Recycling Tire Rubber in Asphalt Pavements: State of the Art
Abstract
:1. Introduction
2. Properties and Compositions of Tire Wastes
3. Methods of Crumb Rubber Addition to Asphalt Mixtures
4. Interaction Effects of Crumb Rubber-Modified Asphalt Binder
5. Durability and Performance of Asphalt Rubber Pavements
5.1. Durability and Aging of Asphalt Rubber Pavements
5.2. Fatigue Cracking
5.3. Resistance to Rutting
5.4. Field Performance
6. Summary and Conclusions
- The use of recycled tire rubber as an additive in asphalt binder can improve various binder properties by reducing the temperature susceptibility of the asphalt binder.
- The addition of crumb rubber from waste scrap tires to asphalt binder can improve the resistance to rutting and permanent deformation of the pavement (owing to an increase in viscosity), reduce fatigue cracking, improve durability against traffic loads, and enhance pavement sustainability by saving energy and natural resources and lowering the maintenance and repair costs of asphalt pavements.
- Factors such as the shape, content, and particle size of the crumb rubber waste significantly affect the rheological properties of the rubber-modified asphalt binder.
- Adding warm-mix additives to crumb rubber-modified asphalt can have adverse effects on the rutting and fatigue resistance of crumb rubber-modified asphalt, which needs further research.
- Adding crumb rubber into asphalt binders can enhance the asphalt’s resistance to age hardening.
- An increase in the rubber content in asphalt binder increases the elastic component of the dynamic shear modulus, leading to improved recovery and rutting resistance of asphalt pavements.
- However, a large increase in the rubber content increases the binder viscosity (and changes flow characteristics from Newtonian to shear thinning), which can lead to construction difficulties.
- Further field testing, such as non-destructive testing, is required on rubberized asphalt pavements constructed in different zones to gain a more profound understanding of the behavior of rubberized asphalt in aggressive exposure conditions.
- Crumb rubber-modified asphalt binder contains less asphalt than conventional asphalt binder. This reduction in asphalt content can increase air voids within the binder matrix, thus increasing permeability, which could negatively affect the durability of rubberized asphalt pavements. Further research is needed to examine the permeability and moisture damage characteristics of rubberized asphalt pavements in various exposure conditions.
Author Contributions
Funding
Conflicts of Interest
References
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Binder | Asphalt-Rubber Specification (ASTM D6114) | Standard | ||
---|---|---|---|---|
Designation | Type I | Type II | Type III | |
Viscosity in 177.5 °C | 1500–5000 | 1500–5000 | 1500–5000 | ASTM-D2196 |
Penetration at 25 °C, unit: 0.1 mm | 25–75 | 25–75 | 50–100 | ASTM-D5 |
Penetration at 4 °C, | Min 10 | Min 15 | Min 25 | |
unit: 0.1 mm | ||||
Softening Point, °C | Min 57.2 | Min 54.4 | Min 51.7 | ASTM-D36 |
Resilience at 25 °C (%) | Min 25 | Min 20 | Min 10 | ASTM-D5329 |
Flash Point, °C | Min 232.2 | Min 232.2 | Min 232.2 | ASTM-D93 |
Thin Film Oven Test (TFOT), residual penetration at 4 °C, (%) | Min 75 | Min 75 | Min 75 | ASTM-D1754, ASTM-D5 |
Climatic region | Hot | Moderate | Cold | - |
Average minimum monthly temperature (°C) | Min -1 | Min -9 | Min -9 | - |
Average maximum monthly temperature (°C) | Min 43 | Min 43 | Max 27 | - |
(a) Terminology for Recycled Waste Tire Particles Referring to [29] | (b) Recycled tire Materials Properties [30] | |||||
Classification | Lower Limit (mm) | Upper Limit (mm) | Material | Tire Chips (%) | Crumb Rubber (%) | Steel Cords (%) |
Chopped Tire | Unspecified dimensions | Unspecified dimensions | Rubber volume | 95–99 | 99–100 | 35–75 |
Rough Shred | 50 × 50 × 50 | 762 × 50 × 100 | ||||
Tire Derived Aggregate | 12 | 305 | Steel volume | |||
Tire Shreds | 50 | 305 | 1.5–8 | 0 | 35–75 | |
Tire Chips | 12 | 50 | ||||
Granulated Rubber | 0.425 | 12 | Density (g/cm3) | |||
Ground Rubber | - | <0.425 | 0.8–1.6 | 0.7–1.1 | 1.5–3.9 | |
Powdered Rubber | - | <0.425 | ||||
(c) Essential Compositions of Tires [31] | (d) Chemical Compositions of Waste Tire Rubber [24] | |||||
Composition Weight (%) | Automobile Tire (wt%) | Truck Tire (wt%) | Material | Mass Percentage (%) | ||
Natural Rubber | 14 | 27 | Rubber | 54 | ||
Synthetic Rubber | 27 | 14 | Textile | 2 | ||
Carbon black | 28 | 28 | Carbon black | 29 | ||
Steel | 14–15 | 14–15 | Oxidize zinc | 1 | ||
Fabre, Filler, Accelerator, and Antiozonants | 16–17 | 16–17 | Sulfur | 1 | ||
Additive | 13 |
Properties of Rubber [47] | Effect of Temperature on Physical Properties of Rubber [2] | ||
---|---|---|---|
Feature | Property | Temperature °C | Effect |
Compacted density | 2.3–4.8 kN/ compared to compacted density of soil 15.6–19.5 kN/ | −10 | Brittle and opaque |
Compacted dry unit weight | 1/3 that of soil | 20 | Soft, resilient and translucent |
Compressibility | 3 times more compressible than soil | 50 | Plastic and sticky |
Density | 1/3 to ½ less dense than granular fill | ||
Durability | Non-biodegradable | ||
Earth pressure | 50% less pressure than soil or sand | 120–160 | Vulcanized when agents (e.g., Sulphur) are added |
Friction characteristics | Higher friction than soil | ||
Horizontal stress | Lower than in conventional backfills | ||
Modulus in elastic range | 1/10 of sand | 180 | Break down as in the masticator |
Permeability | >10 cm/s (>0.39 in/s) | ||
Poisson’s ratio | 0.2–0.3 corresponding to 0.3–0.4 earth pressure coefficient () values | ||
Specific gravity | ±1.14–1.27 kg/ | 200 | Decomposes |
Thermal insulation | 8 times more effective than gravel | ||
Unit weight | 50% of the typical unit weight of gravel | ||
Vertical stress | On weak base: smaller than granular backfill |
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Alfayez, S.A.; Suleiman, A.R.; Nehdi, M.L. Recycling Tire Rubber in Asphalt Pavements: State of the Art. Sustainability 2020, 12, 9076. https://doi.org/10.3390/su12219076
Alfayez SA, Suleiman AR, Nehdi ML. Recycling Tire Rubber in Asphalt Pavements: State of the Art. Sustainability. 2020; 12(21):9076. https://doi.org/10.3390/su12219076
Chicago/Turabian StyleAlfayez, Saud A., Ahmed R. Suleiman, and Moncef L. Nehdi. 2020. "Recycling Tire Rubber in Asphalt Pavements: State of the Art" Sustainability 12, no. 21: 9076. https://doi.org/10.3390/su12219076