This
report presents a
laboratory study on the effectiveness
of various fog seal
materials and the effects of application rates on fog seal
curing behaviors. This
report is divided into two parts: fog seal emulsion properties and fog seal
emulsion applications. In this research, four types of emulsion, including both
unmodified and modified emulsions, are used for fog seal testing. The unmodified
emulsions are CSS-1h emulsion that is used commonly for fog seal applications
and CQS-1h emulsion that is employed for slurry seals. The polymer-modified emulsions
(PMEs) are ReviveTM and Grip-Tight and are designed
specially for fog seals. The North
Carolina State University research team developed the rolling ball test and
damping test to verify the fog seal field construction. The curing time studies, which include the
evaporation test, PATTI test, rolling ball test, and damping test, have
identified some advantages of using PMEs, but ound no advantages for the use of the
unmodified CQS-1h emulsion. The curing time study results suggest appropriate emulsion
application rates (EARs) and emulsion types, which are verified for fog seal
performance tests,
such as the third-scale model mobile load simulator (MMLS3) test for aggregate
loss and bleeding, mean profile depth (MPD) analysis, and skid resistance testing. The fog seal performance test results also
reveal advantages of PMEs. Except in the case of the unmodified CSS-1h emulsion
with a high EAR, in general fog seals can improve aggregate retention. High EARs lead to high bleeding percentages and can thereby reduce the skid
resistance of the surface. Fog seals in themselves do not provide skid
resistance; however, all the skid numbers acquired from conditioned samples
satisfy the NCDOT skid resistance requirements. Overall, modified emulsions are better than unmodified
emulsions in terms of curing time and performance. Although the difference
between the ReviveTM and Grip-Tight emulsions is not significant in most cases,
the Grip-Tight emulsion exhibits the better properties. However, only one type of chip seal texture (i.e., that recommended by the
chip seal mix design project) is employed for this research. Therefore,
additional research into different chip seal surface textures is necessary to
show whether fog seals are applicable for other chip seal surfaces.
