A presentation on the use of geosynthetics in civil engineering. An introduction to value engineering technologies

1. Geosynthetics Applications in Civil Engineering; An
Introduction to value Engineering (VE) Technologies
Solutions that Last
GEOSYNTHETICS EAST AFRICA Ltd
TEXTILE AND LEATHER CONFERENCE 2013
ORGANIZED BY KENYA BUREAU OF STANDARDS
VENUE :BOMA HOTEL
DATES: Thursday, 29th August 2013
Presentation:
Sirmoi Wekesa
Technical Director
Geosynthetics EA Ltd

2. Introduction to Geosynthetics
Part I
ASTM (2006) D 4439 defines a geosynthetic as a
planar product manufactured from a polymeric
material used with soil, rock, earth, or other
geotechnical-related material as an integral part of
a civil engineering project, structure, or system.
A number of geosynthetics are available, including
geotextiles, geogrids, geomembranes, geonets,
geomeshes, geowebs, and geocomposites.

3. DIFFERENT TYPES OF GEOSYNTHETICS
Geotextile Geonet Geocell Geogrids
Geocomposite Erosion Control Geosynthetics

4. GEOGRID TYPES
Different Types of Geogrids used for ground
Improvement:;; and
(a) Triaxial
(b) Biaxial (c) Uniaxial
New Four-axial
New Quaxial

5. Applications Of Geosynthetics

6. GROUND STABILIZATION/ IMPROVEMENT

7. GROUND STABILIZATION/ IMPROVEMENT….CNTD

8. PAVEMENTS: ROADS, PARKING BAYS, HARD STANDINGS

9. PAVEMENTS: RUNWAYS, APRONS & TAXIWAYS

10. HEAVY DUTY PAVEMENTS: PORTS AND HABOURS

11. PAVEMENTS: ASPHALT REINFORCEMENT

12. RAILWAYS

13. EROSION CONTROL

14. RETAINING, RE WALLS AND BRIDGE ABUTMENTS

15. BUILDING FOUNDATION IMPROVEMENTS

16. VALUE ENGINEERED BENEFITS

17. VALUE ENGINEERING
BENEFITS
 Construction cost-time savings
through the reduction of required
pavement material quantities, whilst
maintaining enhanced structural
performance.
 Elongated pavement structural life –
span particularly as a result of
incorporating the filtration/separation
geotextile.
 Reduction in maintenance
requirements as a result of enhanced
structural performance.
 Environmental conservation -
mainly due to reduction in material
quantities and erosion control.
Appropriate application of
geosynthetics can realize the
following benefits.

18. Construction Time Savings Benefits
Enhanced Geotechnical Engineering Properties

19. VALUE ENGINEERED BENEFITS
Description Quantity placed per day
[m3]
Area [m2] Layer thickness[m] Quantity in volume [m3] Time taken in Days [in
weeks]
Import place and
compact ground
stabilization material
[cement]
300 311,550 0.2 62,310 200 days [28weeks]
Import place and
compact granular
material for sub-base
193 311,550 0.4 124,620 646 days
[92 weeks]
Excavation to spoil of
poor quality material
1000 51,031 1.5 76,546.50 77 days
[11 weeks]
Import, place and
compact capping layer or
backfill material
578 51,031 2.0 102,062 177 days
[25 weeks]
TOTAL DURATION TAKEN TO CONSTRUCT THE PAVEMENT* 156 weeks

20. VALUE ENGINEERED BENEFITS
Description Quantity placed
per day [m3]
Area [m2] Layer
thickness[m]
Quantity in
volume [m3]
Time taken in
Days [in weeks]
Import place
and compact
granular
material for
sub-base
193 311,550 0.3 93,465 484 days
[69 weeks]
Top Soil
stripping and
disposal or
grading*
680 51,031 0.15 7,654.65 12 days
[2 weeks]
TOTAL DURATION TAKEN TO CONSTRUCT THE PAVEMENT* 71 weeks
*This might not be necessary especially if the water table is very high. Grading normally
helps to create the platform for grid placement.
• Time saved is approximately 50%.

21. Construction Cost Savings Benefits
Enhanced Geotechnical Engineering Properties

22. VE BENEFITS – ROAD OVER SWAMP CROSSING
 The proposed road was crossing a 1.2km swampy stretch.
 The soils were peat with low bearing capacities with CBRs of
about 0.5%.
 The design assumed the peat thickness to be 1.0m before getting
on to hard ground.
 The actual thickness was deeper than 1.0m; instead it went
beyond 3m.
 The contractor wanted to finish the section before the rains
started.

