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Comparison of California Bearing Ratio and Pin Puncture Strength Testing Used
in the Evaluation of Geotextiles
Article in Transportation Research Record Journal of the Transportation Research Board · January 2017
DOI: 10.3141/2656-01
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Comparison of California Bearing Ratio
and Pin Puncture Strength Testing
Used in the Evaluation of Geotextiles
Stacy Van Dyke, Hani Titi, and Rani El-Hajjar
applications. ASTM D4833 (Standard Test Method for Index Punc­
ture Resistance of Geomembranes and Related Products) has been
used in the past to determine the puncture resistance value. ASTM,
AASHTO, and the geotextile industry have replaced ASTM D4833
with D6241 (Standard Test Method for the Static Puncture Strength of
Geotextiles and Geotextile-Related Products Using a 50-mm Probe),
because ASTM D4833 has been deemed insufficient in classifying
geotextile materials. However, many departments of transporta­
tion throughout the country and FHWA Section 716 still refer to
ASTM D4833. Other state departments of transportation refer to
ASTM D4833 and D6241 or provide a list of alternative test methods
to be considered in place of these tests.
Narejo et al. (1), Jones et al. (2), Hsieh and Wang (3), Koerner
and Koerner (4), Rawal and Saraswat (5), and Askari et al. (6) con­
ducted studies of varying relationships based on exclusive material
types, with woven or nonwoven materials. Studies have compared
ASTM D4833 and D6241 or determined a trend in a specific manu­
facturing or material classification. A study of the correlation of the
pin and California bearing ratio (CBR) puncture resistance testing
methods, independent of manufacturing or material type, has not
been attempted.
The objective of this research was to use ASTM D4833 and D6241
to test several geotextiles with a controlled material type and mass
per unit area, to describe the relationship between the pin and CBR
puncture strength, rather than between material types. In addition,
the study investigated whether weave type affects the puncture
resistance of a geotextile’s performance.
Geotextiles are commonly used in pavements, earth retaining structures,
and landfills, as well as in other geotechnical applications. The puncture
strength test evaluates the ability of geotextiles to withstand stresses and
loads during construction, which are among the severe conditions that
geotextiles can experience. ASTM has recently replaced the standard
pin puncture strength test, D4833, with the California bearing ratio
(CBR) puncture strength test, D6241. However, many state departments
of transportation and the FHWA still refer to ASTM D4833. Other state
departments of transportation refer to ASTM D4833 and to D6241 or
provide a list of alternative test methods to be considered in place of
either of these tests. The objective of this research was to correlate the
CBR and pin puncture strengths for various categories of geotextiles,
regardless of weave type and mass per unit area. Five types of polypropylene geotextiles, three nonwoven and two woven, were subjected to
testing in accordance with ASTM D4833 and D6241 standard procedures. Ten and 15 samples of each geotextile type were tested with CBR
and pin puncture strength tests, respectively. All five types of geotextiles
exhibited puncture strength values, whether pin or CBR, which were
consistent within each group. Similarly, distinct load-displacement curves
were exhibited within each material group. Statistical analyses were
conducted to establish a correlation between the CBR and pin puncture
strength values. The correlations were successfully used to estimate the
CBR puncture strength values from the pin test with reasonable accuracy
(R2 = .78).
Geotextiles are a broad group of fabrics used in civil and geo­
technical engineering applications. According to ASTM D4439,
a geotextile is “a permeable geosynthetic comprised solely of tex­
tiles. Geotextiles are used with foundation, soil, rock, earth, or any
other geotechnical engineering-related material as an integral part
of a human-made project, structure, or system” (p. 3). Geotextiles
are commonly classified by the function they serve, the manufactur­
ing process used to make them, and their base material. Geotextiles
typically serve one or more of the following functions: separation,
filtration, reinforcement, protection, and drainage.
One common test used with geotextiles is the puncture strength
test, which evaluates the ability of geotextiles to withstand stresses
and loads during service life, including the construction process, the
severe conditions that geotextiles are subjected to in geotechnical
Background
Puncture strength testing of geotextiles dates to the 1970s with
ASTM D751, but it was found that this test produced inaccurate
data because the probe tip slipped through textiles rather than ruptur­
ing them. By the 1980s, the ASTM D35 committee recommended
that the puncture test be run with ASTM D3787, but with a constant
rate of extension, an 8-mm diameter, flat-tip probe, strain rate of
300 mm/min, and compression ring clamps (7).
