Pavement Structural Analysis of the Design Recommendations for ...

Pavement Structural Analysis August 2004
Report No. 15953-2/1 ARA-ERES Consultants
shown in figure 16 and included in table 5. Using the stiffer asphalt will reduce rutting to
an acceptable level, even for the 40-year analysis period.
Rut Depth, inches
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
PG 76-22 PG 70-22
0 10 20 30 40 50
22
Age, Years
Figure 16 Comparison of predicted rutting for HMA mixtures with a PG 70-22
and a PG 76-22.
As shown in figure 1, a PG 70-22 asphalt is planned for use in the top two HMA layers.
Whether the dynamic modulus regression equation will adequately estimate the stiffness
values for the PG 70-22P mixtures is questionable. Whether a PG 70-22P or PG 76-22 is
used should be defined based on asphalt or mixture modulus testing or some type of
torture test to ensure that the HMA mixtures will be resistant to rutting. Without any
additional mixture testing, it is suggested that a PG 76-22 asphalt be included in the top
two mixtures. In addition, it should be confirmed that the pavement materials meet or
exceed the assumptions used in design. It is also recommended that sufficient testing be
completed during construction to ensure that the design assumptions are satisfied prior to
construction.
6. Limitations
All work performed under this study was conducted in accordance with generally
accepted pavement engineering practices using data and project information provided by
the Mr. Curtis Bleech. No other warranty, express or implied, is made. The generalized