An American National Standard

Designation: D 1195 – 93 (Reapproved 2004)

Standard Test Method for

Repetitive Static Plate Load Tests of Soils and Flexible
Pavement Components, for Use in Evaluation and Design of
Airport and Highway Pavements1
This standard is issued under the fixed designation D 1195; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.

1. Scope loaded with sufficient weight to produce the desired reaction on

1.1 This test method covers a procedure for making repeti- the surface under test. The supporting points (wheels in the
tive static plate load tests on subgrade soils and compacted case of a truck or trailer) shall be at least 8 ft (2.4 m) from the
pavement components, in either the compact condition or the circumference of the largest diameter bearing plate being used.
natural state, and provides data for use in the evaluation and 4.2 Hydraulic Jack Assembly, with a spherical bearing
design of rigid and flexible-type airport and highway pave- attachment, capable of applying and releasing the load in
ments. increments. The jack shall have sufficient capacity for applying
1.2 The values stated in inch-pound units are to be regarded the maximum load required, and shall be equipped with an
as the standard. accurately calibrated gage that will indicate the magnitude of
1.3 This standard does not purport to address all of the the applied load.
safety concerns, if any, associated with its use. It is the 4.3 Bearing Plates—A set of circular steel bearing plates
responsibility of the user of this standard to establish appro- not less than 1 in. (25.4 mm) in thickness, machined so that
priate safety and health practices and determine the applica- they can be arranged in pyramid fashion to ensure rigidity, and
bility of regulatory limitations prior to use. having diameters ranging from 6 to 30 in. (152 to 762 mm).
The diameters of adjacent plates in the pyramid arrangement
2. Terminology shall not differ by more than 6 in.
2.1 Definitions: NOTE 1—A minimum of four different plate sizes is recommended for
2.1.1 deflection—the amount of downward vertical move- pavement design or evaluation purposes. For evaluation purposes alone, a
ment of a surface due to the application of a load to the surface. single plate may be used, provided that its area is equal to the tire-contact
2.1.2 rebound deflection—the amount of vertical rebound of area corresponding to what may be considered as the most critical
a surface that occurs when a load is removed from the surface. combination of conditions of wheel load and tire pressure. For the purpose
of providing data indicative of bearing index (for example, the determi-
2.1.3 residual deflection—the difference between original
nation of relative subgrade support throughout a period of a year), a single
and final elevations of a surface resulting from the application plate of any selected size may be used.
and removal of one or more loads to and from the surface.
4.4 Dial Gages, two or more, graduated in units of 0.001 in.
3. Significance and Use (0.03 mm) and capable of recording a maximum deflection of
3.1 Field, in-place repetitive static plate load tests are used 1 in. (25 mm) or other equivalent deflection-measuring de-
for the evaluation and design of pavement structures. Repetive vices.
static plate load tests are performed on soils and unbound base 4.5 Deflection Beam—A beam upon which the dial gages
and subbase materials to determine a measure of the shear shall be mounted. The beam shall be a 21⁄2-in. standard black
strength of pavement components. pipe or a 3 by 3 by 1⁄4-in. (76 by 76 by 6-mm) steel angle, or
equivalent. It shall be at least 18 ft (5.5 m) long and shall rest
4. Apparatus on supports located at least 8 ft (2.4 m) from the circumference
4.1 Loading Device—A truck or trailer or a combination of of the bearing plate or nearest wheel or supporting leg. The
both a tractor-trailer, an anchored frame, or other structure entire deflection measuring system shall be adequately shaded
from direct rays of the sun.
4.6 Miscellaneous Tools, including a spirit level, for prepa-
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This test method is under the jurisdiction of ASTM Committee D04 on Road ration of the surface to be tested and for operation of the
and Paving Materials and is the direct responsibility of Subcommittee D04.39 on equipment.
Non Destructive Testing of Pavement Structures.
Current edition approved Dec. 1, 2004. Published December 2004. Originally
approved in 1952. Replaces D 1195 – 57. Last previous edition approved in 1997 as
D 1195 – 93 (1997).

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.

