analysis of strength characteristics of soil
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ANALYSIS OF CLAYEY SOIL REINFORCED WITH
RECRON 3S (Polyester) Fiber
ByB101184 – M Akshay KumarB101501 – B SandhyaB101580 – P UmamaheswariB101570 – D Manoj KumarB101590 – B Akhil Naik
09-05-2016 1
Under the Guidance of
Mr. Ranadheer Sagi(Head of the Department)
Contents
1 Theme
2 History of development
3 Methodology
4 Tests conducted
5 Results
6 Conclusion
7 References
09-05-2016 2Dept. of Civil Engineering, RGUKT - Basar
ThemeThe objective of this project is to investigate the use of fibres as
reinforcement to soil and evaluate their effect on Dry Density and ShearStrength of soil.
This includes: i. Analytical study on Fibers and Methods of Inclusion
ii. Getting the engg properties of proposed soil and fibreiii. Lab tests to find optimum fibre content
This aims at identifying optimum fiber content in terms of Length offiber and % fiber by weight of soil.
09-05-2016 3Dept. of Civil Engineering, RGUKT - Basar
Need for project
Soil properties vary a great deal and construction of structures depends a lot on thebearing capacity of the soil.
Hence, there is a need to improve the strength of the soil by making it uniformlygraded which makes it easier to predict and even improve the strength of the soil.
But, mixing different types of soils together to improve the soil strength propertiesand replacing the inferior soil entirely is very expensive.
Therefore we have to look upon the alternatives.
09-05-2016 4Dept. of Civil Engineering, RGUKT - Basar
History of development
Romans developed soil reinforcement based on the principle of plant roots that impartstrength to the beneath soil.
This technique was also used in the construction of THE GREAT WALL OF CHINA.
In 1966, A geotechnical researcher, Er. Vidal innovated the soil reinforcementmethods and developed the principles.
He nearly built 4K structures in around 37 countries across the world.
In recent times, this technique was attracted by the use of synthetic fibres.
Though very old, still does not has a scientific standard and relatively a new technique.
09-05-2016 5Dept. of Civil Engineering, RGUKT - Basar
SELECTION CRITERIA:
After we reviewed many fiber reinforcement papers, we determined that the fiber selection parameters were the following:
• It must not be a hazard to its surroundings.
• It should not degrade so easily in the soil.
• It must be easily obtainable and inexpensive.
• Its preparation and inclusion method should be simple.
• It must work with the selected soil.
09-05-2016 6Dept. of Civil Engineering, RGUKT - Basar
METHODOLOGY – For selection of Fiber
Fibres
Natural
Man-made
Coconut coir fibre
Sisal fibre
Bamboo Cane
palm
Jute
Polypropylene Fiber
Polyvinyl alcohol
Nylon Glass
Polyester
Polyethylene
09-05-2016 7Dept. of Civil Engineering, RGUKT - Basar
What to select??
About proposed fibre – Recron 3S (Polyester)
100% synthetic – No natural constituent It’s a polymer – Monomer being Propylene Thermoplastic – Plasticity Temperature Transformed from 85% propylene By product of petroleum refining Prone to sunlight and fire. Resistant against abrasion, chemical and biological reactions. Mostly used as a secondary reinforcement to concrete.
09-05-2016 8Dept. of Civil Engineering, RGUKT - Basar
09-05-2016 Dept. of Civil Engineering, RGUKT - Basar 9
Available Length Product Type Bag Size Price per Kg
6mm CT 2012 125 gr 450 Rs
12mm CT 2024 125 gr 450 Rs
18mm CT2436B, CT2436 450 gr 250 Rs
12mm CT2424B, CT2424 900 gr 400 Rs
Different lengths available in Recron 3S:
Source: Extracted from the broacher of Recron 3S fiber. Manufacturer: Reliance industries ltd
As 18mm fiber is not suitable for laboratory experiments, we have chosen to use rest of the types i.e. 6mm and 12mm fiber.
We have purchased the Recron 3S (Polyester) fiber manufactured by Reliance Industries Limited from Vasanth enterprises private limited, Punjagutta, Hyderabad.
