fourdimensions technics technics secugrid® · quality advantages: round the clock quality control,...

FOURDIMENSIONSSecugrid®TECHNICS

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naue_4D_fly01_05_2009_technical:08_2009 19.08.2009 15:53 Seite 1

The four dimensions of length (the bar), width (the geogrid), depth (the soil) and the time (durabi-

lity) greatly influence construction project scope, design, product selection and expected service

life. Today, NAUE introduces you to a new four-dimensional way of understanding reinforcement

applications: the Four Dimensions of Secugrid®.


Geogrid reinforcement materi-als must transfer one dimen-sional strength appropriatelyto provide sustainable, long-term support to roads (pavedand unpaved), retaining wallsand mechanically stabilisedearth (MSE) structures. When itcomes to strength transfer, thetechnical advantages of NAUESecugrid® are significant. They reveal themselves whenlooking at strength, strain,modulus, and frictional surface.

Secugrid® provides highstrength at low strains - an ab-solute necessity for all reinfor-

cement applications. Secugrid®geogrids possess uniformstrength in all of the material’sbars due to a manufacturingprocess that uses extruded flatpolyester or polypropylenebars. Rollers uniformly stretchthe ribs and uniformly orientthe polymers into high-tena-city flat bars. Additionally,

these high tensile strengthbars are embossed, which crea-tes a frictional surface that im-proves the frictional perfor-mance in soils.

This manufacturing process*produces superior stress/straincharacteristics, especially inthe key elongation range - lessthan 2% - for which many pro-jects must be designed and bywhich geogrids are often jud-ged. The tensile strength ofSecugrid® is excellent at lowelongation.

Secugrid® bars have a veryhigh modulus, which means itwill pick up the stresses quicklywith little or no movement inthe overlying soil materials.

While Secugrid® typically has amaximum elongation at nomi-nal strength of 8%, realisticdesign conditions ask for astrength transfer in the rangeof less than 2%. Secugrid®bars excel at these realistic de-sign levels and show a highstrength transfer in this de-sign range, demonstrating ahigh modulus. Testing in ac-cordance with national and in-ternational standards providesthese necessary, very strongtensile modulus values.

DIMENSION1The Bar is our Strength

»Why settle with less?«

Technical advantages: High-strength, high-modulus, robust geogrid bars for sustainable performanceCustomer advantages: Safe and long-lasting stress transfer in the designQuality advantages: Superior manufacturing method for ensuring reinforcement strengthEcological advantages: Roads hold up better with less aggregate; steeper walls can be built.

Typical tensile strength/elongation curves for Secugrid® and market available geogrids


In this second Secugrid® di-mension, the one dimensionalbar characteristics, throughNAUE’s patented welding tech-nology*, form a structurallysound and stable geogrid and

create a rigid, high-perfor-ming, two-dimensional Secu -grid® bar structure. Four keyelements to look at in this se-cond dimension are torsionalrigidity, the interlocking ef-fect, the polar diagram, andgeogrid robustness.

The stability of the firmly wel-ded flat bar geogrid construc-tion creates a rigid and stabletwo dimensional geogrid thatis just as strong in its trans-verse alignment as it is in its

longitudinal alignment. Due toits product stiffness, Secugrid®biaxial geogrids have a highpolar (radial) strength that iscomparable to, if not betterthan, other similar geogrids.

When Secugrid® is installedwith a granular/soil layer, suchas beneath a road, on a slopeor in a wall, the aggregate in-

terlocks withthe geogrid throughthe apertures, which physicallyprevent lateral movement ofthe aggregate. This aperturestability, also known as torsio-nal rigidity, enables what isknown as the interlocking ef-fect. As forces are induced intothe soil from above, Secugrid®

absorbs thetensile forcesand distribu-tes themthrough the

overall interlocked system. Theabsorption and distribution oftensile forces, plus the aper-ture strength of Secugrid®,locks the aggregate in place,especially if radial movementoccurs. It will then not migrateas the aggregate interlocks la-terally with the geogrid andstresses are transferred to thereinforcement. In a base

course of aroad, the risk of verti-

cal deformation (rut depth) atthe road surface is greatly re-duced. As such, the biaxialstrength of the geogrid provi-des support in all directionsfor the entire design.

Geogrids with high torsionalstiffness and a good inter -locking of the aggregate pro-vide greater resistance againstthe described twisting stres-ses. Again, a high strength at

design elongations combinedwith a high torsional rigidityvalue are important. The polar(radial) diagram for biaxial Se-cugrid® geogrids helps unders-core these principles. Here, Se-cugrid® shows its strength.The Secugrid® polar diagramat the relevant design elonga-tion of 0.5% illustrates thehigh performance of Secugrid®polyester and polypropylenebiaxial geogrids. The integrityof the installation is protec-ted in 360°.

