Anchoring system

An anchoring system safely connects components to the load-bearing structure or the ground and transfers forces in a controlled manner into concrete, natural stone, or in-situ rock. In demolition, deconstruction, and rock engineering, such fixings are key building blocks for occupational safety and process safety: they secure anchor points, guide rails and saw rigs, stabilize components before separation, and hold temporary shoring. Especially in combination with concrete demolition shears as well as rock and concrete splitters from Darda GmbH, the appropriate anchoring determines whether cuts, splitting operations, and lifting processes proceed as planned, controlled, and with stable edges.

Definition: What is meant by anchoring system

An anchoring system is the entirety of the anchor, mounting parts, and attached component that introduces loads from tension, shear forces, and moments into a suitable substrate. This includes mechanical and chemical (bonded) anchors, rock bolts, tie and micropiles, as well as associated components such as threaded rods, sieve sleeves, washers, and anchor plates. Anchors can be temporary or permanent. They are designed based on substrate (e.g., uncracked or cracked concrete, natural stone, masonry), type of loading, and installation conditions. The goal is a reproducible, documentable load transfer that respects the resistance level of the substrate and maintains safety distances.

Types and operating principles of anchoring systems

Anchors use different mechanisms. Selection depends on substrate, load level, edge distances, temperature, moisture, and construction sequence. In the practice of concrete demolition, strip-out, rock excavation, and tunneling, the following types have proven themselves:

• Mechanical anchors: expansion and bolt anchors, substructures with undercut anchors or sleeve–cone principle. Load transfer via expansion, form fit, or undercut in the concrete.
• Chemical (bonded) anchors: injection systems with mortar or resin and a threaded rod or reinforcement. Load transfer via bond to the borehole wall, suitable for cracked concrete and variable in embedment depth.
• Rock bolts and self-drilling anchors: continuously grouted anchors for brittle, jointed rock; standard in tunnel and slope construction for temporary or permanent stabilization.
• Tension anchors and micropiles: tension members with cement grouting to take high tensile/compressive forces, e.g., for guys, hanging points, or temporary tie-backs of scaffolds.
• Special solutions: stud welding, casing or clamping anchors on steel, releasable anchors with sleeves for selective deconstruction.

Configuration, components, and load transfer

An anchoring system consists of the load-bearing anchor element, the mortar or expansion element, attachment parts (plate, washer, nut), and the component being fixed. Load transfer occurs via defined failure mechanisms, whose control ensures safety:

• Concrete breakout cone and pull-out under tensile loading (embedment depth and concrete strength are decisive).
• Edge spalling when the edge distance is too small or with transverse load toward a free edge.
• Steel failure of the anchor due to insufficient diameter or material grade.
• Pry-out under shear load with a large lever arm.
• Splitting failure with insufficient member thickness, missing crack reinforcement, or unfavorable borehole spacing.

For groups of anchors, center-to-center spacing, plate stiffness, and uniform load distribution must be considered. Near cut joints, notches, and future split lines—such as when using rock and concrete splitters—the anchoring influences the cracking pattern. Anchors are therefore either deliberately placed outside the areas to be opened or used to limit unwanted movements.

Planning and design in deconstruction: from load assumptions to release

Planning and design are based on substrate condition, load spectrum, boundary conditions, and construction sequence. In concrete demolition and special deconstruction, additional effects arise: dynamic loads from hydraulic tools, vibrations, fluctuating temperature and moisture, and stepwise geometry changes. A systematic workflow supports execution:

1. Determine loads: self-weight, additional loads from equipment, installation forces, safety allowances for dynamic actions.
2. Assess the substrate: concrete age, crack condition, compressive strength, reinforcement layout, natural stone anisotropy, moisture, and temperature.
3. Select the anchoring type: mechanical, chemical, rock bolt; temporary/permanent; define corrosion protection.
4. Define geometry: embedment depth, edge and center distances, plate thickness, permissible drill diameters; consider split or cut lines.
5. Plan installation: drilling method, dust and water management, borehole cleaning, curing times, tightening torque.
6. Specify tests: torque checks, anchor pull-out tests on a sampling basis, documentation with measured values.
7. Issue release: log installation, visual inspection, release prior to loading.

Fields of application in concrete demolition and special deconstruction

Anchors are versatile in demolition work: they fix swing arms and rails of wall and wire saws, hold core drilling stands used in core removal and cutting, create anchor points for controlled lifting of components, and secure temporary props. When working with concrete demolition shears, strategically placed anchors stabilize wall or slab fields before the shear introduces compressive forces. In the context of splitting operations with rock and concrete splitters, anchors limit unwanted crack propagation or define load paths for temporary shoring.

