ASTM D6916-03

Standard Test Method for Determining the Shear Strength Between Segmental Concrete Units (Modular Concrete Blocks)

SCOPE
1.1 This test method is used to determine the shear strength between two layers of segmental concrete block units used in construction of reinforced soil retaining walls. The test is carried out under conditions determined by the user that reproduce the facing system at full-scale. The results of a series of tests are used to define a relationship between shear strength developed between segmental concrete units and normal load.
1.2 This is a performance test used to determine properties for design of retaining wall systems utilizing segmental concrete units and soil reinforcing geosynthetics, either geotextiles or geogrids. The test is performed on a full-scale construction of the facing system and may be run in a laboratory or the field.
1.3 The values stated in SI units are regarded as the standard. The values stated in inch-pound units are provided for information only.
1.4 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Sep-2003
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: D35 - Geosynthetics
• Drafting Committee: D35.01 - Mechanical Properties

Relations

• Replaced By: ASTM D6916-06 - Standard Test Method for Determining the Shear Strength Between Segmental Concrete Units (Modular Concrete Blocks)
• Effective Date: 15-Jan-2006

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D6916–03
Standard Test Method for
Determining the Shear Strength Between Segmental
Concrete Units (Modular Concrete Blocks)
This standard is issued under the fixed designation D 6916; 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 3. Terminology
1.1 This test method is used to determine the shear strength 3.1 Definitions:
between two layers of segmental concrete block units used in 3.1.1 displacement criteria, n—a user prescribed maximum
construction of reinforced soil retaining walls. The test is movement, mm (in.), of the top segmental concrete unit out
carried out under conditions determined by the user that from the back of lower segmental concrete units.
reproducethefacingsystematfull-scale.Theresultsofaseries 3.1.2 geosynthetic, n—a planar product manufactured from
of tests are used to define a relationship between shear strength polymeric material used with soil, rock, earth, or other geo-
developed between segmental concrete units and normal load. technical engineering related material as an integral part of a
1.2 This is a performance test used to determine properties man-made project, structure or system. D 4439
for design of retaining wall systems utilizing segmental con- 3.1.3 granular infill, n—coarse grained soil aggregate used
crete units and soil reinforcing geosynthetics, either geotextiles to fill the voids in and between segmental concrete units.
or geogrids. The test is performed on a full-scale construction 3.1.4 peak shear strength, n—the maximum shear capacity
ofthefacingsystemandmayberuninalaboratoryorthefield. between segmental concrete units.
1.3 The values stated in SI units are regarded as the 3.1.5 segmental concrete depth, n—the segmental concrete
standard. The values stated in inch-pound units are provided unit dimension perpendicular to the wall face.
for information only. 3.1.6 segmental concrete unit (modular concrete block),
1.4 This standard may involve hazardous materials, opera- n—a concrete unit manufactured specifically for mortarless,
tions, and equipment. This standard does not purport to dry-stack retaining wall construction.
address all of the safety concerns, if any, associated with its 3.1.7 segmental concrete unit width, n—the segmental con-
use. It is the responsibility of the user of this standard to crete unit dimension parallel to the wall face.
establish appropriate safety and health practices and deter- 3.2 For definition of other terms relating to geosynthetics,
mine the applicability of regulatory limitations prior to use. refer to Terminology D 4439.
2. Referenced Documents 4. Summary of Test Method
2.1 ASTM Standards: 4.1 In this test method, segmental concrete units are as-
D 448 Classification for Sizes of Aggregate for Road and sembled in two rows (layers). The bottom row is laterally
Bridge Construction restrained. The top row is loaded vertically to a constant
D 4354 Practice for Sampling of Geotextiles for Testing surcharge load and the interface is sheared at a constant rate of
D 4439 Terminology for Geosynthetics displacement until a drop of load after the peak load occurs.
D 4595 Test Method for Tensile Properties of Geotextiles The test may be run with the geosynthetic reinforcement
by the Wide-Width Strip Method sandwiched between the two rows of segmental concrete units
D 6683 Test Method for Determining the Connection to determine the shear strength between segmental concrete
Strength Between Segmental Concrete Units and Geosyn- units at the connection between the units and the geosynthetic
thetic Reinforcement reinforcement.
5. Significance and Use
This test method is under the jurisdiction of ASTM Committee D35 on
5.1 The shear strength between segmental concrete units
Geosynthetics and is the direct responsibility of Subcommittee D35.01 on Mechani-
(with and without geosynthetic reinforcement) and is used in
cal Properties.
design of reinforced soil retaining walls.
Current edition approved Oct. 1, 2003. Published November 2003.
For referenced ASTM standrds, visit the ASTM Web Site, www.astm.org. or
5.2 This test is used to determine the shear strength for the
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
design of the facing stability of segmental retaining walls.
Standards volume information, refer to the standard’s Document Summary page on
Performing a series of these shear tests at varying normal loads
the ASTM web site.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6916–03
permits development of a relationship between shear strength 6.4 Restraining Box/Plate—A rigid restraining box/plate is
