A concrete testing station is the central foundation for reproducibly determining the mechanical and physical properties of concrete and deriving reliable decisions for design, execution and deconstruction. Especially in concrete demolition, special demolition as well as in building gutting and cutting, a precise test stand enables the determination of parameters that support the selection and design of tools such as concrete demolition shear or stone and concrete splitter as well as the operation of associated hydraulic power units. In this way, materials-science measurements become practice-relevant knowledge for the construction site, tunnel construction, special demolition and natural stone extraction.
Definition: What is meant by concrete testing station
A concrete testing station is a testing and experiment facility (test rig, test stand, concrete testing machine) with which concrete specimens or component cutouts are loaded, monitored, and evaluated under defined boundary conditions. The goal is the characteristic description of the material behavior such as strength, stiffness, deformation capacity, fracture mechanics, durability, and bond behavior to reinforcement. The testing station comprises the load and drive unit (e.g., hydraulic), the specimen fixtures, sensors, and the measurement as well as control technology. The results form the basis for design, quality assurance, condition assessment, and the safe and efficient planning of deconstruction and separation/cutting processes with tools from Darda GmbH, for example when selecting suitable concrete demolition shear or stone and concrete splitter.
Structure and components of a concrete testing station
A high-performance concrete testing station is modular. The components must match the specimen geometry, the expected forces, and the desired loading sequence.
Load and drive unit
The heart is the load axis, usually hydraulically driven. It delivers compressive or tensile forces at constant or variable speed. Performance data such as maximum pressure, flow rate, and control quality are crucial for reproducible results. In concept, hydraulic power pack resemble the units also used for mobile tools in concrete demolition; however, on the test station accuracy takes precedence over power, which is why pressure regulation, pulsation damping, and temperature control are particularly important.
Frame, fixtures, and tools
The test frame must be sufficiently stiff. Specimen fixtures (compression platens, spherical seats, wedge grips) ensure proper load introduction. For bond tests with reinforcement, special tensile heads are required. When testing component cutouts, supports, clamps, and boundary conditions are reproduced so that the loading is realistic.
Sensors and measurement chain
Typical are load cells, displacement and strain sensors, pressure and temperature sensors, as well as acoustic or optical systems for crack detection. A clean measurement chain with calibrated sensors and suitable sampling rates guarantees the necessary resolution, for example to capture the brittle–ductile transition behavior or the crack propagation energy.
Control, regulation, and data acquisition
Control is force-, displacement-, or deformation-controlled. Modern test systems allow force- and deformation-controlled sequences, cyclic loading, and overload protection. Data acquisition stores raw data and derived parameters in a synchronized manner to assign events such as crack initiation, spalling, or bond failure precisely in time.
Environmental conditions and safety
Temperature and humidity chambers, spray or immersion systems, and freeze–thaw cycling systems simulate long-term exposure. Protective hoods, fragment protection, and emergency stop secure the environment against sudden failure, as can occur with brittle materials.
Test methods and key parameters
The choice of test method depends on the question, component size, concrete age, and reinforcement ratio. It is important that the results are transferable to practice, especially for demolition methods in special demolition.
Mechanical short-term tests
- Compressive strength and modulus of elasticity to determine basic load-bearing capacity and stiffness.
- Splitting tensile and flexural tensile strength to assess crack initiation behavior, relevant for splitting processes and the design of stone and concrete splitter.
- Fracture-mechanics tests (fracture energy, crack tip opening) to describe crack propagation, important for controlled size reduction with concrete demolition shear.
Bond and reinforcement tests
- Pull-out tests and bond stresses between steel and concrete for planning separation sequences when steel shears or Multi Cutters cut reinforcement after concrete removal.
- Shear and punching shear tests for slab and node regions in component cutouts.
Durability and environment
- Freeze–thaw, chloride contamination and concrete carbonation, moisture balance to forecast the condition prior to building gutting.
- Non-destructive testing (ultrasonic, rebound, acoustic emission) for preselecting suitable demolition methods in special demolition.
Sampling, specimen preparation, and conditioning
The informative value of a test stands and falls with the specimen. Concrete cores from existing components must be representative (location, moisture, age, proximity to reinforcement). Conditioning (temperature, humidity, storage) is documented. For shotcrete in tunnel construction, specimens with comparable layer thickness and curing must be selected. For cement paste and natural stone composites, such as in natural stone extraction, analogous principles apply.