In the past decade, four key standards have been available for geo­
textile puncture strength testing. The first standard, ASTM D3786, uses
an inflatable rubber membrane to deform the geotextile into the shape
of a hemisphere through a ring with a diameter of 30 mm until the
geotextile bursts. The second standard, ASTM D4833, is a variation of
ASTM D3787, which utilizes a slip-free ring clamp and probe with an
8-mm diameter and a 45° beveled edge. The samples are subjected to
tension or compression until rupture occurs. Neither ASTM D3786 nor
D4833 is currently recognized by ASTM as an acceptable geotextile
Department of Civil and Environmental Engineering, University of Wisconsin–
Milwaukee, 3200 North Cramer Street, Milwaukee, WI 53211. Corresponding
author: H. Titi, hanititi@uwm.edu.
Transportation Research Record: Journal of the Transportation Research Board,
No. 2656, 2017, pp. 1–11.
http://dx.doi.org/10.3141/2656-01
1
2
Transportation Research Record 2656
test method. These tests are no longer accepted because, as described
by Koerner, “lightweight nonwoven fabrics had a rather large statisti­
cal variation” in puncture strength “between small areas of somewhat
dense fibers and other small areas with sparse fabrics” (8) (http://
geosyntheticsmagazine.com/2013/10/01/mullen-burst-test/). The
larger probe used in the D6241 standard reduces this statistical impact.
The final method, D5494, is also relevant but should only be used on
a geotextile when a geotextile-geomembrane system is being tested.
Measure
ASTM D4833 (Pin)
Currently, AASHTO M288 has replaced ASTM D4833 with
D6241. In 2010, ASTM D3786 and D4833 information was no longer
reported by Geosynthetic Materials Association members (9).
The ASTM D4833 and D6241 standards are similar, except
for a few key alterations of the clamp and probe system. Figure 1
presents a summary comparison of the pin and CBR standards, as
well as the testing fixtures and plungers used in puncture strength
testing.
ASTM D6241 (CBR)
Probe Diameter
8 mm ± 0.1 mm
50 mm ± 1 mm
Probe Chamfer–Edge
45°, 0.8 mm
2.5 mm ± 0.5 mm
Specimen Minimum Outer
Diameter
100 mm
Clamp outer diameter
+ 10 mm
Specimen Unsupported Diameter
45 mm ± 0.025 mm
(clamp inner diameter)
150 mm
Compression Speed
300 mm ± 10 mm/min
50 mm/min
Maximum Allowable Slippage
None allowed
5 mm
Number of Tests
15
10
Lab Temperature
21°C ± 2°C
21°C ± 2°C
Lab Relative Humidity
65% ± 5%
50%–70%
Test Conclusion
Break
Break
Resistance Reported
Maximum
Maximum
(a)
(b)
Probe
Probe
Clamp
Clamp
CBR
Pin
Base
(c)
Base
(d)
FIGURE 1 Comparison of ASTM pin and CBR puncture strength testing of geotextiles: (a) table comparing ASTM D4833 (pin) and
ASTM D6241 (CBR) values, (b) plungers used for CBR and pin puncture strength testing, (c) pin puncture fixture, and (d) CBR fixture.
Van Dyke, Titi, and El-Hajjar
Studies on this topic have consisted of two groups: investigations
that address variations in puncture strength testing methods (3, 6),
and studies that address variations in the materials tested (2, 4, 5).
Clamping Mechanism
Because ASTM D4833 and D6241 have a dual plate-screw clamping
mechanism, clamping slippage and technician variations inherently
result. Hsieh and Wang suggested hydraulic clamping mechanisms
for pin puncture strength testing (3). They tested a polypropylene
(PP) and woven PP and polyester (PET) mix. All the tests were
conducted at constant rates of compression of 300 ± 10 mm/min
and 50 mm/min for ASTM D4833 and D6241, respectively. The
puncture strength resistance varied more significantly for the ASTM
apparatus than it did for the hydraulic testing mechanism. The CBR
puncture strength (ASTM D6241) for the PP and PP-PET geotextiles,
both woven materials, was eight times the pin puncture strengths
(ASTM D4833). Hsieh and Wang also indicated that ASTM D4833
results varied less than those for ASTM D6241 (3).
Rate of Compression
The rate of compression used for puncture resistance testing is inher­
ently expected to affect the maximum value of puncture strength.
Askari et al. studied the effects of test speed and fabric weight on
the puncture resistance of PET needle-punched, nonwoven geo­
textiles using ASTM D6241 and D4833 (6). The material weights
were 460, 715, 970, and 1,070 g/m2 and the tests were conducted
at five speeds: 25, 50, 75, 100, and 125 mm/min. Askari et al. deter­
mined that weight and speed affected the maximum puncture strength
resistance for both tests (6). The 50-mm plunger size used in ASTM
D6241 is preferred, because it is less influenced by irregularities in
the fiber densities (8).
Askari et al. also described the failure of a geotextile using three
distinct stages of material failure (6). During the first stage, the com­
pression forces resulted in a rearrangement or movement of fibers.
