Research Article
Effect of Recycled Rubber on the Properties of Road Bitumen
Table 4
Properties of bitumen modified at 220°C.
| | Property | Sample no. | | 7 | 8 | 9 | 10 | 11 | 12 | 13 |
| | Penetration at 25°C (0.1 mm) | 80 | 78 | 80 | 104 | 96 | 97 | 86 | | Softening point (R&B) (°C) | 55.4 | 52.8 | 49.9 | 48.0 | 50.8 | 51.9 | 51.6 | | Penetration index | 1.3 | 0.60 | 0.00 | 0.60 | 0.80 | 0.33 | 0.60 | | Fraass breaking point (°C) | −28 | −27 | −26 | −26 | −28 | −26 | −25 | | Elastic recovery at 25°C (%) | 70 | 70 | 63 | 62 | 60 | 76 | 63 | | Stability (values of penetration top/penetration bottom) (0.1 mm) | 93/88 | 82/80 | 74/76 | 87/96 | 73/76 | — | 79/73 | | Delta penetration (difference between top and bottom of the tube) (0.1 mm) | 5 | 2 | 2 | 9 | 3 | — | 6 | | Stability (R&B top/R&B bottom) | 50.2/58.2 | 52.0/57.4 | 52.8/60.6 | 52.4/46.5 | 52.2/54.0 | 51.0/58.8 | 51.6/56.0 | | Delta R&B (°C) | 8 | 5.4 | 9.2 | 6 | 1.8 | 3.4 | 4.4 | | Retained penetration at 25°C after RTFOT (%) | 62.4 | 60.5 | 61.2 | 55.0 | 58.0 | 66.0 | 60.2 | | Increasing of softening point R&B after RTFOT (°C) | 7.0 | 7.7 | 11.4 | 7.0 | 7.2 | 8.4 | 8.6 | | Mass change after RTFOT (%) | −0.68 | −0.70 | 0.73 | 0.84 | 0.64 | 0.24 | -0.47 | | Cohesion energy at 5°C (J/cm2) | 2.9 | 3.1 | 3.3 | 1.1 | 2.6 | — | 2.3 | | Cohesion energy at 10°C (J/cm2) | 1.3 | 1.5 | 1.4 | 1.1 | 1.1 | — | 1.3 | | Maximal tensile force at 5°C (N) | 17.8 | 17.5 | 19.4 | 14.3 | 16.3 | — | 23 | | Maximal tensile force at 10°C (N) | 9.0 | 9.3 | 7.7 | 7.0 | 7.5 | — | 10.5 |
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