Masonry has shaped building construction and structural engineering for centuries—from massive brick walls to natural-stone vaults. For planning, repair, and especially controlled deconstruction, solid material understanding, precise detail knowledge, and suitable methods are decisive. In many projects—such as strip-out and cutting, concrete demolition and special demolition, work in tunnel construction, or in natural stone extraction—hydraulic tools like concrete pulverizers as well as hydraulic rock and concrete splitters from Darda GmbH play an important role when masonry is to be worked safely, precisely, and with minimal vibration.
Definition: What is meant by masonry
Masonry is a structural element built from individual units (for example brick, calcium silicate brick, aerated concrete, lightweight concrete blocks, or natural stone) that is held together by mortar joints or—for dry-stone walls—by interlock alone. It acts predominantly under compression and derives its stability from geometry, the bond of the units, the quality of bed and head joints, as well as from constructive details such as lintels, ring beams, and bracing elements. Masonry can be load-bearing or non-load-bearing, single-wythe or multi-wythe, and, in addition to load transfer, also fulfills building-physics functions such as thermal insulation, sound insulation, and fire protection.
Structure, materials, and types of masonry
The variety of masonry constructions ranges from homogeneously laid brick masonry to large-format precision units to irregular natural-stone masonry. Decisive factors are material properties (compressive strength, bulk density), mortar group, and bond. Equally relevant are interfaces to concrete and steel components, such as at slab bearings, steel-beam penetrations, or concreted openings, which are often resolved during later deconstruction precisely with concrete pulverizers or separated with stone and concrete splitters in a low-vibration manner.
Common masonry units and formats
- Brick (solid brick, hollow brick) for load-bearing and non-load-bearing walls with good thermal insulation.
- Calcium silicate brick with high bulk density and good sound insulation, often as large-format precision elements.
- Aerated concrete units for lightweight, thermally insulating walls, often in thin-bed construction.
- Lightweight concrete and concrete blocks for high loads or basement exterior walls.
- Natural-stone masonry (rubble, ashlar), frequently encountered in existing structures as vaults, retaining walls, and plinth areas.
Joints, bonds, and wythes
The bed joint transfers vertical loads, the head joint connects the units along the wall’s length. The bond (for example stretcher, header, or block bond) distributes stresses and increases bracing. Multi-wythe constructions combine functions: a load-bearing inner wythe, an insulated middle layer, and a weather-resistant outer wythe. For deconstruction and when creating openings, the bond must be known in order to plan cuts, redirect loads, and purposefully control break edges—here stone and concrete splitters can initiate crack propagation in a controlled manner, while concrete pulverizers crush stiffening concrete elements such as ring beams or reinforced-concrete lintels.
Load-bearing behavior, building physics, and details
Masonry is strong in compression but sensitive to bending and tension. Shear actions are resisted by interlocking in the bond, by joint adhesion, and by constructive measures. In terms of building physics, moisture balance, salt contamination, thermal bridges, and sound insulation are decisive. Connections to slabs, walls, and foundations determine crack formation and durability. For deconstruction, load-bearing functions may only be removed after shoring measures are in place.
Mortar types and joint quality
- General-purpose mortar (cementitious, lime-containing) for conventional masonry with typical joint thicknesses.
- Thin-bed mortar for dimensionally accurate precision units with small joint thickness and high flatness.
- Trass and renovation mortars in existing structures, particularly for natural stone and salt-laden components.
- Joint filling and tensile bond strength are decisive for shear resistance and crack behavior.
Typical details at connections
- Lintels and over-spans: frequently as reinforced-concrete or steel construction; in deconstruction to be processed with concrete pulverizers or steel shears (for reinforcement).
- Ring beams and ring girders: increase bracing; require sectional separation in selective deconstruction.
- Slab bearings: consider load redistributions; temporary shoring is required before opening masonry.
Processing, cutting, and controlled deconstruction of masonry
For precise intervention in masonry—such as during strip-out and cutting or special demolition—hydraulic methods are preferred, as they work with low vibration, reduced dust, and lower noise. Concrete pulverizers from Darda GmbH are suitable for crushing concrete portions within masonry assemblies (e.g., reinforced-concrete lintels, concreted piers), while stone and concrete splitters and stone splitting cylinders create controlled fracture lines in masonry and natural stone. compact hydraulic power units ensure the energy supply; combination shears and Multi Cutters support the separate cutting of embedded parts, sheet metal, or light profiles; steel shears are used for reinforcing steel and steel connections.
Selective deconstruction and strip-out
- Pre-investigation: determine material composition, bond, load-bearing functions, and embedded parts (installations, steel components).
