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8.8.2 Conditioning and Testing--Carry out conditioning and testing of the modified<br />
asphalt binder in accordance with section 6 or 7 of PP6.<br />
8.8.3 Evaluation--Evaluate the modified asphalt binder by comparing the results of<br />
the performance-based tests to the limits contained in MP1. This permits the capabilities of<br />
the modified asphalt binder to be objectively measured and gauged against those of<br />
conventional asphalt binders.<br />
8.8.3.1 Control the contribution of the asphalt binder to permanent deformation by<br />
specifying a minimum value for the stiffness parameter, G*/sin _ (= 1/J", the inverse of the<br />
loss compliance), at a maximum pavement design temperature. Correlate this parameter to<br />
that portion of the accumulated, non-recoverable deformation occurring in a pavement that is<br />
attributable to the asphalt binder. Comparison of the value of G*/sin _ for the modified<br />
asphalt binder with that of the base asphalt cement or of the conventional asphalt binder<br />
(under similar loading and temperature conditions), or with the limits in MP1, will indicate<br />
how well the modified asphalt binder will perform with respect to permanent deformation.<br />
8.8.3.2 Control the contribution of the asphalt binder to low temperature cracking by<br />
specifying limits for the creep stiffness, slope of the stiffness-time relationship, and the<br />
tensile strain at failure at test temperatures related to the lowest expected pavement design<br />
temperature. These properties affect the ability of the pavement to dissipate the tensile strains<br />
that result from rapid reductions in temperature or continual low-temperature cycling.<br />
Comparison of the measured values of these three properties for the modified asphalt binder<br />
with those of the base asphalt cement or the conventional asphalt binder (under similar<br />
loading and temperature conditions), or with the limits in MP1, will indicate how well the<br />
modified asphalt binder will perform with respect to low temperature cracking.<br />
8.8.3.3 Control the contribution of the asphalt binder to fatigue cracking by<br />
specifying a maximum value for the stiffness parameter, G'sin 6 (= G", the loss modulus),<br />
at the average pavement design temperature. This parameter is related to the contribution of<br />
the asphalt binder to the dissipation of energy in a pavement during each loading cycle.<br />
Comparison of the value of G'sin 6 for the modified asphalt binder with that of the base<br />
asphalt cement or of the conventional asphalt binder (under similar loading and temperature<br />
conditions), or with the limits in MP1, will indicate how well the modified asphalt binder<br />
will perform with respect to fatigue cracking.<br />
8.8.3.4 Aging may be divided into the changes which occur during construction<br />
(short term) and the changes which occur during the service life of the pavement (long term).<br />
Measure the binder property related to permanent deformation on asphalt binders aged by<br />
T240 or T179 to simulate changes that take place during construction. This helps limit the<br />
occurrence of early failure of the pavement due to rutting. Measure the binder properties<br />
related to fatigue cracking and low-temperature cracking on asphalt binders additionally aged<br />
by PP1 to simulate approximately 5 to 10 years pavement service. These types of distress<br />
tend to arise later in the service life of the pavement.<br />
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