Material testing is a central foundation for safe, predictable, and efficient work in concrete demolition, special demolition, rock excavation and tunnel construction, as well as in natural stone extraction. It provides robust parameters for concrete, steel, and rock, forming the basis for decisions about methods, equipment deployment, and the sequence of work steps. In practice, this means: only those who know the properties of construction and building materials can use concrete pulverizers, hydraulic rock and concrete splitters, hydraulic power packs, as well as shears (hydraulic demolition shear, steel shear, multi cutters) and cutting torch professionally and safely—without unnecessary risks, downtime, and tool wear.
Definition: What is meant by material testing
Material testing includes all non-destructive and destructive tests that quantitatively and qualitatively capture the properties of construction and building materials. This includes determining strengths (e.g., compressive, tensile, flexural-tensile), elasticity, toughness, hardness, density, porosity, moisture content, microstructure, crack and joint conditions, as well as identifying embedded components and reinforcement. The goal is a reliable understanding of the material initial state to select methods, reduce risks, coordinate equipment deployment—such as concrete pulverizers or hydraulic wedge splitters—and increase occupational safety.
Methods of material testing: non-destructive and destructive
Two methodological approaches are available: non-destructive testing (NDT) for rapid, large-area condition imaging without intervention in the structure, and destructive testing for robust reference values from samples. In practice, both approaches are intelligently combined.
Non-destructive testing (NDT)
- Surface hardness and rebound methods: Assessment of the near-surface concrete strength and its scatter; first orientation of member hardness and degree of wear.
- Ultrasonic and impulse-echo: Localization of inhomogeneities, voids, delaminations; estimation of member thicknesses.
- Rebar locating and cover measurement: Determination of reinforcement position, direction, and depth for planning separation and gripping points for concrete pulverizers.
- Thermography and moisture measurement: Identification of moisture zones that influence brittle fracture behavior and required splitting forces.
- Magnetic/electromagnetic: Assessment of steel component thicknesses, coating thicknesses, and defects as a basis for using steel shear and cutting torch.
Destructive testing
- Concrete cores: Direct determination of compressive strength, bulk density, pore content; reliable calibration of NDT results.
- Split-tensile and flexural-tensile tests: Relevant for brittle-fracture and crack initiation, important for hydraulic wedge splitters.
- Metal specimens: Tensile tests, Charpy impact, hardness tests to classify shearing and cuttability for steel shear, hydraulic demolition shear, and multi cutters.
- Rock testing: Point-load test, compressive strength, shear strength; description of jointing, anisotropy, and layering for rock excavation and tunnel construction.
Parameters and their significance in demolition and deconstruction
Several parameters are particularly decisive for the selection of methods and equipment. They determine cutting, gripping, and splitting behavior and influence both cycle times and safety distances.
- Concrete compressive strength class and age: Higher compressive strengths and dense matrices increase resistance to jaw forces and required splitting forces. Young concrete behaves tougher, older concrete more brittle.
- Reinforcement ratio and bar diameter: Decisive for the effectiveness of concrete pulverizers as well as the need for supplementary cutting operations with steel shear or multi cutters.
- Rock compressive and split-tensile strength: Key parameters for dimensioning borehole grids and the use of split cylinders in natural stone extraction and rock excavation.
- Moisture and temperature condition: Influences brittle fracture and crack propagation; can affect equipment deployment (e.g., wedges) and the choice of hydraulic parameters.
- Microstructure and jointing: Preferred directions for split lines and gripping points; determines whether demolition with concrete pulverizers or hydraulic wedge splitters is more efficient.
- Metal properties (steel, alloys): Yield strength, strength, toughness, and existing coatings guide the choice of steel shear, hydraulic demolition shear, or cutting torch.
From parameters to equipment selection: targeted deployment of concrete pulverizers and hydraulic wedge splitters
Precise material data help optimize the interplay of tool geometry, hydraulics, and procedure. The following notes are general in nature and do not replace project-specific planning.
Concrete pulverizers
- Suitable when reinforcement is accessible, concrete structures can be gripped and crushed, and deconstruction is to proceed in segments (e.g., beam ends, wall sections, ceiling openings).
- Material testing provides reinforcement layout, concrete strength, thickness: from this follow gripping points, opening paths, and hydraulic pressures. High strengths require more robust jaws and adjusted cycling.
- Limits with massive cross-sections with dense reinforcement or very brittle concrete that breaks unfavorably; pre-splitting or targeted cutting of reinforcement with steel shear can help here.
Hydraulic wedge splitters
- Suitable when controlled crack initiation along defined lines is desired—e.g., to minimize noise and vibration in special demolition, in sensitive areas, or in natural stone extraction.
