Du Pont Fibre

DuPont at a glance With almost 200 years of scientific breakthroughs, DuPont is one of the oldest continuously operating companies in the world. Some figures from 1999: • • • •

Sales revenue of $ 26.9 billion Employer of 97 000 people Operates in 65 countries 135 manufacturing facilities

DuPont’s invention of Neoprene® synthetic rubber in 1933 and the Nylon fibre in 1938 marked the beginning of the modern materials revolution. Numerous synthetic materials subsequently cascaded from the DuPont research laboratories including household names such as Teflon®, Silverstone®, Stainmaster®, Nomex®, Kevlar®, Cordura®, Corian®, Lycra®, Tyvek®, Mylar®, Sontara®, Typar®…….

The secret’s in the DuPont fibre production technique ... Typar® is composed of thermally bonded continuous polypropylene filaments. The fibre extrusion process produces thousands of superfine continuous filaments, which pass through a DuPont patented “pre-stretch” stage. The superfine tough filaments are directionally oriented producing a fibre web sheet that is then thermally and mechanically bonded. By varying polymer and process conditions a range of high strength Typar® sheet structures with differing denier and physical properties can be produced. DuPont’s patented production technique is one of the main reasons for the unique properties of Typar® compared to other Geotextiles

DuPont Typar® high strength spunbond nonwoven DuPont Typar® high strength spunbond is a tough versatile nonwoven used in numerous applications ranging from carpet backing, packaging solutions, roof linings to Geotextiles. Invented 25 years ago and manufactured at the DuPont Luxembourg site, the high quality and performance of Typar® has proven the test of time. In the Geotextile market alone, Typar® has covered road sub-soils, railway tracks and construction surfaces equivalent to a three lane motorway of 15 meter width once around the world. With over 25 years experience, DuPont is a major Geotextile supplier to the construction industry.

Quality Typar® is manufactured to ISO 9001 standards. DuPont’s stringent quality requirements ensure that only high quality products are released to the market place. The integrated production and laboratory system ensures the manufacturing process conditions and laboratory results for every roll are traceable.

Applications :1. Temporary roads, access roads, forest roads 2. Permanent roads, airport runways and taxiways,.highways 3. Parking lots, storage yards 4. Railways, new tracks and tracks renewal 5. Embankments on compressible soil 6. Steep slopes 7. Retaining walls 8. Drains with Typar® and French drains 9. Vertical drains 10. Agricultural and pipe drains 11. Blanket drains in roads, in sports fields 12. Road and civil engineering drainage, side drains 13. Wall drainage 14. Waterworks, erosion control of earth dam slopes, river and lake embankments 15. Erosion control of sea embankments, ocean and bay shores 16. Breakwater and jetties on soft soil sea bed 17. Land reclamation with hydraulic fill 1. Temporary roads, access roads, forest roads •

allows aggregrate saving

•

easy to install under any weather conditions

•

allows better compaction

•

avoids contamination by subsoil

•

allows more traffic at equal aggregate thickness

•

limits rutting formation

2. Permanent roads, airport runways and taxiways, highways •

increases road durability (less rut)

•

avoids contamination of frost-resistant support layer by freezing subsoil

•

allows better compaction and aggregate saving

•

ensures longer service life

•

reduces costs and maintenance disturbance

3. Parking lots, storage yards •

avoids contamination

•

allows better compaction and aggregate saving

•

ensures longer service life by reducing rutting

4. Railways, new tracks and track renewal •

avoids ballast contamination by pumping effect due to dynamic loading

•

allows better compacting and aggregate saving

•

retains soil particles without clogging

•

ensures longer service life

5. Embankments on compressible soil •

avoids contamination of filter layer by subsoil and/or fill

•

allows uniform settlement

6. Steep slopes •

allows construction of steeper slopes

•

savings in required land surface and fill material

7. Retaining walls •

most economical retaining wall system

•

accommodates settlements better than traditional methods

8. Drains with Typar® and French drains •

well-graded aggregate substituted by cheaper, coarse aggregate

•

easy to install, very uniform

•

French drains without pipe

9. Vertical drains

•

allows up to 10 times faster settlement of soil under static load

•

faster removal of water in saturated compressible soils

•

more economical than conventional vertical sand drains

10. Agricultural and pipe drains •

corrugated pipe wrapped with Typar® can be put into subsoil with or without digging a trench

