EFFECT OF SEGREGATION ON HOT MIX ASPHALT PROPERTIES AND PERFORMANCE

Abstract

This thesis is conccmed with the effects of segregation on the properties of hot mix asphalt (HMA) and the relationships bet wee;; segregation and pavement distresses. The objectives and scope of work for this study are to; propose a classification for segregation in HMA, evaluate the effects of segregation in HMA on the properties of the mix (density, air voids. voids in mineral aggregate, and asphalt cement content), and to study the relationship between the segregation in HMA and some pavement distresses (raveling, rutting, and fatigue).

Five pavement test sections were selected for research investigation. Three of them were newly constructed pavements or under construction, the other two pavement sections were old deteriorated constructed between "I 980 and 1985" both exhibited two types of distresses; raveling and fatigue cracking. The new pavements were evaluated to study the effects of segregation on the properties of HMA (density, air voids, voids in mineral aggregate, and asphalt cement content). The old pavements were evaluated to study the relationship between segregation and pavement distresses. A thorough literature review was conducted. Previous research covering causes and remedy of segregation, effects of segregation on HMA properties (density, air voids, voids in mineral aggregate, and asphalt cement content), and the rel tionships between segregation and some pavement distresses (raveling, rutting, and fatigue) were reviewed.

The overall plan of study, laboratory investigation plan, and summary of test results are presented in Chapter 3. Forty-two cores were extracted from site (I) in Mussafah west nearby Abu Dhabi city, ten cores from site (2) 5-km from site (I) on AI Ain - Abu Dhabi truck road, ten cores from site (3) in Bani-Yas city 25-km from Abu Dhabi city, nine cores from site (4) nearby Urn Al-Nar refinery, I 0-km from Abu Dhabi city, and eleven cores from site (5) in Mussafah east. Tests were perfonned to detennine the mixture properties in the laboratory. The nuclear thin-lift gauge was used to locate the segregated areas and samples were obtained from segregated and adjacent non-segregated areas.

Rutting and fatigue data were obtained from previously published studies. The data were analyzed statistically and statistical models were developed for; the effects of segregation on HMA properties, relationships between segregation and each of raveling, fatigue life and rutting.