Injection technology/methods describes the targeted introduction of flowable materials into cracks, joints, pores, and voids in concrete, masonry, or rock. It is a central process in structural preservation, special foundation engineering, and controlled demolition. Especially in combination with low-noise, low-vibration tools such as hydraulic rock and concrete splitters and concrete demolition shears, injection technology/methods enables predictable stabilization, water sealing, and material separation with high precision—from building gutting to rock breakout and tunnel construction.
Definition: What is meant by injection technology/methods
Injection technology/methods refers to the grouting or introduction of mineral or polymer injection media into existing voids within a structure or the ground. The goals are waterproofing (e.g., against hydrostatic pressure), consolidation (increase in strength), load transfer, filling of cavities, as well as targeted crack injection in concrete components. This is carried out with packer and pump systems at defined pressures and flow rates. Injections are used as a stand-alone remediation method or serve to prepare mechanical demolition work with concrete demolition shears, rock and concrete splitters, and other hydraulic tools.
Methods and materials in injection technology/methods
Depending on the objective, crack width, moisture level, and base material, different methods and injection media are used. Common are crack injections with epoxy resins for structural bonding of dry, structurally relevant cracks, and sealing injections with polyurethane resins (including foaming systems) for water-bearing cracks. Cement and microfine-cement suspensions are used for filling and strengthening larger pore spaces and rock mass; acrylate gels are used to create flexible, very fine sealing curtains.
Injection types and equipment
- Low- and high-pressure injection, matched to the structure, crack pattern, and objective (typically from a few bar into the moderate double-digit bar range)
- Packer technology: mechanical or adhesive packers, surface packers for thin elements, drill packers for deeper zones
- Injection pumps: 1C and 2C systems with controlled mixing and delivery, pressure- and flow-monitored
- Drilling pattern: grid, fan, or linear along the crack or joint path; drilling angles for cross-penetration
Material selection – criteria
- Moisture level and water presence (PU for water, EP for dry cracks, microfine cement for dense matrices)
- Structural relevance (structural bonding vs. purely sealing)
- Temperature, reaction time, and viscosity (processing window, injection reach, cream time)
- Substrate compatibility, durability, and environmental compatibility
Interfaces with rock and concrete splitters and concrete demolition shears
Injections are frequently combined with hydraulic demolition tools to stabilize edges, minimize water ingress, or define deliberate planes of weakness. Concrete demolition shears benefit from prior sealing injections in water-bearing components: this reduces uncontrolled water release, improves visibility, and minimizes consequential damage. Rock and concrete splitters create low-stress separations; a preceding consolidation injection can strengthen the edge zone, making splitting behavior more predictable—particularly in heterogeneous older concretes or damaged rock areas.
Typical combination scenarios
- Selective removal: crack sealing and cavity filling, followed by controlled biting with concrete demolition shears in special demolition
- Openings in existing concrete: pre-injection for edge stabilization, then low-vibration separation with rock and concrete splitters
- Tunnel and rock works: pre-injection (curtain or contact injection) to reduce water ingress, followed by cross-section creation by splitting and shears
- Component penetrations: sealing injection at service penetrations before separation; subsequent cutting and removal with concrete demolition shears, combination shears, or multi cutters
Planning and execution: step-by-step procedure
Robust injection planning structures the approach and minimizes risks. The following sequence has proven itself in practice and can be seamlessly integrated into workflows with suitable hydraulic power units and demolition tools.
- Investigation and diagnosis: visual inspection, crack mapping, moisture analysis, and, if necessary, probing and endoscopy
- Objective definition: sealing, structural bonding, cavity filling, ground consolidation
- Material selection: resin or cement systems based on substrate and objective; align reaction time and viscosity
- Drilling pattern and packers: define geometry, drilling diameter and depth; mark packer positions
- Trial sequences and reference areas: small-area trial injection to set parameters (pressure, flow rate)
- Main injection: inject in a pressure-controlled, stepwise manner; observe backflow and degree of filling
- Post-treatment: remove packers or cut them flush, close openings, check curing
- Documentation: records of pressures, quantities, temperatures, batches
- Mechanical processing: subsequent shearing, splitting, or cutting with suitable tools and hydraulic power packs
Pressure and volume control
The control variable is an injection pressure chosen as high as necessary, as low as possible. Excessive pressures can widen components, while pressures that are too low prevent sufficient distribution. Control is via the pump, throttling, and pause cycles; volumes and returns serve as indicators of degree of filling and network reach.
Quality assurance and documentation
- Logging of pressure, flow rate, total quantity, material batches, and temperatures
- Checkpoints: visual inspection at exit points, tapping test, core drilling/endoscopy if required
- Observe material properties (e.g., curing time, final strength, water compatibility)
- Follow-up observation for sealing injections (moisture monitoring)
Safety and environmental aspects
For resin systems, appropriate protective measures must be observed: personal protective equipment, skin and eye protection, adequate ventilation. Any spilled material must be absorbed immediately and disposed of properly. When working in water-bearing areas, water protection and retention measures must be provided. Follow manufacturers’ instructions and applicable technical rules; legal requirements may vary by project.
Typical applications in practice
Concrete demolition and special deconstruction
Injections stabilize edges and close water ingress before components are selectively removed with concrete demolition shears. Cavity fillings reduce uncontrolled breakage, facilitating the controlled extraction of components. Combinations with rock and concrete splitters reduce vibrations and protect adjacent structures.
Strip-out and cutting
For openings in existing concrete, a preceding crack injection can help produce clean cut edges. Sealing injections at penetrations reduce moisture ingress during separation. Subsequent mechanical processing is carried out with concrete demolition shears, combination shears, or multi cutters; steel portions can be cut with steel shears.
Rock breakout and tunnel construction
Pre- and contact injections in the rock mass reduce water ingress and consolidate loose rock. This allows rock wedge splitters and rock and concrete splitters to be used more efficiently and predictably. In confined areas at the tunnel face, the combination of sealing, consolidation, and low-vibration splitting supports safe construction.
Natural stone extraction
In specific cases, finely dosed injections stabilize joints or edge zones to secure contours. Blocks can then be split with stone splitters along natural planes of weakness. Component and rock diagnostics are crucial for this.
Special applications
In areas with increased requirements for emissions or vibrations, the combination of injection (for sealing/consolidation) and hydraulic tools such as concrete demolition shears, steel shears, or tank cutters enables a controlled approach, provided the boundary conditions are professionally assessed.
Limits of injection technology/methods and alternatives
Not every crack or void is suitable for injection. Heavily contaminated or dynamically moving cracks, or very high water flow, can reduce effectiveness. Alternatives include negative-side waterproofing systems, overlays, mechanical removal with concrete demolition shears or rock and concrete splitters, as well as supplementary structural measures. A reliable decision is based on investigation, trial injection, and a project-specific assessment.
Terminology and practical recommendations
Injection technology/methods differs from pure filling in that distribution and penetration depth are controlled through pressure, material properties, and packer guidance. For high execution reliability, a coordinated overall concept is recommended: careful diagnosis, appropriate material selection, controlled injection, and the planned combination with hydraulic demolition tools from Darda GmbH. In this way, sealing, consolidation, and low-vibration separation in concrete and rock can be combined efficiently.