S.No. Property Value
1 TypeCT2012 and
CT2024
2 Length 6mm and 12mm
3 Cross Section Triangular
4 Colour White
5 Effective Diameter 35 – 40 microns
6 Melting Point 162 – 167° C
7 Flash Point >329° C
8 Relative Density 0.89 – 0.94 g/cm3
9 Tensile Strength 350 MPa
General specifications:
Recron 3S –Polyester fiber09-05-2016 11Dept. of Civil Engineering, RGUKT - Basar
Method of orientation
09-05-2016 12Dept. of Civil Engineering, RGUKT - Basar
1. Oriented fiber reinforcement:In this type of orientation the fibers are arranged in some order and all the
fibers are placed in the same orientation. The fibers are laid layer by layer. Continuousfibers in the form of sheets, strips or bars etc. are used systematically in this type ofarrangement.
2. Random fiber reinforcement:This arrangement has discrete fibers distributed randomly in the soil mass.
The mixing is done until the soil and the reinforcement form a more or lesshomogeneous mixture. Materials used in this type of reinforcements are generallyderived from paper, nylon, metals or other materials having varied physical properties.
Oriented vs RandomOriented Random
1. Fibre inclusion requires high work and energy i.e. Not easy to add and mix
2. Similar to steel reinforcement in concrete.
3. Strength distribution is uniform over soil layers but not over soil mass.
4. Lesser ductility.
5. High Chances of formation of potential failure planes.
1. Fibre inclusion requires comparatively less work and energy i.e. Easy mixing
2. Similar to fly-ash reinforcement in concrete.
3. Strength distribution is more or less uniform over entire soil mass.
4. Higher ductility.
5. Less chances of formation of potential failure planes.
09-05-2016 13Dept. of Civil Engineering, RGUKT - Basar
Mechanism
1. Soil matrix and Fibre surface interaction
2. Soil particles and Fibre surface interaction
09-05-2016 14Dept. of Civil Engineering, RGUKT - Basar
09-05-2016 15Dept. of Civil Engineering, RGUKT - Basar
METHODOLOGY – For analysis
Parent soil is tested for its index properties, dry density by proctor compaction test and shear strength were carried out as per the procedures and guidelines laid down in Indian Standards Codes of practice.
A total of sixteen samples (8 with each length of fiber) of soil – Recron 3S fiber mixture were made (0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8% of the total dry weight of the soil).
After the determination of various index properties of soil, Proctor compaction tests were conducted, followed by direct shear tests on the reinforced soil.
1. Atterberg limit :1.1 Liquid Limit Test:
Sample No 1 2 3
Weight of empty Can in gms 10 9 10
Weight of Can + Wet soil in gms 28 26 35
Weight of Can + Dry soil in gms 25 22 29
Weight of soil solids 15 13 19
Weight of pore water 3 4 6
Water Content (%) 20 30.76 31.57
No of blows 57 28 15
09-05-2016 17Dept. of Civil Engineering, RGUKT - Basar
15
17
19
21
23
25
27
29
31
33
0 5 10 15 20 25 30 35 40 45 50 55 60
Mo
istu
re C
on
ten
t (%
)
No of Blows
# of Blows vs Moisture Content
From Graph:Liquid Limit = Moisture content corresponding to 25 blows = 28.6%
LL = 28.6% < 35% therefore, the soil is Low Compressible.
09-05-2016 18Dept. of Civil Engineering, RGUKT - Basar
1.2 Plastic Limit Test:
Sample No 1 2
Weight of empty Can in gms 9 10
Weight of Can + Wet soil in gms 31 30
Weight of Can + Dry soil in gms 28 27
Weight of soil solids 3 3
Weight of pore water 19 17
Water Content (%) 15.78 17.64
Results of Plastic Limit Test on parent soil
Average Plastic Limit = 16.71 %Plasticity Index (PI) = wl – wp where, wl = Liquid Limit; wp = Plastic Limit
= 28.6 – 16.71= 11.89 %
Hence, the soil is Medium plastic. Since, Ip lies between 7 and 17 %.09-05-2016 19Dept. of Civil Engineering, RGUKT - Basar
1.3 Specific Gravity Test:
Sample Number 1 2
Weight of empty bottle (W1) in gms 65 65
Weight of bottle + Dry Soil (W2) in gms 75 76
Weight of bottle + Dry Soil + Water (W3) in gms 174 177
Weight of bottle + Water (W4) in gms 169 169
Specific Gravity (G) 2.0 2.2
Results of Specific Gravity Test
Average specific Gravity of Parent Soil = 2.1
09-05-2016 20Dept. of Civil Engineering, RGUKT - Basar
1.4 Differential Free Swell Test:
Volume of Water (ml) Volume of Kerosene (ml)
Before Swell 100 100
After Swell 101 100
By this test, Swell is observed to be 1%.
