Improvement of Bearing Capacity in Recycled Aggregates Suitable for Use as Unbound Road Sub-Base
Abstract
:1. Introduction
2. Materials
2.1. Natural Aggregates (NA)
Properties | NA | RCA | MRA | Standard Established Limits |
---|---|---|---|---|
Density SSD (Mmg/m3) (0.063–4) (UNE-EN 1097-6:2001) | 2.77 | 2.68 | 2.54 | – |
Density SSD (Mmg/m3) (4–31.5) (UNE-EN 1097-6:2001) | 2.76 | 2.63 | 2.47 | – |
Water absorption (%) (0.063–4) (UNE-EN 1097-6:2001) | 1.96 | 2.45 | 5.83 | – |
Water absorption (%) (4–31.5) (UNE-EN 1097-6:2001) | 0.54 | 2.37 | 5.01 | – |
Nominal size (mm) | 25 | 25 | 25 | – |
Sand Equivalent (UNE EN 933-8:2000) | 38 | 52 | 46 | T3 to T4: SE > 35 |
L.A. abrasion value (%) (UNE EN 1097-2:1999) | 24.00 | 32.92 | 36.40 | T3 to T4: <35% * |
Flakiness index (UNE EN 933-3:1997) | 13 | 5 | 13 | <35% |
Acid-soluble sulphate (%SO3) (UNE 1744-1:1999) | 0.05 | 0.53 | 0.70 | 0.5%(c); <1%(d) |
Organic matter (%) (UNE 103204:1993) | 0 | 0.75 | 0.43 | <1% |
2.2. Recycled Aggregates (RA): Recycled Concrete Aggregates (RCA) and Mixed Recycled Aggregates (MRA)
Properties | RCA | MRA |
---|---|---|
Ra (%) (Asphalt) | 8.9 | 8.1 |
Rb (%) (Ceramics) | 0.3 | 23.7 |
Rc (%) (Concrete and mortar a) | 42.1 | 31.5 |
Ru (Unbound aggregates b) | 48.5 | 36.5 |
X1 (%) (Natural soil) | 0 | 0 |
X2 (%) (Others) | <0.1 | <0.1 |
X3 (%) (Gypsum) | <0.1 | <0.1 |
3. Experimental Tests
3.1. Modified Proctor Test
3.2. California Bearing Ratio (CBR) Standard Test
3.3. Accelerated Swelling Test for Soil Treated by Lime and/or Hydraulic Binder According to UNE-EN-13286-49
3.4. X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM)
4. Results and Discussion
4.1. Modified Proctor Test
Blend | Optimum Moisture Content (%) | Maximum Dry Density (g/cm3) |
---|---|---|
NA | 5.96 | 2.38 |
RCA | 10.18 | 2.08 |
MRA | 11.20 | 2.02 |
4.2. California Bearing Ratio (CBR) Standard Test
4.3. Accelerated Swelling Test
Blends | Initial Density (g/m3) | Compressive Strength (MPa) | Swelling after 7 Days of Soaking (%) |
---|---|---|---|
NA | 2.37 | 0.04 | 2.60 |
RCA | 2.16 | 0.55 | 2.30 |
MRA | 2.14 | 1.15 | 4.00 |
4.4. SEM and Diffraction Analyses of the Blended Mixtures
5. Conclusions
Acknowledgments
Author Contributions
Conflicts of Interest
References
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Garach, L.; López, M.; Agrela, F.; Ordóñez, J.; Alegre, J.; Moya, J.A. Improvement of Bearing Capacity in Recycled Aggregates Suitable for Use as Unbound Road Sub-Base. Materials 2015, 8, 8804-8816. https://doi.org/10.3390/ma8125493
Garach L, López M, Agrela F, Ordóñez J, Alegre J, Moya JA. Improvement of Bearing Capacity in Recycled Aggregates Suitable for Use as Unbound Road Sub-Base. Materials. 2015; 8(12):8804-8816. https://doi.org/10.3390/ma8125493
Chicago/Turabian StyleGarach, Laura, Mónica López, Francisco Agrela, Javier Ordóñez, Javier Alegre, and José Antonio Moya. 2015. "Improvement of Bearing Capacity in Recycled Aggregates Suitable for Use as Unbound Road Sub-Base" Materials 8, no. 12: 8804-8816. https://doi.org/10.3390/ma8125493