Investigation of certain engineering characteristics of asphalt concrete exposed to freeze-thaw cycles

In this study the effects of freeze and thaw cycles on asphalt concrete materials are investigated for binder and wearing surface coats, separately, and for different freeze and thaw cycles. Asphalt concrete (AC) was produced in a laboratory environment, and tests were conducted. Different specimens were prepared with different binders and wearing course based on the calculated pre-optimum bitumen amount, and the optimum bitumen amount was experimentally determined for each layer. According to the value determined for amount of bitumen, 15 AC specimens were prepared for each layer, for a total of 30 specimens. The prepared specimens were exposed to freeze and thaw cycles for 6, 12, 18, and 24 days. Before and after each cycle, the voids ratios filled with asphalt (Vf), void ratio (Vh), and the voids ratios inside mineral aggregate (VMA) parameters; ultrasonic velocity; and Marshall Stability (MS) values were experimentally determined for each specimen. The results obtained for reference specimens were compared against the values experimentally obtained from the specimens that were exposed to the freeze-thaw effect for 6, 12, 18, and 24 days.

► The MS value was reduced by 77.4% and 63.8% for the binder and wearing course respectively. ► The Vf value was reduced by 10.6% and 11.0% for the binder and wearing course respectively. ► The VMA value was increased by up to 7.4% and 6.4% for the binder and wearing course respectively. ► The Vh value was increased by 61.9% and 70.0 for the binder and wearing course respectively. ► The ultrasonic velocity was increased by 19.6% and 29.8% for the binder and wearing course respectively.