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As for all other
recommendations in the Road Note, the information given is “guidance”
only – not a specification. Consequently, the stage 1 binder spread
categories for the individual layers in table 9.2.3c may be varied for
specific binders and site conditions.
For instance there is a school of thought that suggests that the first
layer has more binder because it is holding the bigger chip, but
conversely it can be argued that the second layer has more surface area
to cover, as it is being applied to a textured surface. These are issues
which are clarified by experience, however as a general guide you should
expect the over all rate of spread to be at least 0.3 litre / sq metre
greater than the corresponding racked in dressing.
In any event any variation in the binder-spread category for one of the
layers should be
offset by a similar opposite variation in the other layer. (See the
second paragraph in 9.2.3)
Advice on such variations should be obtained from the binder supplier
and / or contractor
being used.
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