- Securing: plan shoring and load redistribution; establish protection against uncontrolled breakout and sliding.
- Dust and emission control: enclosures, extraction, wetting; prefer low-vibration methods.
- Segmental work: split masonry along defined lines, crush concrete portions with concrete pulverizers, orderly material separation.
- Logistics: disposal, reuse of source-separated material streams, safe handling of fragments.
Creating openings: doors, windows, penetrations
Before cutting out, lintels must be designed and installed; existing ring beams or concrete bearings are removed in sections with concrete pulverizers. In solid-unit and perforated-unit walls, the wall cross-section can be opened by splitting with stone and concrete splitters so that demolition pieces are released in a controlled manner. Multi Cutters support severing thinner component connections without imposing high loads on adjacent masonry areas.
Masonry in tunnels and vaults
In rock excavation and tunnel construction, masonry linings, abutments, and vaults are found. The load-bearing arching action requires a step-by-step approach with temporary shoring. Splitting methods reduce vibrations, while concrete pulverizers deconstruct concrete additions or reinforced-concrete ribs. Work proceeds in sections from low-pressure zones; crack propagation and deformations must be continuously monitored.
Damage patterns, diagnosis, and material-appropriate repair
Typical damage to masonry arises from moisture, salts, freeze–thaw cycles, settlement, overload, or improper alterations. Systematic diagnosis—visual inspection, moisture measurement, crack monitoring—forms the basis for selecting measures. In severely damaged areas, partial removal and replacement may be appropriate; for this, masonry packages are released in a controlled manner, concrete additions are selectively removed, and subsequently restored using compatible materials.
Cracks, moisture, salts
- Settlement and restraint cracks: determine causes, secure load paths, create openings only after stabilization.
- Moisture ingress and salt contamination: use salt-tolerant mortars, steer drying carefully, do not seal surfaces.
- Freeze spalling: remove weathered zones, take out loose mortar, restore the facing with compatible materials.
Strengthening and replacement of masonry
For strengthening (e.g., ring beam additions, bearing reinforcements), concrete can be removed precisely from the assembly with concrete pulverizers; masonry is released along joints with splitters. This reduces damage to the existing structure and preserves the bond in adjacent areas.
Occupational safety, emissions, and environment
- Dust protection: local extraction, wetting, controlled airflow; consistently use personal protective equipment.
- Noise reduction: hydraulic methods tend to be quieter; observe operating times and surroundings.
- Vibrations: splitting and crushing methods minimize oscillations; monitoring is advisable in sensitive areas.
- Load securing: shore before separating, avoid tipping and sliding hazards; defined separation and lifting concept.
- Material flow management: clean separation of brick, concrete, natural stone, and metal fractions supports recycling.
Selection criteria for tools and methods
The choice of approach depends on material, structural condition, and environmental constraints. The goal is a safe, reproducible process with manageable emissions and high edge quality.
- Building material and strength: brick and calcium silicate respond well to splitting forces; concreted zones require concrete pulverizers.
- Component thickness and accessibility: massive walls and tight spaces favor compact hydraulic tools with an external hydraulic power pack.
- Separation quality: for defined break edges and minimal edge spalling, stone and concrete splitters are suitable; for concrete portions and reinforced concrete, concrete pulverizers and steel shears are appropriate.
- Environmental requirements: in sensitive areas (hospitals, heritage protection), low-vibration, low-dust methods are advantageous.
- Site logistics: choose fragment sizes so that removal and sorting are efficient.
Fields of application at a glance
- Concrete demolition and special demolition: a combination of concrete pulverizers for reinforced-concrete portions and splitters for masonry sections enables selective removal with low vibration.
- Strip-out and cutting: openings in interior walls, removal of infills, separation of ring beams and lintels—sectional and controlled.
- Rock excavation and tunnel construction: deconstruction of masonry linings and abutments while preserving adjacent areas; splitting cylinders for crack control.
- Natural stone extraction: controlled splitting of ashlars for masonry; stone splitting cylinders create defined separation joints.
- Special operations: work in confined, hard-to-access areas or with special emission requirements; compact hydraulic tools with an external power pack are advantageous here.
Planning, approvals, and documentation
Deconstruction, openings, and repairs in masonry are subject to planning and approval when load-bearing capacity, fire protection, or sound insulation are affected. Procedures should be planned, documented, and supervised by competent personnel. The information in this article is general in nature and does not replace an object-specific assessment. A robust concept includes structural assessment, occupational safety, emission control, separation and demolition sequence, as well as documentation of the measures carried out.