PHASE II REPORT - Caltrans

7.0 CHAPTER 7 SUMMARY AND CONCLUSIONS
7.1 SUMMARY
This study, “Slurry Seal/Micro-Surfacing Mix Design Procedure”, was conducted from July 2003
to November 2008 by Fugro Consultants Inc., Austin, Texas serving as the prime contractor
with support from Applied Pavement Technology, Inc., Urbana, IL, MACTEC Engineering and
Consulting Co., North Highlands, CA and CEL Laboratories, Oakland CA. The project was the
result of a 14 state pooled fund solicitation managed by the California Department of
Transportation.
The purpose of the study was to develop a rational mix design procedure for slurry seal and
microsurfacing mixtures. After conducting an extensive national and international literature
review and an industry survey of existing practices, the research team posited a mix design
process that formed the basis for the remainder of the study. A number of possible test
methods were identified that would potentially assist the study in identifying the characteristics
of slurry surfacing mixes that relate to mixing, spreading, and curing. The intention was to use
procedures, either existing or developed ones that would minimize operator (technician) bias
and also relate to various placement conditions in the field.
Two test procedures that had been used in Europe, the “German” mixing test which the team
renamed the Automated Mixing Test (AMT) and the “French” Wet Track Abrasion Test renamed
the Cohesion Abrasion Test (CAT) were identified in the literature survey and were selected to
be studied in comparison to existing International Slurry Surfacing Association test methods TB-
113 and TB-100. A third procedure, an automated cohesion tester, was developed by an
equipment manufacturer for the study and was named the ACT.
The benefit of using the AMT mixing test, once all the equipment details were worked out, was
the standardization of the mixing process under various temperature and humidity conditions
that could be expected in the field. The CAT was adopted since the method used standard
equipment used in TB-100 but used the entire gradation of the mix unlike TB-100 which the plus
#4 material is scalped off. The ACT eliminates the operator bias associated with the torque
wrench that is used to apply the load to the specimen.
In addition to the test procedure development, test protocols were developed for both the AMT
and CAT and ruggedness testing was conducted for both test methods.
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