ASTM D6918-09(2022)

Standard Test Method for Testing Vertical Strip Drains in the Crimped Condition

SIGNIFICANCE AND USE
5.1 This test method is considered satisfactory for the acceptance of commercial shipments of vertical strip drains.  
5.1.1 In case of dispute arising from differences in reported test results when using this test method for acceptance testing of commercial shipments, the purchaser and the supplier should conduct comparative tests to determine if there is any statistical bias between their laboratories. Competent statistical assistance is recommended for the investigation of bias. As a minimum, the two parties should take a group of test specimens that as homogenous as possible, and that are from a lot of material of the type in question. The test specimens should be randomly assigned in numbers to each laboratory for testing. The average results from the two laboratories should be compared using Student's t-test for unpaired data and an acceptable probability level chosen by the two parties before the start of testing. If a bias is found, either its cause must be found and corrected, or the purchaser and the supplier must agree to interpret future test results in light of the known bias.  
5.2 Vertical strip drains are installed in areas where it is desired to increase the rate of soil consolidation. It has been shown that as the soil around the vertical strip drain consolidates, a crimp may form in the vertical strip drain due to the movement of the drain in the area of soil consolidation.  
5.3 This test method can be used to evaluate if there is any reduction in flow rate of water through the drain due to the crimping, and what effect, if any, this crimping may have on the rate of consolidation of the soil.
SCOPE
1.1 This test method is a performance test that measures the effect crimping has on the ability of vertical strip drains to transmit water parallel to the plane of the drain.  
1.2 This test method is applicable to all vertical strip drains.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Jul-2022
• ICS: 91.060.20 - Roofs
• Technical Committee: D35 - Geosynthetics
• Drafting Committee: D35.03 - Permeability and Filtration

Relations

• Refers: ASTM D4439-24 - Standard Terminology for Geosynthetics
• Effective Date: 01-Feb-2024
• Refers: ASTM D4354-12(2020) - Standard Practice for Sampling of Geosynthetics and Rolled Erosion Control Products (RECPs) for Testing
• Effective Date: 01-May-2020
• Refers: ASTM D4439-18 - Standard Terminology for Geosynthetics
• Effective Date: 15-Apr-2018
• Refers: ASTM D4439-17 - Standard Terminology for Geosynthetics
• Effective Date: 01-Aug-2017
• Refers: ASTM D4439-15a - Standard Terminology for Geosynthetics
• Effective Date: 01-Sep-2015
• Refers: ASTM D4439-15 - Standard Terminology for Geosynthetics
• Effective Date: 01-Jul-2015
• Refers: ASTM D4439-14 - Standard Terminology for Geosynthetics
• Effective Date: 01-Mar-2014
• Refers: ASTM D4354-12 - Standard Practice for Sampling of Geosynthetics and Rolled Erosion Control Products(RECPs) for Testing
• Effective Date: 01-Jul-2012
• Refers: ASTM D4439-11 - Standard Terminology for Geosynthetics
• Effective Date: 01-Oct-2011
• Refers: ASTM D4354-99(2009) - Standard Practice for Sampling of Geosynthetics for Testing
• Effective Date: 15-Jan-2009
• Refers: ASTM D4354-99(2004) - Standard Practice for Sampling of Geosynthetics for Testing
• Effective Date: 01-Nov-2004
• Refers: ASTM D4439-04 - Standard Terminology for Geosynthetics
• Effective Date: 01-Jun-2004
• Refers: ASTM D4439-02 - Standard Terminology for Geosynthetics
• Effective Date: 10-Aug-2002
• Refers: ASTM D4439-00 - Standard Terminology for Geosynthetics
• Effective Date: 10-Sep-2001
• Refers: ASTM D4439-01 - Standard Terminology for Geosynthetics
• Effective Date: 10-Sep-2001

Overview

ASTM D6918-09(2022), titled Standard Test Method for Testing Vertical Strip Drains in the Crimped Condition, is an internationally recognized test method developed by ASTM International. This standard measures how crimping-typically formed as soils consolidate around vertical strip drains-impacts the drain’s capacity to transmit water along the plane of the drain. It provides procedures for both laboratory and field acceptance of commercial shipments of vertical strip drains, ensuring reliable and consistent performance for geotechnical and civil engineering projects.

