UFC 3-260-02

30 June 2001

APPENDIX N

PROCEDURE FOR DETERMINING THE RESILIENT MODULUS

OF GRANULAR BASE MATERIAL

N-1. PROCEDURE. This procedure is designed to determine resilient properties of granular base

(subbase) materials. The test is similar to a standard triaxial compression test, the primary

exception being that the deviator stress is applied repetitively at several stress levels. The

procedure allows testing under a repetitive stress state similar to that encountered in a base

(subbase) course layer in a pavement under a moving wheel load.

N-2. DEFINITIONS. The following symbols and terms are used in the description of this procedure:

a. F1 = total axial stress.

b. F3 = total radial stress, i.e., confining pressure in the triaxial test.

c. Fd = deviator stress (F1 - F3), i.e., the repeated axial stress in this procedure.

d. ,1 = total axial strain due to Fd.

e. ,R = resilient axial strain due to Fd.

f.

,R = resilient lateral strain due to Fd.

g. MR = the resilient modulus = Fd/,R.

h. <R = the resilient Poisson's ratio = ,R/,R.

i

2 = sum of the principal stresses in the triaxial state of stress (F1 + 2F3 = Fd + 3F3).

j.

F1/F3 = principal stress ratio.

k. Load duration = time interval during which the sample is subjected to a stress deviator.

l.

Cycle duration = time interval between successive applications of the deviator stress.

N-3. SPECIMENS. For base-course materials, 152-millimeter- (6-inch-) diameter specimens are

generally required with the maximum particle size being limited to 25 millimeters (1 inch). The

specimen height should be at least twice the diameter.

N-4. EQUIPMENT.

a. Triaxial Test Cell. The triaxial cell shown schematically in Figure N-1 is suitable for use in

resilient testing of soils. The equipment is similar to most standard cells. However, there are a

few specialized criteria that must be met to provide acceptable test results. Generally, the

equipment is slightly larger than most standard cells to accommodate the 152-millimeter- (6-inch-)

diameter specimens and the internally mounted load and deformation measuring equipment.

N-1

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