Development of Functional Rubber-Based Impact-Absorbing Pavements for Cyclist and Pedestrian Injury Reduction
Abstract
:1. Introduction
1.1. Vulnerable Road Users’ Safety and Public Health
1.2. Recycling and Responsible Consumption for Sustainable Urban Communities
1.3. Inspirations and Previous Studies
1.4. Implementation of the Current Study
2. Materials and Methods
2.1. End-of-Life Tyre Rubber
2.2. Bituminous Binder
2.3. Virgin Aggregates
2.4. Mix Design and Production of Specimens
2.5. Characterisation
2.5.1. Geometrical and Volumetric Analysis
2.5.2. Cantabro Loss Test
- CL: Cantabro loss (%)
- mi: the initial mass of the specimen (g)
- mf: the final mass of the specimen (g)
2.5.3. Indirect Tensile Stiffness Modulus (ITSM) and Indirect Tensile Strength (ITS)
2.5.4. Head Injury Criterion (HIC)
- t1: start time
- t2: end time
- a: acceleration
3. Results and Discussion
3.1. Geometrical and Volumetric Assessement
3.2. Cantabro Loss and Abrasion Results
3.3. Pavement Mechanical Performances
3.4. Attenuation of Impacts and Injury Prevention
3.4.1. Influence of the Rubber Amount
3.4.2. Influence of the Testing Temperature
3.4.3. Influence of the Testing Layer Thickness
4. Conclusions
- Adopting the dry process method made it possible to produce samples with a rubber content larger than 30% total weight (larger than 50% total volume). Those bituminous samples also contained coarse crumb rubber particles (0 mm to 4 mm size).
- The bitumen quantity should be kept as low as possible for a given rubber amount as the CFH variation observed between the IAP 2a 2b 2c and IAP 3 was not significant.
- The swelling reaction played a role in the geometrical expansion of the material. However, the addition of a high amount of rubber did not cause critical abrasion behaviour when tested with the Cantabro loss method. The percentage of loss was four times less than the reference asphalt, but future work will have to specifically assess the reliability of the applied test method.
- As a result of ITSM measurements, it was observed that for the IAP 3 samples containing 33% wt. rubber, the stiffness modulus was 40 times smaller than the reference asphalt. Additional stiffness or mechanical tests are needed to investigate different testing method or conditions (i.e. simulating different climates).
- The greater the amount of rubber that was added, the higher the impact-attenuation effect that was measured through HIC, and the higher the calculated CFH. The addition of rubber consistently enhanced this property even at low testing temperatures.
- The obtained HIC and CFH were approaching the recommendations for playgrounds. IAP 3 samples lowered the AIS parameter from 3 (REF AC) to 0, thus reducing the risk of severe injuries.
- The optimal thickness of the pavement rubber layer appeared to be between 4 and 9 cm. The thickest samples recorded auspicious results even at cold temperatures. Thicker layers can require multiple layers using the traditional paving techniques.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Crumb Rubber (CR) Granulates | Particle Size (mm) | Bulk Density 1 (kg·m3) EN 1097-3 | Specific Gravity 2 EN 1097-6 | PAHs 8 REACH 1 (mg/kg) (Specification ≤ 20) |
---|---|---|---|---|
Fine (F) | 0–1.2 | 0.440 | 1.028 | 6.5 |
Medium (M) | 1–2.8 | 0.440 | 1.028 | 6.5 |
Coarse (C) | 2.5–4 | 0.440 | 1.028 | 6.5 |
PAH 16 | Concentration Detected (mg/kg) | Sum of PAH Detected (mg/kg) |
---|---|---|
TOTAL PAH 16 | Sum 16 PAH Approx.2.3 | |
Naphthalene Acenaphthylene Acenaphthene | <0.5 <0.5 <0.5 | Sum PAH-L <1.5 |
Fluorene | <0.5 | Sum PAH-M Approx. 1.0 |
Phenanthrene | <0.5 | |
Anthracene | <0.5 | |
Fluoranthene | <0.5 | |
Pyrene | 1.0 | |
Benzo a anthracene | <0.5 | Sum PAH-H Approx.1.3 |