Key Topics

• Vertical Strip Drains: Geocomposite products installed vertically into soil to accelerate consolidation by providing drainage channels.
• Effect of Crimping: The standard evaluates whether crimping, which can occur as soil consolidates, reduces water flow through the drain and potentially affects the rate of soil consolidation.
• Performance Measurement: Outlines methods to test the flow rate of water through uncrimped and crimped strip drains under controlled conditions.
• Comparison and Dispute Resolution: Specifies procedures for statistical comparison (including Student’s t-test) when buyer and supplier test results differ.
• Sampling and Test Units: Instructions for sampling rolls of prefabricated vertical strip drains and preparing specimens.
• Test Apparatus: Describes the use of a constant head water chamber and alternative discharge capacity testers to simulate field conditions.

Applications

ASTM D6918-09(2022) is applicable across geotechnical, civil, and environmental engineering where rapid soil consolidation is required:

• Site Improvement for Infrastructure: Used in the design and quality assurance of vertical strip drains in highway embankments, railways, airport runways, and port facilities where ground improvement is critical.
• Land Reclamation: Essential for projects that require accelerated consolidation of soft soils, particularly in reclaimed land or marshes.
• Flood Mitigation Projects: Ensures the reliable performance of drains in levees and flood control structures where rapid water dissipation is vital.
• Commercial Shipment Acceptance: Provides guidance for manufacturers, contractors, and buyers to evaluate drain quality before installation, minimizing risk and dispute.

The test method supports the verification that delivered vertical strip drains meet project specifications and maintain the required water flow even after crimping, which is likely in real soil consolidation scenarios.

Related Standards

This standard is often used in conjunction with other ASTM geosynthetics and drainage product standards, enabling comprehensive quality assessment in construction and earthworks:

• ASTM D4354 – Practice for Sampling of Geosynthetics and Rolled Erosion Control Products (RECPs) for Testing
• ASTM D4439 – Terminology for Geosynthetics

These referenced standards ensure that terms, procedures, and sampling methods are consistent and recognized across the geotechnical industry.

