Stiffness and drainage characteristics of unbound aggregate bases

Abstract This study focused on evaluating the effect of various gradations on the resilient modulus (Mr) and permeability of two-limestone aggregate bases, known as Dolese and Anchor. Three gradations, namely, upper limit of Oklahoma Department of Transportation (ODOT) Type A (UL-A), lower limit of ODOT Type B (LL-B) and lower limit of ODOT Type C (LL-C) were used to prepare specimens. Specimens were compacted at moisture contents drier than the optimum moisture using the same energy specified by the AASHTO T 180 test method. Results showed that the Mr values of specimens with UL-A gradation were higher than the Mr values for LL-C specimens, followed by LL-B. In addition, Dolese specimens exhibited higher Mr values compared to the corresponding values of Anchor. It was also found that the Mr values decreased with the uniformity of coefficient and the coefficient of gradation. On the other hand, the resilient modulus increased with the percent passing US Standard No. 200. In addition, higher coefficient of permeability (k) values were obtained for LL-B specimens, followed by LL-C and then UL-A. The Mr results determined in this study were within the range reported in the literature and the actual k values were lower than the k values predicted from existing regression models in the literature.