ISO 10319
Wide-Width Tensile Test for Geosynthetics

Downloads: ISO 10319 Wide-Width Vise Grip for Geosynthetics – Universal Grip Data Sheet (PDF)

Written by Chris Thomas, Universal Grip Company · Reviewed by Frank Bertini · Updated October 31, 2026

ISO 10319 is the international index test for the tensile properties of geosynthetics using a wide-width strip. A specimen nominally 200 mm wide is clamped across its full width, stretched at a constant rate of strain until it breaks, and the result is reported as tensile strength in kN per metre of width, together with the strain at maximum force and secant tensile stiffness. Manufacturers use it for CE-marking declarations and factory production control, specifiers use it to compare reinforcement and separation products, and independent labs use it for conformity testing on geotextiles, geogrids, geocomposites and clay geosynthetic barriers. It looks like a simple pull test, but it is easy to get wrong: wide, strong specimens slip or break at the jaws, strain must be measured on a 60 mm gauge length rather than from crosshead travel, and geogrids need a different width correction from fabrics. This guide covers the current edition, specimens, conditioning, speed, the Universal Grip wide-width vise grip, machine choice, a step-by-step procedure, a worked calculation, common errors and how ISO 10319 compares with ASTM D4595.

ISO 10319 at a glance

• Current edition: ISO 10319:2024 (fourth edition, published October 2024), adopted in Europe as EN ISO 10319:2024. It replaced ISO 10319:2015.

• Scope: most geosynthetics, including woven and nonwoven geotextiles, knitted geotextiles, geocomposites, geonets, geomats, geogrids and clay geosynthetic barriers. It does not apply to polymeric or bituminous geosynthetic barriers (geomembranes).

• Specimen: wide-width strip, nominally 200 mm wide, gripped across its full width; 100 mm between the jaws is the usual set-up. Geogrids and products narrower than 200 mm have their own dimension rules.

• Strain measurement: extensometer on a nominal gauge length of 60 mm (30 mm either side of the specimen centre).

• Rate: constant rate of strain of 20 % per minute (commonly about 20 mm/min with 100 mm between the jaws).

• Pre-tension: 1 % of the expected maximum tensile force.

• Conditioning: standard atmosphere of (20 ± 2) °C and (65 ± 5) % RH per ISO 554; optional wet testing; the 2024 edition adds tests at lower or higher temperatures (Annex A).

• Results: tensile strength (kN/m), tensile strain at maximum force (%), strain at nominal tensile strength, secant tensile stiffness (kN/m) at chosen strains, and second-peak values where they occur.

• Related standards: ISO 9862 (sampling), ISO 10318-1 (terms), ISO 10321 (seams and joints), ISO 12236 (CBR puncture), ASTM D4595 and ASTM D6637.

What ISO 10319 measures and who uses it

Geosynthetics are sold and designed by strength per unit width, not by stress. A reinforcement engineer wants to know how many kilonewtons a metre of geogrid will carry and how stiff it is at 2 % or 5 % strain, because that governs how much the soil has to move before the reinforcement takes load. ISO 10319 delivers exactly those numbers on a specimen wide enough to minimise the necking that makes narrow strip tests on fabrics unrepresentative. Because it is an index test, it is used for product comparison, quality control and specification compliance rather than as a direct design value; long-term design strength is derived separately using creep and reduction-factor methods.

Typical users include geotextile and geogrid manufacturers running factory production control, third-party labs certifying products against European product standards for roads, railways, drainage, erosion control and landfills, contractors verifying deliveries, and research groups studying new polymers or composite structures. Results are routinely quoted on data sheets as machine-direction (MD) and cross-machine-direction (CMD) strengths, with strain at maximum force and often tensile force at 2 % and 5 % strain.

• Tensile strength: maximum tensile force per unit width, kN/m.

• Tensile strain at maximum force: in percent, measured on the gauge length.

• Secant tensile stiffness: force per unit width divided by an associated strain, kN/m, for example at 2 %, 5 % or 10 %.

• Second-peak values: for products with two load peaks (some composites and geomats), the 2024 edition clarifies how to report strength and strain at the first and second peak.