Concrete demolition shears: controlled separation through targeted tie-back

Concrete demolition shears generate local high compressive and shear forces, particularly at the edges of slabs and wall panels. Anchors serve to temporarily fix components, prevent spalling at edges, and transfer loads into auxiliary structures. Sufficient edge distances, embedment depths, and placement outside future cut lines are important. Anchor points for lifting operations are dimensioned to safely absorb moments due to eccentricity and the self-weight of the released segment.

Rock and concrete splitters: influence on split lines and crack guidance

Splitting cylinders transfer wedge forces into the substrate via boreholes. Anchors must not impede this crack guidance. In practice, anchors are therefore placed at sufficient distance from split axes or used to hold components on the non-splitting side. This avoids unwanted crack paths and keeps the outcome controllable—an advantage especially in selective deconstruction and in preparing further steps with concrete demolition shears.

Rock demolition, tunneling, and natural stone extraction

In rock works, rock bolts and grouting systems secure loosely bedded blocks and slabs before cutting or splitting begins. In tunnel headings, systematically distributed anchors stabilize the tunnel face and crown area until the support (e.g., shotcrete) fully carries. In natural stone extraction, temporary anchors secure extraction benches, hold separation planes, and guide split lines. The interaction with rock and concrete splitters from Darda GmbH makes it possible to target predefined separation planes and minimize side breakout.

Installation sequence: from borehole to inspection

1. Mark position: define edge distances, center distances, and orientation to the load path.
2. Drill: diameter and depth per design; rebar detection to avoid steel collisions.
3. Clean the borehole: blow out and brush in the prescribed sequence; only clean boreholes ensure bond.
4. Set: expand/set mechanical anchors; for bonded anchors, fill with mortar and insert the rod while slowly rotating.
5. Observe rest and curing time: note temperature-dependent times; avoid premature loading.
6. Tighten: apply torque in a controlled manner; seat washers and plates without inducing stress.
7. Inspect and document: visual inspection, and if necessary, pull-out test; record values.

Suitable tools such as calibrated torque wrenches, blow-out devices, hole brushes, and test equipment for tensile tests are essential. An orderly sequence shortens downtime for subsequent work with concrete demolition shears and cutting technology.

Substrates and compatibility

Substrates determine the choice of anchoring system. In uncracked concrete, mechanical anchors are often efficient; in cracked concrete, bonded systems offer advantages. Natural stone often shows bedding and joints—here a careful borehole assessment is recommended and, if necessary, anchoring in compressive zones with increased embedment. Moisture and temperature affect mortar systems as well as steel corrosion. In chloride-laden environments, in tunneling, or with splash water, stainless steel is advisable. For lightweight or porous base materials, sieve sleeves or special anchors are required.

Quality assurance, testing, and documentation

Quality assurance includes approvals for products and installation situations, adherence to installation instructions, and sampling load tests. Anchor pull-out tests provide evidence for the specific site conditions, particularly with variable concrete quality or natural stone. Documented are positions, edge distances, drilling data, embedment depths, curing times, tightening torques, and test results. This documentation supports coordination with subsequent steps, such as separation with concrete demolition shears or splitting large blocks.

Safety, occupational protection, and environmental aspects

Safe anchoring serves personal protection and a controlled construction process. Personal protective equipment, low-dust drilling, and careful handling of injection mortars are mandatory. Anchor points for fall protection must be designed and released accordingly. Statements on standards, approvals, and test procedures are always general in nature; specific projects require independent assessment. Environmental aspects involve dust and noise reduction, collecting drilling slurries, and proper handling of residual materials from mortar systems.

Typical mistakes and how to avoid them

• Insufficient edge distances and embedment depths: leads to cone and edge failure.
• Inadequate borehole cleaning: reduces bond strength in chemical systems.
• Premature loading: curing times not observed; risk of creeping failure.
• Incorrect tightening torque: either setting errors or excessive pre-tension leading to cracking.
• Disregard of split and cut lines: interference with concrete demolition shears or splitting cylinders causes uncontrolled crack patterns.
• Unsuitable materials in corrosive environments: insufficient corrosion protection reduces durability.

Integration with hydraulic technology and cutting processes

Anchoring systems provide the prerequisite for hydraulic equipment—from hydraulic power units to shears—to operate safely. Guide rails for saws, cable pulley redirections, anchor points for lifting gear, and temporary shoring are secured with anchors. A coordinated sequence reduces downtime: first anchor, test, and release; then release components with concrete demolition shears or separate them with rock and concrete splitters. This keeps the load path defined and ensures a controlled deconstruction process.

Material selection and corrosion protection

The choice of steel grade (e.g., galvanized or stainless), mortar chemistry, and plate geometry follows the exposure class and intended service life. In humid, chloride-exposed, or temperature-cycling areas, stainless steel improves durability. For selective deconstruction, releasable systems that minimize residues in the component are advantageous. This supports single-grade separation and conserves resources.