Rubber crumb specific weight: weight of 1 m³
Used automobile tires are excellent secondary raw material for producing different kinds of materials, such as rubber tiles for sports and children’s playgrounds, new rubber mixtures, various modifications of bitumen and bitumen mastics, floor galvanic coatings for workshops, sports equipment and more. To make it possible to use rubber waste, it must be processed into a semi-finished product called rubber crumb.
Processing consists of grinding old automobile rubber into very small particles from 0.2 to 5 mm. Each particle, regardless of shape and size, retains the molecular structure and properties of the elastomer. For further use of rubber crumb, different methods of activating the surface layers must be applied.
Production of rubber crumb
Different methods of destroying old rubber technical products can be used to produce rubber crumb. The most effective method, crushing, can occur under cutting, electromagnetic or ultrasonic action, shear deformation, electricity, laser, shock-wave or explosive-circulation action. At different temperatures, rubber is mechanically divided into increasingly smaller fractions.
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
Can the density of rubber crumb be used for precise calculations?
The density and weight values for rubber crumb in this article are reference values. They are suitable for preliminary estimates, but design, construction, production and other critical calculations should be checked against standards, material datasheets or measurement results.
Why can the actual weight of rubber crumb differ from the table?
The actual weight of rubber crumb depends on composition, moisture, temperature, porosity, fraction size, material grade and measurement conditions. Because of this, real values may differ from the average table data.
How do you calculate the mass of rubber crumb from density?
For an approximate calculation, use the formula: mass = density × volume. If the density of rubber crumb is given in kg/m³ and the volume is in m³, the result will be in kilograms.