23. VE BENEFITS – ROAD OVER SWAMP CROSSING
COST AS PER CONVENTIONAL DESIGN
DESCRIPTION UNITS LENGTH[m] WIDTH[m] DEPTH[m] QUANTITY RATE TOTAL
Excavate 1m thick to spoil m3 1200 15 1 18000 $ 5.33 $ 96,000.00
Fill 1m thick of rock m3 1200 15 1 18000 $ 16.00 $ 288,000.00
TOTAL AMOUNT $ 384,000.00

24. VE BENEFITS – ROAD OVER SWAMP CROSSING
COST AS PER THE GEOSYNTHETICS DESIGN
DESCRIPTION
UNI
TS
LENGT
H[m]
WIDTH
[m]
DEPTH
[m] QITY RATE TOTAL
Tensar TX 170 Geogrids
[Supply and Placement] m2 1200 15 - 18000 $ 13.26 $ 238,653.60
TOTAL AMOUNT AS PER THE TENSAR PROPOSAL
$ 238,653.60
AMOUNT SAVED $ 145,346.40
PERCENTAGE OF AMOUNT SAVED [%] 37.85 %

25. VE BENEFITS – ROAD OVER SWAMP CROSSING

26. TRAFFIC BENEFIT RATIO (TBR)
 𝑙𝑜𝑔𝑊18 = 𝑍 𝑅 × 𝑆0 + 9.36 × 𝑙𝑜𝑔 𝑆 𝑁 + 1 −
0.2 +
𝑙𝑜𝑔∆𝑃𝑆𝐼
2.7
0.4+
1094
𝑆 𝑁+1
5.19
+ 2.32 × 𝑙𝑜𝑔𝑀 𝑅 − 8.07
 𝑊18
𝑈
= 𝟏𝟏𝟒𝟎𝟖𝟖 𝑬𝑺𝑨𝑳 𝒄𝒚𝒄𝒍𝒆𝒔
 𝑊18
𝑠/𝑟
= 𝟔𝟔𝟖𝟎𝟑𝟔𝟐 𝑬𝑺𝑨𝑳 𝒄𝒚𝒄𝒍𝒆𝒔
 𝑇𝐵𝑅 =
𝑁 𝑠/𝑟
25𝑚𝑚
𝑁 𝑈 25𝑚𝑚
= 𝟓𝟖. 𝟓𝟔
 𝑊18 𝑟𝑒𝑖𝑛𝑓𝑜𝑟𝑐𝑒𝑑
= 𝑇𝐵𝑅 × 𝑊18 𝑢𝑛𝑟𝑒𝑖𝑛𝑓𝑜𝑟𝑐𝑒𝑑
=
𝟔𝟔𝟖𝟎𝟗𝟗𝟑 𝑬𝑺𝑨𝑳 𝒄𝒚𝒄𝒍𝒆𝒔
The AASHTO method , which considers the
pavement as a multi-layer elastic system with
an overall structural number (SN) that reflects
the total pavement thickness and its resiliency
to repeated traffic loading, is employed.

27. VERIFICATION OF TRAFFIC
BENEFIT RATIO (TBR) AND BASE
COURSE REDUCTION (BCR)
Determination of TBR and BCR based on Base Course remaining life structural thickness
0
250
0.0 1.0 2.0 3.0 4.0 5.0 6.0
RemainingLifeBaseCourseStructural
Thickness,fscXTD
2
No. ESAL Load Cycles (Traffic Passes) X106
Remaining Life Base Course Structural Thickness
Thickness Structural
Depreciation Curves
Terminal Thickness
Unreinforced
Unreinforced
EXTRAPOLATED
Curve
125mm
102.0mm
200mm
Scenario
• No. filtrations/separation/reinforcement geosynthetics in unreinforced
• Loss in base course structural thickness predominantly due to black cotton soil ingression
• Reinforced pavement structure includes geotextile for filtration/separation and stress mobilization of black cotton soil
152mm
Legend
• = Remainig Life Layer Coefficient Ratio
• = Design Thickness
• = Reinforced Design Thickness
• = Unreinforced Design Thickness
• = Reinforced Structural Capacity Factor
• = Unreinforced Structural Capacity Factor
Premature
FAILURE due to
BCS subgrade
Geosynthetics Reinforced

28. Example of Structural Benefits
Enhanced Geotechnical Engineering Properties

29. Comparison of Unreinforced and Reinforced UCS for
swampy BCS for Drilling Project of White Nile Oil in
Jonglei State, Southern Sudan
No. Unreinforced
[Mpa]
Reinforced
[Mpa]
Description % Increase Remarks
1 1.45 No soil reinforcement
2 1.45 2.1 Geogrid SS20G, 1/3H 45 >30<100
3 1.45 2.15 Geogrid SS20G, 1/5H 48 >30<100
4 1.45 2.2 Double Geogrid SS20G,
1/3H, 2/3H
52 >30<100
5 1.45 1.55 Mat 1/3H 7 >30<100
6 1.45 1.85 Mat 1/5H 28 ≈30<100
7 1.45 2.1 Double Mat 1/3H, 1/5H 45 >30<100

30. NEAT BLACK COTTON SOIL
SAMPLES
Comparison of Unreinforced and
Reinforced UCS for swampy BCS for
Drilling Project of White Nile Oil in
Jonglei State, Southern Sudan