Measurement chain, calibration, and measurement uncertainty
Calibrated force and displacement measurement devices, regular checks of the hydraulics (zero point, hysteresis, drift), and a transparent uncertainty analysis are indispensable. Especially in brittle failure, sampling rate, filtering, and synchronization influence the evaluation of peak forces, which are later used for sizing concrete demolition shear or the required pressures in hydraulic power pack.
Evaluation, reporting, and transferability
Evaluation includes curves (force–displacement, stress–strain), parameters (characteristics, mean and scatter values), and observations of failure mode. For transfer to practice, parameters are converted into load models for demolition and splitting processes. For example, one can derive whether a structure is better size-reduced layer by layer with a concrete demolition shear or whether a splitting method with stone and concrete splitter offers advantages in terms of vibration and noise.
Practical relevance: Concrete testing for demolition, building gutting and special demolition
A testing station provides the data basis for methodological decisions:
- Concrete demolition shear: Crack initiation and fracture energy help determine the optimal jaw position, jaw geometry, and working pressure to achieve controlled removal with low edge effects.
- Stone and concrete splitter: Splitting tensile strength, anisotropies, and existing crack systems determine wedge geometry, cylinder force, and splitting sequence—important in massive components, foundations, and in tunnel construction.
- Hydraulic power pack: Required flow rates and pressure levels can be estimated from load–time histories to ensure continuous operation without overheating.
- steel shear and Multi Cutters: Bond and pull-out tests show when concrete should first be detached and where cutting the reinforcement is sensible.
- Combination shears and tank cutters: In composite constructions with steel sheet or inserts, shear and cutting tests provide guidance on separation sequences and avoiding uncontrolled load redistributions.
Reinforced concrete, fibre-reinforced concrete and composite systems
Reinforcement and fibre content alter crack formation and energy absorption. Tests on reinforced specimens capture bond, slip, and post-cracking tensile behavior. From this arise strategies for the sequence of size reduction (concrete demolition shear), exposure, and subsequent cutting of reinforcement (steel shear, Multi Cutters) to keep sparking, vibration, and structural response manageable.
Field testing station versus laboratory testing station
Laboratory stations offer the highest reproducibility. Field testing stations—mobile, compact test frames and measurement systems—deliver quick parameters directly on the structure, for example before building gutting or a special demolition under confined conditions.
Advantages of mobile field tests
- Direct assessment of the in-situ material condition including moisture, aging, and stress state.
- Short paths from findings to tool selection, for example for stone and concrete splitter in massive walls.
Limits and compensation
- Higher scatter due to environmental variables; compensation through repetitions and conservative interpretation.
- Reduced measurement channels; prioritization of force and displacement measurement as well as acoustic crack monitoring.
Safety, occupational and environmental protection
When operating concrete testing stations, covers, fragment protection, stable specimen support, and clear responsibilities are essential. Measurement personnel are trained in emergency stop procedures. In field tests, dust, noise, and vibration are minimized; extraction and shielding protect people and the environment. Legal requirements are context-dependent and should always be implemented in a general and precautionary manner.
Sustainability and resource efficiency
Targeted tests reduce trial-and-error on the construction site, lowering energy use and tool wear. Parameters on crack propagation support selective deconstruction, facilitating reuse and recycling. In tunnel construction and natural stone extraction, splitting and fracture data help optimize fracture surfaces and reduce blasting works.
Planning, setup, and operation of a concrete testing station
- Goal definition: Which parameters are needed for which applications (concrete demolition, building gutting, tunnel construction)?
- Load spectrum (structural): Sizing of the hydraulics (pressure, flow rate), choice of control strategy (force- or deformation-controlled).
- Specimen logistics: Extraction, storage, conditioning; documentation of origin, age, and reinforcement.
- Measurement concept: Selection and calibration of sensors, data acquisition, synchronization.
- Validation: Comparative tests, repetitions, plausibility checks with reference concretes.
- Operation: Maintenance, regular calibrations, quality management, and safe work procedures.
Typical error sources and how to avoid them
- Eccentric loading: Use centering aids, spherical seats, and markings.
- Insufficient specimen conditioning: Document and maintain temperature and humidity conditions.
- Incorrect sampling rates/filters: Define and test the measurement plan before the test.
- Unsuitable supports: Clean contact surfaces, use parallel compression platens.
- Transmission errors: Check the measurement chain regularly, secure cables and connectors.
Digitization, monitoring, and data quality
Modern testing stations integrate event-based recording, automatic parameter extraction, and secure data storage. Image and acoustic analysis supports identification of crack initiation—an added value for predicting fracture behavior when using concrete demolition shear. Data models link laboratory and field data so that tool selection for special demolition is fact-based.