The Development of Moisture Sensitivity Test for Compacted Asphalt

Abstract

Moisture damage is one of the major issues in asphalt distress. It is due to the adhesive and
cohesive failure of asphalt mixture and it will shorten pavement life. Moisture-sensitive
mixtures need to be identified during the course of the mixture design process which fulfills
the specified minimum standard. The laboratory testing procedures currently available for
compacted Hot Mix Asphalt (HMA) to test the moisture sensitivity were primarily developed
to determine the degree of resistance to moisture damage by a particular combination of
asphalt and aggregate. These moisture sensitivity tests evaluate the effect of moisture damage
in laboratory by measuring the relative change of a single parameter before and after
conditioning (i.e., Tensile Strength Ratio, Resilient Modulus Ratio). The tests were simple to
conduct and widely accepted by various state and federal agencies, but their drawback include
the empirical nature of the procedures, the dependence of the results on the moisture
conditioning methodology and in several cases, the poor correlation with field performance.
Many new approaches were conducted to overcome the weaknesses of the existing method.
These new approaches mostly designed to conduct the test as close as the field condition and
consider the material properties of asphalt to give the useful result for the asphalt
performance. For better asphalt mixture design, it needs to have the test procedure which
considered the effect of traffic loading. The moisture conditioning methodology should avoid
using the vacuum saturation method since this method contributes to the asphalt mixture
strength. The scale of performance measurement can be conducted either microscale or
macroscle. Besides that the test also must be repeatable, reproducible, feasible, practical, and
economical enough that it can be included in routine asphalt mixture design practice.