Moisture Damage Resistance of Hot Mix Asphalt made with Recycled Rubber Materials and Determining the Optimal Percentage with an Economic Approach

Moisture susceptibility is one of the most important distresses that affects the life of the flexible pavement. Various methods, such as adding the appropriate additive, have been proposed to improve the asphalt mix properties. Some of these additives have environmental, and some have economic characteristics. In this study, three additives were used to study the moisture susceptibility and rutting of Hot Mix Asphalt (HMA), including rubber powder (RP), Tire Reclaim (TR10), and Butyl Reclaimed (BR120). For this purpose, the Marshall Stability test, Marshall Ratio (for determining the rutting), and Indirect Tensile Strength (ITS) were performed on the samples. Also, the economic analysis of the additive's effects on HMA was evaluated. The results of the Marshall test showed that adding all three additives increased the Marshall Stability and the Marshall ratio. As a result, adding TR10 and BR120 improved the Marshall ratio or rutting more than rubber powder. Indirect tensile strength test results also showed that the addition of rubber powder and TR10 led to improved HMA performance against moisture susceptibility. However, the use of BR120 as an additive reduced HMA moisture susceptibility. On the other hand, the economic analysis showed that adding 20% of rubber powder and TR10 would make the project much more economical. Further, adding BR120 to the asphalt mix provided economic benefits in every percentage. Consequently, based on the presented arguments, adding 20% of rubber powder and TR10 for technical and economic reasons leads to the best result.