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Keywords: ASTM D6918, vertical strip drains, crimped condition, geosynthetics, flow rate testing, soil consolidation, standard test method, drainage performance, civil engineering, quality control.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6918 − 09 (Reapproved 2022)
Standard Test Method for
Testing Vertical Strip Drains in the Crimped Condition
This standard is issued under the fixed designation D6918; 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 4. Summary of Test Method
1.1 This test method is a performance test that measures the 4.1 This test method presents two methods for determining
effect crimping has on the ability of vertical strip drains to the effect of a crimp forming in the vertical strip drain due to
transmit water parallel to the plane of the drain. the consolidation of soils around it in the field.
4.1.1 A vertical strip drain is sealed in a waterproof mem-
1.2 This test method is applicable to all vertical strip drains.
brane to prevent any water from escaping out through the
1.3 The values stated in SI units are to be regarded as
geotextile during the test.
standard. No other units of measurement are included in this
4.1.2 The sealed vertical strip drain is placed in the appro-
standard.
priate crimping device and water is allowed to pass through it
1.4 This standard does not purport to address all of the under a constant head of water.
safety concerns, if any, associated with its use. It is the
4.1.3 Acrimp is placed on the specimen, and water allowed
responsibility of the user of this standard to establish appro- to pass through it under a constant head in the crimped
priate safety, health, and environmental practices and deter-
condition.
mine the applicability of regulatory limitations prior to use. 4.1.4 The flow rate of water along the plane of the un-
1.5 This international standard was developed in accor-
crimped vertical strip drain is compared to the flow rate in the
dance with internationally recognized principles on standard- crimped condition.
ization established in the Decision on Principles for the
5. Significance and Use
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
5.1 This test method is considered satisfactory for the
Barriers to Trade (TBT) Committee.
acceptance of commercial shipments of vertical strip drains.
5.1.1 In case of dispute arising from differences in reported
2. Referenced Documents
test results when using this test method for acceptance testing
2.1 ASTM Standards:
of commercial shipments, the purchaser and the supplier
D4354 Practice for Sampling of Geosynthetics and Rolled
should conduct comparative tests to determine if there is any
Erosion Control Products (RECPs) for Testing
statistical bias between their laboratories. Competent statistical
D4439 Terminology for Geosynthetics
assistance is recommended for the investigation of bias. As a
minimum, the two parties should take a group of test speci-
3. Terminology
mens that as homogenous as possible, and that are from a lot of
3.1 Definitions:
material of the type in question. The test specimens should be
3.1.1 For general geosynthetics terms used in this test
randomly assigned in numbers to each laboratory for testing.
method, refer to Terminology D4439.
The average results from the two laboratories should be
3.2 Definitions of Terms Specific to This Standard:
compared using Student’s t-test for unpaired data and an
3.2.1 vertical strip drain, n—a geocomposite consisting of a
acceptable probability level chosen by the two parties before
geotextile cover and drainage core installed vertically into soil
the start of testing. If a bias is found, either its cause must be
to provide drainage for accelerated consolidation of soils.
found and corrected, or the purchaser and the supplier must
agree to interpret future test results in light of the known bias.
This test method is under the jurisdiction of ASTM Committee D35 on
5.2 Vertical strip drains are installed in areas where it is
Geosynthetics and is the direct responsibility of Subcommittee D35.03 on Perme-
ability and Filtration.
desired to increase the rate of soil consolidation. It has been
Current edition approved Aug. 1, 2022. Published August 2022. Originally
shown that as the soil around the vertical strip drain
approved in 2003. Last previous edition approved in 2014 as D6918 – 09 (2014).
consolidates, a crimp may form in the vertical strip drain due
DOI: 10.1520/D6918-09R22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or to the movement of the drain in the area of soil consolidation.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
5.3 This test method can be used to evaluate if there is any
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. reduction in flow rate of water through the drain due to the
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6918 − 09 (2022)
crimping, and what effect, if any, this crimping may have on
the rate of consolidation of the soil.
6. Apparatus
6.1 Method A:
6.1.1 The test device must be capable of maintaining a
constant head of water on the vertical strip drain being tested.
The apparatus consists of a water chamber assembly, a speci-
men holder, and a crimping wedge, all of which are attached to
