Resin grouting denotes the targeted placement of reactive synthetic resin systems into voids, joints, boreholes and undergrout zones to anchor components, inject cracks or shim surfaces. In fields such as concrete demolition and special demolition, strip-out and cutting, rock demolition and tunnel construction as well as natural stone extraction, resin grouting enables precise control of load transfer, secure fastening of temporary anchorage points and reliable sealing against water or other media. In practice, resin grouting is often combined with mechanical methods, for example when components are separated in a controlled manner using a concrete demolition shear or when massive elements are split in a targeted way with hydraulic splitters.
Definition: What is meant by resin grouting
Resin grouting refers to the processing of liquid or pasty grouts based on reactive resins (typically epoxy, polyurethane or vinyl ester) which cure chemically after mixing and form load-bearing, low-shrinkage cross-linked structures. The term covers the undergrouting of bearing surfaces, the injection of cracks and fissures, the anchoring of studs and threaded rods in boreholes, as well as the casting of voids for stabilization or sealing. Resin grouting differs from cementitious grouts by higher bond tensile strengths, lower shrinkage tendency, chemical resistance and defined reaction times; however, it is more sensitive to volume and temperature (exothermy) and requires careful substrate assessment and processing control.
Areas of application and typical scenarios in deconstruction
Resin grouting becomes relevant wherever controlled interventions in concrete, masonry or rock must be combined with defined load transfer and sealing. In deconstruction practice, applications range from temporary tension and compression anchoring to crack injection and the undergrouting of equipment and shoring. The connection to devices from Darda GmbH arises when components must be secured, fixed or sealed against media ingress before, during or after using a concrete demolition shear, hydraulic splitters, combination shears or multi cutters.
- Temporary and permanent anchoring: Grouting of threaded rods, anchors or rails in boreholes for load uptake, for suspending components, or for guying during controlled demolition with a concrete demolition shear.
- Crack and void injection: Injection of low-viscosity resins to consolidate cracked zones, to prevent uncontrolled crack propagation during splitting or shearing, or to reduce water ingress (e.g., in tunnel construction).
- Undergrouting and bearing optimization: Resin shimming beneath shoring, presses, rails or skid bases for full-surface load transfer and to compensate unevenness, especially where limited curing times apply.
- Rock breakout and tunnel construction: Use of resin cartridges or injection resins for rock bolt installation and for sealing water-bearing fissures prior to cutting or splitting.
- Natural stone extraction: Stabilizing brittle beds and setting lifting anchors in fragile sedimentary rocks to promote controlled splitting.
Material types and properties at a glance
The choice of resin system depends on substrate, moisture, temperature, chemical exposure and load requirements. Key material families are:
- Epoxy resins (EP): Very high bond tensile and compressive strengths, low shrinkage, good chemical resistance; preferred for dry to slightly damp substrates and precise undergrouting. Suitable for high-capacity anchors in concrete.
- Polyurethanes (PU): Partly moisture- or water-reactive, stress-relieving and more elastic; suitable for sealing and for dynamically loaded joints or crack injection when some elongation is required.
- Vinyl esters (VE): Fast curing, good temperature and chemical resistance; often supplied as cartridge systems for anchors with short waiting times, e.g., in weather-driven deconstruction windows.
Essential selection parameters
- Bond tensile strength and bond stress on mineral substrates
- Compressive strength and modulus of elasticity for undergrouting applications
- Viscosity and thixotropy for horizontal, vertical or overhead application
- Pot life (working time) and curing time as a function of temperature
- Heat generation (exothermy) and permissible layer/grout thickness
- Resistance to water, chlorides, oils, fuels and other media
Practical guide: How to execute resin grouting on site
A structured workflow minimizes risks and ensures reproducible results, especially when resin grouting is combined directly with mechanical cutting or splitting operations.
- Define the objective: Set load level, durability, sealing requirements and boundary conditions (temperature, moisture, accessibility).
- Select materials: Determine the resin system based on required parameters, substrate moisture and temperature window; choose cartridge, pail goods or injection depending on volume and geometry.
- Prepare the substrate: Provide a sound, clean, frost-free substrate; remove loose material, dust out and dry boreholes or condition as per system approval.