During the second stage, the fibers became more tightly packed and
had an added frictional interaction among them, which increased
their ability to resist higher loads. The third stage included puncture
failure as a result of a sudden separation of fibers.
Mass per Unit Area
Jones et al. found the relationship between mass per unit area and
puncture strength resistance to be nonlinear for needle-punched geo­
textiles (2). It was proposed that the performance was derived from the
frictional interaction between fibers. The study tested high-, medium-,
and low-performance, needle-punched, nonwoven geotextiles with
matching mass per unit area of 1,000 g/m2.
Koerner and Koerner directly compared nonwoven PP and PET
samples with similar mass per unit area (4). All the PP samples were
continuous filament, but two types of PP materials were used: con­
tinuous filament and staple fibers. They were all tested without a
geomembrane system and on three puncture resistance tests, ASTM
D4833, D5494, and D6241, two of which were explored in this
study. Five mass per unit areas of three classifications of materials
were used. Unlike Jones et al. (2), all the materials tested by Koerner
and Koerner (4) showed an essentially linear connection between
3
increased mass per unit area and puncture resistance. Because the
material used by Jones et al. (2) was not indicated, it is difficult to
say why a linear relationship was not found. Koerner and Koerner
also found relationships between the three puncture mechanisms
used (4). The test relationships were developed among nonwoven
materials exclusively. The PP continuous filament resulted in com­
parable pyramid and pin resistances, and CBR about seven times
the pin resistance. With ASTM D4833, the PP continuous filament
and staple fiber yielded similar results, which were two times larger
than the PET values. With ASTM D5494, the PP results were, again,
about the same, and 35% higher than the PET puncture strengths.
With ASTM D6241, the PP puncture strengths were comparable, and
25% higher than the PET values.
Weave
Of the studies found involving pin and CBR puncture tests, none
used a combination of woven and nonwoven materials. The studies
examined exclusively nonwoven or exclusively woven materials.
It is of interest to discover if geotextiles made of like materials and
with the same mass per unit area, yet with different manufacturing
processes, perform similarly in puncture resistance tests.
Methodology
This study examined literature from geotextile suppliers used in the
midwestern United States. Of the most common materials used in
those states, nearly all were composed of 100% PP. This was likely
because PP costs less than PET and has a lower specific gravity,
resulting in about 25% more fibers per unit weight (10). The high
fiber count increases the mass per unit area and, therefore, the punc­
ture strength of the material. The average and standard deviation of
the puncture strength of the PP materials also vary less than those
of PET (3). For these reasons, PP materials were tested because they
are more commonly used and statistically vary less, allowing for a
better comparison of the tests rather than the material.
This study’s researchers contacted major geotextile manufacturers
in the United States to obtain materials for testing, to accom­
plish the research objectives. The geotextiles selected for testing were
woven and nonwoven and had one of three mass per unit areas. The
material uses varied. Table 1 presents a description of the materials
that were tested.
All the geotextile materials were supplied in approximately 12-by12-ft sections. Fifteen 120-mm diameter samples were cut along
the material diagonal for testing with the ASTM D4833 standard.
Ten 240-mm-diameter samples were prepared for testing with the
ASTM D6241 standard, and were taken along a parallel diagonal over
approximately the same width of material. The sample selection
layout is illustrated in Figure 2a.
Diagonal sampling captures maximum material variability in
both directions. The samples were taken parallel to one another and
over the same material width to reduce the impact of variability in
material location on the results of the two test methods. High-quality
sewing shears were used to cut all the samples. The samples were
taken no closer than 6 in. from the edge for the ASTM D6241 test­
ing, and no closer than 16 in. from the edge for the ASTM D4833
testing, to meet all the requirements. In addition, any crushed or
deformed areas were excluded. In the event of a deformed area, best
efforts were made to select samples from nearby areas, as shown
4
Transportation Research Record 2656
TABLE 1 Materials Selected for Research
Geotextile
Designation
Material
Type
Weave Type
Use–Application
PP
PP
PP
PP
PP
Nonwoven
Woven
Nonwoven
Woven
Nonwoven
Drainage–separation
Separation
Drainage–separation
Filtration–separation
Drainage–separation
A
B
C
D
E
in Figure 2b. The samples follow the general diagonal, but do not
include the folded material. The samples were labeled for later iden­
tification as needed. A small crosscut scissors was used to cut bolt
holes in each specimen. Figure 2, c and d, shows samples that were
prepared to be tested. Material B easily lost fibers during handling,
because it was a woven material with limited fiber-to-fiber frictional
interaction. To prevent changes in mass and loss of material, all the
woven Material B samples were outlined with a thin glue layer. The
Mass/Unit Area,
oz/yd2 (g/m2)
4 (136)
4 (136)
8 (271)
8 (271)
12 (406)
glue layer was close enough to the perimeter of the sample so that it
would never contact the clamping fixture.
