The Properties and Performance of Tensar Uniaxial...

The Properties and Performance of Tensar Uniaxial

GeogridsThe essential guide to thelong-term properties ofTensar Uniaxial Geogrids

for use in designing:

Bridge abutments

Retaining walls

Steep embankment slopes

Slip repairs

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How to use this guideThis is your essential guide to the long-term properties ofTensar uniaxial polymer geogrids for use in reinforced soilstructures. Polymers are not simple elastic materials. Theirload-strain behaviour is also affected by time andtemperature. These effects are product specific and theylead to a unique design strength for each project and setof conditions. There is a simple conceptual formula:

Design strength = Long-term strengthfactors

Long term strength may be defined in terms of rupture(ultimate limit state) or limiting strain (serviceability limitstate). One of the purposes of this document is to assist

engineers to derive the appropriate design strength fortheir project. The terms in the “conceptual formula” areexplained so that the working formula can be created.The major topics of importance are: strength, durabilityand mechanical interaction with soils. Each topic isdiscussed, and information presented from actual testingor trials. The important parameters are highlighted.At the end of the guide is a comprehensive list of thedesign parameters for the Tensar RE uniaxial geogrids.

Tensar uniaxial geogrids have been developed specificallyfor reinforcing soils. The Tensar SR geogrids weredeveloped in the early 1980s, and have been usedextensively in the construction of retaining walls, bridgeabutments and steep slopes. In the early 1990s theTensar RE geogrids were introduced, using improved

polymers to give better long-term strength and betterresistance to construction damage. During the last 20years a huge number of structures have been built usingthese products, in a wide variety of soil types andclimates.

Brief history of Tensar Uniaxial Geogrids

Tensar Technology - provenpractical solutions and theknow-how to get them built

Based on the characteristic properties of Tensar geogrids, TensarTechnology is widely adopted for ground stabilisation and soilreinforcement problems, delivering real savings in cost and time. Wecan help you apply Tensar Technology to improve the bottom line onyour project.

FEATURES

� High quality durable polymers

� Consistent manufacturing process

� Consistent data and information

� Reliable design parameters

� Confidence from extensive third partyaccreditation

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Figure 1: Effect of temperature and strain rate on tensile strength of polymer geogrid.

Tensile strengthAll polymer based products are visco-elastic. Theirstrength and stiffness are affected both by temperatureand by rate or duration of loading, as shown on Figure1. Therefore, it is important that standard methods oftensile testing are used, so that temperature and strainrate are defined. For Tensar uniaxial geogrids, qualitycontrol (QC) tensile testing is carried out using themethod given in International Standard BS EN ISO10319:1996. This is a wide width method withspecimen width at least 200mm. Strain rate is 20% perminute and test temperature is 20ºC.

The ISO 10319 QC test procedure consists of testing fiveindividual specimens and the lower 95% result isreported. The test equipment is shown on the adjacentpicture and a typical result from an ISO 10319 QC test isshown on Figure 2.

These tests are carried out at prescribed intervalsaccording to the certified quality control procedures. Thespecified QC strength is the 95% lower confidence limitdetermined in accordance with ISO 2602:1980, basedon statistical analysis of all tests carried out.

Tensile testing gives quality control strength -Tult

Figure 2: Test result for ISO 10319 tensile test on Tensar 80RE.

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Long-term creep rupture behaviourDue to the visco-elastic nature of polymers, it is notpossible to use tensile tests to determine load-strainbehaviour for long durations of sustained loading. To dothis, a different type of test is used, normally referred toas a creep test. A creep laboratory is shown on Figure 3,where a number of creep tests can be seen in progress.

A weight is hung on each specimen, and strain ismeasured for a standard duration of 10,000 hours.However, many tests are left to run for much longerdurations. Each grade of geogrid is subjected to a rangeof loads. The temperature of each creep laboratory iscarefully controlled. Creep tests are run in laboratories at10ºC, 20ºC, 30ºC, 40ºC and 50ºC. The testing procedurefollows the requirements of BS EN ISO 13431:1999.Figure 4a shows a family of results from creep tests onTensar 55RE carried out at 10ºC.

