Modification of the Properties of Warm Mix Asphalt Using Recycled Plastic Bottles

The construction of flexible pavements with hot mix asphalt (HMA) consumes considerable energy, which impacts global resources and environment. Warm mix asphalt (WMA) is an effective alternative because it is produced with mixing and compaction temperatures lower than those used in HMA production. This technology decreases energy consumption, saves money and reduces the environmental pollution. Moreover, this technology can generate a revolution in sustainable construction if combined with the use of waste materials to improve the properties of WMA. Polyethylene terephthalate (PET) wastes are increasingly accumulated over the world. However, to the best of knowledge of authors, no research has adopted using PET wastes in combination with improving WMA properties. Therefore, the present study covers the usage of PET waste bottles to modify the properties of WMA. Ground PET waste bottles with a maximum particle size of 2.36 mm with different contents (0.1, 0.3, 0.5, 0.7, 0.9 and 1.1% by the weight of aggregate) were used to replace an equivalent portion of fine aggregate. Laboratory tests were conducted to investigate the effects of different PET contents on the properties of WMA. The testing programme included Marshall, rutting susceptibility and indirect tensile strength (ITS) tests. Results exhibited significant improvements in the engineering properties of the mixtures modified with the optimum PET content (which was found to be 0.5%) in terms of increase in stability, stiffness, ITS and moisture damage resistance and decrease in rutting susceptibility, without adverse effects on the other desirable properties of the mixtures.