Each geotextile sample was affixed to the corresponding ASTM
test fixture. The sample was then marked along the inside circum­
ference of the clamp. This marking was used to determine whether
slippage had exceeded the maximum allowed per ASTM require­
ments. Using the universal testing machine located in the University
of Wisconsin–Milwaukee Engineering Mechanics and Composites
12 ft
Specimen selected
for testing
16 in.
6 in.
Specimen for
ASTM D4833
(CBR)
Specimen
for ASTM
D4833 (pin)
Crushed–deformed
areas are excluded
12 ft
(b)
Half of geotextile roll not used in testing
(a)
A
CBR
Specimens
B
C
D
Pin
Specimens
(c)
(d)
FIGURE 2 Preparation of geotextile specimens for testing: (a) layout of samples, (b) sample selections near a deformed area,
(c) geotextile specimens prepared for pin and CBR puncture stress tests, and (d) woven and unwoven geotextile materials.
E
Van Dyke, Titi, and El-Hajjar
5
TABLE 2 Summary of Pin and CBR Puncture Strength Tests
Geotextile
Material Type
ASTM Test
Number of
Test Samples
Average Puncture
Load, lb (N)
Standard Deviation
in Puncture Load,
lb (N)
Coefficient of
Variation in
Puncture Load (%)
Average
Elongation
(mm)
D4833
D6241
D4833
D6241
D4833
D6241
D4833
D6241
D4833
D6241
15
10
15
10
15
15
10
15
10
15
73 (324)
362 (1,611)
100 (443)
733 (3,261)
115 (510)
595 (2,648)
178 (790)
1,392 (6,190)
240 (1,069)
1,268 (5,642)
10 (43)
41 (184)
7 (29)
20 (92)
21 (93)
57 (255)
18 (81)
151 (673)
16 (73)
101 (451)
13.3
11.4
6.6
2.8
18.3
9.6
10.3
10.9
6.8
8.0
0.50 (12.7)
1.89 (48.0)
0.35 (8.9)
1.40 (35.6)
0.46 (11.7)
1.88 (47.8)
0.46 (11.7)
1.44 (36.6)
0.59 (15.0)
2.47 (62.7)
A (nonwoven)
B (woven)
C (nonwoven)
D (woven)
E (nonwoven)
Results and Analyses
Research Lab, the puncture rod was lowered at a constant rate of
extension until it completely ruptured the test sample. R-Controller
was used to record the time, load, and displacement for all the sam­
ples. Geotextile materials sometimes display a double peak in the
load-displacement graph. Per ASTM standards, the initial puncture
strength value was reported even if the second peak was higher.
The results of the pin and CBR puncture strength tests on the geo­
textile samples are summarized in Table 2. Figure 3 depicts the pin
puncture strength of 15 specimens of Material A. The puncture load
versus displacement is shown in Figure 3a. Inspection of Figure 3a
Displacement (mm)
6
8
10
12
14
16
18
20
22
24
26
100
440
90
400
80
360
70
320
280
60
240
50
200
40
160
30
500
120
400
250
150
40
0
0.4
0.5
0.6
0.7
0.8
0.9
1
0
1
0
0.3
500
100
80
0.2
1,000
200
10
0.1
1,500
300
50
0
Average
350
20
0
2,000
450
2
3
4
5
6
7
8
9 10 11 12 13 14 15
Test Sample Number
1.1
(b)
Displacement (in.)
(a)
Displacement (mm)
5
10
15
20
25
30
35
40
45
50
55
500
60
1,750
350
1,500
1,250
250
1,000
200
750
150
350
250
150
100
50
250
50
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
Displacement (in.)
(c)
1.8
2.0
2.2
2.4
1,000
200
100
0
1,500
300
500
0
2,000
400
Puncture Strength (lb)
2,000
400
Load (N)
Load (lb)
450
300
Average
450
500
500
0
0
1
2
3
4
5
6
7
8
Test Sample Number
9
10
(d)
FIGURE 3 Pin and CBR puncture strengths for samples of Material A, nonwoven geotextile: (a) pin load-displacement curves,
(b) pin puncture strength bar chart, (c) CBR load-displacement curves, and (d) CBR puncture strength bar chart. In the bar charts,
the error bars indicate standard deviations.
Puncture Strength (N)
0
Puncture Strength (N)
4
Puncture Strength (lb)
2
Load (N)
Load (lb)
0
6
Transportation Research Record 2656
A representative puncture strength failure curve of Material D,
one of the woven materials tested, is shown in Figure 4b. The curve
consists of five phases: fiber rearrangement, load resistance, mono­
filament failure (puncture resistance), secondary fiber rearrange­
ment, and multifilament failure. In the woven material, the first peak
is followed by a second peak due to load redistribution increasing the
maximum resistance before material failure after the second peak.
