Investigation of the use of geopolymers obtained from garbage wastes in hot mix asphalt pavements

In this study, the effect of using ashes obtained from garbage waste as a geopolymer in asphalt as an additive on the performance properties of hot mix asphalts (HMA) were investigated. For this purpose, firstly, geopolymer modified binders were prepared by adding 1.25%, 2.5%, 5% and 7.5% ash by weight and sodium silicate (AA) up to 45% by weight of ash into the asphalt binder. Characteristics of pure and modified binders were determined by softening point, penetration, ductility, specific gravity, flash point, thin film oven (TFO), storage stability, rotational viscometer (RV), dynamic shear rheometer (DSR), bending beam rheometer (BBR), linear amplitute sweep (LAS) and multiple stress creep rebound (MSCR) tests. The microstructural properties of the binders were determined by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and elemental analysis tests. Then, HMA samples were prepared with pure and geopolymer added binders based on Marshall mix design method. These samples were subjected to performance tests such as Marshall stability and flow, retained Marshall stability (RMS), indirect tensile strength (ITS), Modified Lottman, indirect tensile stiffness modulus (ITSM), dynamic and static creep, indirect tensile fatigue test. According to the binder test results, it was determined that the hardness of the binder increased and the penetration class changed, the temperature sensitivity decreased and the aging resistance increased with the geopolymer additive. In addition, it was observed that both high and low temperature resistances of the binders increased with the geopolymer additive and the binder performance grade changed from PG 58-28 to PG 70-34 class at the rate of 2.5% geopolymer. In addition, it was determined that the geopolymer additive a homogeneous and single-phase stable structure by chemically reacting with the asphalt. According to the mixture test results, it were observed that the stability, moisture resistance, permanent deformation resistance and fatigue life of the mixtures produced with the 2.5% geopolymer ratio increased significantly. As a result, the applicability of the ashes obtained from the garbage wastes as a geopolymer in asphalt and therefore HMA in highway engineering has been determined.