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41
can cause a chip seal project to fail. If an unexpected rainstorm preparation of a pavement surface for chip sealing (Asphalt
ensues, sufficient aggregate should be spread to cover all of the Surface Treatments--Specifications undated):
applied binder. If possible, the road should be closed to traffic
and, if not, traffic must be kept to a minimum speed during this · Repair all holes and depressions and replace with a tight
period, because adhesion between the binder and aggregate is surface conforming patch;
at risk (Asphalt Seal Coats 2003). The amount of rolling · Fill and seal all cracks;
should be reduced, if not completely ceased, while the aggre- · Level all bumps, waves, and corrugations that will
gate is wet, because the binder may emerge from the voids and impair riding qualities;
be picked up on the wheels of the roller (Bituminous Sprayed · Remove all excess asphalt on patches and joints; and
Surfacing Manual 2003). · Clean full width of the surface to be treated.
Wind Repairs
Chip sealing during windy conditions raises a number of Significant deficiencies in the pavement surface must be
issues. Wind can be either beneficial or detrimental to a chip repaired before applying a chip seal to the roadway. Potholes
seal during construction. The benefits of wind are directed must be filled, and ruts of significant depths must be leveled.
toward the curing process for emulsions, because wind may The survey analysis revealed that the most common repair
speed up this process and thus allow for earlier sweeping and activities to be completed before a chip seal are hot-mix and
opening to traffic (Gransberg et al. 1998). The destructive cold-mix patching and crack sealing. In addition to prevent-
nature of wind is noted during the application of the binder. ing water from entering the base, crack seals prevent loss of
Wind can distort spray patterns, which may lead to a non- chip seal binder through existing cracks, and patches are
uniform application (Asphalt Seal Coats 2003). A shield may intended primarily to level up the pavement surface as well as
be installed on the distributor to prevent any disturbance to address isolated pavement distresses. The type of material
the spray pattern from wind (Seal Coat . . . 2003). used for the various repairs is important and can affect the
quality and overall longevity of the finished chip seal surface.
ROAD PREPARATION Patching materials and crack sealant need time to cure before
placing a chip seal. This work, when possible, needs to be pro-
Preparation activities before the chip seal work are essential grammed and scheduled to take place several months in
to produce a uniform surface, because most chip seal activ- advance of the chip seal construction to allow for crack
ities are applied on pavements that show various distresses. sealant and paving materials to cure (Sprayed Sealing Guide
A pavement that is well prepared for chip sealing should 2004). As a rule of thumb, patching should be completed at
have a uniformly textured surface and a smooth ride, and it least 6 months before construction and crack sealing should
should contain only those minor defects that can be corrected be applied at least 3 months before the application of chip
by the chip seal. Figure 42 shows the results of the survey seals (Gransberg et al. 1998). Road Note 39, the United
responses for this area. The following are requirements for Kingdom's chip seal design and construction policy manual,
Texturizing
Patch and Level
Fog Coat
Crack Sealing
Fresh Pavement
0% 20% 40% 60% 80% 100%
North America AU, NZ, UK, SA
FIGURE 42 Typical road preparation methods.
