30 June 2001
PROCEDURE FOR DETERMINING THE DYNAMIC MODULUS
OF BITUMINOUS CONCRETE MIXTURES
H-1. GENERAL. The purpose of this procedure is to determine dynamic modulus values of
bituminous concrete mixtures. The procedure described covers a range of both temperature and
loading frequency. The minimum recommended test series consists of testing at 4.5, 21, and
37.8 degrees Celsius (40, 70, and 100 degrees Fahrenheit) at loading frequencies of 2 and
10 hertz for each temperature. The method is applicable to bituminous paving mixtures similar to
the 25.4, 19, 12.7, and 9.5 millimeter (1-, 3/4-, 1/2-, and 3/8-inch), and No. 4 mixes as defined
by Table 3 of ASTM D 3515.
H-2. APPLICABLE STANDARDS. The following ASTM standards are applicable to this procedure:
C 617, D 1559, D 1561, and D 3515.
H-3. SUMMARY PROCEDURE. The dynamic modulus test is run by applying a sinusoidal
(haversine) axial compressive stress to a specimen of bituminous concrete at a given temperature
and loading frequency. The resulting recoverable axial strain response of the specimen is measured
and used to calculate the dynamic modulus.
H-4. DEFINITIONS. The following terms are used in this procedure:
a. Dynamic Modulus. The absolute value of the complex modulus which defines the elastic
properties of a linear viscoelastic material subjected to a sinusoidal loading.
b. Complex Modulus. A complex number which defines the relationship between stress and
strain for a linear viscoelastic material.
c. Linear material. A material whose stress-to-strain ratio is independent of the loading stress
H-5. APPARATUS. An electrohydraulic testing machine with a frequency generator capable of
producing a haversine wave form has proven to be most suitable for use in dynamic modulus
testing. The testing machine should have the capability of applying loads over a range of
frequencies from 1 to 20 hertz and stress levels up to 0.69 MPa (100 psi). The temperature
control system should be capable of a temperature range of 0.0 to 49 degrees Celsius (32 to
120 degrees Fahrenheit). The temperature chamber should be large enough to hold six specimens.
A hardened steel disk with a diameter equal to that of the test specimen should be used to transfer
the load from the testing machine to the specimen.
H-6. SPECIMENS. The laboratory-molded specimens should be prepared according to Appendix H.
A minimum of three specimens is required for testing. The molding procedure is as follows: Cap all
specimens with a sulfur mortar meeting ASTM C 617 requirements prior to testing. Bond the
strain gauges with epoxy cement to the sides of the specimen near midheight in position to
measure axial strains. (Baldwin Lima Hamilton EPY 150 Epoxy Cement has been found satisfactory
for this purpose. On specimens with large-size aggregate, care must be taken so that the gauges