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Geotechnical Engineering 1 > Lesson 8-Geosynthetics > Flashcards

Lesson 8-Geosynthetics Flashcards

1
Q

5 major types of geosynthetic products:

A
  1. Geomembrane
  2. Geosynthetic Clay Liner
  3. Geotextiles
  4. Geonets
  5. Geogrids
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2
Q

-also known as flexible membrane liner (FML)
-one of the five major types of geosynthetic products used in landfill engineering

A

Geomembrane

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3
Q

Relatively thin sheets of flexible thermoplastic or thermoset polymeric materials that are manufactured and prefabricated at a factory and transported to the site.

A

Geomembrane

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4
Q

Primary function of geomembrane in landfill engineering is as a

A

liquid and/or vapor barrier

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5
Q

Are made of one or more polymers along with other ingredients such as carbon black, pigments, fillers, plasticizers, crosslinking chemicals, processing aids anti-degradants and biocides.

A

Composition of Geomembrane

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6
Q

The polymers used to manufacture _________________ include a wide range of plastics and rubbers differing in properties.

A

Composition of Geomembrane

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7
Q

Category of Polymeric Materials: (Composition of Geomembranes)

A
  1. Semi-crystalline thermoplastics – such as:
    a. HDPE – high density polyethylene
    b. LLDPE – linear low density polyethylene
    c. VLDPE – very low density polyethylene
    d. fPP – flexible polypropylene

2.Thermoplastics – such as:
a. PVC – polyvinyl chloride

3.Thermoplastics elastomers – such as:
a. CSPE – chlorosulphonated polyethylene

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8
Q

The thickness of geomembranes range from __________ to __________

A

0.75 mm to 3.0 mm

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9
Q

The recommended thickness for all the geomembranes is _______________ except for HDPE which should be at least __________ to allow extrusion for seaming.

A

0.75 mm, 1.50 mm

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10
Q

The most widely used geomembrane in waste management industry

A

HDPE- high density polyethylene

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11
Q

What are the salient features of HDPE:

A

a. Chemical resistance – landfill leachates pose no threat to a liner made of HDPE
b. Low permeability
c. Ultraviolet resistance – carbon black and antioxidants provide a synergistic effect

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12
Q

Geomembrane designed for waste containment applications requiring greater flexibility than HDPE. Lower weight allows to conform to nonuniform surfaces.

A

LLDPE- Linear lower density Polyethylene

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13
Q

Salient features of LLDPE:

A

a. Multi-axial tension properties – exhibits high out-of-plane elongation, allowing it to conform to differential settlement without jeopardizing the integrity of liner.
b. Puncture resistance – provides excellent puncture resistance due to its flexibility.
c. Chemical resistance – also resistant to leachate and other chemicals.

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14
Q

One of the polyolefin family of polymers which is often reinforced with an open weave fabric called scrim.

A

fPP- flexible polypropylene

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15
Q

Salient features of fPP:

A

Chemical resistance – chemical resistance is quite good in this product.
b. Ultraviolet
c. Installation Survivability – with tear resistance being high, puncture, impact characteristics are comparably high as well.

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16
Q

One of the original geomembranes used for waste containment applications. Components are: resin, plasticizers, filler, and pigment.

A

PVC – polyvinyl chloride

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17
Q

Salient features of PVC:

A

a. Flexibility – exhibits excellent out-of-plane flexibility and conformance to irregular subgrades.
b. Seameability – can be seamed by solvent method or thermal techniques.
c. Constructability – the easiest to install of all the geomembranes.

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18
Q

They are scrim reinforced and they have been used for essential all-barrier (waterproofing) applications, including landfill liners and covers.

A

CSPE – chlorosulphonated polyethylene

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19
Q

Salient features of CSPE:

A

a. Chemical resistance – excellent.
b. Ultraviolet resistance – excellent.
c. Installation Survivability – seaming can be performed by both thermal and solvent methods.

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20
Q

Use of geomembrane with an underlying
compacted clay liner (CCL) provides the optimal
liner system. This approach is referred to as a _______________

A

composite liner system

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20
Q

Are thin hydraulic barriers containing approximately 5kg/ sqm of bentonite, sandwiched between two geotextiles or attached with an adhesive to a geomembrane.

A

Geosynthetic Clay Liner (GCL)

21
Q

Geosynthetic material used in bottom liners for and impoundments, final covers for all types of landfill and remediation projects.

