Geo Sint Etik

8/11/2019 Geo Sint Etik

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Testing of

.

Department of Civil Engineering

IIT Madras, Chennai

e-mail: [email protected]


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Need for Testing

Identification of product

design specifications or regulations

Quality Assurance during the

Testing of Geosynthetics-1 2/34


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Collection of Test Samples

ASTM D4354 Standard Practice for Sampling ofGeosynthetics for Testing

and/or testing specifications ISO 9862 Geotextile Sampling and Preparation

IS 14706 Geotextile Sampling and Preparation

of Test Specimen ,

collected at uniform intervals for quality controlpurposes.

,collected at specified intervals

Number of specimens to be tested is given in.



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Brand roducer su lier

Descriptionof

the

type

(grade,

etc.)

Dateofsampling

,

protectedagainstchemicalandphysicaldamageatambienttemperature.

Samplesshould

be

packed

properly

during

shipping

tothetestinglaboratories.



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Geotextile Pro erties

MechanicalProperties

Hydraulic

Properties EnduranceProperties



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Geotextiles Physical Properties

Mass per Unit Area

Stiffness



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Specific Gravity ASTM D792

weight to that of distilled, de-aired water at 27Ctemperature.

y y y

bottle method Sinkers used for testing materials that float in

water

Typical valuesSteel 7.87

Soil 2.7

Rock 2.4

PVC 1.69

. .

Nylon 1.05 to 1.14

Poly ethylene 0.90 to 0.96

Polypropylene 0.91



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Mass per unit area (ASTM D5261)

Cut five to ten specimens, each of anarea not less than 10,000 mm2.

100,000 mm2 Dimensions are measured without

applying any tension

Measure the mass of the samplesaccura e o . g

Mass per unit area = total mass/total area

.



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Thickness (ASTM D5199)

Distance between the upper

and lower surfaces of a fabric

at a pressure of 2 kPa

Expressed in mm

oven geo ex es . o

mm

to more than 10 mm

Com ressibilit is chan e in

thickness with pressure



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Stiffness

Stiffnessisameasureoftheinteractionbetweenthegeotextileweightanditsbendingstiffness

Slidea25

mm

wide

strip

of

geotextile

on

an

inclined

planeatanangleof41.5andmeasurethelengthoft eover ang w ent et p en sun er tsownweight

=

Subgrade CBR Stiffnessrequirements(mgcm)

.

12 5000 10000

>



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Mechanical Properties

Compressibilit

Tensile Strength Seam Strength

Fatigue trength

Burst Strength

Impact Tests

Puncture Tests

Friction Behavior

Pullout Tests



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survivability

theforcerequiredtotearthesampleis

Forceisappliedonthesampleinsuchaway

t att e

n t a

tear

sopene

up.

Resultisreportedinforceunits.



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200100

7615 mm cut

25

grip along these

ed es

Width of grips 76

Rate of test: 300 mm/minute



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Wedge type grips used for trapezoidal tear test in progress


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Grab Tensile Strength (ASTM D4632)

Construction survivability

test

Es eciall for se arator

100

applications in pavements

25mm wide Narrow grips

used to perform the test

25

Newtons and rupture

strain

Loading at 300 mm per 200

75mm

minute

25mmwide

grips



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Photos of Grab tensiontest



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Tensile Strength Tests on Geotextiles

Different Types of Tests

Wide width tests 200 mm wide and 100 mm length

Narrow strip tests 50 mm wide strips used for tests

amp es usua y gr ppe n ro er gr ps

Load applied at 10-20% strain per minute

Result is reported in units of force/unit width and the strain

at eak load



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Wide width tensile strength test on geotextiles


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30

20

25

/m

5

10

Force

kN Series2

Series3

Series4

0

0 10 20 30 40 50 60 70 80 90 100

Force-strain behaviour of a typical nonwoven geotextile

Testing of Geosynthetics 23/34


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Geotextile tubular structures undergo

ground movements

Force developed in fabric is very low as

they are not filled completely

Forces depend on the ill ratio



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Punching Strength ASTM D4833

8 mm diameter probe punched into a stretched

Container diameter is 45 mm Peak load developed is reported in Newtons



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CBR Puncture Test

Probe is 50 mm diameter

on a ner s mm ame er

10 specimens across roll width

Strength and deformation monitored

Average value is reported



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Tensile strength from CBR Test data

r

FT

p

f2

strength,tensilewidthwide

Tf = force in kN/mFp = punching force, kN

r = radius of CBR plunger

Strain at failure, f

a

100*a

)ax(f

a = horizontal distance between

outer edge of plunger and inner

edge of mould



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rope net gabions


Punching strength test on rope net gabions


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droppedfrom

aheight

of

1m

onto

astretched

Diameteroftheholemadebytheconeis

Thelargertheholediameter,largeristhe

construct on

n uce

amage



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SeamStrengthTests

Normalsizeofrollwidthis3to5mandlength100m.

Lar ersizeareascoveredb seamin eotextiles

Preferably

the

thread

for

seaming

should

be

same

type

as

thegeotextile polyester,polypropylene,etc.

Singlestitch,doublestitch,Jseam,Butterflyseam,etc.

Seamstrengthisimportantasitmaycontrolthedesigns

ens es reng es sper orme on eseams

Procedureissameasthatfornormaltensilestrengthtests

Efficiency=strength

of

seam/strength

of

virgin

material



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Fatigue strength

Tensile strength of coir geotextile after repeated loading



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