ISO 10319 test specimens

Dimensions

The basic specimen is a strip with a nominal width of 200 mm and enough length to leave 100 mm between the jaws plus the clamped lengths. The full width is gripped, which is why the test needs wide, purpose-built jaws rather than the 25 mm or 50 mm faces used for textile strip tests such as ISO 13934-1. For geogrids and other open structures the specimen is adjusted so it contains whole tensile elements (ribs) across the width and appropriate rows of junctions along the length; the strength calculation then uses rib counts rather than the nominal width. The 2024 edition also adds a procedure for products narrower than 200 mm, such as geostrips, and limits metallic products to woven steel wire meshes. Check clause 6 of the current edition for the exact rule for your product type.

Number of specimens and sampling

Sampling and specimen preparation follow ISO 9862: discard the outer layers of the roll, avoid the edges, and cut specimens so that no two test the same longitudinal or transverse strands. Test at least five specimens in the machine direction and five in the cross-machine direction; check the current edition for any additional requirements. Wet tests and tests at other temperatures need their own sets.

Preparation

• Cut cleanly with sharp tools so edges are not frayed or notched; for woven products, cut along a yarn line and remove loose yarns before measuring width.

• Mark the specimen centre line and the two gauge marks 60 mm apart (30 mm either side of centre) if your extensometer needs targets.

• Measure and record the actual width; for geogrids record the number of ribs in the specimen and the number per metre of product width.

• Protect thin or slippery products in the clamping zone if needed, but never with anything that changes the free length between the jaws.

Conditioning

Specimens are conditioned and tested in the standard atmosphere of ISO 554: (20 ± 2) °C and (65 ± 5) % relative humidity, normally until successive weighings show no meaningful change in mass. Conditioning can be omitted for products shown to be insensitive to humidity, but the report must say so. Some national adoptions change the temperature (India, for example, uses (27 ± 2) °C), so state the atmosphere you actually used.

• Wet tests: specimens are immersed in water before testing to give wet strength values; follow the immersion time, water quality (ISO 3696) and time-to-test limits in the current edition.

• Low and high temperature (new in 2024): Annex A gives a normative procedure for testing at temperatures other than standard, with matching conditioning. This needs an environmental chamber large enough for wide-width grips and a non-contact strain measurement.

Test speed and machine requirements

ISO 10319 is a constant-rate-of-strain test at 20 % per minute. With 100 mm between the jaws, that is usually set as about 20 mm/min of crosshead speed, then confirmed: the standard defines the strain rate as the strain at maximum force divided by the time from pre-tension to maximum force, so a test that runs far too fast or too slow because of slack, slippage or machine compliance shows up in the report. Compare this with ASTM D4595, which runs at 10 % per minute; the two speeds give different results for rate-sensitive polymers such as polypropylene and polyethylene.

• Machine: constant-rate-of-extension tensile machine whose force system is verified to ISO 7500-1 (class 1 is the usual requirement; check the current edition).

• Capacity: large enough that the maximum force sits well within the verified range. A 200 mm specimen of a 50 kN/m product breaks at about 10 kN; a 400 kN/m geogrid needs about 80 kN; very high-strength reinforcement can exceed 200 kN.

• Travel: enough for the strain at break. A nonwoven that reaches 80 % strain needs about 80 mm of extension between the jaws, plus slack take-up.

• Jaws: at least as wide as the specimen, able to hold it without slippage or jaw breaks; the 2024 edition adds an illustration of suitable jaws and grips.

• Extensometer: measures the change between two reference points on the 60 mm nominal gauge length.

The Universal Grip ISO 10319 wide-width vise grip

Universal Grip builds a heavy-duty twin-screw vise grip specifically for wide-width tensile testing of geotextiles and geogrids to ISO 10319. Two lead screws close a full-width jaw onto the specimen, and finely knurled faces distribute clamping pressure across the whole width, so the specimen breaks in the gauge length rather than at the jaw. It belongs to our vise grips range.

• Twin lead screws close the jaw evenly across the full specimen width, avoiding the edge-to-edge pressure differences that cause skewed breaks.

• Finely knurled, wear-resistant jaw faces resist slippage under high load; other faces are available on request for products that need them.

• Scaled alignment marks and a pointer for consistent, centred specimen placement from test to test.

• Open U-frame for quick loading of bulky or stiff products such as geocomposites and geogrids.

