Effect of Filler Type and Particle Size on Moisture Susceptibility of Stone Mastic Asphalt Mixtures

Moisture damage is one of the common distresses found in asphalt pavements and moisture sensitivity in asphalt concrete mixtures is often associated with high concentrations of fine aggregate particles. Fines in asphalt pavements can have a detrimental impact on asphalt mixtures because of their impact on mixture stiffness, air voids content, and moisture sensitivity. This study aims to evaluate and to examine the moisture susceptibility behavior of the laboratory performance-based properties of Stone Mastics Asphalt (SMA) mixtures using four different mineral fillers (limestone as reference, ceramic waste, coal fly ash, and steel slag). The selected fraction of mineral filler was blended in three different proportions 100/0, 50/50, and 0/100 passing the 75 and 20 micron to determine the effects of these fillers and particle size on the SMA mixture properties such as Stiffness, Retained Marshall Stability (RMS), and Moisture Susceptibility. The coarse aggregate and Fine aggregate fractions were kept constant throughout the study and the binder content of each aggregate mix was optimized using the Marshall Mix Design Method. The results of the study showed that the SMA mixtures are not prone to moisture damage and the uses of these fillers are very effective in improving Marshall Stability, Stiffness Modulus (Sm), and Tensile Strength Ratio (TSR) values. Specimens containing ceramic waste with a filler ratio of 50/50, have the highest stiffness modulus which is 1.03 times higher than those of the reference mixture and on the other hand , coal fly ash and steel slag with a 50/50 filler ratio showed slight reduction in stiffness modulus compared to the reference mixture. Specimens containing ceramic waste with a filler ratio of 0/100 showed the least reduction in tensile strength ratio and Retained Marshall Stability while steel slag and coal fly ash maintaining more than 85 and 80 percent Tensile Strength Ratio, 85 and 70 percent retained Marshall Stability respectively.