Effect of zycotherm on moisture susceptibility of Warm Mix Asphalt mixtures prepared with different aggregate types and gradations

Asphalt concrete mixtures have various types of distresses, of which, water damage referred as stripping is a major form. This paper is aimed to determine effects of zycotherm- a liquid and nano-organosilane warm mix and anti stripping additive- on water susceptibility of Warm Mix Asphalt mixtures prepared with different aggregate types and gradations. Hence, X-ray Fluorescence (XRF) test was performed on aggregates, Fourier Transformed Infrared spectroscopy (FTIR) test was performed on original and modified binder. Moreover, a total number of 252 asphalt mixtures were fabricated and water damage related test methods such as AASHTO T283 (modified Lottman test), Resilient Modulus Ratio (RMR), Marshall Stability Ratio (MSR), Fracture Energy Ratio (FER) and boiling water were used. The results indicated that although zycotherm significantly improves water susceptibility performance of asphalt mixtures prepared with all aggregate types and gradations, it does not function properly as a WMA additive because an effective additive should improve both the unconditioned and moisture conditioned characteristics of bituminous mixtures to make sure appropriate performance of asphalt pavements in the long run. It was also observed that although gradation of aggregates affects the results of tests related to functional properties of both Hot Mix Asphalt and WMA, types of aggregates seems to have greater impact and it is highly recommended not to use siliceous aggregates without an effective anti-stripping additive because all HMA (control) samples prepared with siliceous materials did not satisfy the least acceptable value to ensure good functioning against stripping of the mixtures.