• Specimens: wide-width strips, nominally 200 mm wide.

• Load capacity: 50 kN per grip standard; higher capacities on request.

• Construction: high-strength steel body with hardened jaw inserts.

• Machine connection: clevis pin or threaded adapter to suit your frame; compatible with electromechanical and servo-hydraulic universal testing machines.

• Part reference: UGC-ISO10319-VG.

When you ask for a quote, tell us the specimen width, product type and strength range, the capacity you need and your machine connection. Be realistic about capacity: the standard 50 kN grip covers nonwovens, most woven separation and filtration fabrics and lighter geogrids (up to roughly 250 kN/m on a 200 mm specimen), while high-strength reinforcement needs the higher-capacity option. Specifications are typical and confirmed at the time of quote. See also our broader tensile grips range.

Choosing a testing machine for ISO 10319

The machine choice follows from your strongest product. Multiply the highest tensile strength you expect (kN/m) by 0.2 m to get the peak specimen force, then add margin so the result lies comfortably inside the verified load-cell range.

Mark-10 motorized testers: only for light products

A Mark-10 F1505 (1,500 lbF, about 6.7 kN, 813 mm travel, 10 to 600 mm/min) can run 20 mm/min and has ample travel, so in principle it covers lightweight nonwovens up to roughly 30 kN/m. In practice most ISO 10319 work exceeds it: a 50 kN/m woven fabric already breaks at about 10 kN, and a 50 kN wide-width vise grip pair is heavy for a compact frame. We recommend Mark-10 testers for related lighter QC tests, not as the main ISO 10319 machine.

Galdabini universal testing machines

A Galdabini universal testing machine is the right platform for this standard, with closed-loop rate control, high-resolution data and room for wide grips and extensometers.

• 50 kN benchtop: nonwovens, woven geotextiles and lighter geogrids up to about 200 kN/m with the standard grip.

• 100 kN benchtop: the common choice for mixed geotextile and geogrid labs, covering up to about 400 kN/m with higher-capacity grips.

• 200 kN or 250 kN floor-standing: high-strength polyester geogrids, woven reinforcement and strips above about 400 kN/m.

• Hydraulic models: for the very highest capacities and steel wire meshes.

Grips, extensometers and accessories

Grips

The wide-width vise grip is the standard choice. Labs testing very strong, stiff reinforcement products sometimes use roller grips that wrap the specimen to spread the clamping load, and hydraulic grips or pneumatic grips for consistent clamping force on high-throughput lines. Whatever you choose, the jaw must cover the full specimen width and hold without slippage.

Extensometers

Here an extensometer is genuinely required, not optional: ISO 10319 measures strain between two reference points 60 mm apart, and crosshead travel includes jaw seating, slippage and the 100 mm free length, so it overstates strain and understates stiffness. A video extensometer is the best fit: it is non-contact, so nothing is damaged when a geogrid releases a large amount of energy at break, it tracks marks on open structures, and it works inside an environmental chamber for the 2024 temperature annex. Long-travel XL extensometers are an alternative for high-strain nonwovens. A clip-on extensometer is rarely suitable on soft fabrics and should be removed before failure.

Specimen cutting and other accessories

Clean, square specimens matter. A ribbon-steel cutting die with an arbor press or die press gives repeatable widths for nonwovens and fabrics; ask about a die to suit your specimen. Adapters connect the grips to your frame, and software handles the per-unit-width, strain-at-force and stiffness calculations automatically.

ISO 10319 test procedure step by step

• 1. Prepare: sample per ISO 9862, cut at least five MD and five CMD specimens, measure width (or count ribs), condition at (20 ± 2) °C and (65 ± 5) % RH.

• 2. Set up the machine: set the jaw separation to 100 mm, select a load cell suited to the expected force, and set the rate to give 20 % per minute.

• 3. Insert the specimen: centre it using the alignment marks so its axis is in line with the pull, tighten both lead screws evenly on the top jaw, let it hang straight, then close the bottom jaw without introducing slack or pre-load.

• 4. Fit the extensometer: set the 60 mm nominal gauge length symmetrically about the specimen centre, or place video targets 30 mm either side of centre.

• 5. Apply pre-tension: load to 1 % of the expected maximum force and record the elongation at pre-tension; this defines the true gauge length.