09-05-2016 21Dept. of Civil Engineering, RGUKT - Basar
2 Tests on Reinforced Soil
Fiber Content (%) 0% 0.1% 0.2% 0.3% 0.4% 0.5% 0.6% 0.7% 0.8%
Internal Diameter of Mould, d (Cm) 10.16 10.16 10.16 10.16 10.16 10.16 10.16 10.16 10.16
Mould height, h (Cm) 11.64 11.64 11.64 11.64 11.64 11.64 11.64 11.64 11.64
Mould Volume, V (Cm3) 944 944 944 944 944 944 944 944 944
Wt. of mould + base plate, Wl (gr) 4305 4305 4305 4305 4305 4305 4305 4305 4305
Wl + Compacted soil, W1 (gr) 5860 6060 6090 6120 6130 6140 6150 6140 6130
Wt. of Compacted soil, W1-Wl (gr) 1560 1760 1793 1810 1820 1835 1851 1840 1820
Bulk Density, γbulk = (W1-Wl)/V gr/cc 1.81 2.03 2.07 2.10 2.11 2.12 2.14 2.13 2.11
Water Content, W% 6.5 8.5 9.3 9.5 9.7 9.85 10.50 10.7 10.8
Dry Density, γd=Vt/[1+(W/100)] gr/cc 1.70 1.88 1.90 1.92 1.93 1.935 1.94 1.925 1.91
1. Proctor Compaction Test with 6mm fiber
Results of soil reinforced with 6mm fiber 09-05-2016 22Dept. of Civil Engineering, RGUKT - Basar
1.65
1.7
1.75
1.8
1.85
1.9
1.95
2
0 0.2 0.4 0.6 0.8 1
MD
D (
g/C
C)
Fiber Content (%)
Fiber Content vs MDD - 6mm Recron 3S
MDD vs Fiber…
0
2
4
6
8
10
12
0 0.2 0.4 0.6 0.8 1
OM
C (
%)
Fiber Content (%)
Fiber Contet vs OMC - 6mm Recron 3S
OMC vs FiberContent
Results of Compaction test with 6mm fiber
09-05-2016 23Dept. of Civil Engineering, RGUKT - Basar
1. Proctor Compaction Test with 12mm fiber
Results of soil reinforced with 6mm fiber
Fiber Content (%) 0% 0.1% 0.2% 0.3% 0.4% 0.5% 0.6% 0.7% 0.8%
Internal Diameter of Mould, d (Cm) 10.16 10.16 10.16 10.16 10.16 10.16 10.16 10.16 10.16
Mould height, h (Cm) 11.64 11.64 11.64 11.64 11.64 11.64 11.64 11.64 11.64
Mould Volume, V (Cm3) 944 944 944 944 944 944 944 944 944
Wt. of mould + base plate, Wl (gr) 4305 4305 4305 4305 4305 4305 4305 4305 4305
Wl + Compacted soil, W1 (gr) 5860 5900 5950 6014 6070 6110 6090 6060 6055
Wt. of Compacted soil, W1-Wl (gr) 1560 1590 1650 1700 1760 1811 1790 1750 1750
Bulk Density, γbulk = (W1-Wl)/V gr/cc 1.81 1.84 1.91 1.98 2.04 2.09 2.07 2.03 2.02
Water Content, W% 6.50 6.90 7.60 8.20 10.10 11.60 12.2 13.0 13.4
Dry Density, γd=Vt/[1+(W/100)] gr/cc 1.70 1.73 1.78 1.83 1.86 1.88 1.85 1.80 1.79
09-05-2016 24Dept. of Civil Engineering, RGUKT - Basar
1.68
1.7
1.72
1.74
1.76
1.78
1.8
1.82
1.84
1.86
1.88
1.9
0 0.2 0.4 0.6 0.8 1
MD
D (
g/cc
)
Fiber Content (%)
Fiber Content vs MDD - 12mm Recron 3S
MDD vs Fiber…
0
2
4
6
8
10
12
14
16
0 0.2 0.4 0.6 0.8 1
OM
C (
%)
Fiber Content (%)
Fiber Content vs OMC - 12mm Recron 3S
OMC vs Fiber…
Results of Compaction test with 12mm fiber09-05-2016 25Dept. of Civil Engineering, RGUKT - Basar
1. Direct Shear Test
