The foundation is the interface between the structure and the subsoil: it takes up permanent and variable loads, distributes them into the ground, and ensures that structures remain stable, durable, and free of damage. In planning, construction, repair, and deconstruction, foundations are subject to specific requirements regarding structural analysis, subsoil, water management, and construction sequencing. Especially for selective deconstruction or refurbishment in existing structures, controlled, low-vibration methods are important—this is where tools such as concrete pulverizers or hydraulic wedge splitters as well as coordinated hydraulic solutions come into play across different applications, from concrete demolition and deconstruction to rock demolition and tunnel construction.
Definition: What is meant by foundation
A foundation is the lowest, load-transferring structural element of a building that directs forces such as self-weight, live loads, wind and seismic actions, and, where applicable, machine vibrations into the subsoil. Foundations are usually made of reinforced concrete but can also be formed as pile heads, foundation beams, or slabs with various geometries. They are part of the founding system and are directly related to the properties of the subsoil (load-bearing capacity, settlement behavior, groundwater, frost). Decisive factors are adequate load distribution, controlled deformation behavior, and durable protection against water and chemical exposure.
Types of foundations and build-up
The choice of foundation type depends on load level, structure geometry, soil parameters, and boundary conditions such as groundwater or adjacent buildings. The typical build-up includes a blinding layer, reinforcement, the concrete element, any frost aprons, connection reinforcement, as well as waterproofing and bearing joints.
- Isolated foundation: Point load transfer, e.g., under columns or machines. Often cubic or prismatic, with concentrated reinforcement and higher concrete strength for dynamic loads.
- Strip foundation: Linear load transfer under walls or rows of columns, often with frost depth and a capillary-breaking layer.
- Foundation slab: Areal founding for uniform load distribution on low-capacity soil or heterogeneous subsoil conditions.
- Socket and cup foundations: Seats for column bases with lateral enclosure and defined load transfer.
- Pile foundations with pile head slab: Load transfer into deeper, competent layers; pile heads are fixed into a slab that collects the loads.
- Foundation beams: Girder-like founding elements to bridge soft zones or to distribute loads between individual point loads.
Key structural details include sizing the bearing area, the layout and lap lengths of the reinforcement, the formation of joints, and the consideration of water exposure. For machine foundations, tuning to natural frequencies and vibration protection is additionally required.
Design, subsoil, and load behavior
The load-bearing capacity of a foundation results from the interaction of element geometry, concrete and reinforcement content, and soil parameters. Governing aspects include allowable bearing pressures, settlement limits, shear strength, pore water pressure, and frost depth. Careful subsoil investigation is the basis of every founding decision.
Soil parameters and settlements
Soils differ in grain size, density, fines content, and permeability. From these, friction and cohesion properties are derived. Settlements are determined by load level, soil type, and time behavior; differential settlements must be limited by sufficiently stiff foundations and load distribution.
Water, frost, and chemical exposure
Groundwater level, drainage routing, and frost attack influence execution and durability. Waterproofing, capillary-breaking layers, and frost-free founding depths reduce risks. For chemically aggressive water or soils, suitable concrete compositions and protection systems must be selected.
Dynamic loads
Foundations for units, presses, or rotating machines require a tailored mass–spring–damper behavior. Execution considers vibration isolation, crack width control, and robust interfaces to superstructures.
Foundations in existing structures: investigation, strengthening, and underpinning
Existing foundations are often checked in the course of repurposing of structure, extensions, or structural changes. The goal is to assess load-bearing capacity, serviceability, and durability, as well as to plan strengthening measures with minimal intervention.
Survey and diagnostics
- Document analysis, probes, and, if necessary, low-destructive testing to determine geometry, concrete strength, reinforcement, and soil parameters.
- Assessment of crack patterns, spalling, breakouts, and any corrosion.
- Verification of connection details, joints, waterproofing, and load paths.
Typical strengthening options
- Foundation widenings or thickenings to reduce bearing pressure.
- Underpinning to lower the founding level or to redistribute loads.
- Incorporation of micropiles and foundation beams for increased loads.
- Crack repair and concrete repair for surface-level damage.
For adaptations in existing structures, precise separation cuts and material-conserving removals are crucial. Concrete pulverizers enable controlled biting of foundation edges and the exposure of reinforcement, while hydraulic wedge splitters create powerful, low-vibration splitting processes to divide massive foundation blocks into transportable pieces.
