Gradation Segregation Analysis of Warm Mix Asphalt Mixture

Abstract

In this study, properties of warm mix asphalt (WMA) compacted with various levels of gradation segregation were evaluated in the laboratory. Six segregated gradations were designed to compare with the control gradation and test sections were paved with the control gradation. Then pavement quality indicator (PQI) and field coring were used to evaluate the uniformity of the WMA test sections with the statistical method. In addition, sieve analysis of the cores was conducted to evaluate the level of segregation. The test results show that gradation segregation has a remarkable effect on water stability, high-temperature stability, low-temperature cracking, and tensile strength of WMA mixtures. Statistical analysis results show that the levels of segregation in localized areas are quite typical because the air void contents follow a normal distribution and the mixtures along the central line are denser than other areas. Sieve analyses of the cores show that most places of the typical segregated localized areas in the test sections have no segregation or low-level segregation, so the construction quality is good. It also shows that the air void content increases as the gradation gets coarser, which is consistent with laboratory test results.