- Plan borehole geometry: Select diameter, penetration depth and edge distance depending on anchor diameter and base material strength; for hydraulic splitters, consider the intended split lines.
- Temperature management: Bring resin, cartridge and substrate into the permissible temperature range; consider pot life in warm weather and longer curing in cold conditions.
- Mixing and deaeration: Homogeneously mix components in the specified ratio; for cartridge systems, discard start-up material until a uniform color/viscosity is expressed; minimize entrapped air.
- Application: Inject from the bottom of the borehole while withdrawing the nozzle; fill undergrouts from one side until emergence on the opposite side; for crack injection work with packers and staged pressure.
- Allow to cure and verify: Apply loads only after the release time has been reached; perform visual checks and, if applicable, document pull-off or anchor pull-out tests.
Avoid common sources of error
- Excessive grout thicknesses causing strong exothermy and shrinkage stresses
- Inadequate borehole cleaning with dust residues and reduced bond stress
- Missing moisture assessment: foaming on damp substrates with unsuitable resins
- Incomplete mixing or deviation from the mix ratio
- Premature loading before the curing time has elapsed
Interfaces to devices from Darda GmbH
Resin grouting complements mechanical deconstruction and splitting methods by securing components, sealing joints and establishing defined load paths. When using a concrete demolition shear, resin-grouted anchors can serve as temporary anchorage points or guying to guide demolition bodies in a controlled manner. When working with hydraulic splitters, adjacent corridors can be sealed by pre-injected cracks so the split line follows the target path more precisely. Undergrouts also stabilize shoring, press or rail systems for precise cutting or shearing.
- Temporary installation points: Chemical anchors in edge areas to secure slabs, beams or parapets before the shear engages.
- Crack sealing: Injection of low-viscosity resins to reduce water or slurry ingress in tunnel work prior to splitting or cutting.
- Underfilling: Resin undergrout beneath skid bases or shoring feet where plane, full-surface bearing is required.
Sequence of operations in combination
- Define the drilling and anchoring plan with edge distances and load cases
- Execute resin grouting of anchors or crack injection in accordance with system specifications
- Inspect, document and issue release
- Perform mechanical cutting, shearing or splitting and continue monitoring
Quality assurance, standards and documentation
Product specifications and processing guidelines are decisive for resin grouting. General guardrails are provided by relevant standards series and technical bulletins on repair, injection and anchoring. In practice, project-specific documentation of material batches, ambient temperatures, moisture assessment, mixing and processing times, records of pull-out or pull-off tests, as well as photo- and location-accurate logging of grout points has proven effective. Such measures create traceability and support occupational safety without constituting legal advice.
Occupational safety and environmental aspects
Reactive resins can be irritant; appropriate personal protective equipment, skin and eye protection and good ventilation are advisable. Exothermic reactions require adherence to maximum grout thicknesses. Moisture- or water-reactive systems containing isocyanates must be handled with particular care. Residues and contaminated packaging must be managed in accordance with applicable disposal requirements. These notes are general in nature and do not replace a project-specific hazard analysis.
Selection criteria for deconstruction projects
The optimal resin grouting solution results from the combination of technical boundary conditions and construction sequence:
- Time window: Short pot and curing times for tight schedules; longer systems for processing reserves with complex geometries
- Temperature and moisture: Formulation suited to the local climate, potentially preheating/conditioning
- Load case: Tension, shear, transverse load and sustained loads; static or dynamic loading
- Chemicals and media: Resistance to water, salts, fuels, oils or wastewater
- Geometry: High penetration for fine cracks versus stand-up systems for overhead or wide joints
Limitations and alternatives
Resin grouting is not suitable for unlimited volumes because reaction heat can induce stresses and microstructural damage. For large-volume undergrouts or massive voids, cementitious grouts are appropriate. For non-load-bearing sealing, swellable gels or mineral systems can be an option. Mechanical anchoring is an alternative when loads must be introduced immediately and the substrate is suitable. In many deconstruction projects, combining resin grouting with mechanical methods such as a concrete demolition shear or hydraulic splitters yields robust, controllable workflows.