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GEOSYNTHETICS ENGINEERING: IN THEORY AND PRACTICE
Prof. J. N. Mandal
Department of Civil Engineering, IIT Bombay, Powai , Mumbai 400076, India. Tel.022-25767328email: [email protected]
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Module - 2LECTURE - 8
AN OVERVIEW OF GEOSYNTHETICS
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
RECAP of previous lecture….. Functions of geosynthetics Geosynthetic functional applications Multiple functions of geosynthetics Design of geosynthetic Geosynthetics type and functions Applications and functions of geotextile Design parameters and applications of geosynthetics The correct choice of geosynthetics
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Example: Determine properties of geosynthetic forhighway design using the AASHTO M288 Tables,
Case 1: Strain of nonwoven geosynthetic used for filtrationis greater than 50 %. In situ soil passing 0.075 mm sieve is65%. Design for filtration under mild and severesurvivability conditions.
Case 2: Strain in woven geotextile used for separation isless than 50%. In situ soil passing 0.075 mm sieve is 65%.Design for separation under mild and severe survivabilityconditions.
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Solution:
AASHTO M288 geotextile specification provides threedifferent conditions for several applications of geosyntheticsin various infrastructures of civil engineering.
Class 1: Severe survivability conditions,
Class 2: Typical survivability conditions where there is no sitespecific information, and
Class 3: Mild survivability conditions
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Geotextile ClassClass 1 Class 2 Class 3
Test Method
Unit Elongation
Elongation
Elongation
Elongation
Elongation
Elongation
< 50% ≥ 50% < 50% ≥ 50% < 50% ≥ 50%
GrabStrength
ASTMD 4632
N 1400 900 1100 700 800 500
Sewn SeamStrength
ASTMD 4632
N 1260 810 990 630 720 450
TearStrength
ASTMD 4533
N 500 350 400 250 300 180
PunctureStrength
ASTMD 4833
N 500 350 400 250 300 180
BurstStrength
ASTMD 3786
kPa 3500 1700 2700 1300 2100 950
Permittivity ASTMD 4991
Sec-1 Minimum property values for permittivity, AOS, and UV stability are based on geotextile application.
ApparentOpening Size
ASTMD 4751
mm Depends on subsurface drainage, separation, stabilization, and permanent erosion control
UltravioletStability
ASTMD 4355
%
Table 1 AASHTO M288 geotextile strength property requirements
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Table 2 AASHTO M288 geotextile subsurface filtration (drainage)property requirements for highway under drains
Property Test methods units RequirementsPercent in- situ soil passing 0.075 mm
<15 15-50 > 50
Geotextile class
Class 2 (/Class 3)
Permittivity ASTM D 4491
Sec-1 0.5 0.2 0.1
Apparent opening
Size
ASTM D 4751
mm 0.43 maxavg. roll
value
0.25 maxavg. roll value
0.22 maxavg. roll
value
Ultraviolet stability
ASTM D 4355
% 50% after 500 hrs of exposure
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Table 3 AASHTO M288 geotextile separation propertyrequirements for firm strength subgrades
Test methods Units RequirementsGeotextile class Class 2 (/Class 3)
Permittivity ASTM D4491 Sec-1 0.02Apparent opening
sizeASTM D4751 mm 0.60 max avg. roll
valueUltraviolet
stabilityretained strength
ASTM D4355 % 50% after 500 hrs of exposure
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Case 1 (Filtration): (geotextile strain > 50 %)
Mild survivability conditions:
From Tables 1 and 2, we obtain the following properties ofnonwoven geosynthetic:
Grab tensile strength ≥ 500 N Sewn seam strength ≥ 450 N Tear strength ≥ 180 N Puncture strength ≥ 180 N Burst strength ≥ 950 kPa Permittivity ≥ 0.1 sec-1
Apparent opening size (AOS) ≤ 0.22 mm UV stability ≥ 50% of 500 N ≥ 250 N after 500 hrs of exposure
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Severe survivability conditions:
From Tables 1 and 2, we obtain the following properties ofnonwoven geosynthetic:
Grab tensile strength ≥ 900 N Sewn seam strength ≥ 810 N Tear strength ≥ 350 N Puncture strength ≥ 350 N Burst strength ≥ 1700 kPa Permittivity ≥ 0.1 sec-1
Apparent opening size (AOS) ≤ 0.22 mm UV stability ≥ 50% of 900 N ≥ 450 N after 500 hrs of exposure
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Case 2 (Separation) (geotextile strain < 50 %)
Mild survivability conditions:
From Tables 1 and 3, we obtain the following properties ofwoven geosynthetic:
Grab tensile strength ≥ 800 N Sewn seam strength ≥ 720 N Tear strength ≥ 300 N Puncture strength ≥ 300 N Burst strength ≥ 2100 kPa Permittivity ≥ 0.02 sec-1
Apparent opening size (AOS) ≤ 0.60 mm (max. avg. roll value) UV stability ≥ 50% of 800 N ≥ 400 N after 500 hrs of exposure
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Severe survivability conditions:
From Tables 1 and 3, we obtain the following properties ofwoven geosynthetic:
Grab tensile strength ≥ 1400 N Sewn seam strength ≥ 1200 N Tear strength ≥ 500 N Puncture strength ≥ 500 N Burst strength ≥ 3500 kPa Permittivity ≥ 0.02 sec-1
Apparent opening size (AOS) ≤ 0.60 mm (max. avg. roll value) UV stability ≥ 50% of 1400 N ≥ 700 N after 500 hrs of exposure
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
SUSTAINABILITY USING GEOSYNTHETICS Sustainability means to enjoy the better quality of lifeand satisfy the basic needs. The goal is to focus on thefollowing areas:
Protect environment and resource Climate change and energy Production and consumption
Now a days it is utmost important to save energy andmaterial consumption and reduce emission of globalwarming green house gases like methane and carbondioxide in geotechnical, transportation, hydraulic, costaland mining engineering for sustainable developmentaround the world.
