Eliminating the Stripping Potential of the Sioux Quartzite by Means Other Than Hydrated Lime

Moisture damage, otherwise known as Stripping or Debonding , to hot mix asphalt pavements has been a sporadic but persistent problem in the United States. Hydrated Lime is widely being used as an antistripping additive for reducing moisture damage susceptibility of asphalt concrete mixtures. However, the practice of using Lime is posing some problems to the asphalt industry in the United States due to uneven dispersion, removal of lime from aggregate surface before coating with asphalt cement, messy operation, skin irritation, hazardous breathing, and higher production cost associated with reduced production. One of the main objectives of this research project is to identify an alternative antistripping agent, in a liquid form, that produces equal, if not better, results to that of Lime. With this end in view, eight different antistripping additives including Hydrated Lime as a control, were studied to observe the stripping resistance of each additive when included in the asphalt hot mixtures. Liquid antistripping agents were mixed with the asphalt first and then both asphalt and aggregate were mixed to form the hot mixtures. In this study, only Quartzite aggregate was used. Two different gradations, namely dense and gap, were tested. ASTM D-1664, ASTM D-3625, ASTM D-4867, and AASHTO T-283 test methods have been used for the evaluation of stripping resistance of different additives. Statistical analysis of test results indicates that Hydrated Lime has the greatest potential for reducing moisture damage susceptibility. Two liquid antistripping agents (Redicote, and Tall Oil) have been identified to have similar effect to that of Hydrated Lime in reducing stripping potential of quartzite. Parameters such as Indirect Tensile strength (ITS), Tensile strength Ratio (TSR), and visually observed stripping of specimens made with the two liquid antistripping agents were not significantly different from those produced with the Hydrated Lime