SHRP-A-379 traducir

where
%NA = Percent net adsorption.
Ia ]×1®
High values of %NA indicate increased resistance of the asphalt-aggregate
stripping by water.
bond to
10. REPORT
10.1 Figure 1 is a sample data sheet prepared to simplify entry of required
measurements. It, or a similar form, shall be used to report the following:
10.1 Ai--Initial absorbance readings at 410 nm.
10.2 Aa--Absorbance readings at 410 nm after 6 hours.
10.3 Ar--Absorbance readings at 410 nm after water desorption step.
10.4 A--Initial absorption, mg/g.
10.5 An--Net adsorption, mg/g_
10.6 %NA--Percent net adsorption.
11. NOTES
11.1 Some sedimentary aggregates contain 1 or 2% naturally occurring organic
compounds that could potentially interfere with this method. The use of a blank sample
(section 8.4.1) will allow correction of this problem if it should occur.
11.2 Highly adsorptive aggregates may not stabilize after the 6-hour adsorption
period. If such an aggregate is suspected, the adsorption period should be extended and
additional adsorption measurements taken as described in sections 8.12, 8.13, and 8.14.
These values can then be calculated using the equation in 9.1, after adjusting the volume V of
the sample to reflect the additional amounts of toluene removed from the flask. The proper
adsorption time can be determined when the adsorption values stabilize, and no more
additional asphalt cement is being adsorbed by the aggregate. A similar caution is also
appropriate for the desorption step.
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