As with the nonwoven materials, the curve begins with a slight slope
as the plunger makes contact with the sample. Because the geotextile
weave still contains voids, the fibers are free to rearrange without
resisting the probe motion. As the fibers lose their ability to move rel­
ative to one another, they begin to develop internal material stresses
as the fiber-to-fiber interaction increases and the respective filaments
develop tensile strains. Eventually, the tensile strain increases until
the displacement, where monofilaments begin to rupture. Unlike non­
woven geotextiles, woven geotextiles may reach a secondary peak
resistance that is greater than the puncture strength when the multi­
filaments fail. The dip between successive peak resistances occurs
because the material fibers are again able to rearrange and fill newly
formed voids in the geotextile weave. Additional peaks may be
observed if extension of the probe is allowed to continue. The images
of the CBR puncture test to failure of the Material D specimen shown
in Figure 5, g to l, describe these stages.
The results for all pin and CBR puncture strength tests of the
geotextile samples are plotted in Figure 7a to compare the two
test puncture strength values. The geotextile samples tested with
ASTM D6241 showed a lower coefficient of variation compared
with ASTM D4833 for Materials A, B, and C but a higher coef­
ficient of variation for Materials D and E. Thus, one test is not
preferred over the other based on testing variability. The study
developed a means to estimate the CBR puncture strength based
on a known pin puncture strength. Askari et al. used ASTM D6241
to study the effects of test speed on the puncture resistance of PET
needle-punched nonwoven geotextiles (6). Although the material
tested was PET rather than PP, the results of the tests were used in
the current study to develop the general relationship between test
speed and puncture resistance. The ratio of increase in puncture
strength caused by an increase in speed was determined to be
1 to 4, or 0.25.
demonstrates that all the geotextile samples that were tested exhibited
consistent behavior. Figure 3b depicts a bar chart of the pin puncture
strengths for all the Material A samples. The pin puncture load at
failure varied from 56 lb (250 N) to 94 lb (418 N), with an average
73 lb (324 N) and a coefficient of variation of 13.3%.
Figure 3c depicts the CBR puncture load versus displacement
for the Material A samples. Figure 3d shows a bar chart of the CBR
puncture strengths for all the Material A samples. The CBR puncture
load at failure varied from 324 lb (1,441 N) to 457 lb (2,033 N), with
an average 362 lb (1,611 N) and a coefficient of variation of 11.4%.
A representative CBR puncture strength failure curve of
Material A, nonwoven, is shown in Figure 4a. The curve consists
of four phases: fiber rearrangement, load resistance, maximum
resistance, and puncture failure. The curve begins with a slight slope
as the plunger makes contact with the sample. Because the fibers
still contain voids, they are free to rearrange without resisting the
probe motion. As the fibers lose their ability to move relative to one
another, they begin to develop internal material stresses as the fiberto-fiber interaction increases. The load resistance increases because
of the fiber-to-fiber interaction, resulting in the region of increased
slope. Eventually, the material develops new voids as the fiber-tofiber interaction fails. When the pressure on the material extends
beyond the load that the fiber-to-fiber interaction can withstand,
the material punctures. The images of the CBR puncture test to
failure of a Material A specimen shown in Figure 5, a to f, describe
these failure stages.
Figure 6, a and b, depicts the pin puncture strength of 15 indi­
vidual Material D geotextile samples. The pin puncture load versus
displacement is shown in Figure 6a. Inspection of Figure 6a dem­
onstrates that all the geotextile samples that were tested exhibited
consistent behavior. Figure 6b depicts a bar chart of pin puncture
strengths for all the Material D samples. The pin puncture load at
failure varied from 150 lb (669 N) to 208 lb (926 N), with an aver­
age 178 lb (790 N) and a coefficient of variation of 10.3%. Fig­
ure 6c depicts the CBR puncture load versus displacement for the
Material D samples. Figure 6d shows a bar chart of CBR puncture
strengths for all the Material D samples. The CBR puncture load at
failure varied from 1,152 lb (5,125 N) to 1,557 lb (6,925 N), with an
average 1,392 lb (6,190 N) and a coefficient of variation of 10.9%.
Displacement (mm)
0
5
10
15
20
25
30
Displacement (mm)
35
40
45
50
0
400
5
10
20
25
30
35
40
45
50
2,000
Load (lb)
800
Material Failure
Load (lb)
200
400
6,000
1,200
5,000
Load Resistance
4,000
800
Material
Failure
Fiber Rearrangement
Fiber Rearrangement
100
7,000
Puncture Resistance
(Monofilament Failure)
1,200
Load Resistance
3,000
2,000
400
Nonwoven
0
0.2
0.4
0.6
0.8
1
1.2
Displacement (in.)
