Grouting technique comprises underpouring, casting, and pressure grouting of voids, joints, and boreholes using mineral or reactive systems. The objectives are bonded, load-transferring bedding, the durable filling of voids, sealing against water and other media, and the anchoring of structural elements. In conjunction with concrete demolition and special deconstruction, special demolition, and rock excavation it provides a clean technical closure of interventions previously executed with concrete demolition shears, hydraulic rock and concrete splitters, or cutting and shearing tools. In this way, structural elements are stabilized after deconstruction, anchors are bonded in a load‑transferring manner, and boreholes are professionally closed.
Definition: What is meant by grouting technique
Grouting technique refers to the totality of methods for placing grout mortars, injection resins, and injection systems into cracks, joints, drill holes, and beneath bearing surfaces. Technically, a distinction is made between undergrouting (e.g., under machine foundations), anchor grouting (e.g., for rock and concrete anchors), void filling (e.g., after drilling and splitting operations), and sealing injection (e.g., against water ingress). Key requirements include flowability, low shrinkage tendency, adequate compressive strength, good bond, and an E‑modulus suited to the intended use.
Materials and systems at a glance
The selection of the system is guided by loads, environmental conditions, and application method. In the deconstruction and rock context the following groups have become established:
Cement‑based grout mortars
Used as low‑shrinkage or expansive systems with a graded particle-size distribution. Typical are high compressive strengths, good flow values, and robust placement even in larger cross‑sections. They are suitable for undergrouting of foundation slabs, filling split and drill holes, and for anchor grouting in concrete and rock.
Microfine and ultrafine cement
For injections into fine cracks and rock pores, for example in tunnel construction for consolidation or to reduce water inflows. The small particle size enables penetration into capillary structures; stability and filtration behavior must be considered.
Reactive resins (epoxy, polyurethane)
Epoxy resins provide very high bond (pull‑off) and compressive strengths as well as low creep; they are used for highly loaded undergrouting, anchors in dynamically loaded areas, or for thin bearing joints. Polyurethanes are primarily used for sealing injections, especially in the presence of water ingress. Exothermy, temperature control, and emissions must be carefully managed.
Thixotropic and vertically stable systems
For overhead or vertical applications, such as grouting core drill holes in walls or slabs after using concrete demolition shears and cutting methods. Here, thixotropic additives prevent run‑off while still providing sufficient working time.
Design and planning in the deconstruction context
In projects involving concrete demolition and special demolition, proper planning of the grouting technique governs load behavior, tightness, and durability. Load paths, contact surfaces, and temperature histories must be defined in advance.
Undergrouting of bearings and equipment
When undergrouting machine plates, rails, and pedestals—such as for mobile hydraulic power units that are operated temporarily or permanently on foundations—a flowable, low‑shrinkage grout mortar is selected. Important parameters are the E‑modulus, compressive strength, and the ability to fill the bearing area without voids.
Anchor grouting in concrete and rock
After removal with concrete demolition shears or splitting with hydraulic wedge splitters for stone and concrete, temporary or permanent anchors are often installed. The grout must reliably transfer loads, make use of borehole roughness, and respect edge distance. In wet boreholes, water‑tolerant systems must be provided.
Process chain: preparation, placement, curing
Reproducible quality arises from a structured approach from substrate preparation through to documentation.
- Prepare the substrate: expose concrete, remove loose material, clean bonding surfaces, pre‑wet mineral systems (saturated surface‑dry).
- Set formwork and dams: tight and stable; plan vent paths and pour openings; provide a gradient for material flow.
- Mixing: adhere precisely to water addition, observe mixing time, ensure freedom from lumps and control temperature; for resins, keep component ratio exact.
- Placement: place continuously from one side, promote venting, avoid material changes; respect the placement time (pot life).
- Curing: protect early against drying, frost, or heat; control exothermic reactions; rework edge areas.
- Control: record flow spread, air temperature, component temperature, compressive strength of fresh mortar/hardened concrete, and, where applicable, pull‑off tests or an anchor pull-out test.
