PHASE II REPORT - Caltrans

Note that the ratio of the two averages (i.e. 19.9/11.22) equals 1.77, which is very close to the
correction factor of 1.75 obtained from the tests on slurry systems.
4.2.3 Development of the Cohesion-Abrasion Test (CAT)
The Cohesion-Abrasion Test is a modified version of the Wet Track Abrasion Test (WTAT),
ISSA TB-100. A two-wheel fixture is used instead of the standard abrasion head. As a result of
this modification, the abrasive action is less severe and the test can be used to evaluate system
cohesion buildup during curing and before opening to traffic as well as abrasion resistance after
opening to traffic or on oven cured specimens. The test can be performed on test samples
similar to those for the wet cohesion test as developed by the French. It is a better replication of
traffic than the hose.
It was also hoped that the test could be used to differentiate between slurry quick set,
microsurfacing, and slow set slurry. For specification purposes, ranges of loss would be more
appropriate than minimum or maximum losses alone.
The first modification made to the standard Wet Track Abrasion Test (TB-100) setup was the
use of a N50 Hobart unit with the wheel attachment; this has a smaller abrasion area so the loss
levels needed to be reestablished when compared to the existing TB-100 test. Figure 4.22
shows the CAT with the wheel attachment during testing.
The following variables were identified and evaluated during the development phase:
1. Effect of test specimen base support type (Roofing Felt/Steel/Aluminum)
2. Effect of assessment method for aggregate loss (Wet Loss/Aggregate Loss
Recovery/Dry Loss)
3. Effect of tack coat
4. Effect of soaking samples in relation to cure time
5. Stripping effects in aggregates at different test conditions
6. Effect of system on aggregate and emulsion behavior
7. Compaction by hand surface consolidation (Hand Roller)
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