•

drainage surface of corrugated pipe is increased up to 90 times

•

influence zone of wrapped drain is higher

•

drain spacing can be increased

•

stiffness of Typar® prevents fabric from entering the pipe corrugations

11. Blanket drains in roads, in sports fields •

optimal drainage system

•

in sport fields, the thickness of cover soil can be reduced and the filtration and anticontamination effects avoid clogging of drainage blanket by soil particles carried by rain water

•

in roads, prevents contamination and failure of the drainage layer

12. Road and civil engineering drainage, side drains •

optimal drainage system

•

automated installation equipment

13. Wall drainage •

prevents clogging of drainage slabs and toe drains

•

avoids hydraulic pressure build-up

14. Waterworks, erosion control of earth dam slopes, river and lake embankments •

replaces a conventional well-graded filter between soil to be protected and gabion, rip-rap or concrete slabs revetments

•

special care to anchor Typar® at top and toe of the slope

•

for rip-rap revetment, install a layer of finer aggregate (5 to 10 cm) to protect Typar® against puncturing and to ensure good fabric-to-soil contact for filtration

15. Erosion control of sea embankments, ocean and bay shores •

big rip-rap must be installed on a bed of small sized aggregate to protect Typar® against puncturing and to dissipate water forces. A single layer of fabric held in place by big rip-rap cannot resist the tons of pressure of breaking waves without this support.

•

The bed of aggregate ( 5 to 10 cms) ensures a good fabric-to-soil contact for efficient filtration

16. Breakwater and jetties on soft soil sea bed •

separation layer of Typar® prevents rip-rap from sinking into soft soil

•

Typar® must be protected by a layer of smaller-sized stones

17.Land reclamation with hydraulic fill •

separation and filtration layer of Typar® avoids piping of hydraulic fill

•

avoids use of expensive and difficult-to-install filter lay

Functions :1. Separation 2. Filteration 3. Reinforcement 4. Drainage Separation:-

It is widely recognised that wet soils are weaker than dry soils and fine soils are weaker than coarser soils.

A suitable Geotextile can: o o o

prevent the reduction of load bearing capacity caused by the mixing of fine-grained subgrade with the aggregate base. increase the bearing capacity by preventing the migration of aggregate or armour blocks into soft subgrade. The use of a Geotextile can increase the degree of compaction possible. reduce the deterioration of roads through frost heave effects.

This results in: 1. Lower installation costs due to lower aggregate requirements for the same bearing capacity 2. Faster construction time 3. Lower maintenance costs 4. Increased road service life

Filteration:-

The Geotextile maintains the filtration strata and prevents finer particles being washed out thus ensuring consistent and continuous drainage performance over a wide range of civil engineering applications. This results in:

1. Lower material costs since cheaper, coarser filtration aggregates can be used 2. Faster and cheaper installation 3. More consistent long term drainage performance 4. Preventing clogging of drainage systems

5. Preventing soil erosion Reinforcement:-

Soils and similar materials are generally good in compression but poor in tension. This lack of tensile strength can be counteracted by using a Geosynthetic reinforcement to strengthen and stabilise the soil. As a result, the strength of the total system has considerably been improved.

Typical applications are: 1.Retaining walls 2.Steep slopes 3.Landslide repairs 4.Soft-soil embankments 5.Embankments on very soft soils, combined with vertical drains 6.Roadway reinforcement 7.Reinforcement under tramways or railway ballast 8.Erosion control in sea embankments and waterworks slopes or beds 9.Reinforcement of foundation layers 10.Reinforcement or bridging over potential weak zones, voids or cavities 11.Piled embankments with basal reinforcement.

Drainage:There are two types of drainage systems namely vertical and composite drainage.

Composite Drainage:-

Water needs to be effectively controlled and evacuated in ground engineering structures if their function is not to be impaired or eliminated. Traditionally, water has been controlled and evacuated using graded natural materials. However, more and more over the past 30 years or so geotextile filters have been used to augment the natural drainage capacity of impervious soils. Typically known as composite drains or 'fin drains', low compressibility synthetic drainage mats sandwiched between geotextile filter membranes have proven very economic, efficient and reliable in use for applications of this type. The function of the outer geotexile is to keep soil particulates out of the drainage core and ensure sufficient water evacuation under different hydraulic gradients. It is therefore very important that such drainage systems are capable of maintaining adequate drainage capacity for long term performance even when subjected to high earth pressures.

