Laboratory Evaluation of Moisture Damage in Asphalt Mixes
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Date
2020-04
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Addis Ababa University
Abstract
Moisture damage usually called stripping happen when water infiltrates between an asphalt
film and the aggregate surface, and replaces the asphalt aggregate's coating. These situations
cause a loss of bond between the aggregate and the asphalt cement. The most serious
consequence of stripping is the loss of strength and integrity of the pavement which result in
premature failure of asphalt pavement. Moisture damage contributes significantly to the
premature deterioration of asphalt pavements, which, leads to an increase vehicle operating
cost and maintenance costs of a pavement. These conditions also make driving dangerous,
and driving comfort and safety are often compromised.
This thesis utilized laboratory evaluations to study the effects of moisture damage in asphalt
mixes. Two different sources of aggregates and one type of asphalt binder were used. The
aggregates quality test were conducted namely Los Angeles abrasion, soundness loss, sand
equivalent, flakiness index, specific gravity and absorption. The asphalt binder conventional
tests were evaluated which were flash point, ductility, penetration, thin film oven test,
softening point and solubility. Marshal Flow and stability test were conducted. Moisture
susceptibility using indirect tensile strength test and single wheel tester were performed.
The quality test results of the aggregates and the bitumen were met the specification set by
ERA. From the aggregate test result the more strong, the higher weathering resistance and the
lesser water absorbent aggregate found to be less moisture sensitive. The research conclude
that moisture in asphalt mix has a significant effect on the performance of asphalt mix which
is decrease in Marshal stability, decrease in tensile strength and increase the rutting of a
mixture. The test result from ITS show that the tensile strength values were higher for the dry
specimens than the wet specimens. From wheel tester result the rutting of a mix were higher
for the wet samples than the dry one.
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Keywords
Hot Mix Asphalt, Moisture Susceptibility, Stripping, Tensile Strength, Rutting