# A Review of Nanomaterials' Effect on Mechanical Performance and Aging of Asphal Mixtures
## 4 Effect of the Modification with Nanomaterials in the Mechanical Performance of Asphalt Mixtures
### Nanoclay
[99] studied an asphalt mixture (NMAS 11.2 mm) with 5.7% binder content, modified with of 6% organically modified nanoclay (cloisite). For the mixture production, granitic aggregates and 40/60 asphalt binder (control binder) were used. The modified mixture presented 12% average increase in resilient modulus in the range from 5 \({}^{\circ}\)C to 35 \({}^{\circ}\)C (evaluated by the indirect tensile resilient modulus test). Regarding indirect tensile strength, the modified mixture presented 8%, 19%, 17%, 28%, and 39% increase for 5 \({}^{\circ}\)C, 12.5 \({}^{\circ}\)C, 20 \({}^{\circ}\)C, 27.5 \({}^{\circ}\)C, and 35 \({}^{\circ}\)C, respectively (Figure 8). The modification also enhanced the resistance to permanent deformation (50% increase in the flow number in dynamic creep tests at 60 \({}^{\circ}\)C and 200 KPa). [PERSON] et al. [97] studied an asphalt mixture (NMAS 19 mm) modified with 3% nanoclay (montmorillonite). The asphalt mixture was produced with limestone aggregates, limestone filler, 60/70 (control binder) and 5.5% binder content. The authors observed that the nanoclay modified mixture presented 55% increase in Marshall stability (Figure 10), decrease in retained Marshall stability (85% for control and 77% for nanoclay modified), 40% increase in indirect tensile strength (Figure 8), and similar indirect tensile ratio (Figure 9). [PERSON] et al. [25; 36; 100] studied an asphalt mixture modified with 4% nanoclay hydrophilic bentonite. The mixture was an asphalt concrete (AC 14) using granitic aggregates, limestone filler, 35/50 asphalt binder, and 4.5% binder content. The modification had a positive effect in the properties of the asphalt mixture. The following effects were reported: 13% increase in Marshall stability (Figure 10); improvement in retained Marshall stability from 77% to 99%; 46% increase in indirect tensile strength (Figure 8); improvement in indirect tensile strength ratio from 57% to 61% (Figure 9); improvement in affinity aggregate-binder (from 40% to 67% of binder coverage); 10% reduction in permanent deformation (Figure 11); 7.2% reduction in stiffness modulus at 20 \({}^{\circ}\)C and 4.3% increase in stiffness modulus at 30 \({}^{\circ}\)C; and better fatigue resistance (7% increase in the strain for 10\({}^{\circ}\) cycles). Figure 10: Marshall stability of control and nanoclay modified asphalt mixtures. Figure 9: Indirect tensile strength ratio of control and nanoclay modified asphalt mixtures. [PERSON] and [PERSON] [35] studied the modification of a PG 58-22 asphalt binder with 3% organically modified montmorillonite. The asphalt mixture, NMAS 19 mm, had 4.35% binder content and, was produced with basaltic aggregates, and hydrated lime. The modified mixture presented: 15% increase in indirect tensile strength (Figure 8), improvement in indirect tensile strength ratio from 81% to 100% (Figure 9); 39% reduction in permanent deformation (Figure 11); 20% and 57% average increase in stiffness modulus at the temperature of 20 \({}^{\circ}\)C and 30 \({}^{\circ}\)C, respectively; and increase in fatigue resistance (22% increase in the strain for 10\({}^{6}\) cycles). [PERSON] et al. [101] studied an asphalt mixture (AC14) modified with 5% organically modified nanoclay (cloisite-15). For the mixture production, sandstone aggregates and 35/50 asphalt binder were used. The authors tested for permanent deformation using a wheel-tracking machine. After applying 50,000 cycles, the 5% nanoclay modified mixture presented 10% reduction in permanent deformation (Figure 11). [PERSON] et al. [43] studied the effects of the modification with 1% and 2% polysiloxane-modified montmorillonite in the indirect tensile strength of an asphalt mixture. The mixtures were produced with 5.2% binder content and the PG 58-28 was the control binder. On the one hand, in the indirect tensile strength of the unconditioned (dry) specimens, the modified mixtures presented 1% and 4% reduction for the 1% and 2% dosage (Figure 8), respectively.