PHASE II REPORT - Caltrans

4.3.2 Evaluation of Cohesion-Abrasion Test (CAT)
The proposed CAT test method covers the measurement of the wearing qualities of slurry seal
and micro-surfacing mixture systems under wet abrasion conditions and early cohesion
properties at different levels of cure.
Currently, test practices for abrasion are not performed on uncured mix specimens. The
cohesion abrasion test is appropriate for measuring early cohesion build up as the mixture cures
under various curing conditions. If high losses during initial curing of the mix are observed,
generally this indicates that the mix will have a poor performance.
Differences between proposed and current test methods:
• In the original wet track abrasion test per TB-100, the test is performed on the aggregate
after it has been scalped over the #4 sieve.
• In the proposed method, testing is performed on the bulk sample that has 100% passing
the 3/8 inch (9.65 mm) sieve.
• In the original wet track abrasion test per TB-100, the test specimens are aged in a
140°F (60°C) oven before initiating moisture conditioning.
• In the proposed method, testing is performed on specimens that are cured at specified
temperatures, representing ambient field conditions at 59°F (15°C), 77°F (25°C), or 95°F
(35°C). Additionally, this is done at varying ambient field moisture conditions at 50% or
90% humidity.
• In the original wet track abrasion test per TB-100, the test specimens are not compacted
before curing.
• In the proposed method, one set of test specimens are compacted before curing and
another set of test specimens are not compacted before curing to note the difference.
• In the original wet track abrasion test per TB-100, the abrasion head rotates a fixed
rubber hose along the surface of the sample.
• In the proposed method, the abrasion head rotates a set of two free-spinning rubber
wheels along the surface of the sample.
• In the original wet track abrasion test per TB-100, the test specimen loss is determined
from the original weight of an oven cured test specimen after it has been abraded, and
fines rinsed, and the remaining test specimen is oven dried.
• In the proposed method, the test specimen loss is determined from the final weight of
the test specimen after it has been abraded, and the fines rinsed, without oven drying.
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