In uniaxial applications, e.g.slope reinforcement and MSEwalls, Secugrid geogrids ensurestress transfer in the desireddirection by means of this des-cribed interlocking effect.

Finally, the robustness of Secugrid® protects the geogrid

during installation, when manygeosynthetics are damaged byequipment, poor handling orlack of proper site preparation.

DIMENSION2Strength Transfer in all Directions

»Protect yourself in every direction.«

Technical advantages: True biaxial strength and radial stress transfer and interlockingCustomer advantages: Reduced long-term maintenance issues. Ease of installationQuality advantages: Round the clock quality control, ISO 9001 audited, CE marking Ecological advantages: Optimised Secugrid® for soil reinforcement reduces transport needs (and costs) to site

Radial Secant Stiffness of Secugrid® and other geogrids at 0.5% elongation

Aperture stability(torsional stiffness)of geogrid types


Fill material is rarely exact to aproject’s specifications. Soilsand coarse stones always havetheir variations, and the fric-tion and stresses produced bythese imperfections cangreatly affect an installation’ssurvivability. The robustness ofthe reinforcement material be-comes quite important.

As noted in Dimension 2, therobustness of Secugrid® provi-des vital protection during in-stallation. But whether Secu -grid® is installed in a retaining

wall, MSE structure, or road,the grid’s survivability againstthe imperfections of fill mate-rial allows good designs to be-come great projects.

Furthermore, many projects be-come even more affordable inthat the robustness of Secu -grid® reduces the need for somuch fill material. For exam-ple, the interaction betweenSecugrid® and base course ag-gregate increases the elasticmodulus to a point where thestiffness or load distributioncapacity of the base course isimproved. As such, less aggre-gate is needed in the base

course, without reducing theperformance of the road. Addi-tionally, a reduced amount ofaggregate in the base course,while simultaneously increa-sing its performance, canequate to significant transpor-tation and installation savings.Further, the risks of reflectivecracking and rutting in theroad are greatly reduced, a factthat leads to fewer long-termmaintenance needs while ex-tending road life.For walls, steeper designs areenabled through Secugrid®,

thus optimising the use of landspace. With their highstrength, high modulus, inter-locking effect and low creeprates, Secugrid® polyester geo-grids are the best candidatefor such applications. The com-bination of excellent stress/strain characteristics and thevery good long-term creep- resistance values of these Secugrid® geogrids allows foran economical selection ofhigh-strength Secugrid® geo-grids for critical applicationssuch as MSE wall designs. Stee-per walls offer numerous ad-vantages. Notably, the use ofspace is maximised while site

disturbance is minimised. Inbuilding steeper walls throughthe installation of Secugrid® -which can make mountain ro-ads possible, promote sustai-nable urban development, and

increase landfill air space andprofitability - one also realisesa valued environmental bene-fit.

Additionally Secugrid's productstructure offers an optimal fric-tion interaction with the soil,

even during the smallest dis-placements, because of itslarge, structured rib surface. Asdisplacement increases, trans-verse ribs become involved inload distribution. Strong

junction strength ensures thatpull-out resistance is maximi-sed by transverse rib torsion(torque/twist) as loads in-crease.

DIMENSION3 How to Build Smart

»Involving or relating to three dimensions gives

you the illusion of depth.«

Technical advantages: High stress/strain characteristic provides multiple benefits - better distribution of tensile forces, longer service lives, improved long-term project economy, and much more

Customer advantages: Reduced dependency on aggregate, less long-term maintenance, maximised site useQuality advantages: The wide range of quality products made of polypropylene or polyester with strengths up to 400 kN/mEcological advantages: Maximising space use is a project characteristic that improves sustainability. Reducing material shipments

(e.g., heavy aggregate) is also an important environmental benefit

Permanent deformation response versus load cycles

Calculation of the base course thickness for unpaved roads (unreinforced and Secugrid® reinforced)based on the Giroud/Han method (2004))

s)


Forensic engineering is almostentirely about failure. But ifthere might be a forensics ofsuccess, it might first be judgedin time: the longevity of a Secu -grid® installation.

The other three dimensions ofSecugrid® highlight the vitalcharacteristics that make thisfourth dimension possible -strength transfer in the geogridbars; strong performance at verylow elongations; the inter -locking effect with aggregatewhich provides not only a stiff -ening of the soil base but also360° of strength transfer; geo-grid robustness; a reduced de-pendency on fill material; steeper wall construction; etc.

The geogrid stiffness and highinitial modulus of NAUE Secu -grid® provide excellent creepperformance and pull-out char -acteristics, and long-term resis -tance to stress. Soil, whetherbeneath a road or within awall, may be under stress, butSecugrid® locks it in place. Theintegrity of the entire system isimproved.

