The temperature behavior of concrete determines how fresh and hardened concrete behave during hydration, cooling, heating, and under service loading. It influences strength, crack tendency, durability, and how concrete is later processed with minimal damage, in a controlled or selective manner. For concrete demolition, building gutting, special demolition as well as for rock breakout, tunnel construction and natural stone extraction, understanding the thermal processes is just as relevant as for the safe, efficient use of concrete pulverizers, hydraulic rock and concrete splitters, hydraulic power units, combination shears, multi cutters, steel shears and tank cutters from Darda GmbH.
Definition: What is meant by concrete temperature behavior
Concrete temperature behavior refers to the entirety of all thermally induced processes and effects on the construction material: generation and dissipation of the heat of hydration, temperature distribution and gradients in the structural element, thermal length changes, time-dependent deformations (creep, shrinkage), microstructural changes as well as interaction with moisture. These factors govern early and final strength, crack formation, resistance to freeze–thaw cycles, chemical reactions, and fire behavior. For deconstruction, this yields crucial guidance for cut planning, splitting technique, load transfer, and the selection of hydraulic tools.
Heat of hydration, temperature gradients and thermal stresses
Cement hydration releases heat. In massive cross-sections the core warms more than the edge zone. During subsequent cooling, temperature differences arise that lead to tensile stresses. If these stresses exceed the respective tensile strength (particularly at young concrete ages), cracks occur. Thoughtful temperature control reduces the risk of thermal crack formation and improves durability as well as later workability during deconstruction.
Member thickness and heat build-up
With increasing thickness, the risk of heat build-up rises. Massive structural elements require a tuned concrete composition, controlled heat removal, and consistent concrete curing to limit temperature peaks.
Curing and boundary conditions
Water-retentive curing, surface protection against evaporation, and adapted formwork striking times reduce temperature gradients. Wind, solar radiation, and ambient temperature additionally affect the heat balance.
Temperature-dependent material parameters: strength, E-modulus, creep and shrinkage
Concrete reacts sensitively to temperature histories. Higher curing temperatures promote rapid early strength but can influence final strength and the E-modulus. Thermally activated creep and temperature-assisted drying shrinkage change stress states. The linear coefficient of thermal expansion lies in a typical range that varies with the aggregate; reinforcing steel also expands, which leads to bond stresses under rapid temperature changes. For deconstruction this means: Under thermal shocks, frost, or intense heating, the fracture energy changes; this can markedly shape the performance of concrete pulverizers, stone splitters and concrete splitters or combined cutting and pressing operations.
Cold-weather and hot-weather concreting: practical rules and quality assurance
At low temperatures, mixing water may freeze in the very early stage, interrupting hydration and reducing strength development. In heat, hardening accelerates, evaporation increases, and early shrinkage cracks are likely. An adapted concrete mix, controlled temperatures of constituents, shading, and effective curing are proven measures. For later interventions—such as core drilling, cutting work or selective deconstruction—homogeneously matured structural elements ensure a predictable response to splitting and pulverizer techniques.
Freeze–thaw cycles, pore structure and durability
Repeated freeze–thaw cycles cause microcracks due to ice pressure in water- and salt-exposed zones. Lasting damage appears as scaling, edge spalling, or reduced residual load-bearing capacity. In deconstruction, pre-damaged areas favor controlled break-up: the wedges of stone splitters and concrete splitters more readily find crack propagation, while concrete pulverizers can remove slabs more efficiently. Conversely, dense, young concretes require higher splitting forces and precise cut planning.
Thermal actions in service: fire exposure and spalling
High temperatures during fire reduce compressive strength, damage the matrix, and can lead to explosive spalling. After thermal loading, the E-modulus, bond to reinforcing steel, and residual load-bearing capacity change. For special demolition, careful condition assessment is essential: heated or fire-remediated structural elements respond differently to cutting, pulverizer stroke, and hydraulic splitting. In uncertain areas, a staged approach with low-vibration methods is advisable before large-volume removal.
Measurement and prediction methods: maturity method, monitoring and documentation
Temperature measurements with embedded sensors, maturity models, and infrared imaging provide insight into hardening and temperature fields. Documentation supports both construction execution and deconstruction planning: areas with high temperature gradients or uneven curing are specifically addressed, cut sequences are adapted, and the choice between pressing, splitting, and shearing methods is optimized.
