ASTM D6916-06c(2011)

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

SIGNIFICANCE AND USE
The shear strength between segmental concrete units (with and without geosynthetic reinforcement) and is used in design of reinforced soil retaining walls.
This test is used to determine the shear strength for the design of the facing stability of segmental retaining walls. Performing a series of these shear tests at varying normal loads permits development of a relationship between shear strength and normal load. This relationship may be linear, bi-linear, or some other complex mathematical expression.
This shear strength test is meant to be a performance test (laboratory or field), therefore, it should be conducted using full-scale system components. The conditions for the test are selected by the user and are not for routine testing.
As a performance test on full-scale system components it accounts for some of the variables in construction procedures and materials tolerance normally present for these types of retaining wall systems.
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.
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-2011
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: D35 - Geosynthetics
• Drafting Committee: D35.01 - Mechanical Properties

Relations

• Replaces: ASTM D6916-06c - Standard Test Method for Determining the Shear Strength Between Segmental Concrete Units (Modular Concrete Blocks)
• Effective Date: 01-Oct-2011
• Replaced By: ASTM D6916-18 - Standard Test Method for Determining the Shear Strength Between Segmental Concrete Units (Modular Concrete Blocks)
• Effective Date: 15-Jul-2018

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 − 06c (Reapproved 2011)
Standard Test Method for
Determining the Shear Strength Between Segmental
Concrete Units (Modular Concrete Blocks)
This standard is issued under the fixed designation D6916; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope D6637 Test Method for Determining Tensile Properties of
Geogrids by the Single or Multi-Rib Tensile Method
1.1 This test method is used to determine the shear strength
between two layers of segmental concrete block units used in
3. Terminology
construction of reinforced soil retaining walls. The test is
3.1 Definitions:
carried out under conditions determined by the user that
3.1.1 displacement criteria, n—a user prescribed maximum
reproducethefacingsystematfull-scale.Theresultsofaseries
movement, mm (in.), of the top segmental concrete unit out
of tests are used to define a relationship between shear strength
from the back of lower segmental concrete units.
developed between segmental concrete units and normal load.
3.1.2 geosynthetic, n—a planar product manufactured from
1.2 This is a performance test used to determine properties
polymeric material used with soil, rock, earth, or other geo-
for design of retaining wall systems utilizing segmental con-
technical engineering related material as an integral part of a
crete units and soil reinforcing geosynthetics, either geotextiles
man-made project, structure or system. D4439
or geogrids. The test is performed on a full-scale construction
3.1.3 granular infill, n—coarse grained soil aggregate used
ofthefacingsystemandmayberuninalaboratoryorthefield.
to fill the voids in and between segmental concrete units.
1.3 The values stated in SI units are regarded as the
3.1.4 peak shear strength, n—the maximum shear capacity
standard. The values stated in inch-pound units are provided
between segmental concrete units.
for information only.
3.1.5 segmental concrete depth, n—the segmental concrete
1.4 This standard may involve hazardous materials,
unit dimension perpendicular to the wall face.
operations, and equipment. This standard does not purport to
3.1.6 segmental concrete unit (modular concrete block),
address all of the safety concerns, if any, associated with its
n—a concrete unit manufactured specifically for mortarless,
use. It is the responsibility of the user of this standard to
dry-stack retaining wall construction.
establish appropriate safety and health practices and deter-
3.1.7 segmental concrete unit width, n—the segmental con-
mine the applicability of regulatory limitations prior to use.
crete unit dimension parallel to the wall face.
2. Referenced Documents
3.2 For definition of other terms relating to geosynthetics,
2.1 ASTM Standards: refer to Terminology D4439.
D448 Classification for Sizes of Aggregate for Road and
4. Summary of Test Method
Bridge Construction
4.1 In this test method, segmental concrete units are as-
D4354 Practice for Sampling of Geosynthetics and Rolled
sembled in two rows (layers). The bottom row is laterally
Erosion Control Products(RECPs) for Testing
restrained. The top row is loaded vertically to a constant
D4439 Terminology for Geosynthetics
surcharge load and the interface is sheared at a constant rate of
D4595 Test Method for Tensile Properties of Geotextiles by
displacement until a drop of load after the peak load occurs.
the Wide-Width Strip Method
The test may be run with the geosynthetic reinforcement
sandwiched between the two rows of segmental concrete units
This test method is under the jurisdiction of ASTM Committee D35 on
to determine the shear strength between segmental concrete
Geosynthetics and is the direct responsibility of Subcommittee D35.01 on Mechani-