And to be able to function inthe long term, Secugrid® geo-grids have a high resistanceagainst biological and chemicaldegradation. Secugrid® geo-grids have a high resistance todegradation from the types ofchemicals typically found insoils used for civil engineeringpurposes, and therefore allowfor long-term designs withoutthe need for major reductionfactors for the project. Addi -

tion ally, Secugrid® is highly re-sistant to microbial attack. Allof this leads to strong, long-term performance.

Secugrid® is durable not onlyfor the long-term design of yourinstallation but against thenear-term damage that mighthappen during installation.Also, when considering instal-lation work, it’s important toknow that Secugrid® can beshipped in rolls and unrolled

quickly and easily at a site;thus, covering a large area in ashort time.

As we build our roads and wallstoday, we can know that thereinforcement provided by Secu -grid® geogrids will mean thoseroads and walls will be theretomorrow. Secugrid® can extendproject life. The installation ofSecugrid® reinforcement todayreinforces the future.

DIMENSION4 The Long-Lasting Design

»Time will tell.«

Technical advantages: Long-term resistance and performance of Secugrid® soil reinforcement geogridsCustomer advantages: Quicker installation in the project, longer lasting designQuality advantages: Excellent and durable long-term creep performanceEcological advantages: Long-lasting designs, reducing carbon footprint and minimising use of finite resources

Long-term creep data based on conventional creep rupture and stepped isothermal method (SIM) of the Secugrid® product families

Comparison ofgeogrid pull-outdata in crushedgravel and sand


The Four Dimen-sions of Secugrid®provide a new, clearway to understand not just what applicationsgeogrids are used in but how manufacturing ad-vances improve geogrid performance, how stres-ses and strains are managed inside a reinforcedinstallation when Secugrid® is used, and whereyou can identify the many short and long-termadvantages in designing with this reinforce-ment material.

But reinforcement alone is not alwaysenough. Geosynthetics are designed for spe-cific functions and reinforcement is only oneof them. For designs that also involve a needfor filtration or the separation of fines, youmay look to an extra dimension: Combigrid®.

Combigrid® geogrids are the next generation ofgeogrids, a truly unique product that takes fulladvantage of state-of-the-art manufacturingtechnology. Combigrid® delivers reinforcement,filtration, separation and drainage in one com-posite material. These geogrids are used mainlyin conjunction with soft and low CBR soilswhere soil reinforcement in combination withseparation and filtration is needed, such as inbase reinforcement, embankment reinforcementand load transfer platforms over pile caps.

Reinforcement is provided by Secugrid®, sousers benefit from all of the characteristicsidentified in the Four Dimensions of Secugrid®:excellent stress/strain characteristics andstrength transfer in the geogrid bars, high

strength and a high modulus atlow elongations, durability and stiffness to pro-mote radial interlocking, a reduced need for fillmaterial, installation longevity, a decreasedneed for maintenance, and much more.

Filtration and separation functions are provi-ded by Secutex®, a nonwoven, needlepunchedgeotextile that is placed between the Secugrid®bars during the manufacturing process. Secu-tex® is bonded firmly between the reinforce-ment bars by NAUE’s patented welding techno-logy.

The three-dimensional nonwoven fibre matrixthat Secutex® adds to Combigrid® acts as a se-paration layer between different grain size soilsand ensures long-term separation and filter sta-bility. Such a separation layer is typically re-commended in base course applications for sub-soils with a CBR of less than 3% or inapplications where fines should be preventedfrom moving into the reinforced aggregateabove. The high elongation capacity of Secu-tex® nonwoven geotextiles ensures excellentresistance to damage. This robust characteristicof Secutex® products allows them to easily ac-commodate irregular or soft subgrades. Whencovered with the aggregate, the Secutex® non-woven geotextile fibres reorientate around thestones, preventing damage to the nonwovenstructure. With this excellent elongation pro-perty, the interlocking effect of Combigrid®with the fill material is not reduced - stresstransfer to the geogrid through the high-strength Secu grid® bars is ensured.

»… combine knowledge, experience and technology and create a new dimension of a

geosynthetic reinforcement …«Combigri d®


The information contained herein is the best to our knowledge, true and accurate. There is no implied or expressed warranty.© 2009 by NAUE GmbH & Co. KG, Espelkamp-Fiestel, Germany · All rights reserved. · Status 08/2009 · *Patent No.: 6,572,718 B2

®

, Combigrid® and Secugrid® are registered trademarks of NAUE GmbH & Co. KG.

NAUE GmbH & Co. KGGewerbestrasse 232339 Espelkamp-FiestelGermany

Phone +49 5743 41-0Fax +49 5743 41-240E-Mail [email protected] www.naue.com

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