Asphalt mixing plant
In asphalt mixing plants and asphalt mixing plants , asphalt mix is produced through a thermal mixing process of mineral rocks , filler ( rock flour ), binding agents (mostly bitumen ) and, if necessary, additives . The mixing process is usually optimal when the mineral is homogeneously mixed and completely wetted by the binding agent. The complex process sequence of the entire asphalt mixing plant is usually made possible by a central control . The average system output of an asphalt mixing plant is usually between 80 and 320 tons of asphalt mix per hour. The necessary safety requirements for asphalt mixing plants are dealt with in the DIN EN 536 standard . The requirements for the asphalt mix are defined in the DIN EN 13108 standard.
In the 1950s and 1960s, mobile asphalt mixing plants were predominantly used. Their operation was very labor-intensive and was largely done by hand. With the advent of electronic controls and stricter environmental requirements in the 1970s, stationary systems were increasingly used. Modern systems can be operated by just one man due to an almost completely automated production process.
Production process
There are basically two production processes :
With continuous production , the mixing process takes place in (non-stop) continuous operation. The individual components are continuously added to the mixing process. This method is particularly suitable for large construction lots with a consistent mix.
In discontinuous production , the previously weighed components of the asphalt mix are mixed in batches in an asphalt mixer according to a recipe . This process is more flexible, as it enables batch changes to be made in the mixing recipe. In addition, a higher mixing quality can usually be achieved here through more precise addition quantities and adapted mixing times or mixing cycles .
In Europe , the discontinuous production process is predominantly used in asphalt production.
Types of asphalt mixing plants
There are three different types of asphalt mixing plants:
- Stationary types of systems are usually placed in a convenient location in order to cover the largest possible delivery area from there (e.g. motorway exits or industrial areas in large cities) and to keep delivery traffic to the construction site short. Some of the asphalt mixing plants are also located in regional mineral deposits such as quarries in order to keep the mineral supply cost-effective. This type of system requires a concrete foundation .
- Easily relocatable system types are suitable for construction sites with a limited time frame, which can then be relocated in one construction phase (e.g. new motorway construction). This type of system usually has its own steel foundation.
- Mobile system types are mostly used when only smaller batch sizes are required in remote rural areas (e.g. road construction in Siberia). This type of system only needs a place where trucks can drive as a foundation.
Plant assemblies
Asphalt mixing plants are mostly modular in structure with various elementary assembly functions:
- Dosers for minerals (pre-dosing)
- Drying the minerals ( drying drum with burner )
- Filter dedusting for the recovery of the dust generated in the process ( dedusting )
- Hot sieve unit ( sieve module )
- Silo for storage of hot aggregates (Hot aggregate silo)
- Module with scales for weighing the various components (scale module)
- Module with a mixer for mixing the required components (mixer module)
- Storage facility for storing the finished mix (mix silo). This module can be arranged under the mixer module or next to it. From here, the asphalt mix is (mostly) loaded onto trucks for immediate transport to the construction site.
- Storage containers for fillers (filler silos)
- Storage container for binding agents (bitumen tank system)
The most common assemblies for an extended range of functions include:
- Adding unit for asphalt granulate (reclaimed asphalt) directly into the mixer
- Adding unit for asphalt granulate (reclaimed asphalt) via a parallel drum
- Color additions for colored asphalt mix
- Foamed bitumen addition for the production of foam asphalt ( low temperature asphalt )
- Adding unit for fiber
- Burner with the fuel supply z. B. Lignite dust as an inexpensive energy source
Manufacturer (selection)
- Ammann
- Amomatic
- Astec
- Benninghoven (part of the Wirtgen Group )
- Comaco (has taken over Gibat-Ohl)
- Cesan
- E-MAK
- EKIP
- Fayat Group (includes: Marini, Ermont (since 1987 Fayat Marini-Ermont) and ATS Asphalttechnik)
- Intrame
- Lintec
- Teltomat
- Wasmus
literature
- Gerhard Drees : Baumaschinen und Bauverfahren , Expert-Verlag, 2002, ISBN 3-8169-2060-8 , page 176 ff.
- Horst König: Machines in construction: Basics and application . Springer Verlag, 2014, ISBN 978-3-658-03289-0 .