Creep testing of Tensar RE geogrids started in 1993, andFigure 4b includes four tests which have reached morethan 100,000 hours duration. However, this is still muchshorter than typical design lifetimes, which can be up to120 years depending on the application. Mathematicalextrapolation of the data on Figures 4a and 4b wouldresult in considerable uncertainty due to the extent ofextrapolation required. In order to avoid extrapolation tolong durations, a method of interpretation is used whichcombines tests carried out both at differenttemperatures (by using time shifting) and on differentgrades of geogrid (by normalising the rupture load).

The result of this interpretation is shown on Figure 5,which shows all available rupture data for the Tensar REgeogrids summarised on a single plot. There is sufficientdata on this plot to be able to determine a lower boundrelationship. This relationship is used to calculate long-term lower bound rupture loads for differenttemperatures and design lives, without the need to makeany direct extrapolation of data.

The high quality, duration and completeness of this datais recognised in BBA Certificate No 99/R109 for Tensar REgeogrids (for design of retaining walls and bridgeabutments), where the partial factor for extrapolation ofdata is 1.0.

Figure 3: Temperature controlled creep test laboratory.

Creep rupture testing gives long-term rupturestrength - PC or TCR

Figure 5: Normalised rupture load versus time to rupture for all Tensar REgrids shifted to 20ºC.

Figure 4a: Strain-time plots for Tensar 55RE at 10ºC.

Figure 4b: Strain-time plots for Tensar 80RE at 20ºC.

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The long-term deformation behaviour of polymer geogridis assessed by constructing isochronous load-straincurves. Isochronous data is taken directly from the strain-time curves shown on Figures 4a and 4b by reading offthe data from the plotted lines at fixed time values.Figure 6 shows isochronous load-strain curvesdetermined in this way for Tensar 120RE at 20ºC, forboth 1 month and 120 years duration. For serviceabilitylimit state design to BS8006:1995, isochronous curvesare used to find the geogrid load which limits post-construction strain to:

� 1% over the period between 1 month and 120years for retaining walls,

� 0.5% over the period between2 months and 120 years for abutments.

Long-term creep strain behaviour

Effects of construction activities

Extensive full scale field trials have been carried out toevaluate the effects of construction activities on Tensaruniaxial geogrids. These trials are carried out followingthe method given in BS8006:1995, using hard angularcrushed limestone aggregates. Typical samples of thethree gradings used are shown on Figure 7.

Maximum particle sizes are 125mm, 37.5mm and 6mmrespectively for the coarse, medium and fine gradings(interpolation is used for other particle sizes). Figure 8shows the arrangement used for the trial.

Figure 7: Coarse, medium and fine crushed limestone used ininstallation damage trials.

Figure 8: Section of full scale site damage trial carried out to BS8006:1995.

Creep strain testing gives long-term strengthbased on limiting strain - Tcs

Figure 6: Isochronous curves for Tensar 120RE.

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The trial procedure is illustrated in Figure 9. A layer of fillis placed both below and above the geogrid. The upperlayer is compacted to three levels of compaction andthen carefully excavated so that the geogrid can berecovered. The geogrid is examined to check for damage.Based on this examination, test specimens are selectedfrom the areas which exhibit the greatest damage. Widewidth tensile tests are carried out on these specimens,and the results are compared to tests carried out oncontrol samples.

Typical tensile test results for two conditions are shownon Figure 10. The results for Tensar 40RE (the lightestuniaxial grid) and 125mm crushed rock fill (the coarsestfill) represent the most severe conditions tested. Thedifference in the measured ultimate tensile strengthbetween the control and the site damaged samples isused to calculate partial safety factors (fd) to take intoaccount the effects of installation activities. These factorsare used when calculating long term design strength forthe ultimate limit state.

Examination of the results shown in Figure 10 indicatesthat fd is quite high for Tensar 40RE, but much less forTensar 80RE, which is the case in the published fd values.This illustrates the importance of testing all grades froma particular family of products. For serviceabilityconditions, behaviour at low strain is more appropriate.In this case, load at 2% and 5% strain is used tocalculate fd, and the resulting values may be taken as 1.0for all conditions. This has also been investigated bycarrying out creep tests on site damaged uniaxialgeogrid. These tests confirm that, under long termloading at likely working loads, the effects of siteinstallation activities are minimal.