Grouting technique in conjunction with stone and concrete splitting devices
Stone and concrete splitting devices create defined splits via wedge‑based stresses in predrilled holes. The resulting voids, split joints, and bore channels are often grouted for structural or building‑physics reasons, following the wedge principle.
Borehole and split‑joint grouting
After controlled splitting in natural stone extraction or in concrete demolition, boreholes can be filled with low‑shrinkage mortars to homogenize surfaces, block water paths, or set anchors with a bonded load transfer. In water‑bearing areas, consolidating injections with microfine cement or water‑reactive systems are appropriate.
Crack injection for stabilization
For secondary cracks resulting from load redistribution, injections with low‑viscosity systems can restore integrity. Decisive factors include suitable packer arrangement, controlled pressure, and monitoring of material intake.
Applications with concrete demolition shears, hydraulic demolition shears and multi cutters
Selective dismantling with concrete demolition shears exposes reinforcement, produces edge breakouts, and creates local voids. Proper closure includes grouting of:
- Core drill holes and penetrations after gutting works, including the annular space around sleeves and lines.
- Undergrouting beneath newly installed steel plates or brackets after removal.
- Reinforcement anchors for temporary shoring or permanent attachments, with their boreholes pressure‑grouted.
In steel cutting operations (e.g., with a steel shear or a cutting torch), supports and brackets often need to be re‑grouted to transfer loads safely into existing structures. System selection is based on vibrations, corrosion risks, and ambient humidity.
Rock excavation and tunnel construction: injection, consolidation, sealing
In rock excavation and tunnel construction, grouting technique supports both preparatory and concluding steps: prior to splitting, injections calm water‑bearing zones; after intervention, pressure grouting consolidates loose edge areas. Anchors (rock bolts) are grouted in boreholes, contact grouting behind linings closes voids, and curtain injections reduce inflows. Parameters such as injection pressure, viscosity, and gel time must be matched to the rock mass.
Gutting and cutting: properly closing penetrations
Gutting creates openings for utilities, cable ducts, and ventilation. After cutting, annular spaces, casing pipes, and core drill holes are grouted with vertically stable systems to satisfy fire protection, building acoustics, and tightness. Thixotropic mortars prevent run‑off on vertical surfaces; for dynamic loads or high temperatures, epoxy resins can be suitable.
Quality assurance and test methods
For a durable bond, testing and documentation steps are essential. Common practices include flow spread measurements, density determination, temperature tracking, compressive strength testing on specimens, as well as pull‑off or an anchor pull-out test for anchors. Boundary conditions such as component temperature, humidity, and wind are recorded. This information allows a traceable assessment of installation quality in the context of concrete demolition and special demolition.
Occupational safety and environmental aspects
When handling dusting mortars and reactive resins, personal protective equipment, dust suppression, and proper ventilation are required. Resin systems require controlled skin and eye protection and measures against uncontrolled exothermy. Washout into soil and water bodies must be avoided; residual quantities are collected separately and transferred to a certified disposal company. The information in the technical data sheets must be observed; notes are general in nature and do not replace project‑specific planning.
Typical failure patterns and practical countermeasures
Frequent causes of deficiencies include excessive water additions, insufficiently cleaned bonding surfaces, lack of curing, material changes during placement, or unconsidered temperature gradients. Countermeasures include precise water dosing, the saturated surface‑dry concept for mineral systems, continuous placement from one side, venting of the formwork, and effective moisture protection and temperature control during the first hours.
Terminology distinctions within grouting technique
Undergrouting denotes the flowable, void‑free creation of a bonded contact joint, for example beneath machines and bearings. Pressure grouting or injection describes the introduction of low‑viscosity systems into cracks, pores, and boreholes under pressure or by gravity. Void filling covers the casting of larger volumes. In many projects—especially when using concrete demolition shears as well as stone and concrete splitting devices—these procedures occur in combination: splitting, dismantling, anchoring, and, finally, undergrouting or injection form a continuous process chain for safe, tight, and durable structures.