Evaluation of Durability of Existing Base Aggregates in Wisconsin Pavements

Abstract

ABSTRACT EVALUATION OF DURABILITY OF EXISTING BASE AGGREGATES IN WISCONSIN PAVEMENTS by Mahmoud Dakwar The University of Wisconsin-Milwaukee, 2017 Under the Supervision of Professor Hani Titi Highways are an integral part of modern societies, and high volumes of traffic are serviced by highways every hour of the day year-round. The base-course aggregate layer acts as the foundation of the pavement system, and it supports the overlaying layers in the pavement structure. The objective of this research study was to evaluate the durability of existing base-course aggregates as they are impacted by external factors. Samples from fourteen sites were collected and additional data were obtained from other relevant studies. Aggregates from eleven sites out of the fourteen served in base layers. Durability and strength related lab tests were performed on the collected samples, and the test results along with the data from other studies were analyzed by utilizing visual comparison statistical procedures and regression statistical methods. For the eleven samples of existing base-course aggregates, the results of the Micro-Deval abrasion test showed that two samples exceeded a recommended threshold limit of 18%, the results of the sodium sulfate soundness test showed that none of the samples exceeded the Wis.DOT threshold limit of 18%, and the results of the aggregate absorption test showed that six of the samples exceeded a recommended threshold limit of 2%. For the entire data used in the study, the results of regression analyses showed that the regression model MD% Loss = 5.62 × Absorption + 2.09 (with R2 value of 0.86) can be used to make predictions and assess the performance quality of base-course aggregates accurately. The regression analyses results also demonstrated that the mass loss by sodium sulfate soundness test did not have strong correlations with either absorption or the mass loss by Micro-Deval abrasion.