- Material testing provides split-tensile strength, joint orientations, moisture condition: these determine borehole spacing, embedment depth, and the required splitting force of the cylinders.
- Limits in inhomogeneous composite zones (e.g., heavy reinforcement nodes) or very tough concretes; combining with concrete pulverizers and supplementary cutting can be beneficial.
Hydraulic power packs and shears
- Hydraulic power packs must be matched to required flow rates, pressures, and duty cycles; material testing supports parameterization (e.g., longer hold times for high strengths).
- Hydraulic demolition shear and multi cutters are used when, in addition to concrete, profiles, plates, or cables must be cut. Material data (hardness, strength) prevent overload and improve cut quality.
- Steel shear and cutting torch benefit from information on plate thickness, strength class, coatings, and possible residual media; this is indispensable for safe cutting sequences.
Practical guide: from sample to action plan
- Define the objective: Which components are to be removed, separated, or split? What boundary conditions (vibration, noise, dust) apply?
- Stocktaking: Compile drawings, construction age, repairs, material data; visual inspection and NDT for an initial condition picture.
- Sampling: Take concrete cores or material samples where required; careful extraction and unambiguous labeling are essential.
- Laboratory and field testing: Strengths, density, moisture, reinforcement ratio, rock classes; check and calibrate instruments beforehand.
- Evaluate results: Compare parameters with targets and constraints; account for safety factors.
- Select methods: Specify the use of concrete pulverizers, hydraulic wedge splitters, shears, or cutting torch; if applicable plan combinations.
- Parameterization: Hydraulic pressure, gripping and splitting sequences, borehole grids, cutting sequence; define trial areas.
- Execution and monitoring: Start with a reference section; observe results, fine-tune parameters, continuously update documentation.
- Final inspection: Check quality, dimensional accuracy, and component stability; secure insights for follow-up measures.
Material testing in the application areas
Concrete demolition and special demolition
Decisive factors are compressive strength, reinforcement ratio, bond to masonry, and existing embedded components. Concrete pulverizers benefit from precise rebar locating and accurate thickness data. For massive cross-sections or sensitive environments, pre-splitting can reduce loads and vibrations.
Building gutting and cutting
Heterogeneous materials dominate here: concrete, masonry, composites, metals, plastics. Material testing structures the sequence: first separate utilities and reinforcement (steel shear, multi cutters), then targeted pulverizing or splitting. Layer and coating analyses facilitate clean cut surfaces and avoid tool wear.
Rock excavation and tunnel construction
Rock parameters (compressive strength, point-load index, degree of jointing) and water inflows determine required splitting forces and borehole geometry. Split cylinders are particularly efficient along natural joints. Inhomogeneous, anisotropic rock requires adaptive grids and careful monitoring.
Natural stone extraction
Reproducible fracture planes and low losses are required. Test results on anisotropy and layering control the orientation of the split line. The goal is a controlled break with minimal finishing effort.
Special deployment
For critical structures (e.g., contaminated zones, thin-walled vessels), preliminary investigations of material condition, residual media, coatings, and corrosion level are mandatory. For cutting torch work on tanks, thickness, material quality, and possible residual stresses are central, complemented by conservative safety measures.
Documentation, calibration, and quality assurance
Reliable results require clean documentation and quality-assured measuring equipment. This includes calibration records, test logs, unambiguous sample labeling, and traceability of results. In day-to-day site work, short, standardized check sheets are helpful to record readings, boundary conditions (temperature, moisture), and observations.
Limits, uncertainties, and typical sources of error
- Measurement uncertainty: Every measurement has scatter; combining NDT and laboratory tests reduces risk.
- Transferability: Point measurements are not automatically representative of an entire component or rock mass.
- Correlation pitfalls: Rebound numbers do not replace calibration by concrete cores; assumed equivalences lead to wrong decisions.
- Influence of boundary conditions: Moisture, temperature, and load history change measurement results and fracture behavior.
Safety and boundary conditions
Material testing supports hazard analysis and the selection of suitable safety measures. Notes on standards, guidelines, and regulatory requirements are always general in nature and must be checked project-specifically. Especially for cutting torch work on tanks, deconstruction under operating influences, or in sensitive environments, conservative assumptions, sufficient safety distances, and coordinated release processes are essential.
Making data usable in practice
Material testing has the greatest impact when results flow directly into work instructions, parameter settings of hydraulic power units, and the selection of attack or split points. A lean data set of parameters, photos, sketches, and short notes is sufficient to make decisions transparent and justify later adjustments on a solid basis.