A

Geosynthetic Clay Liner (GCL)

22
Q

Types of GCL

A

a. Geotextile-encased, adhesive-bonded GCL
b. Geotextile-encased, stitch-bonded GCL
c. Geotextile-encased, needle-punched GCL
d. Geotextile-supported, adhesive-bonded GCL

23
Q

A non-reinforced GCL with two light woven or non-woven geotextiles encapsulating a layer of sodium bentonite

A

Geotextile-encased, adhesive-bonded GCL

24
A reinforced GCL consisting of a layer of sodium bentonite encapsulated between two geotextiles. The two woven or nonwoven geotextiles are stitched together with parallel rows of stitches
Geotextile-encased, stitch-bonded GCL
25
A reinforced GCL consisting of a layer of sodium bentonite encapsulated between two woven or non-woven geotextiles, needle punched together.
Geotextile-encased, needle-punched GCL
26
Is a bentonite-geomembrane composite GCL. The geomembrane can be of any type (HDPE or LLDPE usually) can be smooth or textured.
Geotextile-supported, adhesive-bonded GCL
27
Advantages of Geosynthetics Clay Liner (GCL)
a. The small thickness of GCLs tends to conserve landfill space. b. Construction of GCLs is rapid and simple. c. GCLs can be shipped to any location. d. Heavy equipment is not needed to install a GCLs. e. Installation of GCLs requires less vehicular traffic and less energy. f. Weather delays are not problem with GCLs. g. Because GCLs is a manufactured materials, a consistent and a uniform material is produced. There is no need to engage in detailed material characterization for each site (which is necessary for CCLs). h. GCLs can tolerate significantly more differential settlement than CCLs
28
Advantages of Compacted Clay Liners (CCL)
a. Many regulatory agencies require CCLs, use of another type of liner may require demonstration of equivalency to a CCL. b. A CCL should be considered if large quantities of clay are available locally. c. The large thickness of CCLs make them virtually puncture proof. d. The large thickness of CCLs and the fact that they are constructed of multiple layers makes them relatively insensitive to small imperfections inany one layer. e. There is a long history used of CCLs. f. Quality assurance procedures are reasonably well established for CCLs.
29
Geosynthetic material made from polypropylene, polyester, polyethylene, polyamide (nylon), polyvinyl chloride, and fiberglass.
Geotextile
30
______________ and________________ are the most used Geotextile.
Polypropylene and polyester
31
Types of Geotextiles
a. Woven Geotextile b. Non-woven Geotextile
32
Types of Geotextiles
a. Woven Geotextile b. Non-woven Geotextile
33
yarns run parallel with the length of the geotextile panel are interlaced with yarns which run perpendicular to the length of the panel. Woven construction produces geotextiles with high strengths.
Woven Geotextile
34
formed by process other than weaving or knitting, generally thicker than woven products, may be made either from continuous filaments or staple fibers. The fibers are generally oriented randomly.
Non-woven Geotextile
35
Function of Geotextile: the oldest and most used function of geotextiles. Geotextile is placed in contact with and down gradient of soil to be drained.
Filtration
36
Function of Geotextile: ___________________ the oldest and most used function of geotextiles. Geotextile is placed in contact with and down gradient of soil to be drained.
Filtration
37
Function of Geotextile: ____________________ acts as a conduit for the movement of liquids and gases. Examples are geotextiles which are used for wick drains and blanket drains.
Drainage
38
Function of Geotextile: ____________________ protects soil surfaces from the tractive forces of moving water or wind and rainfall erosion. Placed in the surface and is anchored by stakes.
Erosion Control
39
Function of Geotextile: ____________________ geotextile serves to control sediment when it stops particles suspended in surface fluid flow while allowing the fluid to pass through.
Sediment Control
40
Function of Geotextile: ____________________ geotextile interacts with soil through frictional or adhesion forces to resist tensile or shear forces. A geotextile must have sufficient strength and embedment length to resist the tensile forces generated, and to prevent excessive movement of the reinforced structure.
Reinforcement
41
Function of Geotextile: ____________________ process of preventing two dissimilar materials (soil fill for subgrade) from mixing.
Separation
42
Function of Geotextile: ____________________ This function plays an important role in the use of geotextiles in paving overlay systems. In such systems, the impregnated material seals the existing pavement and reduces the amount of surface water entering the base and subgrade. This prevents a reduction in strength of these components and improves the performance of the pavement.
Moisture barrier
43
Member of the geosynthetic family, considered as single function geosynthetic.
Geonet
44
Formed from medium to high density polyethylene. When formed with carbon black and antioxidants, it is under the HDPE category
Geonet
45
-Are unitized set of repeating parallel ribs positioned in layers such that liquids can be transmitted within their open spaces. -Exclusively used for drainage.
Geonet
46
-Covered with either a geomembrane or a geotextile on their upper and lower surfaces. -They are never in direct contact with soil cover since soil particles would fill the apertures. -Not used for reinforcement.
Geonet
47
Geonet bonded (by heat fusion) with geotextiles are referred to as
Drainage Composites or Geocomposites
48
Types of Geonets
a. Biplanar – have two parallel sets of ribs overlapping one another. a. Triplanar – have three parallel sets of ribs
49
These are generally polymeric materials consisting of polypropylene, polyethylene or polyester.
Geogrids

Geotechnical Engineering 1 (1 decks)

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