(a)
1.4
1.6
1.8
1,000
Woven
0
0
8,000
2
0
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
Displacement (in.)
(b)
FIGURE 4 Mechanism of puncture strength failure demonstrated by using a load displacement curve of representative material:
(a) Material A, nonwoven geotextile; and (b) Material D, woven geotextile.
2
Load (kN)
1,600
300
Maximum Resistance
(Multifilament Failure)
Secondary Fiber
Rearrangement
1,600
Maximum Resistance
Load (lb)
15
(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
(l)
FIGURE 5 Failure stages of nonwoven and woven geotextiles subjected to the CBR puncture strength test; for a
Material A specimen, nonwoven geotextile: (a) fiber rearrangement, (b) load resistance begins, (c) fiber extension,
(d) material voids become apparent, (e) puncture, and (f) recoil; for Material D, woven geotextile: (g) fiber
rearrangement, (h) load resistance begins, (i) fiber elongation, ( j ) monofilament failure, (k) fiber rearrangement and
continued multifilament load resistance, and (l ) multifilament failure.
8
Transportation Research Record 2656
6
8
10
12
14
16
18
20
22
220
960
880
800
720
640
560
480
400
320
240
160
80
0
200
180
Load (lb)
160
140
120
100
80
60
40
20
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Puncture Strength (lb)
4
Load (N)
2
1,800
8,000
1,600
7,000
1,400
Average
1,200
6,000
5,000
1,000
4,000
800
3,000
600
2,000
400
Puncture Strength (N)
Displacement (mm)
0
1,000
200
0
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15
Test Sample Number
0.9
(b)
Displacement (in.)
(a)
Displacement (mm)
15
20
25
30
35
40
45
50
55
60
65
70
7,000
6,500
6,000
5,500
5,000
4,500
4,000
3,500
3,000
2,500
2,000
1,500
1,000
500
0
1,400
1,200
Load (lb)
Average
1,800
1,600
1,000
800
600
400
200
0
7,000
1,400
6,000
1,200
5,000
1,000
4,000
800
3,000
600
2,000
400
1,000
200
0
0
1
2
3
4
5
6
7
8
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8
Test Sample Number
Displacement (in.)
(d)
(c)
8,000
1,600
Puncture Strength (N)
10
Puncture Strength (lb)
5
Load (N)
0
9
10
FIGURE 6 Pin and CBR puncture strengths for Material D samples, woven geotextile: (a) pin load-displacement curves, (b) pin bar chart,
(c) CBR load-displacement curves, and (d) CBR bar chart.
With this ratio, Equation 1 is proposed to estimate the CBR puncture
strength based on preexisting pin values for nonwoven geotextiles:
Strength CBR,estimated = 0.25 × Strength pin,measured
 Area p,CBR   Area s,pin   Rate pin 

 Area


p,pin   Area s,CBR   Rate CBR 
(1)
where
Areap,CBR = area of the CBR probe,
Areas,CBR =area of the CBR inner clamp (by using sample
unsupported diameter),
Areas,pin =
area of the pin inner clamp (by using sample
unsupported diameter),
Areap,pin = area of the pin probe,
RateCBR =constant rate of compression of CBR puncture testing,
and
Ratepin = constant rate of compression of pin puncture testing.
Substituting standard ASTM values into Equation 1, the following
equation is obtained for nonwoven geotextiles:
Strength CBR,estimated = 5.270 × Strength pin,measured
(2)
The results of the testing indicate that change in compression rate
has a different effect on puncture resistance for woven materials.
This rate has a relationship of approximately 0.35. Substituting the
standard ASTM values into Equation 1 and using 0.35 instead of
0.25, the following equation is obtained for woven materials:
Strength CBR,estimated = 7.378 × Strength pin,measured
(3)
Equations 2 and 3 were used to estimate the CBR puncture strength
from the pin puncture test results, as depicted in Figure 7b.
