Development of Performance-Related Specification for Fresh Emulsions Used for Surface Treatments and Performance Study of Chip Seals and Microsurfacing

Pavement preservation is a rapidly growing strategy for prolonging pavement service life. Pavement preservation consists of applying a thin layer of asphalt binder or emulsion with or without aggregate to the surface of an existing pavement. Preservation treatments do not provide any structural strength to the pavement but restores skid resistance, seals existing cracks, protects the underlying pavement from intrusion of water, and reduces further oxidative aging of the underlying pavement. In recent years, significant research has been dedicated to improving design of pavement preservation treatments.;In pavement preservation treatments, asphalt emulsion is the predominant binding material used because of its low viscosity compared to asphalt cement which allows for production at greatly reduced temperatures, leading to energy efficiency, and potential cost savings. Currently, specifications for emulsions used in pavement preservation treatments are empirical and lack of direct relationship to performance. This study seeks to improve specifications for emulsions used in preservation treatments by developing performancerelated specifications (PRS) for (a) fresh emulsion properties, (b) microsurfacing emulsion residue, and (c) low-temperature raveling of chip seal emulsion residues.;Fresh emulsion properties dictate constructability and stability, and consequently the resultant performance of a preservation treatment once placed. Specification test methods are proposed for chip seals, microsurfacings, and spray seals that reflect storage and construction conditions of the emulsions. Performance is quantified using viscosity measurements. Specification limits are determined based on a prior knowledge of emulsion performance coupled with statistical analyses.;Microsurfacings are a preservation treatment consisting of application of a thin layer of asphalt emulsion -- fine aggregate mixture. Presently, mixture design and performances of microsurfacing mixtures are appraised using the procedure specified by the International Slurry Surfacing Association (ISSA) with no provision for quantifying microsurfacing residue performance. In this study, residue performance is quantified using the Multiple Stress Creep and Recovery (MSCR) test for rutting and bleeding, the Bitumen Bond Strength Test (BBS) for raveling, Low Temperature Frequency (LTF) test for low temperature Bending Beam Rheometer (BBR) properties prediction, and Single Edge Notched Bend (SENB) fracture test developed under this work. Microsurfacing mixture performance is quantified using the Wet Track Abrasion Test (WTAT) for raveling, Model Mobile Load Simulator (MMLS3) for rutting and bleeding, and SENB test developed for low-temperature cracking. Microsurfacing mixture performance is correlated to residue properties in order to identify critical emulsion residue properties in determining performance and to derive specification limits. Results indicate rutting and thermal cracking are the distresses most directly related to the emulsion residue performance. Correspondingly, specifications are proposed to address rutting at high temperature and thermal cracking at low temperature based on the relationship between residue and mixture results coupled.;In addition, test methods and specification criteria are developed to address lowtemperature raveling resistance of emulsion residues used in chip seals. The SENB test is used to quantify residue resistance to thermal cracking under the assumption that lowtemperature raveling occurs primarily by cohesive fracture of the residue in the chip seal. The Vialit test is modified and employed for quantifying raveling resistance of chip seals mixture for determining if the SENB test captures binder contribution to mixture raveling. The correlation between residue and mixture properties have been used to assess applicability of the residue tests and to derive specification limits.