A tar milling machine – in practice often also referred to as an asphalt milling machine, cold planer, surface planer, or road milling machine – is used for the precise removal of bituminous layers. It is employed in road and civil engineering, in the deconstruction of traffic surfaces, and in structural repair. In the context of concrete demolition and special demolition, milling provides access to underlying concrete slabs, foundations, and structure edges. After removing the surface or binder course, concrete demolition shears, hydraulic rock and concrete splitters, and other hydraulic tools from Darda GmbH can be deployed in a targeted manner to open, separate, or split components with low vibration levels.
Definition: What is meant by a tar milling machine
A tar milling machine is a construction or compact machine with a rotating milling drum equipped with carbide-tipped chisels that cuts and removes bituminous surfacings such as asphalt, mastic asphalt, or old tar-containing surface courses. The milling depth and milling width are adjustable; the removal performance is determined by torque, number of chisels, and feed rate. Modern machines work as cold planers, i.e., without thermally heating the surfacing, often with water spray for dust suppression. Key applications include partial or full-depth removal of pavements, grade correction, fine milling for smoothness and macrotexture, and creating defined edges and transitions to concrete surfaces.
Design, operating principle, and types
The operating principle is based on the tangential action of many individual chisels arranged at close spacing on a cylindrical drum. The milling drum rotates against the direction of travel and removes material layer by layer. The milled material is conveyed by augers and, optionally, a conveyor belt to the side or forward.
Central assemblies
- Milling drum and chisel configuration: Chisel spacing, chisel quality, and drum diameter determine surface texture, particle size distribution, and power draw.
- Leveling and depth control: Sensors for constant milling depth, crossfall, and longitudinal slope; important for smoothness and defined score lines along concrete edges.
- Discharge and dust reduction system: Augers, belt conveyors, and water spray to reduce dust; this facilitates clean work at structural joints.
- Drive: High-performance drive for large planers as well as compact and hand-guided planers for confined areas, halls, or bridges.
Typical types and working methods
- Coarse milling for rapid removal of thick layers.
- Fine milling for high smoothness and defined macrotexture.
- Edge and joint milling for clean tie-ins to concrete components and embedded parts.
- Selective removal (lane or patch milling) for targeted renewal.
Application areas in concrete demolition and special demolition
In deconstruction on concrete, the tar milling machine removes bituminous surface and binder courses to expose load-bearing concrete structures. This is the case, for example, in bridge rehabilitation, parking decks, hall floors, or loading yards. Once the asphalt layer has been removed, concrete edges can be exposed with concrete demolition shears, reinforcement can be made visible, and separation cuts can be prepared. Where low vibration levels are required—e.g., above sensitive utility lines, at adjoining structures, or in inner-city locations—exposed concrete slabs can be split in a controlled manner with hydraulic splitters instead of breaking them with impact energy. This reduces vibration and protects adjacent components.
Gutting and cutting
For the building gutting of industrial areas and logistics halls, a tar milling machine is used to remove wearing courses and surfacings. Subsequently, hydraulic concrete demolition shears can be used at openings, joints, and recesses. This produces clean cut edges on concrete that enable safe follow-on work—such as pulling an anchor or exposing utility lines.
Rock excavation, tunnel construction, and special operations
In tunnels and on ramps, low construction heights, confined cross-sections, and stringent emission-control requirements are decisive. Compact planers enable the removal of bituminous pavements there. After milling—if concrete is exposed—work can proceed with hydraulic shears and splitter cylinders. In special operations, e.g., at airfields or gas stations, exact milling depths are essential for defined rehabilitation windows to avoid damaging the load-bearing concrete, waterproofing, and embedded components beneath.
Sequence from milling to concrete demolition
- Assessment of existing conditions: Record layer buildup, thicknesses, joints, drainage, embedded parts, and utility lines.
- Material assessment: Check for tar-containing old surfacings and hazardous substances; handling is carried out according to applicable regional regulations.
- Milling plan: Define milling depth, passes, transitions, and edges; set leveling parameters.
- Execution: Mill with suitable chisel configuration, dust suppression, and controlled discharge of milled material.
- Exposure of concrete: Clean the surface; visual inspection for cracks, joints, and reinforcement layers.
- Follow-on work on concrete: Use concrete demolition shears for controlled removal, opening of edges, and removal of damaged zones; use hydraulic splitters in vibration-sensitive areas.
