Pavement Structural Analysis of the Design Recommendations for ...

Pavement Structural Analysis August 2004
Report No. 15953-2/1 ARA-ERES Consultants
Figure 7 shows the average test results for a Class IIA sand subbase material in Michigan
that were extracted from the LTPP database. These average test results were used to
determine the design resilient modulus for both M-E design procedures.
Table 2 Median resilient modulus measured on the sand subbases and sand
subgrades recovered from all of the LTPP sites and from those sites
that are located in Michigan.
Material/
Layer
Stress State
Median Resilient Modulus, psi (MPa)
(Refer to figures 17 to 20 in Appendix B)
All LTPP Sites LTPP Sites in Michigan
Sand Confinement = 10 psi 18,400 (126.9) 18,700 (128.9)
Subbase Cyclic Stress = 9 psi (N=62)*
(N=10)
Sand Confinement = 2.0 psi 7,700 (53.1)
8,300 (57.2)
Subgrade Cyclic Stress = 1.8 psi (N=440)
(N=7)
* N = number of resilient modulus tests within each group.
Resilient Modulus, ksi
35
30
25
20
15
10
5
0
0 50 100 150
Bulk Stress, psi
9
Confinement = 3 psi
Confinement = 5 psi
Confinement = 10 psi
Confinement = 15 psi
Confinement = 20 psi
Figure 7 Average repeated load resilient modulus test results extracted from
the LTPP database for a sand subbase that is expected to be similar to
the material placed along I-96.