Installation trials have been carried out using other filltypes, for example: pulverised fuel ash (PFA) and crushedhard igneous rock (diorite). Comparison of the resultsindicates that the trials carried out using crushedlimestone represent the most aggressive conditions likelyto be encountered in practice.

Figure 9: Placing and compacting the rock fill, thencarefully removing the geogrid.

Figure 10: Tensile test results on Tensar 40RE and 80RE from installation trial.

Site trials give partial safety factors to takeaccount of installation - fd

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External exposureIn most applications geogrid will be buried in soil, so that itwill be protected from external environmental conditions.However, at a number of stages during its use, it is likely tobe exposed, certainly during handling and installation onsite, but also possibly in service. Exposure might be for arelatively long duration, and it is therefore important thatthe geogrid material is well protected. Some constructionspecifications and approval certificates provide protection bylimiting the allowable duration of exposure, but theserequirements are difficult to control and enforce. The mostreliable protection is provided by using the optimumcontent of appropriate additives in the polymer.

Ultra-violet light (UV) can damage unprotected polymersrapidly, by breaking down the molecule chains. Tensaruniaxial geogrids are protected by the inclusion of aminimum of 2% well dispersed carbon black, which gives ahigh degree of protection by preventing UV light frompenetrating beyond a thin layer at the surface.

Figure 12 shows the importance of this 2% minimum. Ascarbon black content drops below 2%, the life of thepolymer drops dramatically. Because very small carbon blackpercentages will still make a polymer “look” black, it isimportant that this property is measured using appropriatestandards. Laboratory tests have been carried out in which

During its service life soil reinforcement will be exposedto a wide variety of environmental conditions. Thesewill originate from external agencies, such as ultra-

violet light (UV) and variation of temperature, as well asfrom burial in soil where chemical and biologicalconditions may be aggressive.

Tensar uniaxial geogrids are exposed to intense UV light inweatherometers.

These tests have shown that, under temperate climates,Tensar uniaxial geogrids will retain 90% of their initialstrength for between 20 and 50 years of exposure,depending on their rib thickness. Outdoor exposure trialshave recently been completed at Albury, Australia, where UVintensity is very high. These trials were started in 1994, andFigure 12 shows that, after 8 years exposure, there iseffectively no change in the tensile strength and stiffness forTensar 55RE. This excellent resistance to UV degradationmeans that no special wrapping or covering is requiredduring transportation and storage on site. If grids areexposed during construction, there is no need to specifyminimum duration before cover is established.

The properties of HDPE can be affected by oxidation. Tensaruniaxial geogrids are protected by the inclusion of anappropriate content of a proprietary antioxidant. Tests havebeen carried out on Tensar 40RE to BS EN ISO 13438:2004to determine its resistance to oxidation. This test requiresthat the geogrid is subjected to 100ºC for a period of 56days, measuring tensile strength at 6 hours and 56 days.The results show that no significant degradation resulted.

Effects of environmental conditions

Figure 12: Effectiveness of carbon black to protect HDPE from UV light.

Figure 11: Exposure to external conditions during handling, installation and service.

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Effects of burialChemical resistanceBuried geogrid will come into contact with soil and groundwater, both of which can contain potentially aggressivesubstances. HDPE is resistant to a wide range of chemicals,and it is inert to all aqueous solutions of acids, alkalis andsalts normally found in soils. In addition, it has no knownsolvents at ambient temperatures. Because of its stabilityunder a wide range of chemical conditions, HDPE is used inmany situations where hazardous or aggressive chemicalsare present, for example: liners for hazardous waste sites,gas pipelines and many forms of container for aggressivechemicals. In USA, Tensar uniaxial geogrids have beensubjected to a wide range of chemical exposure testsfollowing the protocol in EP9090, and are accepted for usein landfill sites. Due to their high resistance to alkalineconditions, Tensar uniaxial geogrids may be buried incontact with hydrating cement without any danger ofdegradation. This permits a number of constructiontechniques to be used where geogrid will come into contactwith fresh concrete, such as casting geogrid into concretepanels or shotcreting onto geogrid.