Chrysene | <0.5 | |
Benzo b,j fluoranthene | 1.3 | |
Benzo k fluoranthene | <0.5 | |
Benzo a pyrene | <5 | |
Indeno123cdpyrene | <5 | |
Dibenzo ah anthracene | <5 | |
Benzo ghi perylene | <5 |
Measured Properties 1 | Unit | Value | Standard |
---|---|---|---|
Penetration @25 °C | 0.1 mm | 25/55 | EN 1426 |
Softening point | °C | ≥70 | EN 1427 |
Flashpoint | °C | ≥250 | EN 2592 |
Dynamic viscosity @160 °C | Pa·s | ≥0.4 | EN 13702-1 |
Fraass breaking point | °C | ≤−15 | EN 12593 |
Virgin Aggregates 1 | Particle Size (mm) EN 933-1 | Specific Gravity EN 1097-6 |
---|---|---|
Limestone 1 | 8–14 | 2.661 |
Limestone 2 | 4–8 | 2.669 |
Sand | 0–4 | 2.608 |
Basalt | 0–2 | 2.685 |
Limestone filler | ≤0.063 | 2.667 |
Mixtures | % Weight | % Volume | |||||
---|---|---|---|---|---|---|---|
Name | Rubber Size | % Rubber (Aggregates) | % Rubber (Total Mix) | % Binder (Total Mix) | % Rubber (Aggregates) | % Rubber (Total Mix) | % Binder (Total Mix) |
REF AC | / | 0 | 0 | 8 | 0 | 0 | 8 |
IAP 1 | FM | 17 | 14 | 18 | 35 | 30 | 14 |
IAP 2a | FM | 34 | 28 | 18 | 63 | 52 | 16 |
IAP 2b | FM | 34 | 27 | 21 | 63 | 51 | 19 |
IAP 2c | FM | 34 | 27 | 23 | 63 | 50 | 21 |
IAP 3 | FMC | 41 | 33 | 18 | 66 | 56 | 15 |
HIC | AIS Code | Severity | Description |
---|---|---|---|
>1860 | 6 | Maximum | Fatal, not survivable. |
[1859–1575] | 5 | Critical | Unconscious for >24 h; large hematoma |
[1574–1255] | 4 | Severe | Unconscious for 6–24 h; open skull fracture |
[1254–900] 1000 | 3 | Serious | Unconscious for 1–6 h; depressed skull fracture |
[899–520] | 2 | Moderate | Unconscious for <1 h; linear skull fracture |
[519–135] | 1 | Minor | Headache or dizziness |
<135 | 0 | Null | No injury |
Mixes | EN12697-6 D Density (g/cm3) | EN12697-5 B Maximum Density (g/cm3) | EN12697-8 VA (%) | EN12697-8 VMA (%) | EN12697-8 VFB (%) |
---|---|---|---|---|---|
REF AC | 2.273 | 2.207 | 2.9 | 33.7 | 91.4 |
IAP 1 | 1.740 | 1.605 | 7.8 | 38.0 | 79.6 |
IAP 2a | 1.460 | 1.383 | 5.2 | 38.9 | 82.8 |
IAP 2b | 1.541 | 1.423 | 7.7 | 42.4 | 80.3 |
IAP 2c | 1.654 | 1.586 | 4.1 | 30.1 | 90.4 |
IAP 3 | 1.443 | 1.371 | 5.0 | 33.7 | 83.4 |
Mixes | Indirect Tensile Strength (MPa) 10 °C | Indirect Tensile Strength (MPa) 25 °C | Stiffness Modulus (MPa) 5 °C | Stiffness Modulus (MPa) 10 °C |
---|---|---|---|---|
REF AC | 2.69 | 1.78 | 12,496 | 11,654 |
IAP 1 | 0.91 | / | 1236 | / |
IAP 2a | 0.36 | 0.35 | 301 | 229 |
IAP 2b | 0.51 | 0.31 | 273 | 194 |
IAP 2c | 0.48 | 0.26 | 202 | 124 |
IAP 3 | 0.44 | 0.29 | 248 | / |
Mixes | %Rubber (wt.) | Drop Height (m) | HIC | Standard Deviation HIC | Related AIS Code |
---|---|---|---|---|---|
REF AC | 0 | 0.2 | 1111 | 6 | 3 |
IAP 1 | 14 | 0.2 | 470 | 46 | 1 |
IAP 2a | 28 | 0.2 | 160 | 17 | 1 |
IAP 2b | 27 | 0.2 | 170 | 19 | 1 |
IAP 2c | 27 | 0.2 | 109 | 9 | 0 |
IAP 3 | 33 | 0.2 | 114 | 5 | 0 |
* PLAYGROUNDS | >50 | 0.2 | 22 | / | 0 |
* RUBBER CONCRETE | 20–30 | 0.2 | 195 | / | 1 |
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Makoundou, C.; Sangiorgi, C.; Johansson, K.; Wallqvist, V. Development of Functional Rubber-Based Impact-Absorbing Pavements for Cyclist and Pedestrian Injury Reduction. Sustainability 2021, 13, 11283. https://doi.org/10.3390/su132011283
Makoundou C, Sangiorgi C, Johansson K, Wallqvist V. Development of Functional Rubber-Based Impact-Absorbing Pavements for Cyclist and Pedestrian Injury Reduction. Sustainability. 2021; 13(20):11283. https://doi.org/10.3390/su132011283
Chicago/Turabian StyleMakoundou, Christina, Cesare Sangiorgi, Kenth Johansson, and Viveca Wallqvist. 2021. "Development of Functional Rubber-Based Impact-Absorbing Pavements for Cyclist and Pedestrian Injury Reduction" Sustainability 13, no. 20: 11283. https://doi.org/10.3390/su132011283