units at the connection between the units and the geosynthetic
cal Properties.
reinforcement.
Current edition approved Oct. 1, 2011. Published October 2011. Originally
approved in 2003. Last previous edition approved in 2006 as D6916–06c. DOI:
5. Significance and Use
10.1520/D6916-06CR11.
For referenced ASTM standards, visit the ASTM Web Site, www.astm.org. or
5.1 The shear strength between segmental concrete units
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
(with and without geosynthetic reinforcement) and is used in
Standards volume information, refer to the standard’s Document Summary page on
the ASTM web site. design of reinforced soil retaining walls.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6916 − 06c (2011)
FIG. 1 Shear Test Apparatus (Cross Section View)
5.2 This test is used to determine the shear strength for the 6.1.7 Two (2) Horizontal Displacement Measurement
design of the facing stability of segmental retaining walls. Devices, to record displacement of the top segmental concrete
Performing a series of these shear tests at varying normal loads
unit.
permits development of a relationship between shear strength
6.2 Loading Frame—The loading frame shall have suffi-
and normal load. This relationship may be linear, bi-linear, or
cient capacity to resist the forces developed by the horizontal
some other complex mathematical expression.
and vertical loading pistons/actuators.
5.3 Thisshearstrengthtestismeanttobeaperformancetest
6.3 Shear Loading Plate—The shear loading plate must be
(laboratory or field), therefore, it should be conducted using
sufficiently rigid to apply a uniform force across the full width
full-scale system components. The conditions for the test are
selected by the user and are not for routine testing. of the top course. For some segmental units it may be
necessary to apply the load through a deformable material (that
5.4 As a performance test on full-scale system components
is, stiff rubber) which will conform to an irregular block
itaccountsforsomeofthevariablesinconstructionprocedures
surface, thereby allowing for a uniform load distribution.
and materials tolerance normally present for these types of
retaining wall systems.
6.4 Restraining Box/Plate—A rigid restraining box/plate is
required to prevent horizontal movement of the lowermost
6. Apparatus
segmental concrete units during shear testing. The restraining
6.1 Testing System—An example of a test apparatus and
box/plate area shall be of sufficient width and depth to
setup is illustrated in Fig. 1. The principal components of the
accommodate the full scale “as manufactured” segmental
test apparatus are:
concrete units being tested.
6.1.1 Loading Frame.
6.5 Shear Loading Assembly—The tensile loading unit will
6.1.2 Normal Load Piston/Actuator .
generally be a constant rate of extension screw jack or
6.1.3 Vertical Loading Platen, with stiff rubber mat or
hydraulic actuator that can be displacement rate controlled.
airbag to apply uniform vertical pressure to top of concrete
The loading equipment shall have a capacity that is at least
blocks.
equal to 120 % of the anticipated shear strength of the
6.1.4 Vertical Load Cell, to measure normal load.
segmentalconcreteunits.Thepistonshallbecapableofatleast
6.1.5 Horizontal Piston/Actuator , to apply horizontal load
on the top segmental concrete unit. 150 mm (6 in.) of movement in order to facilitate test set up
andtoensurethatthereisadequatestroketoachievepeakload.
6.1.6 Horizontal Load Cell, to measure applied force on the
top segmental concrete unit. The orientation of the tensioning force shall be horizontal and
D6916 − 06c (2011)
perpendicular to the back of the segmental units. The horizon- 7.1.6 Conditioning—The segmental concrete unit test speci-
tal loading arrangement must not permit rotation of the top men shall be brought to standard temperature and relative
concrete unit during shear. humidityconditionsfortestinginalaboratory.Thetemperature
is to be 21 6 2°C (70 6 4°F) and the relative humidity of 65
6.6 Load Cells—A calibrated load cell shall be used to
6 10 %. For field-testing the specimen shall be brought to
measure the shear force and normal load during the test. The
ambient conditions for not less than one hour. The temperature
load cell used for measuring shear shall have a capacity that is
and humidity at the start and end of the test shall be recorded
greater than or equal to 120 % of the anticipated shear force
for field-testing.
between units. The load cell used for measuring the normal
surcharge load shall have a capacity that is greater than or 7.2 Geosynthetic (if required) :
equal to 100 % of the maximum anticipated normal load. The
7.2.1 If the segmental concrete units are to be used for a
load cells shall be accurate within 6 0.5 % of its full-scale
geosynthetic reinforced segmental retaining wall, then a layer
range.
ofaspecifiedgeosyntheticmaterialshallbeplacedbetweenthe
segmental concrete units.
6.7 Displacement Measuring Devices—Two (2) Linear
7.2.2 Sampling Requirements—The latest version of ASTM
Variable Displacement Transducers (LVDTs) or similar elec-
sampling protocol for geotextiles (Practice D4354) shall be
tronic displacement measuring devices are recommended to
used for the geosynthetic reinforcement material.
