Effect of hydrated lime addition to highway flexible pavements on low temperature cracking strength

The districtions on highway pavement occur according to the trafic and enviromental factors that effect the superstructure. Vehicle loads affect the superstructure by transferring from the axles to the wheels; and cause tension and compression stress in the superstructure. Moreover, the changes in the enviroment temperature cause stresses in the pavement. While the asphalt pavement tries to shrink in cold air conditions; the friction between the layer under it and the mesolayer prevents it from shrinking, so stresses eventuate in the pavement. When the mentioned stresses that occur in the pavement in cold air conditions exceed the tension strength; lateral cracks generate in the pavement. The crack which form perpendicularly to the highway axis are called ?low temperature cracking?. The water leaking from these crack get deeper by time; cause early damages in the asphalt mixture and compose major harm in the pavament. In this study, the effects of adding hydrated lime in certain proportions instead of filler material on cold air resistance is analyzed. With this purpose, a total number of 104 asphalt bricets (lime free, %2, % 4, %6 lime added) were produced. The weights of these samples in air and water, the heights of the samples were measured to calculate their density and void rates. After that, Marshall stability and indirect tension strength tests were applied to the samples (after some certain stages). As a result of the tests, the addition of hydrated lime is determined to increase the strength of the highway pavement against cold temperaturesand water effects. Generally the strength values of lime conditioned materials are to be higher than that of the lime-free materials. Among the premediated mixtures; the best experiment results were obtained with %4 lime-added samples. As a consequence; it is thought to be effective to prevent the interstitials in the highways in the cold climate conditions. Key Words: Highway flexible pavement, low temperature cracking, Marshall stability test, indirect tension strength, hydrated lime