To find a general formula for all samples, Equation 4 is proposed,
using 0.3 in Equation 1 as the average value:
Strength CBR,estimated = 6.324 × Strength pin,measured
(4)
Equation 4 was used to estimate the CBR puncture strength from
the pin puncture test results, as depicted in Figure 7c. For compari­
son, Figure 7d shows the line obtained from Equation 4 as well as
the line of best fit for the measured test results. The line of best fit
equation for the measured puncture strength averages is Equation 5,
which has the coefficient of determination R2 = .789. Equation 4
simplifies to Equation 6 for the samples tested and has R2 = .781. The
Van Dyke, Titi, and El-Hajjar
Pin Puncture Strength (N)
400
800
1,200
0
8,000
Pin Puncture Strength (N)
400
800
1,200
1,600
1,200
4,000
800
Material A
Material B
Material C
Material D
Material E
PS(CBR) = 6.04 PS(pin)
400
0
0
100
200
2,000
CBR Puncture Strength (lb)
6,000
CBR Puncture Strength (N)
6,000
1,200
4,000
800
Measured Averages
Estimated Averages (Equations 2 and 3)
0
300
0
100
200
300
Pin Puncture Strength (lb)
(b)
Pin Puncture Strength (N)
400
800
1,200
0
Pin Puncture Strength (N)
400
800
1,200
1,600
4,000
800
2,000
400
Measured Averages
Estimated Averages (Equation 4)
0
0
0
100
200
Pin Puncture Strength (lb)
(c)
300
CBR Puncture Strength (lb)
6,000
1,200
CBR Puncture Strength (N)
1,600
CBR Puncture Strength (lb)
0
0
Pin Puncture Strength (lb)
(a)
0
2,000
400
6,000
1,200
4,000
800
2,000
400
Measured Averages
Estimated Averages (Equation 4)
Measured Averages Line of Best Fit
0
CBR Puncture Strength (N)
CBR Puncture Strength (lb)
1,600
CBR Puncture Strength (N)
0
9
0
0
100
200
Pin Puncture Strength (lb)
(d)
300
FIGURE 7 Comparison of estimated CBR puncture strength with the proposed equations: (a) CBR versus pin average puncture strength (PS)
for all materials tested, (b) CBR puncture strength estimated with separate equations for woven and nonwoven materials, (c) CBR puncture
strength estimated with Equation 4, and (d) CBR puncture strength estimated with Equation 4 and line of best fit for measured results.
10
Transportation Research Record 2656
statistical results show a reasonable correlation between the measured
and estimated puncture strength values with the pin and CBR tests
based on Equation 6.
Strength CBR = 50.17 + 5.82 × Strength pin
Strength CBR = 6.33 + Strength pin
(all values in lb)
(all values in lb)
(5)
(6)
Jones et al. determined that unit weight is not a good indicator for
geotextile performance (2). In this study, two sets of materials were
tested with the same unit weight. Materials A and B were made of
the same material and had unit weights of 4 oz/yd2, but Material A was
needle punched and Material B was woven. Likewise, Materials C
and D were of like materials, had a unit weight of 8 oz/yd2, and were
needle punched and woven, respectively.
To examine the effects of weave on maximum puncture resistance,
typical CBR puncture results for Materials A and B, which have the
same mass per unit area of 4 oz/yd2 and base material, are plotted in
Figure 8a. Likewise, Materials C and D, which have the same mass
per unit area of 8 oz/yd2, are plotted in Figure 8b. Again, the only
difference in the two sets of materials was whether they were woven
or nonwoven.
The CBR puncture resistance of Material C (8 oz/yd2) was approx­
imately double that of Material A (4 oz/yd2). Material D (8 oz/yd2)
showed a puncture resistance approximately double that of Material B
(4 oz/yd2). These results indicate that woven materials (with the
same base material and mass per unit area as a nonwoven material)
will exhibit a CBR puncture strength approximately double the
nonwoven strength. Further insight into the puncture strength of non­
woven materials was supported by Koerner and Koerner (4). Koerner
and Koerner determined that staple fiber and continuous filament
nonwoven materials exhibit similar CBR puncture strengths (4).
This finding is likely because the puncture resistance of nonwoven
materials is dependent on the fiber-to-fiber contact points, which are
directly proportional to the mass per unit area.
The nonwoven materials (A and C) failed at approximately the same
displacement at failure as shown in Figure 8. The woven materials
(B and D) also experienced similar displacements at puncture fail­
ure. These findings imply that the elongation at puncture failure is
determined by weave type, rather than mass per unit area.
Conclusions
The objective of this research was to correlate the CBR and pin
puncture strengths for various categories of geotextiles, regardless
of weave type and mass per unit area.
Five types of PP geotextiles, three nonwoven and two woven, were
subjected to testing in accordance with ASTM D4833 and D6241
standard procedures. Ten and 15 samples of each geotextile type
were tested using CBR and pin puncture strength tests, respectively.
All five types of geotextiles exhibited puncture strength values,
whether pin or CBR, that were consistent within each group. Sta­
tistical correlations were developed to estimate the CBR puncture
strength values from the pin test with reasonable accuracy. Equation 2
can be used to estimate CBR puncture strength based on the pin test
puncture strengths of PP nonwoven materials only, and Equation 3
can be used to estimate the CBR puncture strength based on pin test
puncture strengths of PP woven materials only.
Equation 4 can be used to estimate the CBR puncture strength
based on the pin test puncture strengths of all PP geotextiles. Equa­
tion 4 had a coefficient of determination of R2 = .781. The line of best
fit for the materials that were tested had a coefficient of determination
of R2 = .789.