and normal load. This relationship may be linear, bi-linear, or required to prevent horizontal movement of the lowermost
some other complex mathematical expression.
segmental concrete units during shear testing. The restraining
5.3 Thisshearstrengthtestismeanttobeaperformancetest
box/plate area shall be of sufficient width and depth to
(laboratory or field), therefore, it should be conducted using
accommodate the full scale “as manufactured” segmental
full-scale system components. The conditions for the test are
concrete units being tested.
selected by the user and are not for routine testing.
6.5 Shear Loading Assembly—The tensile loading unit will
5.4 As a performance test on full-scale system components
generally be a constant rate of extension screw jack or
itaccountsforsomeofthevariablesinconstructionprocedures
hydraulic actuator that can be displacement rate controlled.
and materials tolerance normally present for these types of
The loading equipment shall have a capacity that is at least
retaining wall systems.
equal to 120 % of the anticipated shear strength of the
6. Apparatus
segmentalconcreteunits.Thepistonshallbecapableofatleast
150 mm (6 in.) of movement in order to facilitate test set up
6.1 Testing System—An example of a test apparatus and
andtoensurethatthereisadequatestroketoachievepeakload.
setup is illustrated in Fig. 1. The principal components of the
The orientation of the tensioning force shall be horizontal and
test apparatus are:
perpendicular to the back of the segmental units. The horizon-
6.1.1 Loading Frame.
6.1.2 Normal Load Piston/Actuator. tal loading arrangement must not permit rotation of the top
6.1.3 Vertical Loading Platen, with stiff rubber mat or
concrete unit during shear.
airbag to apply uniform vertical pressure to top of concrete
6.6 Load Cells—A calibrated load cell shall be used to
blocks.
measure the shear force and normal load during the test. The
6.1.4 Vertical Load Cell, to measure normal load.
load cell used for measuring shear shall have a capacity that is
6.1.5 Horizontal Piston/Actuator, to apply horizontal load
greater than or equal to 120 % of the anticipated shear force
on the top segmental concrete unit.
between units. The load cell used for measuring the normal
6.1.6 Horizontal Load Cell, to measure applied force on the
surcharge load shall have a capacity that is greater than or
top segmental concrete unit.
equal to 100 % of the maximum anticipated normal load. The
6.1.7 Two (2) Horizontal Displacement Measurement De-
load cells shall be accurate within 6 0.5 % of its full-scale
vices, to record displacement of the top segmental concrete
range.
unit.
6.7 Displacement Measuring Devices—Two (2) Linear
6.2 Loading Frame—The loading frame shall have suffi-
Variable Displacement Transducers (LVDTs) or similar elec-
cient capacity to resist the forces developed by the horizontal
tronic displacement measuring devices are recommended to
and vertical loading pistons/actuators.
continuously monitor the displacement of the top segmental
6.3 Shear Loading Plate—The shear loading plate must be
concrete unit out from the back of the lower segmental
sufficiently rigid to apply a uniform force across the full width
concrete units. Alternatively, dial gauges may be read and
of the top course. For some segmental units it may be
recorded manually at regular intervals not greater than one
necessary to apply the load through a deformable material (that
is, stiff rubber) which will conform to an irregular block minute. LVDTs, dial gauges or similar measuring devices shall
be accurate to 6 0.1 mm (0.005 in.).
surface, thereby allowing for a uniform load distribution.
FIG. 1 Connection Test Apparatus (Plan View)
D6916–03
7. Sampling 7.2.7 Number of Tests—Asufficient number of tests shall be
conducted to adequately define a relationship between shear
7.1 Segmental Concrete Units:
strength and normal load. Tests shall be conducted at a
7.1.1 Segmental concrete units shall be full-size blocks and
minimum of three unique normal loads within the range of
meet the manufacturer’s material and dimensional specifica-
loads typical of wall design, as directed by the user. Addition-
tions. Model or prototype units shall not be used unless it can
ally, at least two more tests at one normal load will be
be demonstrated that they are equivalent to production units.
necessary to verify repeatability (see 7.2.8).
7.1.2 The user shall specify and/or collect a sufficient
7.2.8 Repeatability of Test Results—The testing agency
sample of representative segmental units, from a standard
shall provide evidence of test results repeatability by conduct-
production lot, to construct the anticipated number of test
ing at least three tests at one normal load level for a specific
configurations for the connection system within the testing
segmental concrete units and geosynthetic reinforcement sys-
agency’s load frame and testing system.
tem. The general range for repeatability of peak shear strength
7.1.3 The shear connection must be constructed with full-
of these three nominally identical tests is 6 10 % from the
size segmental concrete units randomly selected from the users
mean of the three tests (see reference in 13.1). If the test results
sampling of a standard production lot, see 7.1.2.
are outside of this range it shall be duly noted on the report.
7.1.4 Test Width —The width of the shear connection for
testing shall be constructed to a minimum of 750 mm (29.5 in.)
8. Procedure
in width and contain one segmental unit placed on top of two
8.1 Install and brace lower course of concrete segmental
segmental concrete units and include at least one typical
units. Place the units such that a running joint will be located
segmental concrete unit running bond joint. The top unit must
along the centerline of the test apparatus.
be the full width of the unit.
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