Biological resistanceThe engineering grades of HDPE used to manufactureTensar uniaxial geogrids have no nutritional value, andare therefore not attacked by micro-organisms. This isconfirmed in the UK and many other countries by theapproval of such polymers for water supply pipes,where it is critical that they should not supportbiological growth.

Resistance to environmental stresscracking (ESC)ESC can occur in polymers when they are subjected tohigh stress under certain chemical conditions. Surfacemicro-cracks can develop, which can lead to prematurefailure. The resistance of Tensar uniaxial geogrids toESC has been investigated by carrying out special creeptests as shown on Figure 13. A number of creep testswere arranged at different loads, some being exposedto a special chemical which encourages ESC. Controltests were carried out in air. The graph shows that thetwo series of tests give similar performance, and it canbe concluded that Tensar uniaxial geogrids are notaffected by ESC.

Figure 13: Test set-up and results for special creep tests to investigate ESC.

A variety of tests and trials give partial factor for environmental conditions - fe

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Connecting Tensar Uniaxial GeogridsTensar uniaxial geogrids may be easily connectedtogether on site in the direction of loading using apolymer bodkin joint bar. The bodkin joint provides a fullstrength connection, so that no reduction factor orpartial safety factor is required in designs whichincorporate the joint. This versatile connector can beused to:� connect main reinforcement to short starters

(as shown in Figure 14)

� use short off-cuts to minimise waste

� form wrap-around connections in slopeconstruction

The unique form and properties of Tensar uniaxialgeogrids make them ideal for forming mechanicalconnections with concrete retaining wall facings. Thiscan be done by casting the geogrid into a concrete panel(as shown on Figure 14), which results in a full strengthconnection, so that no reduction factor or partial safetyfactor is required. In addition the excellent chemicaldurability of HDPE means that Tensar uniaxial geogridsare not adversely affected by the highly alkalineenvironment created in wet or freshly formed concrete.

Concrete modular block wall facings are now widely useddue to their pleasing looks, ease of construction andeconomy. Tensar’s unique blue polymer connector asshown in Figure 15a, provides a highly efficient methodof joining Tensar uniaxial geogrid into the facing.

The advantage of this type of connector is high strength,even for the low normal loads which occur near the topof the wall, or may be generated during an earthquake.The results of full-scale connection testing are shown onFigure 15b. Two sets of data are shown. The results forthe mechanical connector (of the type shown in Figure15a) show that connection strength is independent ofnormal load, so even very close to the top of the wall,full connection strength is developed. The second set ofdata is for a frictional connection, where the geogrid ismerely “clamped” between the upper and lower faces oftwo layers of blocks. Pins are also used to link the blockstogether, but the connection is mainly frictional innature, so that at low normal loads very low connectionstrength is developed.

Figure 14: The Tensar bodkin joint.

Figure. 15a: Mechanical connection with modular block wall facing.

Figure 15b: Connection test results for different types of modular block facing.

Tensar Bodkin connector provides full strengthconnection in direction of loading

Tensar Polymer connector provides highstrength connection with modular facing block

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Normal load (kN/m)

Test method NCMA SRWU-1Geogrid: Tensar UniaxialC

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Frictional connectionMechanical connection

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Mechanical interaction with soilStabilising soil masses using reinforced soil techniquesrequires mechanical interaction between geogrid andsoil. Interaction can take the form of sliding or pullout.Examples of failure mechanisms which mobilise thesetwo forms of interaction are shown on Figure 16. Slidingbetween geogrid and soil is defined by a simplecoefficient of friction given by:

friction coefficient = αtanφ’

where φ’ = friction angle of the soilα = interaction factor

The interaction factor (α) is therefore a reduction factorto take into account sliding between geogrid and soil.Different types of interaction testing are required tomeasure the interaction factors for sliding (αs) andpullout (αp).