With their proven economic performance synthetic drains incorporating Typar® have proved to be an economic alternative to traditional sand drains, soakaways and other drainage systems.

Vertical Drainage :-

The consolidation settlement of low permeability cohesive soils and clays through applied loadings can be a very slow process. It can take many years to squeeze out the excess water and to close the tiny voids in clays and other fine grained soils before equilibrium is reached. The consolidation of a road embankment, for example, usually takes from 30 to 50 years to reach 90% of the total. It is usually necessary to speed the consolidation process up for road bases and other constructions which overlie clay soils, since surface disturbances and slip plane failures due to soil settlement and gradual shrinkage can be a serious problem. Traditionally, vertical drainage has been carried out using vertical holes filled with carefully graded sand. However, these ‘sand-drains’ often suffer from problems of drainage continuity and reliability over time, require the transport of large quantities of sand and are equipment-intensive to install. An engineered solution to the problem of accelerating the slow consolidation process of low permeability soils can be achieved by the insertion of vertical ‘wick’ drains to facilitate the dewatering process. Vertical drains are ‘flat pipes’ comprising a highly permeable core surrounded by a microporous outer membrane. The core is configured to permit maximum water flow even when distorted under significant movements while the outer jacket allows water, but not clay particles, to diffuse into the core where it can quickly drain away. In this way the jacket prevents clogging of the core and ensures reliable long-term operation. The long-term hydraulic function of a vertical drain is largely governed by the ability of this outer jacket to prevent minute clay colloids from gradually blocking the drainage flow. To expedite the consolidation process, it is necessary to shorten the flow path of the porewater from the soil. This can be achieved by installing the vertical drains to the depth of the compressible layer at evenly spaced intervals. The pressurised porewater flows in a horizontal direction towards the nearest drains and escapes freely. With the aid of vertical drains the consolidation period can be significantly reduced, and can usually be achieved within the construction period. If a surcharge load is difficult to locate or place, a

vacuum system may be used by drawing a vacuum beneath a geomembrane to simulate the pressure normally created by a pre-load.

***herefrom we are just copying*******

Typar® SF is a thermally bonded nonwoven, made of 100% polypropylene. It is designed to have a combination of a high initial modulus (stiffness), high elongation (typically 60%) and outstanding uniformity, to give superior performance ,in all directions.

Resists damage during installation 95% of all damage to Geotextiles occurs during installation. One reason is impact from falling aggregates during offloading. Another common cause of damage is compaction.Typar® SF combines a high initial modulus (first resistance against deformation) with a high elongation to break. This combination enables Typar® SF to absorb a higher level of energy compared with other Geotextiles. This gives it a high resistance to damage during installation.

Resists rutting in the final construction Rutting occurs as a result of the regular passage of wheeled transport over the structure. The resultant deformation develops inplane tensile stresses and related membrane and restraint mechanisms. The high initial modulus of Typar® SF reduces deformation and thus reduces rutting.

Uniform performance Typar® SF is an isotropic material, meaning that its physical properties are present in all directions. This mirrors the stresses and strains of a typical separation application. Typar® SF is manufactured to a very high level of uniformity using a continuous on-line, ß -ray monitoring process. All product that fails to meet the required standards is rejected and recycled.

**just a concept –energy concept >> for cross q’s***

A Geotextile will not perform any function if it is destroyed during or immediately after installation. Analyses indicate that the critical period in the life-cycle of a Geotextile is during the construction process rather than during the service life. Thus 95% of the damage usually occurs during installation, very often simply the result of impact damage during the off-loading of aggregates. In the vast majority of cases, if the Geotextile survives these installation-related stresses, it will also withstand the in-service stresses. There has been considerable work undertaken to understand the relationship between the physical properties of a separation Geotextile and its actual performance in the field. For example, experiments have confirmed that there is a close correlation between the ability of a Geotextile to absorb impact energy and its susceptibility to damage during installation. This energy absorption potential of a Geotextile can be described as the combination of its elongation and its applied strength. The following graph illustrates this concept:

****explaining rutting*******

****explaining rutting*******

Rutting can become a serious problem, especially for temporary roads. The regular passage of wheeled transport results into tension stresses that deform the sub-soil. Different from most other Geotextiles, Typar® SF needs much lower elongation and deformation to take up stresses (high initial modulus) and will therefore considerably reduce the rutting. This advantage has been proven in an independent laboratory test where different Geotextiles were submitted to 1000 dynamic loading cycles. The results indicate that there is a clear relationship between initial modulus and deformation (rutting). The high initial modulus enables Typar ® SF to absorb more external stress before transferring this energy absorption to strain.