continuously monitor the displacement of the top segmental
7.2.3 Conditioning—The geosynthetic reinforcement test
concrete unit out from the back of the lower segmental
concrete units. Alternatively, dial gauges may be read and specimen shall be brought to standard temperature and relative
humidityconditionsfortestinginalaboratory.Thetemperature
recorded manually at regular intervals not greater than one
minute. LVDTs, dial gauges or similar measuring devices shall is to be 21 6 2°C (70 6 4°F) and the relative humidity of 60
6 10 %. For field-testing the specimen shall be brought to
be accurate to 6 0.1 mm (0.005 in.).
ambient conditions for not less than one hour. The temperature
and humidity at the start and end of the test shall be recorded
7. Sampling
for field-testing.
7.1 Segmental Concrete Units:
7.2.4 Specimen Width—When included, the geosynthetic
7.1.1 Segmental concrete units shall be full-size blocks and
reinforcement test specimen shall be the full width of the shear
meet the manufacturer’s material and dimensional specifica-
test interface.
tions. Model or prototype units shall not be used unless it can
7.2.5 Specimen Length—The geosynthetic specimen shall
be demonstrated that they are equivalent to production units.
have sufficient length to cover the interface surface as specified
7.1.2 The user shall specify and/or collect a sufficient
by the user. The specimen must be trimmed to provide
sample of representative segmental units, from a standard
sufficient anchorage at the actuator side of the test apparatus to
production lot, to construct the anticipated number of test
prevent slippage of the front edge of the geosynthetic sample.
configurations for the shear system within the testing agency’s
7.2.6 Anew geosynthetic reinforcement test specimen shall
load frame and testing system.
be used for each test.
7.1.3 The shear interface must be constructed with full-size
7.2.7 Number of Tests—Asufficient number of tests shall be
or modified (see 7.1.4) segmental concrete units randomly
conducted to adequately define a relationship between shear
selected from the users sampling of a standard production lot,
strength and normal load. Tests shall be conducted at a
see 7.1.2.
minimum of five (5) unique normal loads within the range of
7.1.4 Test Width—The width of the shear interface for
loads typical of wall design, as directed by the user.
testing shall be constructed to a minimum of 750 mm (29.5 in.)
Additionally, at least two more tests at one normal load will be
in width. The test section shall consist of at least two bottom
necessary to verify repeatability (see 7.2.8).
course segmental concrete units with at least one top course
7.2.8 Repeatability of Test Results—Thetestingagencyshall
segmental unit placed on top of the lower segmental concrete
provide evidence of test results repeatability by conducting at
units. The shear interface shall include at least one typical
least three tests at one normal load level for a specific
segmental concrete unit running bond joint. The top unit must
segmental concrete units and geosynthetic reinforcement sys-
be the full width of the unit. The bottom units may be adjusted
tem. The general range for repeatability of peak shear strength
to fit into the test apparatus. Testing of segmental concrete unit
of these three nominally identical tests is 6 10 % from the
widths greater than 500 mm (19.7 in.), may be represented in
mean of the three tests. If the test results are outside of this
this test by limiting the test wall to 1000 mm (39.4 in.) in
range it shall be duly noted on the report.
width.
NOTE 1—Any modification to the width of bottom units should
8. Procedure
maintain the integrity of the test shear interface and insure that a
representative (repeatable) test shear interface is maintained.
8.1 Install and brace lower course of concrete segmental
units. Place the units such that a running joint will be located
7.1.5 Test Height—The height of the segmental concrete
along the centerline of the test apparatus.
unit may be reduced to facilitate handling and safety issues.
Any modification to the segmental concrete unit height shall 8.1.1 The facing system shall be constructed using the
not alter the geometry of the test shear interface and shall be geosynthetic reinforcement (if required), granular infill, full-
clearly stated in the test report (see 10.2). scale segmental concrete block units and connectors specified
D6916 − 06c (2011)
FIG. 2 Shear Strength versus Displacement
by the user. The number, type and arrangement of mechanical 8.8 Position the shear loading plate against the top segmen-
connectors shall also be specified by the user. tal concrete unit. The shear load should be applied against the
8.1.2 A single course of segmental units shall be placed on stacked units immediately above the shear interface to mini-
a rigid base. A single segmental concrete unit will later (see mize moment loading.
8.5) be placed over the bottom course of units, with the
8.9 Attach one displacement recording device to each front
geosynthetic reinforcement located and placed between these
(or back) corner tof the top segmental concrete unit.
courses as described by the user or in the same manner
8.10 Applyapredeterminednormal(vertical)loadtothetop
anticipated for field construction.
of the top segmental c
...