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Why recent model development is not sustainable ?
We are living beyond our means.
Sustainable development is not only saving energyand materials but also protect the natural resources,economy and society worldwide
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Traditional materials: Sand and gravel
Clay
Concrete or steel
Infrastructures: Slope/ Erosion (Armoring)
Roads (Reflection cracking)
MSE and landfills
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
In the construction industry huge quantity of soilmasses are needed for excavation, transportation, andinstallation on the project site.
Hugh quantity of carbon dioxide footprint emitted duringconstruction of various infrastructures using traditionalmaterials/systems
Now a days an effort has been made to use sustainablematerials named as geosynthetics.
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
What is geosynthetics?
Geo means soil and synthetics means fabrics.
The combination made of soil and fabric (a compositematerial) is called geosynthetics.
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
How can you compare geosynthetics with traditionalmaterials?
Reinforcement function: Instead of using steel andconcrete, geogrid can be used as reinforcement.
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Drainage function: Instead of sand and gravel, geocompositeand geonet can be used as drainage materials.
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Barrier function: Instead of compacted clay liner, geomembraneand geosynthetic clay liner can be used as barrier for landfill,dam, canal and reservoir.
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
How geosynthetics can help to reduce the carbon print?
Reduction of significant amount of carbon-di-oxide in civilengineering projects by adopting appropriate use ofintelligent material like geosynthetics.
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Application of sustainable geosynthetics in infrastructures:
Slope/Erosion control
Roads, and
MSE at landfills
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
RCC(Ton Co2 /yd2)
ACB(Ton Co2 /yd2)
HPTRM (Ton Co2 /yd2)
*Concrete 0.0941 0.041 -*Steel fibers/ cable 0.0097 0.0446 -
*Geotextile - 0.005 -*HPTRM - - 0.0015*Top soil - 0.0023 0.0023*Seeding - 0.00028 0.00028
**Diesel fuel 0.449 0.505 0.082Total CO2 foot prints 0.533 0.594 0.087
HPTRM is GREEN/ more echo friendly compared to RCC and ACB
Slope/Erosion control:Sustainability comparison of three alternative armoring(Googrum, 2011).RCC = Roller Compacted Concrete, ACB = Articulated Concrete Block.HPTRM = High Performance Turf Reinforcement Mat.
*Material only ** Delivery only
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Existing AC
(mm)
Proposed AC
thickness(mm)
Proposed AC thickness with
Geotextile (mm)
Reduction in AC
thickness(mm)
Asphalt cement
savings per lane mile
(kN)50.0 112.5 62.5 50.0 33075.0 112.5 75.0 37.5 290
100.0 112.5 81.25 31.25 240
Roads: Incorporate geotextile for refractive cracking Saving in aggregates and asphalt concrete
Reduction in Hot Mix Asphalt Concrete (HMAC)
(Miner and Davis, 2011)
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
The age old: “apples to oranges comparison”
Apple Orange
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Traditional method (3H:1V)
MSE berm (1H:2V) Savings
Compacted selected fill 1826 kg/m2 1174.1 kg/m2 651.9 kg/m2
Import of selected fill (Transportation) 177 kg/m2 114 kg/m2 63 kg/m2
HDPE, PP face wrapping - 47 kg/m2 -
Maturing and shipping for MSE berm
(Transportation)- 4 kg/m2 -
Total CO2 foot prints 2003 kg/m2 1339 kg/m2 714.9 kg/m2
MSE berm at landfills (Barron and Liew, 2011)
Carbon foot print reduction using geosynthetics
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Reinforcement function
Applications: Mechanically stabilizes reinforced soil wallsand slopes
542 ton carbon dioxide 101 ton carbon dioxide
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Filtration, drainage and erosion control function
Applications: Erosion control, road, dam, retaining wall
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Barrier function
Applications: Landfill, dam, canal, reservoir
21000 truck load of clay and gravel is equivalent to165 truck load of GCL & geomembrane (Maubeuge etal.,2011)
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Transportation, waste, power and infrastructures are mainlythe reasons for carbon emissions. If we do not control or takecare of carbon footprint, our life will be miserable andunsuitable for living in the planet in foreseeable future.
Every human has to be cautious about their way of living in theplanet. By 2030, it is necessary to decarbonize the world by90% for making the planet sustainable.
Sustainability is like a FEST (i.e. Financial, Environmental, Social Transparency).
Reduce waste and emission. “Save earth Go green and adopt green technology.”
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Please let us hear from you
Any question?
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay
Prof. J. N. Mandal
Department of civil engineering, IIT Bombay, Powai , Mumbai 400076, India. Tel.022-25767328email: [email protected]
Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay