Moisture Resistance of Bituminous Hot Mixtures Modified with Waste PET

In this study, effect of waste PET additive on moisture damage resistance of bituminous hot mixtures were investigated. For this purpose, firstly, 2.5% by weight Triethanolamine (TEO/TEOA) chemical was added to pure B 70/100 bitumen to create a chemical bond between bitumen and PET. Then, modified bitumens were obtained by adding waste PET in the ratios of 2%, 4%, 6%, 8% and 10% by weight of bitumen to this bitumen-TEO blend. Modified bitumen samples were subjected to X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) tests to determine the interaction between bitumen and PET. In the second stage of the study, the optimum bitumen content (obc) of the mixture was determined according to Marshall mixture design method using pure bitumen and aggregate. Modified mixture specimens were prepared by keeping this bitumen ratio constant in order to compare it with pure (control) mixture results. The mixture specimens prepared were subjected to Marshall stability and flow, retained Marshall stability (RMS) and indirect tensile strength (ITS) tests. According to the test results, it was observed that bitumen tends to harden with the addition of waste PET and a good chemical interaction occurs between bitumen and PET. In addition, it was observed that the waste PET additive did not have a serious effect on the Marshall stability and flow value of the mixtures, but increased the moisture damage resistance of the mixtures by generating significant increases in RMS and indirect tensile strength ratio (ITSR) values.