• 6. Test: extend at constant rate until rupture, recording force and extensometer elongation continuously.

• 7. Inspect: note slippage, jaw breaks or failure at a defect; replace invalid specimens according to the standard.

• 8. Repeat for all specimens and each direction, then calculate and report.

ISO 10319 calculations

Results are calculated per specimen, then averaged with the standard deviation and coefficient of variation for each direction. The 2024 edition adds explicit strain formulas, so check clause 9 for the exact notation.

• Tensile strength: T = F_max × c, in kN/m.

• c for fabrics, nonwovens and other closed structures: c = 1/B, where B is the nominal specimen width in metres (5 m⁻¹ for 200 mm).

• c for geogrids and open structures: c = N_m / n_s, where N_m is the number of tensile elements per metre of product width and n_s the number of tensile elements in the specimen.

• True gauge length: L₀ = 60 mm + elongation at pre-tension.

• Tensile strain: ε = (ΔL / L₀) × 100 %, where ΔL is the increase in true gauge length.

• Secant tensile stiffness: J_ε = (F_ε × c) / (ε / 100), in kN/m, where F_ε is the force at strain ε.

Worked example: woven geotextile

• Specimen width 200 mm, so c = 1 / 0.200 = 5 m⁻¹.

• Maximum force F_max = 9.86 kN, so T = 9.86 × 5 = 49.3 kN/m.

• Elongation at pre-tension 0.4 mm, so true gauge length L₀ = 60.4 mm.

• Further elongation at maximum force ΔL = 9.20 mm, so ε = 9.20 / 60.4 × 100 = 15.2 %.

• Force at 5 % strain F₅ = 4.10 kN, so force per unit width = 4.10 × 5 = 20.5 kN/m, and J₅ = 20.5 / 0.05 = 410 kN/m.

• Five MD strengths of 49.3, 50.8, 48.6, 51.2 and 50.1 kN/m give a mean of 50.0 kN/m, standard deviation 1.07 kN/m and coefficient of variation 2.1 %.

Worked example: geogrid

A biaxial geogrid specimen contains n_s = 5 ribs; the product has N_m = 24 ribs per metre. With F_max = 16.0 kN, c = 24 / 5 = 4.8 m⁻¹ and T = 16.0 × 4.8 = 76.8 kN/m. Using 1/B instead would have given 80.0 kN/m, a 4 % overstatement, which is why the rib count matters.

Typical results and the test report

Strengths range from a few kN/m for light nonwovens to well above 1,000 kN/m for high-strength reinforcement. Nonwovens typically reach high strains at maximum force, often above 50 %, while wovens and geogrids usually fail at much lower strains, commonly in the 10 to 25 % range. These are orientation figures only; always compare against the product declaration.

• Reference to ISO 10319:2024 and any deviations.

• Product identification, direction (MD or CMD) and specimen dimensions or rib counts.

• Conditioning atmosphere, or wet or temperature condition used.

• Mean tensile strength (kN/m), strain at maximum force (%), and secant stiffness at stated strains, each with standard deviation and coefficient of variation.

• Second-peak values where relevant, achieved strain rate, and any discarded specimens with the reason.

• Machine, grip type and extensometer used.

Common errors in ISO 10319 testing

• Jaw slippage: knurled faces worn smooth or uneven screw tightening; it shows up as a sawtooth curve and inflated strain.

• Jaw breaks: over-tightening or sharp jaw edges cut the product; adjust clamping or face style.

• Crosshead strain: reporting strain from crosshead travel instead of the 60 mm extensometer gauge length.

• Wrong speed: running at ASTM D4595's 10 % per minute, or forgetting to convert 20 % per minute into the correct crosshead speed for your jaw separation.

• Wrong width factor for geogrids: using 1/B instead of N_m / n_s.

• Skipping pre-tension: without 1 % pre-tension, slack inflates strain and lowers stiffness.

• Off-centre specimens: one edge loads first, so the specimen tears progressively and the peak drops.

• Too little capacity: grip or load cell running near its limit on high-strength products.

• Testing unconditioned polyamide or other moisture-sensitive products without stating it.