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 D 1195 – 93 (2004)
5. Procedure 5.7 Increase the load to give a deflection of about 0.4 in.
5.1 Carefully center a bearing plate, of the selected diam- (10.2 mm), and proceed as directed in 4.5.
eter, under the jack assembly. Set the remaining plates of 5.8 In all cases the standard end point shall be a rate of
smaller diameter concentric with, and on top of, the bearing 0.001 in. (0.03 mm)/min or less for three successive minutes.
plate. Set the bearing plate level in a thin bed of a mixture of 5.9 From a thermometer suspended near the bearing plate,
sand and plaster of Paris, of plaster of Paris alone, or of fine read and record the air temperature at half-hour intervals.
sand, using the least quantity of materials required for uniform 6. Record of Tests
bearing. To prevent loss of moisture from the subgrade during
6.1 In addition to the continuous listing of all load, deflec-
the load test, cover the exposed subgrade to a distance of 6 ft
tion, and temperature data, as prescribed in Section 4, a record
(1.8 m) from the circumference of the bearing plate with a
shall also be made of all associated conditions and observations
tarpaulin or waterproof paper.
pertaining to the test, including the following:
5.2 Where unconfined load tests are to be made at a depth
6.1.1 Date,
below the surface, remove the surrounding material to provide
6.1.2 Time of beginning and completion of test,
a clearance equal to one and one-half plate diameters from the
6.1.3 List of personnel,
edge of the bearing plate. For confined tests, the diameter of the
6.1.4 Weather conditions,
excavated circular area shall be just sufficient to accommodate
6.1.5 Any irregularity in routine procedure,
the selected bearing plate.
6.1.6 Any unusual conditions observed at the test site, and
5.3 Use a sufficient number of dial gages, so located and 6.1.7 Any unusual observations made during the test.
fixed in position as to indicate the average vertical movement
of the bearing plate. When using two dial gages, they shall be 7. Calculation and Plotting of Load-Deflection
set near each extremity of a diameter of the bearing plate, 1 in. Relationships
(25.4 mm) from the circumference. When three gages are 7.1 For each repetition of each load, determine the deflec-
employed, they shall be set at an angle of 120° from each other, tion at which the rate of deflection is exactly 0.001 in. (0.03
and equidistant from the circumference of the bearing plate. mm)/min. This is termed end point deflection and can be
Each individual set of readings shall be averaged, and this determined with sufficient accuracy from visual inspection of
value is recorded as the average settlement reading. the deflection data for each repetition of load recorded.
5.4 After the equipment has been properly arranged, and 7.2 Correct the recorded loads, as read from the pressure
with all of the dead load (jack, plates, etc.) acting, seat and gage of each hydraulic jack employed, by means of the
bearing plate and assembly by the quick application and release calibration curve for each jack and pressure gage used.
of a load sufficient to produce a deflection of not less than 0.01 7.3 Determine graphically the zero point corrections for
in. (0.25 mm) nor more than 0.02 in. (0.51 mm) as indicated by both applied load and deflection. This requires taking into
the dial gages. When the dial needles come to rest following account the weight of the hydraulic jack, that of the pyramid of
the release of this load, reseat the plate by applying one half of bearing plates, etc., and that of the corrected jack loads at
the recorded load producing the 0.01 to 0.02-in. deflection. which the dial gages were set to zero at the beginning of the
When the dial needles have again come to rest, set each dial test.
accurately at its zero mark. 7.4 Plot the corrected deflection at which the rate of
NOTE 2—The use of additional dial gages, placed on the surface of the deflection is exactly 0.001 in. (0.03 mm)/min versus the
material being tested at one half, one, and one and one-half, and so forth, number of repetitions of each corrected load. Similar graphs
bearing-plate diameters from the edge of the bearing plate, is optional. may be prepared in which corrected residual deflection and
rebound deflection are plotted versus the number of repetitions
5.5 Apply a load giving a deflection of about 0.04 in. (1.0
of each corrected load.
mm), start a stop watch, and maintain the same load constantly
until the rate of deflection is 0.001 in. (0.03 mm) per min or 8. Precision and Bias
less for three successive minutes. Then completely release the 8.1 The precision and bias of this test method for making
load, and observe the rebound until the rate of recovery is repetitive static plate load tests on subgrade soils and flexible
0.001 in. per min or less, for three successive minutes. Apply pavement components has not been determined. Soils and
and release the same load in this manner six times. Record the flexible pavement components at the same location may exhibit
readings of the dial gages resting on the bearing plate at the end significantly different load-deflection relationships. No method
of each minute; record the readings of the dial gages set beyond presently exists to evaluate the precision of a group of
the perimeter of the bearing plate just before the application, repetitive plate load tests on soils and flexible pavement
and just before the release of load, for each repetition. To components due to the variability of these materials. The
ensure good contact between the gages and the bearing plate or subcommittee is seeking pertinent data from users of this
other surface on which they are resting, briefly buzz an electric method which may be used to develop meaningful statements
bell attached to the deflection beam, 10 s before the dial gages of precision and bias.
are to be read.
5.6 Increase the load to give a deflection of about 0.2 in. (5.1 9. Keywords
mm), and proceed as directed in 4.5. 9.1 bearing plate; deflection; pavements

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 D 1195 – 93 (2004)
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