PHASE II REPORT - Caltrans

Advantages of the proposed test method:
The most noticeable advantage of this method is that the evaluation is performed on a complete
aggregate gradation. None of the material is scalped as specified in the current method so it
represents the mixture as it will be used in the field.
The other advantage of this method is that it tests the mix system as it begins to cure under
various conditions. This will provide an indication of the behavior of the mix system at different
ambient conditions in the field. This is a reliable indicator of performance of the mix system
representing the early curing and cohesion build up of a mix.
Correlation between the proposed and current methods:
In the original wet track abrasion test per TB-100, and the proposed test method, the test
specimen loss decreases as the emulsion content increases.
Suitability of the proposed method:
The cohesion abrasion test method includes equipment that is easy to operate and the method
is simple to follow and perform.
Currently, test practices for abrasion are not performed on uncured mix specimens. The
cohesion abrasion test method is appropriate for measuring early cohesion build up as the
mixture cures under various curing conditions. If we see high losses during initial curing of the
mix, we can expect to predict a problematic mix.
Additional research needed:
The cohesion abrasion test method would benefit from field validation of various mixes in
predetermined conditions and test sections.
Potentially, this test method could be used to measure early cohesion build up and predict the
early performance of the mix shortly after placement. If an on-site laboratory were available, this
test method may be used to measure early curing in the field to validate the recently placed mix.
The limitation, at this time, is that there has not been a method mutually accepted by industry
and agencies that successfully captures a representative sample of the mixture during
production at the time of placement.
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