraulic splitters.
- Gutting works and cutting: openings and separations with reduced vibrations where blasting concrete must be post-processed and reinforcement separated.
- Rock excavation and tunnel construction: drill-and-blast advance with subsequent removal of concrete shells, anchors, and leveling layers.
- Natural stone extraction: mixed scenarios when concrete foundations, plinths, or backfills in a rock environment are blasted and then removed as single-grade fractions.
- Special operations: complex material composites, confined workspaces, or elevated safety requirements requiring controlled, hydraulic separation methods.
Planning and selection of the separation method: Blasting, splitting, shear work
Whether blasting or hydraulic separation is the first choice depends on boundary conditions such as structure geometry, environmental sensitivity, schedule requirements, and constraints. Where the main separation is performed by blasting, the choice of suitable post-processing tools determines the quality of the result: concrete pulverizers and hydraulic splitters enable controlled fine breakdown, reduce vibrations, and facilitate subsequent sorting. This makes it possible to clearly define interfaces between coarse and fine removal and to control operational risks.
Safety, vibrations, and immission control
Safe work with blasting concrete requires coordinated procedures: secured exclusion zones, visual inspections before every gripping or splitting operation, as well as dust and noise reduction through water misting and appropriate work methods. Hydraulic methods such as splitting and breaking with concrete pulverizers act locally, generate low vibration levels, and support immission control. Legal requirements must always be observed; the specific implementation follows the respective local directives.
Processing and recycling of blasted concrete
The quality of processing begins at the post-processing site. Defined piece sizes and pre-separated steel reduce energy demand in crushing and screening plants. Magnetic separators work more efficiently when reinforcement has already been removed with steel shears. Single-grade fractions improve reusability as recycled construction material. Concrete pulverizers are helpful for removing coatings or composite layers step by step, while hydraulic splitters condition larger blocks for the crushing process.
Best practices for quality and documentation
- Read crack lines: use existing separation joints instead of forcing new fracture surfaces.
- Plan the tool sequence: pre-breaking with concrete pulverizers, targeted splitting, then steel separation.
- Ensure hydraulic power: match hydraulic power packs to the requirements of pulverizers and split cylinders.
- Control material flow: short routes, separate storage, clear labeling of fractions.
- Secondary breakage safety: establish holding points, check load cases, choose gripping and cutting positions conservatively.
Differentiation from similar terms
Blasting concrete must be distinguished from shotcrete. Shotcrete refers to applied concrete for support and lining, whereas blasting concrete refers to concrete that has been loosened by blasting. In deconstruction, both can occur in close sequence: after drill-and-blast advance or demolition blasting, shotcrete shells or leveling layers are often encountered which, together with blasted concrete, are separated using concrete pulverizers and further structured using hydraulic splitters.