https://arpi.unipi.it/bitstream/11568/798598/2/polacco%20798598.pdf

A review of the fundamentals of polymer-modified asphalts: Asphalt/polymer interactions and principles of compatibility

The detrimental effects of water in asphalt mixtures and its manifestation as distresses in asphalt pavements were first recognised in the 1930s and have been studied extensively during the last 35 years. This deterioration process, referred to as moisture damage, is generally defined as the degradation of the mechanical properties of the material due to the presence of moisture in its microstructure. Moisture damage is a complex phenomenon that involves thermodynamic, chemical, physical and mechanical processes. This paper describes the processes by which moisture damage affects asphalt mixtures. A critique of various moisture damage mechanisms is presented, followed by a review of recent work on modes of moisture transport (i.e. water permeability, capillary rise and vapour diffusion) and their relationship to moisture damage. Special attention is given to the characterisation of void structures of asphalt mixtures, which is an important factor that influences moisture transport. Finally, the paper pres...

Moisture susceptibility of asphalt mixtures, Part 1: mechanisms

Molecular dynamics study of oxidative aging effect on asphalt binder properties

Self-healing of open cracks in asphalt mastic

Performance of Warm Mix Asphalt containing Sasobit®: State-of-the-art

The ability to quantify adhesion based on surface energies of the bitumen and aggregate components enables selection of compatible materials and quantitative assessment of moisture susceptibility. Reliable surface energy characterization is required in order to implement this technology successfully. One proven method to estimate bitumen surface energy is to calculate it using contact angles measured with various liquids. However, improper selection of probe liquids or interpretation of resulting data can easily mislead users into drawing inaccurate conclusions. This paper presents a refined test method and analysis procedure customized to estimate bitumen surface energy using contact angles measured by the Wilhelmy plate. Results for five neat and three modified bitumen are presented and results are interpreted to study the relationships between contact-angle based surface energies and damage in hot mix asphalt. In a separate study by Bhasin et al. in 2004, surface energy characteristics of bitumen determined using methods described in this paper were combined with surface energies of aggregates to successfully predict moisture susceptibility of mixes.

Bitumen Surface Energy Characterization Using a Contact Angle Approach

The loss of physical adhesion between the aggregate and the asphalt binder is one of the important mechanisms that accelerate moisture damage in hot-mix asphalt pavements. In this study, two parameters related to bond energy—adhesive bond energy between the aggregate and the asphalt and reduction of free energy when asphalt debonds from the aggregate surface in the presence of moisture—were quantified with surface energies of both materials. Threshold values of these parameters to identify asphalt-aggregate combinations susceptible to premature moisture damage were derived by comparison of the values of these parameters with observed field performance for several mixes. Results show significant differences in bond energies developed between various aggregates and a given binder. This finding illustrates the importance of binder-aggregate compatibility and the sensitivity of calculated bond strength to surface energy measurements. Asphalt binders from different sources with the same performance grade were ...

Limits on Adhesive Bond Energy for Improved Resistance of Hot-Mix Asphalt to Moisture Damage

Moisture damage in asphalt concrete pavements is a major cause for high maintenance costs of state and federal highways. Moisture damage in asphalt concrete is largely due to loss of adhesion between bitumen and aggregate, and loss of cohesive strength in the mastic (bitumen and mineral filler). Surface energy components of bitumen and aggregate are used to calculate their interfacial bond strength and effectively quantify moisture susceptibility of asphalt concrete mixes. This technology has several advantages over conventional mechanical tests currently being used to identify moisture susceptible mixes. However, accurate surface energy characterization of bitumen and aggregate is the key element to calculate interfacial bond strengths. This paper presents development of a sorption based method to measure specific surface area and surface energy components of aggregate. Measured surface energy components and precision statements are presented for five aggregates. The paper also illustrates application of bond strengths calculated from surface energy components of aggregate and bitumen in the selection process of compatible pairs of aggregate and bitumen to produce a durable mix.

Characterization of Aggregate Surface Energy Using the Universal Sorption Device

This document is the final report of an investigation of the effectiveness and practicality of surface energy measurement as a tool for routine screening and selection of materials for optimum performance of hot-mix asphalt pavements. A summary of the report was published as NCHRP Research Results Digest 316.

Amit Bhasin

Papers

Moisture susceptibility of asphalt mixtures, Part 1: mechanisms

Bitumen Surface Energy Characterization Using a Contact Angle Approach

Limits on Adhesive Bond Energy for Improved Resistance of Hot-Mix Asphalt to Moisture Damage

Characterization of Aggregate Surface Energy Using the Universal Sorption Device

Using Surface Energy Measurements to Select Materials for Asphalt Pavement