Investigation of the Impact of Deicer Materials on Thermodynamic Parameters and Its Relationship with Moisture Susceptibility in Modified Asphalt Mixtures by Carbon Nanotube

Road maintenance in winter is one of the road engineers' concerns, especially asphalt specialists. As pavement frosts lead to road closures and accidents, one of the ways to prevent these events is spraying deicer materials on the pavement surface. Therefore, investigation of the impact of the deicer materials on asphalt is essential. So in this study, the effect of deicer materials on the moisture susceptibility of base asphalt mixtures and modified ones by carbon nanotube (CNT) was investigated utilizing penetration and softening point tests and surface free energy (SFE) concept and dynamic modulus (DM) test. Two common deicers CaCl2 and MgCl2 along with distilled water (DW) were used. Results indicated that using CNT increased the softening point and reduced the penetration degree of modified bitumens, which increased the penetration index amounts and improved the sensitivity of the samples against temperature variations. The SFE results showed that modifying bitumen with CNT led to an increase in adhesion free energy (AFE). The samples saturated in CaCl2 and modified with 1% CNT had the highest CFE values. The MgCl2 solution had less detachment energy, which reduced the energy of the system and stripping occurred sooner. Results of the DM test showed that CNT increased the wet-to-dry DM ratio in saturated conditions with deicer materials and DW, improving the resistance of the saturated mixtures to moisture. The GMDH model compared to the MVR method had higher accuracy and less error in prediction of stripping percentage with the R-2 value of 99.46%.

Automated summary

The study found that using CNT can promote the modification of asphalt, increase its penetration index and softening point, and improve the sensitivity of samples to temperature changes. In addition, using CNT can also increase the surface free energy (SFE) of modified asphalt, making it more adhesive. Under saturated conditions with deicer materials and distilled water, CNT can also increase the wet-to-dry dynamic modulus ratio of modified mixtures, enhancing the resistance of samples to moisture.