30 June 2001
PROCEDURE FOR DETERMINING THE FLEXURAL MODULUS AND
FATIGUE CHARACTERISTICS OF STABILIZED SOILS
K-1. LABORATORY PROCEDURE.
a. General. The procedure involves application of a repetitive loading to a laboratory-prepared
beam specimen under controlled stress conditions. Applied load and deflection along the neutral
axis and at the lower surface are monitored, and the results are used to determine the flexural
modulus and fatigue characteristics.
b. Specimen Preparation. Beam specimens should be prepared following the general
procedures indicated in ASTM D 1632. This method describes procedures for molding 76- by 76-
by 286-millimeter (3- by 3- by 11-1/4-inch) specimens; however, any size mold may be used for
the test. For soils containing aggregate particles larger than 19 millimeters (3/4 inch), it is
recommended that molds on the order of 102 by 102 to 152 by 152 millimeters (4 by 4 to 6 by
6 inches) be used. In general, specimens should have an approximately square crosssectional
configuration and a length adequate to accommodate an effective test span equal to three times
the height or width. Specimens should be molded to the stabilizer treatment level, moisture
content, and density expected in the field structures. Cement-treated materials should be moist-
cured for 7 days. Lime-treated materials should be cured for 28 days at 23 degrees Celsius (73
c. Equipment. The following equipment is required:
(1) Loading frame capable of receiving specimen for third-point loading test.
(2) Electrohydraulic testing machine. This machine must be capable of applying static
and haversine loads.
(3) Load cell (approximately 907-kilogram (2,000-pound) capacity).
(4) Two LVDT's and one SR-4 type strain gauge.
(5) Recording equipment for monitoring deflection, strain, and load.
(6) Miscellaneous pins and yokes, as described in the equipment setup below for
mounting the LVDT'S.
d. Equipment Setup. Details of the equipment setup are shown in Figures K-1 to K-3. The
beam should be positioned so that the molding laminations are horizontal. The three yokes are
positioned over the top of the beam and held in place by threaded pins, positioned along the neutral
axis. The end pins, pins A and C, are positioned directly over the end reaction points, and the
middle pin, pin B, is positioned at the center of the beam. A metal bar rests on top of the pin. At
the A position, the bar is equipped with a lower vertical tab having a hole that slips loosely over the
pin. A nut is placed on the end of the pin to prevent the bar from slipping. At the center or B
position, the bar is equipped with a vertical tap onto which an LVDT is cemented in a vertical