Background and Task
In light of continuously increasing traffic loads, surface deformations in asphalt pavements are becoming more frequent. A key method for enhancing the deformation resistance of asphalt layers is the modification of the bitumen binder with polymers.
The addition of polymers significantly increases the elasticity of bitumen, allowing it to stretch and recover under load. This flexibility is essential for preventing cracks and potholes in asphalt surfaces, particularly in regions with substantial temperature fluctuations.
Polymer-modified bitumen (PmB) exhibits far greater resistance to rutting (deformation under heavy loads) and fatigue (cracking caused by repeated stress) than conventional bitumen. This makes PmB ideal for heavily trafficked roads and areas subjected to severe loading, while significantly reducing maintenance and road expansion costs.
The improved bitumen properties achieved through modification are also used in the production of roofing membranes made from PmB/PmA, ensuring long service life and high resistance to weathering and aging.
Challenges
The most common and most effective polymer for producing polymer-modified bitumen is styrene–butadiene–styrene (SBS).
Since SBS tends to separate from the bitumen at elevated storage temperatures, the mixing process is one of the key factors determining the effectiveness of polymer modification. If dispersion is too coarse or incomplete, the morphology of the resulting polymer-bitumen blend becomes non-uniform, which can lead to phase separation or demixing.
Historically, this process involved intensive and very long mixing cycles in conventional agitators.
Solution
At the heart of any PmB/PmA production plant is a Cavitron machine engineered specifically to meet individual customer requirements.
Equipped with a specialized rotor–stator system, it generates high shear forces and turbulent flow, ensuring that the polymers are finely broken down and homogeneously distributed in the bitumen. Particle size reduction simultaneously accelerates the polymer swelling and maturation process.
To accommodate a range of throughput requirements, Cavitron machines are available in four machine sizes and can be equipped with the appropriate rotor–stator configuration for both continuous and recirculation (loop) processing.
Übersicht Kundenvorteile
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High product quality
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Processing of large quantities and high polymer concentrations
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High process control for guaranteed reproducible quality
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Stability and durability
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Improved workability and mix quality
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Low environmental impact and maximum occupational safety
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Robust and versatile
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Reduced maintenance requirements
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Tailor-made solutions
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Accessories and plant engineering:
Customer Benefits in Detail
- High product quality:
Rotor–stator systems developed specifically for bitumen applications ensure uniform distribution of the polymer (e.g., SBS) in the bitumen, prevent agglomeration, and deliver a consistent microstructure. - Processing of large quantities and high polymer concentrations:
With multiple machine sizes available, up to 50 t/h of PmB/PmA can be processed. - High process control for guaranteed reproducible quality:
The machine operates with precision and reliability, consistently delivering uniform product quality. Processes and results are reproducible at all times. - Stability and durability:
Optimal dispersion minimizes phase separation, ensuring higher stability during transport and storage. - Improved workability and mix quality:
Forced conveyance through the Cavitron machine prevents unmixed polymer from entering the final mix. Air entrainment and demixing are reduced, resulting in more stable viscosity and improved compaction performance. - Low environmental impact and maximum occupational safety:
Since processing occurs in a closed system, no particles or vapors are released. - Robust and versatile:
A robust design for operation under demanding conditions, suitable for processing various product grades and formulations. - Reduced maintenance requirements:
Intensive particle size reduction minimizes residue buildup in plant components and reduces the need for frequent cleaning. - Tailor-made solutions:
Cavitron machines can be individually configured to meet specific applications and customer requirements. Options include various rotor–stator systems, shaft seals, motors and drives, heating/cooling jackets, injection ports, and multistream inlets. - Accessories and plant engineering:
In addition to stand-alone machines, Cavitron provides complementary system components (hoppers, tanks, dispersers, etc.) as well as complete process plants.
With many years of experience in the bitumen-processing industry, we have become a highly respected partner—both nationally and internationally—for the design and manufacture of new machinery as well as the optimization of existing process technology.
General Technical Specifications
Static seals:
Viton, Teflon, Kalrez, other elastomers.
Operating pressure:
Application-dependent, up to 100 bar; standard: up to 10 bar.
Operating temperature:
Application-dependent up to 250 °C; standard: 150 °C.
Performance and energy consumption:
Type overview available for download.
Drives and power transmission:
Three-phase motors, high-frequency motors, mechanical gear units, variable-speed drives, stepless electronically controlled and monitored systems.
V-belt and Poly-V belt drives.
Intensity levels:
Application-specific, ranging from coarse mixing to dispersion in the angstrom range.
Bearings:
Tapered roller bearings, angular contact ball bearings (double).
engineered.
