Usage of geogrids in flexible pavement

USAGE OF GEOGRIDS IN FLEXIBLE
PAVEMENT DESIGN
USAGE OF GEOGRIDS IN FLEXIBLE PAVEMENT DESIGN 1
PRESENTED BY
AGLAIA

Introduction
 Roads constructed over loose soil demands higher thickness of
granular materials resulting in the high cost of construction.
 Use of geogrid is thought for road construction to improve the
performance of roads.
 Geogrid a geo synthetic manufactured from polymers is selected
for this purpose.

MATERIALS USED
 Soil
 The sub grade material is a silty sand.
 A set of laboratory unsoaked California bearing ratio (CBR)
tests (ASTM D1188) are performed on the soil at different
geogrid positions.
 When CBR increases the thickness of the pavement will be
decreases and it results in the lesser cost of construction.

Table 1: Engineering Properties of Soil
(Source:EJGE, Improvement of Flexible Pavement With Use of
Geogrid)

GEOGRIDS
 They are open structures formed by bonding polymer strips at
their cross point or punching
 They are used to reinforce retaining walls, sub bases etc since
they have higher ability to distribute load across a large area.
 They are made of polymer materials, such as polyester, polyvinyl
alcohol, polyethylene or polypropylene.

Fig:1 Geogrids
Source: https://theconstructor.org/geogrids.jpg

Table 2: Tested index properties of the geogrid
(Source: ARPN Journal of Engineering and Applied Sciences)

TYPES OF GEOGRIDS
Based on the manufacturing process involved in geogrids it can be of
 Extruded Geogrid
 Woven Geogrid
 Bonded Geogrid
Based on which direction the stretching is done during manufacture,
geogrids are classified as
 Uniaxial geogrids
 Biaxial Geogrids

Fig.2: Uniaxial and Biaxial Geogrids
manufactured by the method of extrusion
Soource:Google.com

APPLICATIONS OF GEOGRIDS IN
PAVEMENTS
 Improvement of sub grade
 Reinforcement of pavement base

ADVANTAGES OF GEOGRID
 The use of geogrids results in a more economical construction.
 It is environmental friendly.
 It resists environmental attacks.
 It prevents the soil from erosion.
 It ensure ease of construction as the placement techniques are
simple.

FUNCTIONAL MECHANISMS
 The purpose of geogrid is to retain the aggregates collectively by
the method of interlacing the aggregates.
 It has the following functional mechanisms when applied for
pavement construction:
1. Tension Membrane Effect
2. Improvement of Bearing Capacity
3. Lateral Restraining CapabilityUSAGE OF GEOGRIDS IN FLEXIBLE PAVEMENT DESIGN 12

1. Tension membrane effect
 This mechanism is based on the concept of vertical stress distribution.
 This mechanism was initially considered as the primary mechanism.
 But later studies proved the lateral restraining mechanism is the major
criteria that must be taken into consideration.
Fig-3 Tension Member Effect
https://theconstructor.org/tension-
membrane-effect-of-geogrids.jpg

2. Improvement of bearing capacity
 The Geogrid layer possesses sufficient frictional resistance that
opposes sub grade lateral movement.
 This improves the bearing capacity of the layer.
 Reduction of outward stresses means inward stresses are formed,
which is the reason behind the increase in bearing capacity.
Fig-4 Mechanism for Improved Bearing Capacity
https://theconstructor.org/tension-membrane-
effect-of-geogrids.jpg

3. Lateral restraining capability
 The Geogrid act a restraint against this lateral movement of the
aggregates produced by wheel loadings over the pavement.
Fig-5 Lateral Restraining Capability
Source: https://theconstructor.org/Lateral Restraining Capability .jpg

USES OF GEOGRID IN PAVEMENT
 To serve as a construction aid over soft subgrades.
 To improve service life.
 To reduce the structural cross section for a given service life.
 To study the different aspects, regarding changes in properties of
soil.

ECOLOGICAL BENEFIT OF GEOSYNTHETICS
 Geogrid reinforced constructions are increasingly used as safe,
ecological and economical solutions.
 Compared to conventional solutions with concrete they often
have the benefit of lower costs and less environmental impact.