Results of Direct shear test
Normal Stress(Kg/Cm2) Shear Stress (Kg/Cm2)
0% fiber 0.2% fiber 0.4% fiber 0.6% fiber 0.8%fiber
6mm Fiber 0.5 0.0244 0.0267 0.0309 0.0271 0.0262
1 0.0256 0.0279 0.0315 0.0311 0.0282
1.5 0.0323 0.0345 0.0363 0.0351 0.0343
12mm Fiber 0.5 0.0244 0.0263 0.0293 0.0278 0.0258
1 0.0256 0.0288 0.0320 0.0286 0.0278
1.5 0.0323 0.0351 0.0349 0.0339 0.0336
09-05-2016 26Dept. of Civil Engineering, RGUKT - Basar
32
32.5
33
33.5
34
34.5
35
35.5
36
36.5
0 0.2 0.4 0.6 0.8 1
She
ar S
tre
ss (
10
-3 K
g/C
m2
)
% Fiber
Fiber Content vs Shear Stress
6mm Fiber
12mm Fiber
Results of Direct shear test with 6 & 12mm fiber09-05-2016 27Dept. of Civil Engineering, RGUKT - Basar
Fiber Content 0% 0.2% 0.4% 0.6% 0.8%
Cohesion, C
(10-3 Kg/Cm2)
6mm fiber 20.8 23.0 28.3 23.0 22.0
12mm fiber 20.8 22.3 26.1 24.9 22.5
18
20
22
24
26
28
30
0 0.2 0.4 0.6 0.8 1
Co
he
sio
n (
Kg/
Cm
2)
% Fiber
Fiber Content vs Cohesion
6mm fiber
12mm fiber
Results of Direct shear test with 6 & 12mm fiber09-05-2016 28Dept. of Civil Engineering, RGUKT - Basar
CONCLUSION :• The maximum dry density of soil when reinnforced with 6mm fiber is observed
at 0.6 % of fiber, where in case of 12mm fiber it is observed at 0.5 % of fiber byweight of soil.
• For 6mm fiber, the maximum dry density is increased from 1.70 to 1.94 gr/cc.,therefore the % increase in dry density is 14.11.
• When 12mm fiber is used the maximum dry density is increased from 1.70 to1.88 gr/cc., therefore the % increase in dry density is 10.11.
• Hence, 6mm (Optimum % = 0.6) fiber is effective.
09-05-2016 29Dept. of Civil Engineering, RGUKT - Basar
(CONCLUSION Cntd…)
• The increase in the Shear strength (τ) is found to be 12.3% (From 0.0323 to 0.0363 Kg/Cm2 ) for 6mm fiber and 9.59% (From 0.0323 to 0.0354 Kg/Cm2) for 12mm fiber observed at OFC of 0.4%.
• The net increase in cohesion was found to be 36% (From0.0208 to.283) for 6mm fiber and 30% (From.0208 to0.0260 Kg/Cm2) for 12mm fiber observed at OFC of 0.4%.
• From this it can be concluded that 6mm fiber aparts more strength to the soil and is recommended over 12mm fiber.
09-05-2016 30Dept. of Civil Engineering, RGUKT - Basar
References
1. Construction and building materialsJournal No : 30 (2012) 100–116 Website : www.elsevier.com/locate/conbuildmat
2. International Journal of science Technology & ManagementVol. No : 04, Spl Issue on. 01, Feb 2015 Website : www.ijstm.com
3. Journal of Rock Mechanics and Geotechnical EngineeringVol. No : 6, Issue on 2,Apr,2014 Website : www.sciencedirect.com
09-05-2016 31Dept. of Civil Engineering, RGUKT -
Basar
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