# 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
On the other hand, in the indirect tensile strength of the conditioned (wet) specimens (standard conditioning in water according to AASHTO T283-03), the modified mixtures presented 7% and 13% increase for the 1% and 2% dosage, respectively. This led to a progressive increase of the indirect tensile strength ratio with the increase in nanoclay dosage, 86%, 92%, and 101% for the 0%, 1%, and 2% dosage (Figure 9), respectively. The authors found the asphalt mixtures modified with polysiloxane-modified montmorillonite less susceptible to deicing solutions. These findings are in good agreement with another study [102], that reported the nanoclay to have a positive effect in mitigating stripping damage of asphalt mixtures exposed to non-chloride deicer solutions. [PERSON] et al. [103] studied the modification of an asphalt mixture, NMAS 12.5 mm, with two types of organically modified montmorillonite nanoclay, nanofil, and cloisite, with the dosages of 2%, 4%, and 7%. Limestone aggregates, limestone filler, and 60/70 control binder were used in the production of the mixtures. The authors concluded that the effects of the modifications increased according to the increase in the nanoclay dosage and the effects of cloisite were stronger than those of nanofil. Regarding the modifications with 7% nanoclay, the Marshall stability increased by 23% and 37% for the nanofill and cloisite (Figure 10), respectively. The increase in the nanoclays dosage lead to an increase in the optimum binder content, possibly explained by the large surface area of the nanoclays. The 7% modified mixtures presented 8% and 6% increase in indirect tensile strength at 25 \({}^{\circ}\)C, 40% and 18% increase in resilient modulus at 40 \({}^{\circ}\)C, and reduction in permanent deformations (37% and 83% increase in the flow number in dynamic creep tests at 60 \({}^{\circ}\)C and 300 KPa), for cloisite and nanofill, respectively. Figure 11: Proportional rut depth of control and nanoclay modified asphalt mixtures. [PERSON] et al. [39] studied the effect of the modifications with 1.5% organically modified montmorillonite (cloisite) in the properties of an asphalt mixture (NMAS 19 mm) with 4.8% binder content. For the production of the mixture the authors used limestone aggregates and considered two control binders, a neat PG 58-10 and a polymer modified binder (PG 58-10 modified with 6% SBS). Regarding the effects in the PG 58-10 binder (NMA), the modification lead to 10% increase in resilient modulus at 25 \({}^{\circ}\)C (Figure 12), 18% increase in resilient modulus at 40 \({}^{\circ}\)C (Figure 12), 26% reduction in permanent deformation, similar (0.5% increase) indirect tensile strength and improvement in indirect tensile strength ratio from 58% to 61%. Regarding the effects in the polymer modified binder (NCMA), the modification lead to 3% increase in resilient modulus at 25 \({}^{\circ}\)C (Figure 12), 12% increase in resilient modulus at 40 \({}^{\circ}\)C (Figure 12), 29% reduction in permanent deformation, similar (0.5% increase) indirect tensile strength, and improvement in indirect tensile strength ratio from 69% to 72%. [PERSON] et al. [92] evaluated the effects of the modifications with non-modified montmorillonite nanoclay (NC) and polymer-modified montmorillonite (PNC) in the performance of an asphalt mixture (NMAS 9.5 mm). The control binder was the PG 58-34 and were studied the dosages of 2% and 4%. The modification with NC presented stronger effects with the higher dosage (4%) while the modification with PNC, with exception of permanent deformation test, presented higher effects with the 2% dosage. With the 4% NC modification, the authors reported 9% increase in indirect tensile strength (Figure 8), 15% average increase in dynamic modulus, 25% increase in resilient modulus (Figure 12) and 59% reduction in permanent deformation (rut depth using APA rutting test).