Figure 16: Failure mechanisms mobilising interaction between geogrid and soil.

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Figure 17b: Set up for shear box test on Tensar 80RE. Figure 18: Results from sliding interaction tests on Tensar 40RE.

Figure 17a: Cross section of shear box test to measure αs.

Sliding interaction factorsThe sliding interaction factor may be determined bycarrying out shear box tests using a large (300mm)specially modified shear box in which grid is clamped tothe bottom half of the box.

In this way the top half of the box slides over thegeogrid, thereby creating sliding between geogrid andsoil. The test set-up is shown on Figure 17. Control testsare carried out in the same way, but without geogridpresent on the sliding plane. Comparison of the twotests gives the required interaction factor(αs = tanφgrid+soil /tanφsoil only).

Results from interaction tests using Tensar 40RE areshown on Figure 18, for fine and coarse soils. Based onthese and similar tests, typical values of slidinginteraction coefficient (αs) for Tensar uniaxial geogridsare:� 0.9 to 1.0 for crushed rocks and gravel

� 0.85 to 0.95 for sands

� 0.8 to 0.85 for pulverised fuelash (PFA)

� 0.6 to 0.7 for clays

Special shear box tests give sliding interaction factor - αs

Normal load

Direct shear box

Shear force

Shear force

Granular fill

Clamp usedto secure

Tensargeogrid

Tensar geogrid

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Figure 20: Results from pullout tests.

Pullout interaction factorsPullout interaction factors are determined using pullouttests. A typical test arrangement is shown in Figure 19. Alength of geogrid is buried in a large box, and a load isapplied to the top surface of the fill to represent therequired overburden pressure. The geogrid extendsthrough a slot in the side of the box, where it isconnected to jacks, which apply load in tension.The results of pullout tests on Tensar uniaxial geogridsare shown on Figure 20. This shows pullout load versusthe number of ribs (ie. length) of geogrid buried in thebox. For just 1.2m of overburden, only 5 ribs (less than1m) are required to generate maximum pulloutresistance.

For greater lengths, failure occurs by rupture of thegeogrid outside the box. This very efficient interaction iscreated by the open structure and integral full strengthjunctions of Tensar uniaxial geogrids. Load is carriedmainly by bearing on the thick transverse bars, andtransferred through the junctions to the longitudinal ribs

at very small deformations. This is shown in the special“X-ray” test, where the light areas represent zones ofcompression in front of the thick transverse bars of thegeogrid. Pullout tests have shown that αp ≈ αs may beused in the absence of specific test data for Tensargeogrids.

“X-ray” of interaction mechanism.

Pullout tests give pullout interaction factor - αp

Figure 19: Set-up of pullout test using Tensar grid.

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Independent certification

Tensar geogrids have been given accreditation by anumber of independent government and other certifyingagencies around the world. No other soil reinforcementmaterial has such a wide range of certification.

� The British Board of Agrément has awardedcertificates both for retaining walls andabutments, and for steep slopes.

� Network Rail, the UK authority responsible forthe maintenance of the national rail tracknetwork, has certified Product Acceptance forTensar SR and RE uniaxial geogrids for use inreinforced soil railway structures (certificatenumbers PA05/175 & PA05/177).

� The British Board of Agrément has alsoawarded certificate No 00/122 (second issue)for the Tensar TWI wall system for reinforcedsoil retaining walls and bridge abutments.

� In Hong Kong, the Geotechnical EngineeringOffice has awarded Certificate RF 5/03 for theuse of Tensar RE geogrids in reinforced fillstructures.

� The Roads & Traffic Authority in Sydney,Australia, has certified both Tensar SR and REgeogrids under Specification R57 for use inReinforced Soil Walls.

