Material Properties of Cold In-Place Recycled and Full-Depth Reclamation Asphalt Concrete (2017) / Chapter Skim
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From page 21... ...
21 Dynamic modulus testing was conducted on small-scale cylindrical specimens while unconfined with axially applied loading using an AMPT in general accordance with AASHTO TP 79. Modifications to the specification included using a reduced set of temperatures (4.4°C, 21.1°C, and 37.8°C)
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From page 22... ...
22 Material Properties of Cold In-Place Recycled and Full-Depth Reclamation Asphalt Concrete with the data quality indicators, no consistent trend was apparent with respect to bulk density and dynamic modulus. Next, an outlier procedure was performed using a quartile analysis.
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From page 23... ...
Dynamic Modulus Test Results 23 Data points identified as outside the IQR are shown with no shading. E = emulsified asphalt, F = foamed asphalt, C = hydraulic cement, and L = lime.
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From page 24... ...
24 Material Properties of Cold In-Place Recycled and Full-Depth Reclamation Asphalt Concrete of 4.4°C. The difference in the mean dynamic modulus for foamed asphalt CIR versus foamed asphalt CIR plus cement was found not to be statistically significant at any of the three temperatures considered.
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From page 25... ...
Dynamic Modulus Test Results 25 significant difference in dynamic modulus values was found at the 4.4°C test temperature (only the CIR process had projects using both hydraulic cement and lime as chemical additives)
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26 Material Properties of Cold In-Place Recycled and Full-Depth Reclamation Asphalt Concrete From Figure 15 and Figure 16 it can be seen that the FDR mixtures had a greater stiffness than the CIR and CCPR mixtures at lower reduced frequencies (less than approximately 10 Hz) , which corresponds to higher test temperatures.
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From page 27... ...
Dynamic Modulus Test Results 27 data envelope minimum values are less than the minimum values of the other recycling process types throughout the range of reduced frequencies. Most highway agencies and design procedures typically assign a lesser layer coefficient (or less modulus)
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28 Material Properties of Cold In-Place Recycled and Full-Depth Reclamation Asphalt Concrete 0 200,000 400,000 600,000 800,000 1,000,000 1,200,000 1,400,000 1,600,000 0 2,000 4,000 6,000 8,000 10,000 12,000 0.0001 0.01 1 100 10000 D yn am ic M od ul us (p si )
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From page 29... ...
Dynamic Modulus Test Results 29 0 200,000 400,000 600,000 800,000 1,000,000 1,200,000 1,400,000 1,600,000 0 2,000 4,000 6,000 8,000 10,000 12,000 0.0001 0.01 1 100 10000 D yn am ic M od ul us (p si )
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From page 30... ...
30 Material Properties of Cold In-Place Recycled and Full-Depth Reclamation Asphalt Concrete reduced frequency ranges, mixtures containing lime were found to be stiffer than mixtures having no chemical additive. At higher reduced frequencies (greater than approximately 100 Hz)
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From page 31... ...
Location Project ID Alpha (α)
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From page 32... ...
32 Material Properties of Cold In-Place Recycled and Full-Depth Reclamation Asphalt Concrete Table 7 also shows that, for CIR mixtures using emulsion versus emulsion plus lime, the difference in the g parameter, representing the rate of change between the minimum and maximum modulus values, was statistically significant. Like the analysis of the dynamic modulus values, the analysis of the fitting parameters shows that differences in foamed asphalt versus emulsified asphalt were not statistically significant.
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From page 33... ...
Dynamic Modulus Test Results 33 mixtures produced in Virginia. The results show that the phase angle peaks at lower stiff- ness values and reaches a maximum value and then decreases.
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34 Material Properties of Cold In-Place Recycled and Full-Depth Reclamation Asphalt Concrete Figure 23. Black Space diagram for mixtures produced by FDR, CCPR, and CIR.
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From page 35... ...
Dynamic Modulus Test Results 35 Figure 25 shows the Black Space diagram for emulsified asphalt CIR mixtures having lime, cement, or no chemical additive. Mixtures including a chemical additive generally have a more elastic response in that their phase angles are smaller than those mixtures with no chemical additive.
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From page 36... ...
36 Material Properties of Cold In-Place Recycled and Full-Depth Reclamation Asphalt Concrete Figure 26. Black Space diagram for foamed asphalt CIR mixtures having cement or no chemical additive.
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From page 37... ...
Dynamic Modulus Test Results 37 used in the emulsion and softer than the RAP binder. In the foaming process, the spot-welding effect allows the RAP binder stiffness to control the mixture performance, hence the more elastic response.
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From page 38... ...
38 Material Properties of Cold In-Place Recycled and Full-Depth Reclamation Asphalt Concrete The R2 value was greater than 0.5 in only 7 of the 33 comparisons, however, indicating that the density describes more than 50% of the variability in the measured stiffness in only 21% of the comparisons. Figure 29 shows the relationship between density and stiffness with respect to recycling process.
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From page 39... ...
Dynamic Modulus Test Results 39 Figure 29. Relationship between specimen bulk density and stiffness.
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From page 40... ...
40 Material Properties of Cold In-Place Recycled and Full-Depth Reclamation Asphalt Concrete A bivariate correlation was performed between the design and performance properties. Correlation coefficients between these two groups are summarized in Table 10.
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From page 41... ...
Dynamic Modulus Test Results 41 Max.
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