Foundation demolition: methods, tools, and sequences
Demolishing foundations requires a coordinated approach of cutting, controlled release, crushing, and separating concrete and reinforcement. The aims are low vibration levels, reduced noise, and clean material separation for recycling.
Cutting and preparation
- Core drilling and saw cuts for defined weakening and to create a demolition edge.
- Placing splitting wedges or cylinders into boreholes to control crack propagation.
- Stepwise exposure of reinforcement for targeted cutting.
Low-vibration demolition by splitting
Hydraulic wedge splitters generate high splitting forces inside the element. Sequential splitting produces defined fracture patterns with minimal edge influence—advantageous in sensitive environments, e.g., near existing buildings or in areas with vibration-sensitive installations.
Crushing and selective demolition
Concrete pulverizers crush concrete, separate it from reinforcement, and enable cleanly sorted picking. In confined spaces, compact pulverizers can efficiently process foundation edges, upstands, and socket areas.
Separating reinforcement
For reinforcing steel, steel shear, combination shears, or Multi Cutters are used. This separates concrete and steel directly at the element, facilitating transport and recycling.
Power supply and control
Hydraulic power units supply pulverizers, shears, and splitting cylinders with the required power. Important are matching operating pressure and flow ranges, reliable quick coupling, and safe hydraulic hose line routing, especially for sectional demolition in shafts or excavations.
Logistics and recycling
- Crushed concrete fractions for processing; steel fractions separately.
- Dust and water management with regard to environmental and occupational safety.
- Coordination of load-cycle plans and crane/transport capacities.
Applications and specifics
Foundations are found in almost all fields of structural construction—accordingly diverse are the requirements for processing and demolition.
- Concrete demolition and special demolition: Selective demolition of foundation slabs, isolated foundations, or machine foundations during ongoing operations. Concrete pulverizers and hydraulic wedge splitters support low-vibration work.
- Gutting works and cutting: Separation cuts at foundation edges, openings for utility crossings, adaptations for new load paths.
- Rock excavation and tunnel construction: Foundations on or in rock require precise splitting and targeted finishing at contact surfaces; splitters are particularly effective here.
- Natural stone extraction: Knowledge of splitting behavior and crack guidance in rock transfers to massive foundation bodies and plinth areas.
- Special operations: Demolition in sensitive areas with strict vibration or noise limits; compact hydraulic solutions and controlled tools are advantageous.
Materials and structural details
Foundation concretes are selected according to exposure classes, compressive strength, and workability. Reinforcement layers ensure crack width control and necessary ductility. For foundations permanently exposed to water, concrete cover, waterproofing, and waterstops are decisive. Interfaces to rising elements require sufficiently long lap lengths and correct connection details for shear and tensile forces.
Occupational, environmental, and neighborhood protection
Safe workflows are mandatory. These include stable excavation slopes or pit shoring, controlled load distribution, personal protective equipment, and a clear communication structure. Emissions such as dust, noise, and vibrations must be minimized—especially in urban environments and with sensitive neighbors. Dewatering measures must be planned to protect soil and groundwater.
Practical tips for planning, refurbishment, and demolition of foundations
- Clarify early subsoil investigation and load assumptions; clearly define interfaces between the structure, subsoil, and execution.
- Define the demolition sequence: Cutting – Weakening – Splitting/Crushing – Separating – Transport.
- Align tool selection with the goal: Concrete pulverizers for selective biting and purity, hydraulic wedge splitters for internal crack formation in thick foundation bodies.
- Size the hydraulic supply: operating pressure, flow rate, hose lengths, and quick coupling matched to the tool and environment.
- Expose reinforcement and cut in sections to avoid uncontrolled breaks; have steel shear and combination shears ready.
- Plan deformation and vibration monitoring in sensitive areas; document load redistributions.
- Work with recycling in mind: separate concrete and steel fractions early, keep transport routes short.
A foundation is more than a concrete block: it is a precisely tuned element between structure and ground. In planning, repair, and demolition, professional procedures pay off—with suitable hydraulic tools, forward-looking logistics, and a clear understanding of load behavior, subsoil, and construction sequence. The product groups of Darda GmbH, such as concrete pulverizers, hydraulic wedge splitters, hydraulic power packs, Multi Cutters, steel shear, or tank cutters, are professionally positioned in their respective fields of application and support controlled, safe processes without unnecessary vibrations.