The CBR puncture resistances of materials with similar mass per
unit area and base material, but with different weave types, were also
examined. Woven PP materials exhibited a CBR puncture strength
that was approximately double that of nonwoven PP materials with
the same mass per unit area. The CBR displacement-elongation at
puncture failure is determined by weave type rather than mass per
unit area for PP materials.
Displacement (mm)
20
40
0
800
1,600
Material A
(Nonwoven, 4 oz/yd2)
Material B
(Woven, 4 oz/yd2)
Material C
(Nonwoven, 8 oz/yd2)
Material D
(Woven, 8 oz/yd2)
3,000
600
6,000
4,000
800
1,000
200
2,000
400
0
Load (N)
2,000
400
Load (lb)
1,200
Load (N)
Load (lb)
Displacement (mm)
20
40
0
0
0
0.4
0.8
1.2
1.6
Displacement (in.)
(a)
2
0
0
0
0.4
0.8
1.2
1.6
Displacement (in.)
2
(b)
2
FIGURE 8 Load-displacement curves for the CBR puncture test: (a) Material A (PP, nonwoven, 4 oz/yd ) and Material B (PP, woven, 4 oz/yd 2),
and (b) Material C (PP, nonwoven, 8 oz/yd 2) and Material D (PP, woven, 8 oz/yd 2 ).
Van Dyke, Titi, and El-Hajjar
11
Acknowledgments
2. Jones, D. R. V., D. A. Shercliff, and N. Dixon. Difficulties Associated
with the Specification of Protection Geotextiles Using only Unit Weight.
Proceedings of the 2nd European Geosynthetics Conference, Bologna,
Italy, 2000.
3. Hsieh, C., and J.-B. Wang. Clamping Mechanism Effects on the Puncture
Resistance Tests of High Strength Geotextiles. Journal of GeoEngineering, Vol. 3, No. 2, 2008, pp. 47–53.
4. Koerner, G. R., and R. M. Koerner. Puncture Resistance of Polyester
(PET) and Polypropylene (PP) Needle-Punched Nonwoven Geotextiles.
Geotextiles and Geomembranes, Vol. 29, No. 3, 2011, pp. 360–362.
http://dx.doi.org/10.1016/j.geotexmem.2010.10.008.
5. Rawal, A., and H. Saraswat. Stabilisation of Soil Using Hybrid Needle­
Punched Nonwoven Geotextiles. Geotextiles and Geomembranes,
Vol. 29, No. 2, 2011, pp. 197–200. http://dx.doi.org/10.1016/j.geotexmem
.2010.06.006.
6. Askari, A. S., S. S. Najar, and Y. A. Vaghasloo. Study the Effect of Test
Speed and Fabric Weight on Puncture Behavior of Polyester Needle­
punched Nonwoven Geotextiles. Journal of Engineered Fibers and
Fabrics, Vol. 7, No. 3, 2012, pp. 1–7.
7. Suits, L. D., R. G. Carroll, Jr., and B. R. Christopher. ASTM Geotextile
Committee Testing Update. Geotextile Testing and the Design Engineer.
ASTM STP 952 (J. E. Fluet, Jr., ed.), American Society for Testing and
Materials, Philadelphia, Pa., 1987, pp. 161–175.
8. Koerner, B. Mullen Burst Test? Geosynthetics, October 2013, p. 15.
9. Bygness, R. Say Goodbye to #4833. Geosynthetics, February 2010, p. 56.
10. Koerner, R. Polypropylene vs. Polyester. Geosynthetics, June 2012, p. 43.
This research was supported in part by the Wisconsin Highway
Research Program (WHRP), the Wisconsin Department of Trans­
portation, and the College of Engineering and Applied Science at the
University of Wisconsin, Milwaukee (UWM). The authors acknowl­
edge the WHRP Technical Oversight Committee chair and members
Andrew Zimmer, Jeff Horsfall, and Bob Arndorfer for their guid­
ance and comments. The authors also acknowledge Issam Qamhia,
Peng Yang, Seyed Shams, and the UWM Engineering Mechanics
and Composites Laboratory for technical assistance, as well as
Brian Mullen and the UWM Structural Laboratory for conditioning
a selection of samples. The authors extend special thanks to Teri
Krock and Brett Odgers of TenCate Geosynthetics for supplying
geotextile materials and to Jay Schabelski of Romus, Inc., for
constructing the clamping fixtures and probes.
References
1. Narejo, D., R. M. Koerner, and R. F. Wilson-Fahmy. Puncture Protection
of Geomembranes Part II: Experimental. Geosynthetics International,
Vol. 3, No. 5, 1996, pp. 629–653. http://dx.doi.org/10.1680/gein.3.0078.
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The Standing Committee on Geosynthetics peer-reviewed this paper.