Fundamental Properties of Asphalts and Modified Asphalts, III
Fundamental Properties of Asphalts and Modified Asphalts, III
Fundamental Properties of Asphalts and Modified Asphalts, III
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limestone. Major RA elemental oxides are CaO (39%), <strong>and</strong> SiO2 (17%). Major mineral<br />
components are calcite (61 %), quartz (7.4%), <strong>and</strong> organics (5%) [Robl 1991].<br />
FTIR-PA analysis was performed on RD <strong>and</strong> RA aggregate batched to the gradation shown in<br />
table 2-2.2.2.<br />
FTIR-PA analysis on the Arizona aggregate was performed on the minus 2.36 mm plus<br />
0.425 mm aggregate from the combined Arizona plant mix aggregate. Lime (approximately 1%<br />
by mass <strong>of</strong> the aggregate) may have been added before aggregate samples were collected on the<br />
project.<br />
Laboratory prepared mastic<br />
Table 2-2.2.2. Gradation for fine, dense graded mastic.<br />
Sieve Size, mm Percent Passing<br />
1.19 100<br />
0.600 75<br />
0.300 50<br />
0.150 30<br />
0.075 20<br />
Mastics were prepared by mixing aged AAD-1 asphalt (RTFO/PAV 80˚C, 480 hours) with RD<br />
<strong>and</strong> RA aggregate (see table 2-2.2.2 for mastic gradation). Four relative concentrations <strong>of</strong> each<br />
mastic were prepared: 20% aggregate/80% asphalt, 50% aggregate/50% asphalt, 80%<br />
aggregate/20% asphalt, <strong>and</strong> 90% aggregate/10% asphalt.<br />
Laboratory aged compacted specimens<br />
Four 75-mm diameter by 120 mm tall compacted specimens were received from North Carolina<br />
State University (NCSU, Dr. Y. Richard Kim). The specimens had been cored from larger 150mm<br />
diameter gyratory compacted specimens. A 9.5-mm nominal maximum sized aggregate was<br />
used to fabricate the specimens. The aggregate was a limestone obtained from a quarry in North<br />
Carolina. SHRP AAD-1 was used as the binder (6.2% by mass <strong>of</strong> the compacted specimen).<br />
Results <strong>and</strong> Discussion<br />
Asphalt Aging <strong>and</strong> FTIR Spectroscopy<br />
In this study, we report a Fourier-Transform Infrared (FTIR) spectroscopic survey <strong>of</strong> eight<br />
asphalts in unaged <strong>and</strong> laboratory aged conditions as well as several common aggregates used in<br />
road construction <strong>and</strong> combined asphalt/aggregate samples prepared in the laboratory. FTIR<br />
photoacoustic (FTIR-PA), <strong>and</strong> transmission liquid-cell techniques were employed to perform the<br />
survey. Results from the survey will be used here <strong>and</strong> in later studies to: (1) compare FTIR-PA<br />
<strong>and</strong> liquid cell techniques; (2) explore <strong>and</strong> confirm previously observed relationships between<br />
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