Evaluation of the effects of anti-stripping agents on the performance of asphalt mixtures

• Asphalt mixtures containing anti-stripping additives exhibited improvement of adhesive property.
• Hydrated lime showed maximum coating in comparison with Iterlene In/400-S.
• Iterlene In/400-S and hydrated lime increase the indirect tensile strengths in dry and wet specimens.
• Applying anti-stripping agents promoted TSR values of asphalt mixes against moisture susceptibility.
• Iterlene In/400-S showed better results of TSR compared with hydrated lime.

Stripping is one of the most commonly occurring distresses in bituminous pavements. This occurs as a result of destruction of the bond between aggregate particles and bitumen. Impacts of traffic loading, aggregate type, bitumen characteristics and properties of the additives in mixes can modify resistance of mixes against moisture damage.This study is aimed at determining the effects of two different anti-stripping additives, namely hydrated lime and a liquid anti-stripping agent (Iterlene In/400-S) on hot mix asphalt (HMA). Moisture susceptibilities of samples were determined by analyzing digital images taken from coated aggregate particles after performing boiling water test (ASTMD 3625). In addition, Modified Lottman test (AASHTO T283) was performed on mixes containing 0.2%, 0.3% and 0.4% of liquid anti-stripping agent and mixes containing 1%, 1.5% and 2% of hydrated lime.The results indicated that the addition of hydrated lime and liquid anti-stripping agent increased moisture resistance of asphalt mixes to some extent (i.e. 13% and 16% of TSR ratio, respectively). Moreover, it was concluded that mix samples prepared using the liquid anti-stripping additive imparted more correlation and greater resistance to water damage, compared with control mixes and those containing hydrated lime.