UFC 3-260-03

15 Apr 01

(eq 4-2)

where

A = intercept

S = slope

j = 1 to the number of deflections

I = 1 to the number of layers with unknown modulus values

c. For WESDEF, a range of modulus values is input with an estimated initial modulus value for

each layer for which modulus values are to be determined. The number of unknown modulus values

cannot exceed the number of measured deflections. Best results are obtained when not more than three

layers are computed in a single execution.

d. Default ranges and initial estimates for the modulus and Poisson's ratio of pavement materials

are recommended in table 4-1.

Range

Initial

Poisson's

Material

Minimum

Maximum

Estimate

Ratio

Asphalt concrete

689 (100,000)

13,780

2,411

0.35

(2,000,000)

(350,000)

Portland cement concrete

17,222

48,230

24,115

0.15

(2,500,000)

(7,000,000)

(3,500,000)

Resin Modified Pavement*

4,823

20,669

11,713

0.27

(700,000)

(3,000,000)

(1,700,000)

High-quality stabilized base

3,445

17,222

6,890

0.20

(500,000)

(2,500,000)

(1,000,000)

Base-subbase, stabilized

689

6,890

2,067

0.25

(100,000)

(1,000,000)

(300,000)

Base-subbase, unstabilized

34

1,033

207

0.35

(5,000)

(150,000)

(30,000)

Subgrade

6.9

344

103

0.40

(1,000)

(50,000)

(15,000)

* To be added to WESDEF later.

e. If the deflection basin includes a deflection measured at an offset distance of 1.83 meters

(72 inches), the initial subgrade modulus is estimated as follows:

(eq 4-3)

4-4