31. White Nile Oil in Jonglei State, Southern Sudan

32. Value Engineering Benefits-
Environmental Benefits

33. Subgrade Improvement – Reduction in Quantity
of Capping Layer
𝑇𝑆𝐺
𝑈𝐶𝑎𝑝
= 2253 × 𝑒−0.455×2
= 𝟗𝟎𝟔𝒎𝒎 𝑇𝑆𝐺
𝑈𝐶𝑎𝑝
= 2253 × 𝑒−0.455×9
= 𝟑𝟕. 𝟓𝒎𝒎
Capping Layer
With Geosynthetic reinforcementWithout Geosynthetic Reinforcement

34. Projects in Kenya
PROJECT MATERIALS YEAR
1. Garsen Bridge
Gauff – China Roads and Bridges
Tensar GM Tube Gabions 1987
2. Garsen / Lamu Junction
Gauff
Asphalt Reinforcement
Experimental Tensar AR1 grids
1987
3. Aberdares – Nairobi Pipeline
Horward Humphreys – Sogea
Soil Erosion Control
Tensar Mat
1989
4. Thika – Makutano
Gibbs – TM AM
Swamp Crossing Reinforcement
Tensar SS2 Biaxial Geogrids
1990
5. Westlands – Limuru Dual Carriageway
Gauff – Federecci
Embankment Reinforcement
Tensar SS2 Biaxial Geogrids
1991
6. Westlands – Limuru Dual Carriageway
Gauff – Federecci
Asphalt Reinforcement
Tensar AR1 Geogrids
1992
7. Eldoret – Burnt Forest Reconstruction
Gauff - Strabag
Swamp Crossing Reinforcement
Tensar SS2 Biaxial Geogrids
1993
8. Webuye – Malaba Reconstruction
Nicholas O’Dwyer – Federecci
Swamp Crossing Reinforcement
Tensar SS2 Biaxial Geogrids
1993
9. Baricho – Mombasa Access Pipeline Rd
Gauff – Sogea
River Crossing Embankment
Tensar SS2
1998
10. Garsen – Lamu Road
Gauff – China Road and Bridge
Embankment Reinforcement
Tensar SS30-SS40 and 55RE
2003
11. Meru – Mikinduri – Maua Road [Phase 1]
KeRRA – H-Young & Co EA
Slope Protection & Erosion Control
Tensar T-mat 400
2010
12. Lake Turkana BGP Marine Seismic Project
BGP _ Tullow Oil Company
Construction of sand access roads and heavily loaded plat
forms – Tensar TriAx TX 160
2012

35. Projects in Uganda
PROJECT MATERIALS YEAR
1. Kabale – Katuna Road
Typsa O’Sullivan & Graham – Stirling
Slip Failure Reconstruction with Tensar Geocell Mattress 1999
2. Kabale – Katuna Road
Typsa O’Sullivan & Graham – Stirling
Slip Reinforcement wrap around
Tensar RE uniaxial Geogrid
2000
3. Kampala – Masaks Road
Stirling
Swamp Crossing Embankment
Tensar SS20 Biaxial Geogrid
2000
4. Mbarara – Ibanda Road
ACE Engineers - Energoprojekt
Embankment Failure Reconstruction
Tensar SS20 Biaxial Geogrid
2000
5. Malaba – Bugiri Road
Gauff - Strabag
Swamp Crossing Reinforcement
Tensar SS2 Biaxial Geogrids
2000
6. Fort Portal – Kyejojo Road
ACE Engineers - Energoprojekt
Embankment Failure Reconstruction
Tensar 80RE
2001
7. Kabala Water Project
Bella Consult - Spencon
Tensar SS30 2001
8. Semliki Oil Drilling
BMS Mineral Services
Tensar SS30 2002
9. Bugiri – Jinja Road
Gauff – Basil
Embankment Widening over Black Cotton Soil
Tensar SS20Biaxial Geogrid
2004
10. Kampala Relief Road
BCEOM - Salini
Embankment Foundation Reinforcement over Swamps
Tensar SS20Biaxial Geogrid
2005
11. Kampala Ring Road
Salini
Swamp Crossing reinforcement
Tensar TriAx TX 160 Geogrid
2010

36. Projects in East and Central Africa than have utilized Geosynthetics
 Timboroa – Eldoret Road [1993]
 Webuye – Malaba Road [1993]
 Thika – Makutano Road [1990]
 Westlands – Limuru Dual Carriageway [1992]
 Garsen – Lamu Road [2003]
 Meru – Mikinduri Road [2010]
 Isiolo Airport [2011]
 Tullow Oil – Loading Platform for Oil rigs and Access Roads in Lake Turkana [2012]
 Kabale – Katuna Road [1999]
 Mbarara – Ibanda Road [2000]
 Malaba – Bugiri Road [2000]
 Kampala Relief Road [2005]
 Bugiri – Jinja Road [2004]
THANK YOU
BY SIRMOI WEKESA
Technical Director and Civil Engineer,
GEOSYNTHETICS EA LTD
Email: sirmoi@geosyntheticsea.com