Synthetic sand
Mixed plastics materials for use in the construction industry
The use of plastics in the construction industry has been a reality since decades.
The use of plastic pellets in traditional building materials has made it possible to obtain many advantages:
- The low thermal conductivity of plastics allows to obtain products with improved thermal insulation
- The low density of plastics determines an increase in yields in terms of material processed
- Minor wear on the mortars transmission lines and processing machines
- Decrease the elasticity modulus, while maintaining the strength of the material: this improves the resistance to cracking
In addition:
- The polymer-based pellets are not compromised during the processing and transport of dry mortars
- The polymer granules act as a support in the mortars matrix, allowing a reduction in the amount of binder used for the same degree of strength obtained.
PROMECO has successfully developed a system to obtain granular materials complying with the more demanding EU legislation- in particular the Italian standard UNI 10667-14 concerning requirements and test methods for mixtures of polymeric materials for recycling and other cellulose-based materials to recycled for use as aggregate in cement mortar (designated as R-PMIX-CEM).
According to regulations, the blends R-CEM-PMIX must consist of a heterogeneous polymer fraction in a percentage greater than or equal to 84% by weight, and other materials (including fillers, additives and pigments) and weighs (less than 16%).
The main features of this product are detailed in the following table:
CEM-R-PMIX for cement mortar
| Feature | Method | Special Conditions | Requirements |
|---|---|---|---|
| Content of plastic and rubber (may be present all types of plastic waste, including packaging waste) | Chosen by agreement between the parties (usually by manual separation) | ≥ 84% by weight | |
| Content of cellulose-based materials (paper, cardboard, wood, cardboard polycoupled), additives | Chosen by agreement between the parties (usually by manual separation) | ≤ 15% by weight | |
| Content of glass, metals and inert | Chosen by agreement between the parties | ≤ 1% by weight | |
| Bulk density | UNI EN ISO 61 | 200 kg / m³ to 500 kg / m³ | |
| Grit | Manual sorting | Sieve and sieving times agreed between the parties | maximum size ≤ 20 mm |
| Color | Visual evaluation | Agreed between the parties | |
| Shape | flake, pellets, granules | ||
| Residual moisture | At 120 ° C for 2 h | ≤ 5% by weight |
Description of the process
The material is received in bales or in bulk. A loading system feeds, through a conveyor belt (1), a disc screen (2). The main purpose of screening is to eliminate aggregates of small size and prepare the material for the next phase of automatic or manual sorting. The selection allows to recover the valuable recyclable fractions and intercept foreign bodies of significant size, if present.
Then the material is conveyed to a shredder PROMECO KR(4), to obtain a product homogeneous in size and facilitate the next stage of densification.
If necessary, over the conveyors (5) carrying the shredded material to the PES (8) are placed a magnetic separator (6) for the removal of ferrous metals, and an eddy current separator (7) for non-ferrous metals.
The Promeco Extruder System (8) includes a hopper, which feeds the material to the machine, and a vibrating table, which optimizes the input material flow into the extrusion chamber, where the actual process of aggregation / homogenization takes place.
Here the material is subject to high friction and pressure, generated by the rotating screw, to obtain a molten matrix, which is transmitted, through a tape immersed in a cooling tank, in a shredder PROMECO KR series (9). This operation allows to obtain a material of desired size.
The process generates heat and steam. The latter, along with any dust, is collected by a suction system of air exhausted (10) in order to be sent to a stage of treatment (11)
Advantages of the Promeco Extruder System line
- Reduced number of machines used
- Low maintenance costs
- Minimum floor area required
- Lower investment cost
- Minimum electric power installed
- Simplified Maintenance
- Increased productivity
- Greater continuity of production
- Versatility