- Source-separated sorting: Collect milled material, concrete debris, and metals separately; choose recycling routes in accordance with local requirements.
Interfaces with products and working methods of Darda GmbH
- Concrete demolition shears: After milling, bridge parapets, curb beams, and edge areas on the exposed concrete can be selectively bitten and removed. Advantageous on impact-sensitive structures.
- Hydraulic splitters: For controlled, low-vibration splitting of massive concrete slabs beneath formerly asphalted areas or in interior spaces.
- Hydraulic power packs: Power supply for hydraulic shears and splitter cylinders; mobile hydraulic power units or stationary setups, matched to power demand and hose lengths.
- Combination shears and multi cutters: Cutting of embedded parts, utility lines, and aggregates that become accessible after milling.
- Steel shears: Deconstruction of guardrails, safety installations, and steel elements along traffic areas after surface exposure.
- Tank cutters: In rehabilitation of areas above underground steel tanks (e.g., in commercial zones) they enable the safe opening and segmenting of tanks, provided the surfaces have previously been milled and exposed.
Quality characteristics of the milling
The quality of the milled surface influences follow-on trades and the durability of new build-ups. Important characteristics are smoothness, defined surface roughness depth, clean edges, and uniform milling depth. Suitable chisel spacing produces a milling pattern optimized for bond or further processing. Higher requirements apply to the transition to concrete components regarding edge stability and accuracy so that concrete demolition shears can be positioned precisely.
Edges, joints, and tie-ins
- Control milling depth at joints to avoid damaging waterproofing.
- Produce edges cleanly with edge milling cutters to prevent spalling on concrete.
- Lay out transitions so that shears and splitters can grip in a controlled manner.
Occupational safety, emissions, and environmental aspects
Milling generates noise, dust, and vibration. Water spray and extraction reduce dust; proper maintenance of chisels lowers noise and increases efficiency. Tar-containing old surfacings can contain polycyclic aromatic hydrocarbons; appropriate protective measures, separate collection, and disposal or recycling in accordance with the applicable rules are required here. Work in interior spaces or tunnels requires emission limitation, adequate ventilation, and coordinated logistics. General guidance does not replace case-by-case assessment; the relevant regional technical and legal requirements are decisive.
Special applications and boundary conditions
- Bridges and parking decks: Low load reserves and sensitive waterproofing demand defined milling depths and low additional loads.
- Tunnels and halls: Compact machines, low-emission working methods, and structured material logistics.
- Airfields and industrial areas: High area performance, smoothness requirements, and rapid reopening; coordinated transition to concrete works.
- Rehabilitation windows: Tight possession times require coordinated teams: milling, cleaning, visual inspection, and immediately following deployment of hydraulic shears or splitters.
Technical parameters and assessment
- Milling depth and milling width: define the removal profile and daily output.
- Chisel spacing and drum diameter: influence the milling pattern, particle size distribution of the milled material, and energy demand.
- Feed speed and torque: determine performance and surface quality.
- Milled material: Purity, gradation, and moisture determine recycling routes.
Planning, logistics, and quality assurance
For smooth workflows, coordination of the milling crew, provision of transport vehicles for the milled material, cleaning of the exposed concrete substrate, and availability of the hydraulic tools are essential. Documented measurements of milling depth, smoothness, and edge quality facilitate acceptance. Handover protocols between milling and subsequent activities—such as the application of concrete demolition shears or the placement of a breakout wedge—secure interfaces and minimize rework.
Alternatives and complements
Depending on the construction objective, high-pressure water jets, shot blasting, or grinding can be sensible as a complement or alternative to a tar milling machine, for example for local removal of thin layers. If low-vibration concrete removal is required after milling, hydraulic splitters are a good option. For targeted opening of edges, breaking out residual wedges, or exposing reinforcement, concrete demolition shears are suitable.
Practical tips for execution
- Locate utility lines and mark transitions to concrete components before starting.
- Check chisel condition; dull chisels increase noise, dust, and energy demand.
- Plan milling lanes so that discharge paths are short and free of crossings.
- Clean exposed concrete edges immediately; this allows concrete demolition shears to grip more securely.
- Choose a conservative milling depth in sensitive areas and deepen in steps if necessary.
- Record milled material separately; this facilitates subsequent recycling.