Masonry anchors securely connect structural elements to masonry or provide temporary attachment points for work and safety equipment. In practice, tasks range from post-installed anchoring of brackets to temporary tie-backs during deconstruction. In conjunction with heavy demolition equipment—such as when using concrete demolition shears or hydraulic rock and concrete splitters—masonry anchors also play a role in securing components, directing load paths, or fixing auxiliary structures.
Definition: What is a masonry anchor
Masonry anchors are fastening elements that introduce loads into masonry and transfer them either permanently or temporarily. Depending on the system, they act through frictional resistance, interlocking, or bonding (e.g., mechanical expansion anchors, injection anchors with mortar, spiral anchors). Typical loads are tension, shear, and transverse forces as well as combined actions. Masonry anchors are used in new construction, existing buildings, and deconstruction—from connecting components and crack repair to shoring when controlled stability is needed before gripping with concrete demolition shears.
Types of masonry anchors and their properties
The selection of the anchor system depends on the substrate, load level, installation situation, and service life. Common solutions include mechanical, chemical, and system-based options, each with specific advantages.
- Mechanical expansion anchors: Work via expansion in the drilled hole. Quick to install, limited suitability in hollow bricks or brittle masonry; short setting times, good for temporary fixings with a defined tightening torque.
- Injection anchors (bonded anchors): Threaded rods or reinforcing bars in drill holes filled with injection mortar; in hollow bricks with mesh sleeves. High performance, good edge and spacing distances, suitable for heterogeneous substrates.
- Spiral anchors and masonry connectors: For reinforcing cracks, closing joints, or connecting wythes. More planar load distribution, common in heritage conservation.
- Frame anchors/facade anchors: For light to medium loads, often in combination with framing systems. Installation sequence and load introduction into load-bearing webs are important.
- Anchor plates and through-bolt systems: For higher loads; load transfer via plate, anchor group, or bonded system.
Substrates and material compatibility in masonry
Masonry is not a homogeneous material. Clay brick (solid and hollow), calcium silicate brick, autoclaved aerated concrete (AAC), natural stone, or concrete exhibit different bulk densities, webs, and joints. This diversity influences drilling method, embedment depth, and edge distances.
Brick masonry
In hollow bricks, mesh sleeves are standard for injection anchors. Mechanical anchors require load-bearing webs; drill-hole diameter and setting energy must be limited to avoid destroying webs.
Calcium silicate brick and concrete
High compressive strengths allow more compact edge distances. Dust-free drill holes and controlled tightening torque minimize splitting cracks. For high loads, bonded anchors are robust.
Autoclaved aerated concrete (AAC)
Low bulk density requires specially approved systems with large effective embedment and low expansion pressure. Injection mortars with matched viscosity prevent bleed-out.
Natural stone and existing masonry
Heterogeneous layers and joint patterns necessitate trial drilling and, if necessary, anchor pull-out tests. In deconstruction projects, anchors can be installed temporarily and removed after use to minimize damage to the structure.
Design, loads, and boundary conditions
Design accounts for characteristic anchor resistances, substrate strength, drill-hole geometry, edge and spacing distances, and the effects from tension, shear, and bending. For anchor groups, consider load distribution, superposition, and possible concrete or masonry edge failures.
Key parameters
- Embedment depth and effective embedment length
- Drill-hole quality and cleaning (brushing, blowing, vacuuming)
- Setting and curing times for injection mortar
- Tightening torque, setting control, documented installation
- Climatic influence (temperature, humidity) and corrosion protection
For temporary installations—such as fixing lifelines, hangers, or guide rails ahead of work with concrete demolition shears or stone and concrete splitters—reproducible installation and easy removability take priority.
Installation sequence in practice
Clean, traceable installation is crucial for load-bearing capacity and later inspection.
- Check substrate: identify masonry type, joint layout, strength, moisture, and edge distances.
- Select drilling method: percussion drilling, rotary hammer drilling, or diamond wet drilling; vibration and low-vibration measures for sensitive existing structures.
- Create the drill hole: diameter and depth per system; avoid spalling.
