Date of Award
Doctor of Philosophy (PhD)
Civil and Environmental Engineering
Louay N. Mohammad
Large stone asphalt mixtures (LSAM) are mixtures that contains maximum aggregate sizes between 25 and 63 mm. LSAMs are used to improve the mixtures' resistance to rutting and also improve the durability of pavements. However, due to historical reasons, LSAM has been rarely used in pavement constructions. The objective of this study was to determine the fundamental engineering properties of LSAM for potential use in Louisiana and to conduct numerical simulations of pavements that contain LSAMs. The scope of this evaluation included two types LSAMs: an open-graded and a dense-graded 37.5-mm Superpave mix, and three types of asphalt binders: an SB polymer modified PG 70-22M, a conventional PG 64-ss, and a gelled asphalt, PG 70-22MAlt. The two LSAMs were compared to their corresponding conventional mixtures: Type 508 and Type 5A. Laboratory performance tests were conducted to characterize the rut susceptibility, durability, moisture susceptibility and permeability of these mixtures. A three dimensional dynamic finite element procedure was developed during this study. Advanced material models of viscoplasticity and elastoplasticity were incorporated into the 3-D dynamic finite element procedure. This procedure was used to compare the structural performance of two groups of pavements, each with two pavements, one with conventional mixtures and one with the LSAM developed in this study. The results indicated that the open-graded LSAM developed in this study exhibited better rut-resistance, durability and moisture susceptibility than the conventional LADOTD Type 508 drainable base mixture, whereas the dense-graded LSAM showed the similar laboratory characteristics to the conventional LADOTD Type 5A base mixture. Similarly, the numerical simulation indicated that the pavement containing open-graded LSAM provided increased structural support when compared to the pavement containing conventional Type 508 drainable mixture, whereas, the pavement containing the dense-graded LSAM showed no appreciable increase in structural support comparing to the pavement containing conventional Type 5A base mixture.
Huang, Baoshan, "Fundamental Characterization and Numerical Simulation of Large Stone Asphalt Mixtures." (2000). LSU Historical Dissertations and Theses. 7367.