CBR TEST IN SOIL REINFORCED WITH
GEOGRIDS
 The California Bearing Ratio (CBR) test is a penetration test
used to evaluate the sub grade strength of roads and pavements.
 They are used to determine the thickness of pavement and its
component layers.
 This is the most widely used method for the design of flexible
pavement.
 The CBR value is expressed as a percentage of the actual load
causing the penetrations of 2.5 mm or 5.0 mm to the standard
loads.

Fig-6 Inclusion of Geogrid at various Positions
(Source: IJESRT, usage of geogrids in flexible pavement design)

Fig7: load vs. penetration graph of soil with various conditions

 CBR value is calculated with Geogrid at various Position and the
graph is plotted.
Table -3 CBR Value Variation with Geogrid Application in Soil Sample
Source: International journal of engineering sciences & research technology ,usage of
geogrids in flexible pavement design

Fig 7: CBR Contrast with geogrid Application

FLEXIBLE PAVEMENT DESIGN PROCEDURE:
 Calculation of total thickness
 Calculation of sub base course thickness
 Calculation of base course thickness

Thickness of the pavement is calculated by plotting curve.
Fig:8 Depth of construction Vs CBR graph
(Source: https://theconstructor.org)

OPTIMUM POSITION OF THE GRID
 The maximum value of all strength parameters was obtained in
the case when the grid was at 3H/4 depth from bottom of the
specimen height.

Fig:9 Geogrids in flexible pavement
Source: http://a4academics.com

APPLICATION BENEFITS
 It is cost saving material.
 It increases construction speed.
 Proper reinforcement is achieved.
 It Improves the quality of pavements.
 less rutting at the surface of the pavement.
 It confined aggregate results in a much stiffer base course layer
and a lower dynamic deflection of the pavement structure.
 Fatigue cracking can be reduced.

CONCLUSION
 Thickness of Pavement is reduced by using geogrids,it also
result in the reduction of the cost of road construction.
 Load carrying capacity of the road or Strength of road is
increased by the used of geogrid.
 Usage of geogrids results in the increase in Service Life of
Road.

REFERENCES
1. Peketi Madhu Ganesh Yadav,Singalareddy Bharath,Mekala Manoj
Kumar,Mallem Niranjan Reddy& Gadikota ChennaKesava
Reddy(2018), “usage of geogrids in flexible pavement
design”International journal of engineering sciences & research
technology.
2. Murad Y. Abu-Farsakh and Qiming Chen(2010) “Evaluation of geogrid
base reinforcement in ﬂexible pavement using cyclic plate load
testing”International Journal of Pavement Engineering ,Louisiana
Transportation Research Center, Louisiana State University, Vol. 12, page
no:275–288

3. I.S: 2720 (Part – XVI), 1979: “Indian Standard Methods of test
for Soils”, Laboratory Determination of CBR.
4. Sarika B. Dhule,S.S. Valunjkar.S.D. Sarkate.,S.S.
Korrane(2011) “Improvement of Flexible Pavement With Use of
Geogrid”.
5. Moustafa Ahmed Kamel, Satish Chandra and Praveen
Kumar(2004) “Behaviour of Subgrade Soil Reinforced with
Geogrid” The International Journal of Pavement Engineering,
Vol. 5,page no:201–209.
6. Nicholas C Reck(2011) “Mechanistic empirical design of geogrid
reinforced paved flexible pavements” Tensar International
Corporation, Atlanta

8. Martin Ziegler (2016) “Application of geogrid reinforced
constructions: history, recent and future developments ”Modern
Building Materials, Structures and Techniques, MBMST
9. Adel A. Al-Azzawi Al-Nahrain (2012) “Fininte element
analysis of flexible pavements strengthed with geogrid ”ARPN
Journal of Engineering and Applied Sciences

THANK YOU
For more…. Mail to aglaiaconnect2018@gmail.com

Usage of geogrids in flexible pavement

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Usage of geogrids in flexible pavement