Flexible or asphalt pavements constitute nearly 94% of the 2.7 million miles of existing roadways in the United States. In a typical rehabilitation project, the existing asphalt pavement is milled up to a prescribed depth for removing the near surface distresses such as excessive cracking and rutting, and a new overlay is placed. The average time between resurfacing projects varies depending on the level of pavement deterioration which is significantly accelerated when poor subgrade conditions are encountered. The use of geosynthetic reinforcement within the new asphalt overlay is often perceived as a mitigation strategy that can delay the onset and propagation of reflection cracking, and also control the rutting and differential settlement. However, some mixed reviews about the performance of the geosynthetic reinforced overlays have been reported in the literature. In Phase I of this study, a laboratory investigation was conducted for evaluating the flexural fatigue behavior, permanent deformation response, and fracture characteristics of geogrid reinforced asphalt beam specimens made from a typical overlay material. The laboratory specimens included geogrid as a single-layer inclusion either at the bottom third depth or at the mid height, and as double-layer inclusion, with geogrid placed both at the bottom third and at the middle of the beam. In Phase II, a case study involving geogrid reinforced overlay constructed over a deteriorated pavement underlain by soft subgrade in southeastern Florida was numerically simulated. It was found that the geogrid reinforcement significantly improved the fatigue and fracture properties of the asphalt beams compared to unreinforced specimens. Results from numerical simulation demonstrated that the double reinforced overlay resulted in the minimum tensile stress at the bottom of the asphalt layer (reducing the cracking potential) and minimum vertical strain on the top of the subgrade (reducing the rutting potential), compared to unreinforced or bottom-third reinforced overlays. Accordingly, it is concluded that the double layer reinforcement of asphalt overlays with an appropriate geosynthetic product can be beneficial for the performance and long term preservation of the pavement system when soft soils are encountered. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

The highway network in the United States, specifically reinforced concrete bridges, is deteriorating at a rapid rate. It is known that chloride-induced corrosion of the reinforcing steel is one of the major causes of the deterioration of concrete bridge decks. Numerous bridge deck protection and overlay systems have been developed to reduce the deterioration rate caused by chloride-induced corrosion. This study investigated the service life of untreated concrete bridge decks and four bridge deck overlay systems: low-slump-dense concrete (LSDC), latex-modified concrete (LMC), micro-silica concrete (MSC), and preformed membranes with hot-mix asphalt overlays (PM-HMA). The research plan consisted of organizing and analyzing data obtained in a 1991 field survey of 52 bridges from various locations in the nation. The field survey was conducted to gather information on existing conditions of untreated and rehabilitated bridge decks. Corrosion measurements were taken to assess the performance of each technique. Statistical models that predict the percent of deterioration on a bridge deck and the corrosion rate for each technique were developed from the field survey data. The components of a deterioration model were combined to define the service life for each bridge deck overlay system and for untreated concrete bridge decks. Other service life estimates for untreated bridge decks and bridge deck overlay systems were also compared. Based on the statistical analysis and service life comparisons, a service life estimate was recommended for predicting the service life for three of the bridge deck overlay systems. / Master of Science

by Chu Shun-wah, Sum Pun-wah, Jeremy. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 85-86). / ABSTRACT --- p.ii / TABLE OF CONTENTS --- p.iii / LIST OF ILLUSTRATIONS --- p.v / LIST OF TABLES --- p.vi / Chapter / Chapter I. --- INTRODUCTION --- p.1 / Background Information of the ILF --- p.2 / Paving Operations --- p.2 / Working Environment --- p.7 / Chapter II. --- PRELIMINARY UNDERSTANDING OF THE PROBLEMS --- p.9 / Interview with Staff Side od the ILF --- p.9 / Interview with the Management side of the ILF --- p.10 / Chapter III. --- STATISTICAL ANALYSIS --- p.12 / Explanatory Notes for the Cost Elements --- p.13 / Data Analysis --- p.16 / Sampling --- p.17 / Visual comparison of the cost data --- p.18 / Statistical Parameters Analysis --- p.19 / Test for the Equality of Variances for Both Samples --- p.20 / Test for the Equality of Means for Both Samples --- p.21 / Interpretation of Results --- p.23 / Paired T-test --- p.25 / Chapter IV. --- MAIN COST FACTORS ANALYSIS --- p.26 / Salary of Direct Labour --- p.26 / Material Cost --- p.28 / Hire of Services --- p.30 / Chapter V. --- SOLUTIONS TO PROBLEMS --- p.33 / Salary of Direct Labour --- p.33 / Material Cost --- p.36 / Hire of Services --- p.37 / Chapter VI. --- ALTERNATIVE ANALYSIS --- p.39 / Visual Comparison of Cost Data After Allocation of Fixed Cost --- p.41 / Statistical Analysis --- p.42 / Interpretation of Results of Alternative Analysis --- p.44 / Chapter VII. --- GENERAL RECOMMENDATIONS --- p.45 / Chapter VIII. --- CONCLUSION --- p.52 / APPENDIX --- p.64 / BIBLIOGRAPHY --- p.85