Load test denotes the systematic determination of how structures, components, and work equipment respond under defined loads. In the context of concrete demolition and special deconstruction, building gutting and cutting, rock demolition and tunnel construction, natural stone quarrying as well as special demolition operations, it is a central instrument for assessing structural stability, functionality, and occupational safety before and during the intervention. Especially for force-based separation and splitting methods—such as working with concrete demolition shears or stone and concrete splitter devices—the load test provides robust foundations to plan method, sequence, and auxiliary shoring in a targeted manner.
Definition: What is meant by load test
A load test is the controlled application of static, dynamic, or cyclic loads to structures, components, or tools to verify their load-bearing behavior, serviceability, and safety. It can be carried out as a trial load, functional test, or pressure/leakage test and includes instrumented acquisition of relevant quantities (e.g., deformation, crack width, hydraulic pressure, temperature). The aim is a traceable statement on performance limits, residual load-bearing capacity, and expected behavior in the planned application. In practice, national and European rules are applied; their suitability and scope must be professionally verified case by case.
Objectives and benefits of the load test in demolition and natural stone extraction
Load tests provide answers to which loads can be safely introduced, transferred, or limited—and how components behave under the actions. For deconstruction they help to understand residual load-bearing capacity and load redistribution before concrete demolition shears create cut sequences or crushing zones. In natural stone extraction and rock excavation, they make it possible to align splitting forces and splitting tensile strength so that desired fracture surfaces arise with minimal vibration. As a result, risks are reduced, auxiliary shoring is planned as needed, and the selection of suitable tools—such as concrete splitter and rock wedge splitter or hydraulic demolition shear—is objectively justified.
Types of load tests: static, dynamic, cyclic
Different test types are used depending on the objective. Each variant has specific strengths and limits and should be aligned with the real load spectrum in the application.
- Static tests: Slowly increasing or constant loads to determine reserve capacity, deformations, and crack face movements, e.g., on floor slabs before demolition sections.
- Dynamic tests: Short-term or oscillating excitations to assess susceptibility to vibration, natural frequencies, and fatigue behavior, relevant for sensitive existing structures.
- Cyclic tests: Repeated load changes to evaluate fatigue and durability, for example during frequent gripping and releasing with concrete demolition shears or during repetitive splitting operations.
- Pressure and leakage tests: Hydraulic systems, cylinders, and lines are subjected to a defined pressure to ensure tightness and functional reserve.
Load test on concrete structures prior to demolition works
Before using concrete demolition shears or multi-cutting tools on load-bearing elements, a trial load is recommended to assess the residual load-bearing capacity and the shoring required. This is particularly important when reinforcement layout is unknown, in the presence of pre-existing damage (chloride contamination, concrete carbonation), or where load paths are unusual.
Residual load-bearing capacity and crack monitoring
Crack widths, settlements, and strains are monitored with appropriate instruments during the trial load. Permanent deformations, crack propagation, or spalling indicate limit states. Monitoring helps select cut lines for concrete demolition shears and sequences for hydraulic demolition shear so that uncontrolled load redistribution is avoided.
Trial load and shoring
Temporary shoring can be verified with moderate load steps. The goal is to demonstrate that the planned shoring concept carries the actions arising during splitting, cutting, or gripping. This quantifies reserves and stiffness before the actual separation work begins.
Load test of tools and power units
In addition to the structure, tools and hydraulic power packs must be checked regularly. The test serves preventive maintenance and safe operation under high load. Concrete demolition shears, stone and concrete splitting devices, stone splitting cylinders, hydraulic demolition shear, Multi Cutters, steel shear, and cutting torch each have specific load paths that should be considered in the test plan.
- Force transmission: Check cylinders, piston rods, clamping elements, cutting edges, and gripper arms for deformation and play.
- Hydraulic pressure: Reconcile working pressure and peak pressures, function of pressure relief valves, tightness of couplings and hoses.
- Thermal aspects: Temperature rise during continuous operation, oil quality and viscosity, influence on efficiency and tightness.
- Structural integrity: Visual inspection for micro-cracks, edge breakage on cutting edges, material fatigue at joints.
- Function test under load: Realistic test specimens (concrete cores, rock blocks) to assess gripping and splitting behavior.
