The Effects of Moisture Damage on Asphalt Mixtures Modified with Additives and Polymer

One of the causes of premature failure is moisture damage due to loss of adhesion and cohesion which then lead to stripping and decrease in mixture strength. previous studies have shown that adding additive, such as nano clay, nano carbon and nano calcium, to binder is useful in enhancing mixture properties. in this study, the effect of adding nano-clay on mixture properties was determined. nano clay in the amount of 2 and 4% by weight of bitumen was added to 60/70 penetration grade bitumen and mixed at a temperature of 150°c using the melt blending technique at a shear rate of 2000 rpm. the indirect tensile strength (its) test was used to evaluate the cracking properties of the asphalt mixtures and the tensile strength ratio (tsr) was calculated to determine the degree of asphalt mixtures’ resistance to moisture damage. the results for the mixtures modified with nano clay were compared with results for mixtures modified by adding 2 and 4% by weight of bitumen polymer modified bitumen (pg76), hydrated lime and cement. the addition of polymer appears to result in the greatest potential benefit amongst the modified binders and its highest tsr value indicate that polymer modified binder is the least susceptible to moisture damage.