ISO 10319 vs ASTM D4595 and related standards

• ASTM D4595: the closest equivalent; also a 200 mm wide-width strip with 100 mm between the jaws, but run at 10 % per minute, so results are not interchangeable for rate-sensitive polymers.

• ASTM D6637: the ASTM wide-width and single-rib tensile method for geogrids.

• ASTM D4632: grab tensile test for geotextiles, a different, narrower-jaw index test common in North American specifications.

• ISO 13934-1: 50 mm strip tensile test for general textile fabrics, not for geosynthetics.

• ISO 10321: tensile test for joints and seams by the wide-width strip method, often run with the same grips.

• ISO 12236: static puncture (CBR) test, usually reported alongside ISO 10319 strength on geotextile data sheets.

• ISO 9862, ISO 9863-1, ISO 9864 and ISO 10318-1: sampling, thickness, mass per unit area and terminology.

Equipment summary for ISO 10319

• Grips: ISO 10319 wide-width vise grip, 50 kN standard, higher on request; also roller grips and hydraulic grips.

• Machine: Galdabini 50 kN or 100 kN benchtop, or floor-standing for high-strength products.

• Strain: video extensometer or XL extensometer.

• Temperature testing: environmental chambers.

• Specimen prep: cutting dies and arbor presses.

• Related pages: tensile testing, textiles, ISO 12236 and the full ISO standards library.

ISO 10319 FAQ

What is ISO 10319?

ISO 10319 is the international wide-width tensile test for geosynthetics. A strip nominally 200 mm wide is pulled to rupture at 20 % per minute and the results are reported as tensile strength in kN/m, strain at maximum force and secant tensile stiffness.

What is the current edition of ISO 10319?

ISO 10319:2024, the fourth edition, published in October 2024. It replaced ISO 10319:2015 and is adopted in Europe as EN ISO 10319:2024.

What changed in ISO 10319:2024?

The main changes are: 'load' became 'force' throughout, strain and elongation are clearly separated, first- and second-peak strength are clarified, an illustration of suitable jaws was added, metallic products are limited to woven steel wire meshes, narrower products and tests at low or high temperature were added, and strain formulas and the test report were updated.

What specimen size does ISO 10319 use?

A wide-width strip with a nominal width of 200 mm, normally with 100 mm between the jaws. Geogrids are adjusted to contain whole ribs, and the 2024 edition adds rules for products narrower than 200 mm.

What is the gauge length in ISO 10319?

The nominal gauge length is 60 mm, 30 mm either side of the specimen centre, measured with an extensometer. The true gauge length adds the elongation at pre-tension.

What test speed does ISO 10319 require?

A constant strain rate of 20 % per minute. With 100 mm between the jaws this is typically about 20 mm/min of crosshead speed, confirmed from the achieved strain rate.

How is tensile strength calculated for geogrids?

Multiply the maximum force by c = N_m / n_s, where N_m is the number of ribs per metre of product width and n_s the number of ribs in the specimen. For fabrics, c = 1/B with B the specimen width in metres.

What is secant tensile stiffness?

The tensile force per unit width at a chosen strain divided by that strain, in kN/m. It is often reported at 2 %, 5 % or 10 % strain to describe how stiffly a reinforcement product picks up load.

Is ISO 10319 the same as ASTM D4595?

They are very similar in specimen geometry, but ASTM D4595 runs at 10 % per minute while ISO 10319 runs at 20 % per minute, and the strain measurement and calculations differ in detail, so results should not be mixed in one specification.

What testing machine do I need for ISO 10319?

Most labs need a universal testing machine of 50 kN to 100 kN; high-strength geogrids and reinforcement may need 200 kN or more. Multiply the highest expected strength in kN/m by 0.2 m to estimate the peak force.

Do I need an extensometer for ISO 10319?

Yes. Strain is measured over the 60 mm gauge length, not from crosshead travel. A video extensometer is the most practical choice because it is non-contact and safe at break.

How do I stop geotextiles slipping in the grips?

Use full-width grips with knurled faces tightened evenly, such as the Universal Grip twin-screw vise grip, check faces for wear, apply the 1 % pre-tension, and ask about alternative faces or roller grips for very strong products.

Need a fixture, grips or a complete test system for ISO 10319? Contact Universal Grip with your material, specimen size and machine connection and we will quote the right setup.