Pressure and leakage test on hydraulic systems
Hydraulic power packs and circuits are pressurized under controlled conditions. Test pressure, hold time, and pressure drop are documented. A stable test pressure without impermissible drop indicates tightness; creeping losses point to threaded joints, seals, or valve seats as focal points for testing. Temperature and oil condition must be considered because they influence readings. Pressure limits and manufacturer specifications must be observed; tests must be planned and performed by qualified personnel.
Planning and sequence of a load test
- Definition of objectives: Which limit states are to be assessed (load-bearing capacity, serviceability, tightness, fatigue)?
- Test plan: Specification of load steps, hold times, measuring points, abort criteria, and safety distances.
- Risk assessment: Evaluation of demolition consequences, fall direction, rebound, stress redistribution, and fluid release.
- Measurement strategy: Selection and positioning of instruments (force, displacement, crack width, pressure, temperature, vibration).
- Load application: Defined, repeatable, and traceable—e.g., with hydraulic cylinders, test loads, or tool force.
- Monitoring: Continuous monitoring, plausibility checks, visual inspections, and documentation.
- Evaluation: Comparison with target criteria, derivation of measures (shoring, cut sequence, tool selection).
- Approval: Written specification of permissible working parameters for the planned deployment.
Measuring equipment, calibration, and documentation
The measurement chain must be traceably calibrated. Common tools are load cells, strain gauges, displacement transducers, pressure sensors, and data loggers. Clean documentation includes test setup, environmental conditions, measurements, event logs, and photos. The test protocol forms the basis for approvals and later audits. Regular calibration intervals and visual inspections of the measuring equipment increase the reliability of results.
Influencing factors: material, reinforcement, support, and environment
Concrete strength, degree of reinforcement, bond, moisture, and temperature significantly determine load-bearing behavior. In existing structures, concrete carbonation, chloride contamination, and corrosion affect reserves. Support conditions (bearing stiffness, friction) influence deformations. In rock, joint systems, layering, and water flow control splitting success. Vibrations must be minimized, especially in sensitive areas such as laboratories, hospitals, or listed structures.
Load test in rock excavation and tunnel construction
When working with stone and concrete splitting devices in rock, borehole geometry, splitting wedge orientation, and local stress distribution are crucial. Trial loading of individual groups of boreholes shows whether the planned splitting forces lead to controlled fracture surfaces or whether additional measures (e.g., changed hole spacing, sequential load steps) are required. In tunnel construction, load tests support the assessment of cast-in-place concrete linings, shotcrete, and anchors. Monitoring close to the tunnel heading helps to detect settlements and crack formation at an early stage.
Load test in natural stone extraction
During block separation, splitting tensile strength, joint spacing, and moisture level are assessed. A stepped load application with stone splitting cylinders shows from which force a clean separation joint forms. This improves yield and surface quality while limiting crack runout. The test results feed into drilling pattern, splitting sequence, and tool configuration.
Load test in special demolition operations
In sensitive environments with heightened protection requirements, accurate prediction of actions is essential. Preliminary work with moderate test loads, tight monitoring, and clear abort criteria reduces the risk of secondary damage. Tools such as cutting torch, steel shear, or Multi Cutters are functionally tested in advance to achieve reproducible results under operating conditions.
Safety and legal classification
Load tests require qualified personnel, suitable work equipment, and a careful hazard analysis. National regulations, applicable standards, and rules of accident insurance bodies provide guidance. Approvals must be documented in a traceable manner. Legal requirements must be checked for each project; only the competent authority can make binding statements.
Correctly interpret failure patterns and limit states
Signs of overloading include permanent deformations, spalling along cracks, edge break-offs, and unusual noises. In hydraulic systems, pressure fluctuations, oil loss, foaming, or temperature rise indicate malfunctions. Such observations lead to immediate interruption, system relief, and adjustment of load steps, cut sequence, or tool selection—for example, switching between concrete demolition shear and hydraulic demolition shear or adjusting the splitting sequence when using stone and concrete splitting devices.
Best practices for meaningful test planning
- Realistic load spectrum instead of purely theoretical extremes.
- Stepped loads with hold times and clear abort criteria.
- Redundant measurands (e.g., displacement and strain) for plausibility.
- Safety distances, barriers, and emergency-stop concepts.
- Combination with non-destructive testing (rebound hammer, ultrasound, rebar locating) to contextualize results.
- Clean separation of test and work operations, unambiguous team communication.
- Documentation with photos, sketches, data series, and approvals.