- Drill-hole cleaning: multi-step brushing and blowing/vacuuming until dust-free.
- For injection anchors, install mesh sleeve (hollow brick) and inject mortar free of air pockets; observe initial extrusion discard.
- Set threaded rod/anchor, position without rotation; observe wait time until hand-tight.
- After curing, assemble with the specified tightening torque; document the torque.
- Final inspection: visual check, dimensional control, and, if applicable, random pull-out testing.
Applications in concrete demolition, deconstruction, and strip-out
In deconstruction, masonry anchors often serve as temporary interfaces between the component and auxiliary structures. Typical tasks include guying wall sections, attaching pulley blocks, or fixing protective walls and ventilation lines during dust-intensive operations. Before gripping with concrete demolition shears or Concrete Crushers, demolition sections can thus be defined and stabilized in a controlled manner. During controlled splitting with stone and concrete splitter equipment, anchors help secure guide rails, survey points, or barriers.
Practical examples
- Temporary anchor points to guide cutting rigs prior to deploying hydraulic demolition shear
- Hangers for slab bays during strip-out and cutting
- Securing facing shells before stone and concrete splitters create separation cracks
- Fixing safety nets, tarps, and dust skirts in interior areas
Interfaces to stone and concrete splitters and concrete demolition shears
The combination of controlled dismantling and temporary anchoring is established in specialist deconstruction. Masonry anchors create attachment points for tie-back anchoring that dampen vibrations and load redistributions arising from the use of concrete demolition shears such as Combi-Shears HCS8 for deconstruction. When splitting with stone cylinders or stone and concrete splitters, anchors can hold sliding rails, measuring rods, or crack indicators without excessively weakening the component. It is important to maintain edge distances and to place drillings so they do not collide with splitting boreholes or pressing channels.
Quality assurance, testing, and documentation
Execution is supported by random pull-out tests, logging of tightening torques, batch and temperature data for injection mortars, and photo documentation of drill-hole cleaning. For sensitive existing structures, test fields are advisable to verify the suitability of the anchor system in the specific masonry. Legal requirements and standards must be considered on a project-specific basis; the following notes are general in nature.
Common failure modes and prevention
- Insufficiently cleaned drill holes: reduce bond surface—strictly follow multi-step cleaning.
- Edge distances too small: risk of breakout—plan positioning and, if necessary, use an anchor plate/anchor group.
- Incorrect drilling method: percussion drilling in brittle material can destroy webs—consider diamond wet or rotary drilling.
- Not observing curing times: reduces capacity—consider ambient temperature and mortar type.
- Over- or under-tightening: lack of torque control weakens the connection—use calibrated tools.
Sustainability and removal of anchors
Temporary anchors should be removed without residue. Drill holes can be closed with suitably matched mortars. Materials should be collected separately. Low-dust drilling and cleaning methods improve occupational and environmental protection; this is particularly important indoors during strip-out.
Decision aid: selection criteria at a glance
- Service life: temporary or permanent
- Substrate: solid brick, hollow brick, autoclaved aerated concrete (AAC), natural stone, or concrete
- Load level and direction: tension, shear, combined actions
- Edge/spacing distances and available embedment depth
- Drilling and installation conditions: low-vibration, wet/dry, temperature
- Corrosion protection and exposure
- Removal requirements and surface finish
In the context of concrete demolition and specialist deconstruction, a clear definition of work sequences—e.g., before using concrete demolition shears or stone and concrete splitters—supports the choice of anchor system and reduces risks.
Checklist for planning and execution
- Record the component and substrate, document boundary conditions
- Select the anchor system according to load and substrate; plan a test field
- Define drilling method, diameter, and depth; perform clash check with cutting or splitting boreholes
- Define installation sequence: drilling, cleaning, setting, curing, tightening torque
- Quality assurance: pull-out tests, torque logs, photo documentation
- Plan removal: disassembly, closing drill holes, material separation
Through the coordinated interaction of masonry anchors, auxiliary structures, and the equipment used in the project—such as concrete demolition shears or stone and concrete splitters—a controlled, safe, and efficient workflow in concrete demolition, strip-out, and special operations is achieved.