Rubber crumb specific weight: weight of 1 m³
Used automobile tires are valuable secondary raw material for producing different materials: rubber tiles for sports and children’s playgrounds, new rubber mixtures, modified bitumen and bitumen mastics, industrial floor coverings, sports equipment and other products. To use rubber waste, it is processed into a semi-finished product called rubber crumb.
Processing consists of grinding old automobile rubber into particles of a specified fraction. Articles and price lists often mention sizes from fractions of a millimeter to several millimeters, but the actual range depends on the technology and intended use. The particles retain the properties of the rubber elastomer, and for some applications their surface is additionally activated or modified.
Production of rubber crumb
Different methods can be used to break down old rubber technical products. In practice, mechanical crushing and grinding are most common, sometimes with cooling to make rubber easier to fracture. More specialized methods are used less often and depend on plant equipment. Different processing modes produce fractions of different sizes.
Mechanical grinding of rubber takes place in several stages, while the specific weight of rubber crumb, or bulk density, changes.
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At the first stage, cutting into “chips”, the particle size ranges up to 50 mm. Maximum density is 490-520 kg/m³.
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During the next cycle, the purpose of grinding is to separate the metal or textile component of the tire, the cord. Rubber particles up to 10 mm are separated: rubber crumb. The weight of 1 m³ of the final product is about 400 kg.
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Vibrating screens, air and magnetic separators and other devices remove foreign inclusions at the following stage.
| Fraction size, mm | Weight of 1 m³, kg | Density, g/cm³ | Tonnes in 1 m³ |
|---|---|---|---|
| 0.5 | 200 | 0.20 | 0.2 |
| 1.0 | 220 | 0.22 | 0.22 |
| 2.0 | 250 | 0.25 | 0.25 |
| 2.8 | 300 | 0.30 | 0.3 |
Another equally effective method, requiring less electricity, time, area and plant equipment cost, is shock-wave grinding. The essence of the method is critical cooling of used rubber tires to -70 degrees. The explosion grinds up to 80% of the material to the required particle size. The final stage is additional grinding of the already cleaned material.
Ground rubber crumb has a smooth surface and poor adhesion. To modify it, various physical and chemical treatment methods are used, allowing the material to be used as a filler for bitumen mixtures, for producing new tires, creating coatings for stadiums, sports and children’s playgrounds, steps, mats, as filling for punching bags, running track surfaces and other rubber technical products.
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Frequently Asked Questions
How much does 1 m³ of rubber crumb weigh?
The approximate weight depends on fraction size: larger chips may have higher bulk mass, while finished rubber crumb is often taken at about 400 kg/m³.
Why does fraction size affect rubber crumb weight?
Particle size and shape change how the material packs in a volume. Bulk density is also affected by cord residues, moisture and compaction.
Can rubber crumb density be treated as constant?
No. For purchasing, transport and dosing, clarify the fraction, production method and batch datasheet.