The research presented in this thesis: (1) quantifies and qualifies the Surface Free Energy (SFE) of neat and Liquid Anti-Strip (LAS) modified asphalt binders (binder); and (2) identifies volumetric mix properties that inhibit or assist in the susceptibility of Hot Mix Asphalt (HMA) to moisture damage based on time dependent phenomenological mechanical responses. These two research elements provide insight into the physical, chemical, mechanical and volumetric mix properties that inhibit or facilitate moisture damage in HMA.
Moisture damage is a mechanism that causes distress and failure in asphalt concrete (AC) pavements due to a loss of durability resulting from the presence of moisture, in the form of a vapour or liquid, originating internally or externally. This reduces the pavements performance by promoting distresses such as: longitudinal cracking, spalling, rutting, shoving, stripping and ravelling. When moisture originates or is introduced in the AC a weakening of adhesion and cohesion of the material occurs, due in part to: binder properties, aggregate properties, volumetric mix properties, environmental conditions, traffic volume and loads, pavement design and construction practices.
The research performed was split in two parts. The first part consisted of conducting SFE measurements on two PG 58-34 binders with different sources. One binder was modified with a LAS agent at concentrations of 0.5%, 2.0% and 5.0% by mass of binder and the other binder was kept neat. The neat and LAS modified binders were subjected to short-term aging by oxidation and then tested with a goniometer to determine their SFE and wettability.
The SFE measurements revealed that an LAS concentration of 0.5% maximizes: (1) the work of adhesion of an unaged and aged binder, and (2) the ability of the binder to repel water. Furthermore, the process of aging increases the hydrophobicity or tendency of the binder to repel water regardless of the LAS concentration. Hence, an LAS concentration of 0.5% minimizes the potential for moisture damage in HMA.
The second part of the research consisted of investigating the potential for moisture damage of seven bituminous type B (Bit B) and eight bituminous type C (Bit C) mix specified by Manitoba Infrastructure and Transportation. Laboratory testing of the resilient modulus and creep compliance was conducted to determine the fundamental mechanical response of the material. The resilient modulus and creep compliance test program were conducted on samples before and after moisture conditioning. As a result of the testing program, it was observed that the susceptibility of AC to moisture damage based on volumetric mix properties can be dependent on the air voids ratio, aggregate gradation and binder content of the mix.
| Identifer | oai:union.ndltd.org:MANITOBA/oai:mspace.lib.umanitoba.ca:1993/22197 |
| Date | 19 September 2013 |
| Creators | Lambert, Jean-Luc |
| Contributors | Shalaby, Ahmed (Civil Engineering), Richards, Norman (Mechanical and Manufacturing Engineering) Bassuoni, Mohamed (Civil Engineering) |
| Source Sets | University of Manitoba Canada |
| Detected Language | English |
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