a holding stand. See Figs. 1 and 2.
6.1.2 Container, for collecting the water as it flows through
the vertical strip drain.
6.1.3 Stopwatch or Electronic Timing Device—Astopwatch
with an accuracy level to 0.1 s, connected to the collection
container,fortimingtheflowofwaterthroughtheverticalstrip
drain.
6.1.4 Blow Dryer, used for applying heat to the heat shrink-
wrap that is placed around the test specimen prior to testing.
6.2 Method B:
6.2.1 Discharge Capacity Tester—The discharge capacity
tester may be pressured by earth pressure when the vertical
strip drains are mounted vertically within the ground to serve
as discharging interstitial water. The apparatus in use for the
FIG. 2 Complete Crimp Test Apparatus for Method A
principle illustrated in Fig. 3 is used for monitoring the
variation of the discharge capacity of the vertical strip drains in
internal component of the cylinder in order to model the
the event of the earth pressure.
pressure arising from the earth mass.
6.2.1.1 The discharge capacity tester is mainly comprised of
6.2.1.4 The pressure controller should be provided for
a sample mounting portion, a pressure controller, water supply,
controlling the pressure applied to the mounted sample.
and a flow rate measurement portion.
6.2.1.5 The water supply for adjusting height is required.
6.2.1.2 The sample mounting portion must maintain all
6.2.1.6 The flow rate measurement portion measures the
vertically mounted vertical strip drains. The length of the
amount of water passing through the mounted sample.
vertical strip drain exposed to external pressure must be 300 6
6.2.1.7 Rubber Membrane—A cylinder-shaped rubber
10 mm.
membrane, of a thickness of 0.35 mm, and formed with
6.2.1.3 The mounted sample is covered by a cylinder, and
synthesized rubber latex.
air pressure or hydraulic pressure must be applied to the
6.2.1.8 Stopwatch—See 6.1.3.
6.2.1.9 Thermometer—A thermometer with an accuracy
level to 0.2 °C.
6.2.1.10 Flow Meter—An instrument capable of measuring
the amount of water with an accuracy level of 10 cm,ora
gauge revised with an accuracy of 5 % for enabling the direct
measurement of the flow velocity.
7. Materials
7.1 Method A:
7.1.1 Heat Shrink Plastic Wrap—The heat shrink plastic
wrap, of the type used in homes for sealing windows from
wind drafts, is used to seal the vertical strip drain so that water
does not flow out through the geotextile wrap on the core. The
water is to flow in a parallel plan to the fabric, along the core
material of the drain.
7.1.2 Bathtub Caulk—The caulk is used to seal the test
specimen into the water chamber assembly as directed in
12.1.2.
7.2 Method B:
7.2.1 Test Water:
7.2.1.1 Water ranging from 18 to 22 °C is used for the test
FIG. 1 Crimping Wedge for Method A water.
D6918 − 09 (2022)
FIG. 3 Test Device for Method B
NOTE 1—The temperature correction (referring to an accompanying
mens per laboratory sample such that the user may expect the
document A) is in relation only to streamline flow, and thus, where the
95 % probability level that the test result is no more than 5 %
flow of water is not the streamline flow, the water temperature should be
above the average for each laboratory sample.
maintained close to a temperature of 20 °C in order to minimize any
inaccuracies caused by the inappropriate correction coefficient.
10.1.1 Reliable Estimate of v—When there is a reliable
estimate of v based upon extensive test records for similar
7.2.1.2 If the test water is directly provided from the water
materials in the user’s laboratory as directed in the method,
supply, air bubbles may be generated in the internal construc-
calculate the required number of specimens using Eq 1 as
tion of the test specimens. Therefore, the test water should be
provided from a distillation tank in a bubble-removed state. follows:
7.2.1.3 Where the test water includes solids or substances
n 5 ~tv/A! (1)
apparent to the naked eye, or where the passage amount of the
where:
water is gradually reduced due to a stacked solid or substances
on the test specimens, the water should be filtered.
n = number of test specimens, rounded upward to a whole
number,
8. Hazards
v = reliable estimate of coefficient of variation of individual
8.1 There are no known hazards, either with the materials or
observations on similar materials in the user’s labora-
in performing this test.
tory under single operator precision, %,
t = the value of Student’s t for I = one sided limits, at 95 %
9. Sampling, Test Specimens, and Test Units
probability level, and the degrees of freedom associated
9.1 Division Into Lots and Lot Samples—Divide the mate-
with the estimate of v, and
rial into lots and take a lot sample as directed in Practice
A = 5.0 % of the average, the value of the allowable
D4354. Rolls of prefabricated vertical strip drains are the
variation.
primary sampling unit.
10.1.2 No Reliable Estimate of v—When there is no reliable
9.2 Laboratory Sample—Remove the outer wrap of drain
estimate of v for the user’s laboratory, Eq 1 should not be used
material from the roll to avoid sampling and testing any
directly. Instead, specify the fixed number of three specimens
material which may have been damaged during storage. Take
for testi
...