Reinforced Fill Product Certificate No RF2/05 for

Tensar 40RE, 55RE, 80RE, 120RE, 160RE and Joint Bars

TENSAR SR GEOGRIDSFOR REINFORCED SOIL

RETAINING WALLAND BRIDGE

ABUTMENT SYSTEMS

TENSAR TW, WALL SYSTEMFOR REINFORCED SOIL

RETAINING WALLSAND BRIDGEABUTMENTS

TENSAR RE GEOGRIDSFOR REINFORCED SOIL

RETAINING WALLAND BRIDGE

ABUTMENT SYSTEMS

TENSAR RE GEOGRIDSFOR REINFORCED SOIL

EMBANKMENTS

ROADS & BRIDGESCERTIFICATE No 00/R122




� Allgemeine bauaufsichtliche Zulassung Z-20.1-102 of the Deutsche Institut für Bautechnik(DIBt), Berlin for reinforced soil with the Tensargeogrids SR55, SR80, SR110.

Z-20.1-102

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Tensar geogrids are manufactured in accordancewith Quality and Environmental ManagementSystems which comply with the requirements of BS EN ISO 9001:2000 and BS EN ISO 14001:1996respectively.

This process creates a geogrid with long narrowapertures, called a uniaxial grid because it has beenstretched in one direction only. The polymer’s long chainmolecules are orientated in the direction of stretchingresulting in a dramatic increase in both strength andstiffness.

This orientation passes through both the narrower ribsand the thicker transverse bars, and is unique to thepatented Tensar manufacturing process.

Manufacturing process

Figure 21a: The Tensar manufacturing process for uniaxial geogrids.

Tensar uniaxial geogrids are manufactured from carefullyselected grades of high density polyethylene (HDPE).HDPE is used in many engineering applications where along service life and excellent durability are required,often under adverse conditions, for example: landfill andhazardous waste lining, water supply pipes andprotective sheathing for stay cables.

Uniaxial geogrids are made by extruding a sheet of HDPEto very precise tolerances, punching an accurate patternof holes, then stretching the sheet under controlledtemperature in the longitudinal direction.

Manufacturing Procedures, QA, Test Databasegive material factor - fm

Figure 21b: A detailed view of the uniaxial geogrid after stretching.

Q 05288BS EN ISO 9001:2000

EMS 86463BS EN ISO 14001:1996

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Calculation of long-term design strengthLong-term design strength of Tensar uniaxial geogrids(Pdes) is given in the form:

PcPdes =

fmfdfeLFwherePdes = long-term design strengthPc = long-term rupture strength from creep testingfm = partial factor for manufacturing, database and

extrapolationfd = partial factor for site installationfe = partial factor for environmental effectsLF = load factor

The derivation of Pc, fm, fd and fe is discussed in thisbrochure and values are given in the table below. LF isa load factor, or overall safety factor, and depends onthe design method used. Guidance and typical valuesof LF are given in various design guidelines and codes.

Example: calculate Pdes for Tensar 80RE for thefollowing conditions:• 10ºC• 120 years design life• ultimate limit state• 37.5mm maximum fill size• pH = 11• LF = 1.0 (Design method HA 68/94)

Referring to the data in the table below:Pc = 39.0 kN/mfm = 1.05fd = 1.07fe = 1.00

Pc 39.0Pdes = fmfdfeLF

= 1.05x1.07x1.00x1.00

= 34.7kN/m

(1) HDPE denotes high density polyethylene

(2) Carbon black inhibits attack by UV light. Determined in accordance with BS 2782:Part 4:Method 452B:1993. Any section of grid fullyexposed to sunlight can be expected to retain 90% of its quality control strength for periods of approximately 40 years in temperatureclimates and 20 years in tropical climates.

(3) Determined in accordance with GRI Test Method GG2-87, and expressed as a % of the quality control strength.

(4) Determined as a lower bound using standard extrapolation techniques to creep rupture data obtained following the test procedure in BSEN ISO 13431:1999 and with test durations up to and in excess of 100,000 hours, for 120 year design life. Creep rupture strengths forother design lives and other design temperatures may be obtained from Tensar International Limited.