GTX 3 = Typar®

GTX 2 = needle-punched, continuous filaments GTX 1 = needle-punched, staple fibers

**separation completed**** ***now installation**** INSTALLATION GUIDELINES:• • • • • • • • •

Temporary roads Permanent roads Drainage systems Embankments on compressible soil Vertical drains Required overlap Erosion control applications Hydraulic applications Handling of rolls

Temporary Roads:Ground separation and support are the two main functions of Typar® in temporary road construction. Since the soil/Geotextile/aggregate system tends to be deformed by imposed traffic loads, special attention must be paid to laps and anchorage: • • • • • • • • •

Remove all large debris which might puncture Typar®. Unroll Typar®. The width of Typar® should be at least as great as that of the aggregate layer. If two or more widths are required, ensure sufficient overlap. If it is windy, use shovelfuls of coarse aggregate at regular intervals to hold Typar® in place. Backdump aggregate without driving on Typar®. Level and compact aggregate before any heavy traffic occurs. Avoid aggregate size in excess of 1/3 of aggregate layer thickness. Fill up ruts, if any, as soon as they exceed 1/3 of aggregate thickness. Rutting will then be stopped. First aggregate layer must be at least 25cm thick.

Permanent Roads:The prime role of Typar® in permanent road construction is that of ground separation. However, during the construction phase the base courses are often used as a temporary road surface and in these cases Typar® also acts as a support membrane. The installation of Typar® in permanent road construction is identical to that for temporary roads.

Drainage system with Typar:a) Trenches • • • •

The base and side walls of the trench should be as free of irregularities as possible (holes, roots, etc.). Lay Typar® parallel to the trench and anchor the edges of the fabric. Do not drag the fabric in the mud. This will result in the deposit of a large amount of fine particles on the surface of Typar® thus creating an impervious film. Off-load the drainage aggregates carefully to avoid the fabric being dragged towards the bottom of the trench.

• • •

Do not use over-large stones to fill up the trench. Gravel of max. size 2 cm is required to ensure good fabric-to-soil contact Compact the aggregate and enclose it withTypar® before backfilling to the top of the trench. Overlap lengths of Typar® by at least 30 cm

b) Blanket drains • • •

Overlap min. 30 cm. Do not unroll Typar® too far in advance, especially in windy conditions. Use relatively small sized aggregate to ensure good fabric-to-soil contact.

Embankments on Compressible Soils :A Geotextile will stretch considerably during consolidation and settlement and, by providing lateral support, will tend to increase embankment stability horizontal. • • • •

Level surface. Unroll Typar® perpendicular to the embankment axis to ensure full efficiency in the principal direction of force. Side-laps must be at least 1m. If necessary, lengths of Typar® can be sewn together in order to obtain a continuous sheet parallel to the embankment axis. To increase rate of settlement it may be beneficial to install a layer of sand or gravel to act as a drainage blanket. In this case Typar® will act as a filter membrane.

Vertical Drains with Typar:•

•

In some cases vertical drains are required to accelerate embankment settlement on soft, saturated soils. To permit installation of vertical drains using heavy plant, it will be necessary to install a layer of coarse aggregate on Typar®. The aggregate layer will then also act as a drainage blanket. SinceTypar® is sandwiched between the subsoil and the gravel layer, friction forces are usually sufficient to hold it in place during perforation by the vertical drain mandrel.

Required Overlaps :•

The side and end laps needed depend on soil properties (CBR), the project nature and on the deformations which might be expected to occur.

Overlaps normally used: • • • •

Drainage systems: 30 cm Parking lots, permanent roads: 30 to 50 cm Erosion control systems: 50 to 100 cm Temporary roads: see graph

Additional area required allowing for over laps:

The following graph shows the amount of extra Typar® needed, depending on the calculated surface area and the overlap width. Estimates of the savings possible by sewing or welding instead of overlapping are clearly demonstrated. For applications where Typar® is used for reinforcement purposes,overlapping requires special attention. Calculations by experienced design engineers may be needed to check the correct transmission of stresses.