Implications for deconstruction: crack management, cut planning and energy input
Thermally pre-formed cracks provide natural separation joints. Smart cut planning leverages existing weak spots, reduces tool load, and minimizes secondary damage. In dense, crack-poor concretes, energy input must be concentrated, for example through sequential splitting followed by grabbing with concrete pulverizers. In massive structural elements, pay attention to residual heat, temperature differences between core and edge, and stress redistributions to avoid uncontrolled fractures.
Tools and hydraulics under temperature: impacts on concrete pulverizers and stone and concrete splitters
Hydraulic systems react distinctly to ambient and structural element temperature. In cold conditions, the viscosity of the hydraulic fluid rises, seals stiffen, and lines become less flexible; power delivery may lag. In heat, viscosity drops, which promotes leakage and wear. For precise work with concrete pulverizers, stone splitters and concrete splitters as well as with hydraulic power packs from Darda GmbH, a stable thermal window is advantageous.
Practical notes for consistent tool performance
- Hydraulic startup and warm-up: Gentle start-up cycles reduce pressure spikes with cold fluid and stabilize stroke speed.
- Fluid selection and care: Seasonal viscosity choice, low-water systems, and clean filters improve responsiveness and service life.
- Surface contact: Before splitting, assess iced or strongly heated contact faces; friction and the wedge effect are influenced.
- Jaws and blades: Temperature-dependent material hardness of the concrete governs the loading of the cutting edges/jaws; inspect and adjust in time.
- Hose routing: Kink-resistant routing and protection from radiant heat and mechanical loads preserve flow.
Applications: concrete demolition, building gutting, rock breakout, tunnel construction, natural stone extraction, special operations
In concrete demolition and special demolition, knowledge of temperature zones and crack patterns enables a safe sequence: pre-compress or prestress, split selectively, then remove with concrete pulverizers. In building gutting and cutting, element temperature, residual moisture, and compaction influence cut quality; in heat, water-based dust suppression supports cooling, while in frost, ice films and slipperiness must be avoided. In rock breakout and tunnel construction, thermal conductivity and moisture vary between rocks; thermal stresses can activate natural joints, which benefits the splitting technique. In natural stone extraction, controlled split lines exploit fabric and temperature state—dry, cool conditions often deliver reproducible fracture surfaces. For special operations (e.g., in sensitive areas, in facilities with temperature restrictions), low-vibration, thermally neutral methods with finely controllable hydraulics are advantageous.
Concrete properties and tool selection: relation to concrete pulverizers and stone and concrete splitters
Where the tensile strength of the concrete is reduced by temperature or microcracking is present, splitting wedges engage more easily, and concrete pulverizers produce cleaner breaks. Dense, cool, and young concretes require higher splitting forces and tighter coordination of stroke speed, pressure, and bite points. On strongly heated structural elements, controlled, stepwise removal is advisable to avoid abruptly releasing local thermal stresses. These considerations apply equally to the use of combination shears, multi cutters, steel shears, and tank cutters when concrete, steel, and composite zones respond to changing temperatures.
Planning, occupational safety and environmental conditions
Temperature management begins in planning: structural element mass, hardening progress, ambient conditions, and work windows are synchronized. Occupational safety accounts for heat and cold stress, visibility conditions (steam, condensate), slip hazards due to ice, as well as fire and spark risks during cutting operations. Dust and noise reduction must be optimized with respect to temperature, for example through water-based dust suppression in heat or alternative measures in frost.
Stepwise approach for thermally informed decisions
- Assess: Record element history, hardening conditions, visible cracks, exposure (sun, wind, moisture), and current temperature.
- Monitor: Use spot temperature measurements and, where available, maturity data; mark critical zones.
- Adapt: Align cut and splitting strategy with temperature differences; vary tool pressure, stroke sequence, and bite points; adapt hydraulic startup to the climate.
- Protect: Concrete curing for fresh concrete, shading/covering in heat, ice-free conditions in cold; ensure safe standing areas and line routing.
- Document: Log measurements, observations, and tool parameters to secure quality and plan follow-on work efficiently.