(5) Determined from creep tests carried out following the test procedure in BS EN ISO 13431:1999 as the load resulting in 1% strainbetween 1 month and 120 years after the start of loading

(6) fm = 1.0 based on the QA procedures, database, use of lower bound values and extrapolation procedures applied by Tensar International. fm = 1.05 is given in BBA Certificates No 99/R109 and No 99/R113 for Tensar RE geogrids

(7) Derived as worst values from site damage trials carried out following the method given in BS 8006:1995, values as given in BBACertificate No 99/R109 for Tensar RE geogrids

(8) Values as given in BBA Certificate No 99/R113 for Tensar RE geogrids

Tensar RE Geogrid specificationsProperty Units Tensar Geogrid

40RE 55RE 80RE 120RE 160RE

Polymer (1) HDPE HDPE HDPE HDPE HDPE

Minimum carbon black (2) % 2 2 2 2 2

Junction strength (3) % 100 100 100 100 100

Long-term creep rupture strength ULS (4)

PC or TCR for 10ºC kN/m 24.0 29.5 39.0 63.1 73.1

PC or TCR for 20ºC kN/m 21.4 26.3 34.8 56.2 65.1

Long-term strain limited strength SLS (5)

TCS for 10ºC kN/m 13.4 17.6 25.0 37.7 48.9

TCS for 20ºC kN/m 11.5 15.4 22.4 34.3 44.8

Factor for manufacture and extrapolation of data (6)

fm 1.0-1.05 1.0-1.05 1.0-1.05 1.0-1.05 1.0-1.05

Installation damage factors for ultimate limit state (7)

fd for crushed stone <6mm 1.00 1.00 1.00 1.00 1.00

fd for crushed stone <37.5mm 1.07 1.07 1.07 1.00 1.00



Installation damage factors for serviceability limit state (7)

fd for all gradings 1.0 1.0 1.0 1.0 1.0

Environmental factor (8)

fe for pH 2.0 to 4.0 1.05 1.05 1.05 1.05 1.05

fe for pH 4.0 to 12.5 1.00 1.00 1.00 1.00 1.00

Amendment issued February 2006 to include increased strength parameters.

Contact Tensar International or your local distributor to receive furtherliterature covering Tensar products and applications.

Also available on request are product specifications, installation guidesand specification notes.

The complete range of Tensar literature consists of:

� Tensar Geosynthetics in Civil Engineering A guide to the productsand their applications

� Ground Stabilisation Reinforcing unbound layersin roads and trafficked areas

� Tensar Structural Solutions Bridge abutments, retaining walls, steep slopes

� Foundations over Piles Constructing over weak groundwithout settlement

� Basal Reinforcement Constructing embankments overweak ground

� Railways Mechanical Stabilisation of Track Ballast and Sub-ballast

� Asphalt Pavements Reinforcing asphalt layersin roads and trafficked areas

� Erosion Controlling erosion on soil and rock slopes

Tel: +44 (0)1254 262431

Fax: +44 (0)1254 266868

E-mail: [email protected]

www.tensar-international.com

Tensar International Limited

Cunningham Court

Shadsworth Business Park

Blackburn BB1 2QX

United Kingdom

Your local distributor is:

Tensar is a registered trade mark.

©Copyright Tensar International Limited

Printed February 2007 Issue 7, 79010056

The information in this brochure is supplied by Tensar International free of charge. TensarInternational do not assume any duty of care to you or any third party. No liability for negligence(other than for death and personal injury) can arise from any use of or reliance on the informationin this brochure or use of any Tensar International product mentioned. Tensar International willnot be liable if this brochure contains any misrepresentation or misstatement. Determination ofthe suitability for any project of the information and any Tensar International product mentioned init must be made by your engineer or other professional advisor who has full knowledge of theproject. You, together with any such engineer or advisor, must assume all risk of loss and damageof any kind arising from use of the information or any product of Tensar International other thanthe risk of death and personal injury. If you or any third party subsequently purchases a productreferred to in this brochure or any other Tensar International product the entire terms of thecontract of purchase and the entire obligation of Tensar International relating to the product orarising from its use shall be as set out in Tensar International's Standard Conditions in force at thetime of purchase, a copy of which may be requested from Tensar International.

Q 05288BS EN ISO 9001:2000

EMS 86463BS EN ISO 14001:1996

The Properties and Performance of Tensar Uniaxial...

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