Erosion Control System with Typar :• •

If possible, grade and compact slopes. If slope width is less than 8m, unroll Typar® along the length of the lower half of the slope first, then place Typar® on upper half of the slope with 0.5 to 1m overlap.

•

If slope is over 8m, place Typar® in full-width lengths from slope top to bottom. Overlap in direction of waterflow. Excavate ditches for anchoring Typar® at top and toe of slope. The toe is the foundation of the structure and should get special attention to prevent undermining. When placing rip-rap or gabions, start at toe and work up the slope to prevent sliding. Install rip-rap smoothly, without dropping it heavily on to the Typar®. To ensure good fabric-to-soil contact, first of all place a layer of bedding material (gravel) on the Typar®. This layer will also help prevent puncturing by heavy rip-rap. Anchor the fabric in the ditch at the top edge of the slope with soil and vegetation. This deep anchoring method will prevent large volumes of surface water from getting under the fabric and lifting the entire structure.

• • • •

Hydraulic Applications :• •

With a density of just 0.91, polypropylene sheets of Typar® float naturally on water. For rapid and consistent installation, attach steel rods (e.g. typical 6 mm diameter rebar) every 5 metres. These rods will keep the fabric flat, thus allowing a regular overlap. (No need for divers. Smaller overlap = cost savings.)

Handling of Rolls:•

No Soak

Thick Geotextiles soak up water.When it rains they are difficult to install because of their increased weight. At sub-zero temperatures they become impossible to use since they freeze solid. Typar® can be stored outside. It does not absorb water and therefore will not freeze. •

Storage

Typar® rolls take up less space than many other Geotextiles, thus storage and transportation are efficient. •

Cutting

Typar® is thin and light making the compact rolls easy to transport and install. Rolls can be easily cut to the desired width with a chain saw. This is almost impossible with most other Geotextiles

Typar® HR Product description Nonwoven component: Typar® , 100% polypropylene heat bonded continuous filaments. Reinforcement component: weft inserted high tenacity polyester yarns. Property

Standard

Unit

HR 35/35

Tensile strength MD

ISO/EN 10319

kN/m

35

55

80

105

155

Tensile strength XD

ISO/EN 10319

kN/m

35

55

80

55

55

Tensile strength MD at 2%

ISO/EN 10319

kN/m

7

10

15

20

30

Tensile strength MD at ISO/EN 5% 10319

kN/m

15

25

35

50

75

Tensile strength MD at 10%

ISO/EN 10319

kN/m

35

55

80

105

155

Tensille strength XD at 2%

ISO/EN 10319

kN/m

7

10

15

10

10

Tensile strength XD at ISO/EN 5% 10319

kN/m

15

25

35

25

25

Tensile strength XD à 10%

kN/m

35

55

80

55

55

Creep (after 1 year)

%

<1

<1

<1

<1

<1

Creep (design life)

%

<2

<2

<2

<2

<2

1

1

1

1

1

0.15

0.15

0.15

0.15

0.15

1

1

2

3

3

1

1

1

1

1

270

340

425

420

500

ISO/EN 10319

-4

Permeability

PrEN 12040 10 m/s

Pore size O90

PrEN 12956 mm

Transmissivity : under 50 kN/m2

-6

NF-G38018 10 m2/s

under 200 kN/m2 Unit weight

HR HR 55/55 80/80

HR 105/55 HR 155/55

10-7 m2/s EN 965

gr/m2

Typar® HR is delivered in: 4.4m x 100m.The tensile values are minimal guaranteed values at 95%. The other above mentioned values are nominal values. DuPont reserves the right to modify these values at all moment.

Typar-SF recommended style:-

conclusion :Nonwoven geotextiles are a proven benefit to your project. Our lightweight, mediumweight and heavyweight Nonwoven geotextiles prove to be excellent filters, allowing subsurface water to pass into the drainage core while preventing adjacent soil from clogging the system. When properly selected, Nonwoven geotextiles are effective in most all soils, particularly in environments where silt and clay are prominent. Nonwoven geotextile are used in applications including separation, filtration and protection applications. Lightweight nonwovens are used predominantly in subsurface drainage applications along highways, within embankments, under airfields and athletic fields. Heavyweight nonwovens are used in critical subsurface drainage systems, soil separation, permanent erosion control, and geomembrane liner protection within landfills.

These geotextiles provide the required strength and abrasion resistance to withstand installation and application stresses to create an effective, long term solution.