Effect of Gradation Segregation on Resistance of Moisture-induced Damage of Asphalt Mixture

The regularities of spreading segregation and compaction segregation of AC-25 and AC-13 asphalt mixtures were investigated according to the results of gradation test and non-nuclear density gauge test.Mixtures of simulated gradation segregation and compaction segregation were designed based on the segregation regularities above to evaluate the resistance of moisture-induced damage with simulated dynamic water pressure test.Compared with splitting test results of target gradation of AC-13 asphalt mixture of maximum coarse gradation segregation allowed showed a splitting strength loss of more than 30% after dynamic water erosion at 25 ℃ for 3 h(after 1 350 positive- negative pressure cycles),so does asphalt mixture of simulated gradation segregation of paver edge.As for inadequately compacted asphalt mixture of maximum coarse gradation segregation allowed,splitting strength lost at 25 ℃ reaches 48.2% after dynamic water erosion for 3 h.Even without consideration of inadequate compaction,neither asphalt mixtures of coarse gradation segregation nor asphalt mixture of simulated gradation segregation of paver edge has sufficient resistance of moisture-induced damage.Finally,suggestions on gradation control in asphalt mixture production and spreading on site from the point of view of keeping mixture moisture stability were given.