DOI : 10.17577/IJERTV5IS080345
- Open Access
- Total Downloads : 222
- Authors : Geethu Chandran, K. Soman
- Paper ID : IJERTV5IS080345
- Volume & Issue : Volume 05, Issue 08 (August 2016)
- DOI : http://dx.doi.org/10.17577/IJERTV5IS080345
- Published (First Online): 26-08-2016
- ISSN (Online) : 2278-0181
- Publisher Name : IJERT
- License:
This work is licensed under a Creative Commons Attribution 4.0 International License
Heave Control and Strengthening of Expansive Soil using Lime Mixed GGBS Column
Geethu Chandran
Student Mtech Geomechanics and structures JBCMET College, perumbavur, India
K. Soman Professor
Department of Civil Engineering JBCMET College, perumbavur,India
AbstractExpansive soils causes alternate swelling and shrinkage with the change in water content. The experimental studies from heave test conducted with installing lime mixed GGBS columns in the clay bed formed in a laboratory test tank. This technique improves swelling problem as well as low shear strength of soil. Various lime-GGBS combinations are used with different spacing and patterns of column to get an optimum combination of lime GGBS proportion, spacing and pattern of the columns. Strength tests were also conducted with three combinations of GGBS and lime. Effect of one column on the surrounding soil mass was noticed by taking UCC samples from different locations from the column in a test tank. Also effect of curing on strength improvement was also studied. The result from the test shows that the method can be effectively used for reducing heaving problem hence to provide additional strength in an economical manner compared to other methods.
KeywordsGGBS,Lime
-
INTRODUCTION
Expansive soil is the adobe soil that we hear so much about. These are soils that have a relatively high percentage of clay minerals and are subject to changes in volume with changing moisture conditions. Expansive soils cause damage to buildings, roads and other structures. Soil stabilization can be achieved by two methods; mechanical stabilization and chemical stabilization. Mechanical stabilization can be attained by compaction, rolling, using geotextiles etc. Treatment with lime is one of the most traditional treatment method. Together with cement and GGBS, lime is referred to as a calcium-based treatment. Most commonly used for treating the sub grade on highway construction projects.
The use of blast furnace slag in expansive soil stabilization is a new process in the geotechnical field. Ground- granulated blast-furnace slag (GGBS) is a by-product obtained from iron and steel-making industry. The use of GGBS to the expansive soil stabilization by determining the beneficial effect on the reduction of expansion and improvement of mechanical properties. The GGBS are commonly available in cement production plant. Soil replacement method are difficult in the case of clayey soil because uniform mixing with additives with clayey soil is very difficult. In this aspect we go for certain soil improvement method like column on soft ground.
-
SCOPE AND OBJECTIVE
To study the heave control of expansive soil using GGBS column .Obtain the optimum percentage of lime out of 2%,4%,6%,8%,16% for reducing the heave of expansive soil further from GGBS column.To study the effective spacing of two column for heave controlling(1D,2D,3D).To study the effect of number of columns(1,2,3,4 columns) on the heave reduction of expansive clay bed.Study the effect of lime stabilized GGBS column on the shear strength properties of expansive soil.To study the effect of curing period(3
,7,14,28 days) on shear strength .The main objective of this research is to To study the heave control of expansive soil using GGBS column.To study the improvement in strength of expansive soil using column
-
MATERIALS USED
In present Study the materials used are soil, GGBS, lime
-
Soil
High expansive clayey soil was used for the study. Expansive nature of soil found out by conducting free swell index test.
Figure 1:lime
-
GGBS
GGBS was collected from m /s JSW cements Amballur, Thrissur. This is off-white colored material. Ground- granulated blast-furnace slag (GGBS or GGBFS) is a by- product obtained from iron and steel-making from a blast furnace in water or steam to produce a glassy product that is then dried and ground into a fine powder.
Figure 2: GGBS
-
Lime
The lime used in this research is hydrated lime Ca (OH)2
Figure 3: lime
-
-
LABORATARY STUDIES
The soil samples prepared for heave test and U.C.C test were prepared.
Heave Test
Computed quantity of air-dried soil, passing through 4.75 mm sieve, is mixed thoroughly. Based on the natural water content in the soil, calculated quantity of water is added to reach 15% moisture content. A test tank of 40 cm diameter and 40 cm height is taken. Sand layer of 1 cm thick has been laid at the bottom of the test tank. An iron casing of size of 30 cm diameter and 50 cm height is coated with oil on both sides and pushed in to the test tank. The gap between tank and casing is filled with sand. The mixed and matured expansive soil is divided into three nearly equal amounts. Each part of the expansive soil is compacted in the space inside of the casing and is compacted to approximately 5 cm thick. The top of the compacted surface is scratched to develop bond between the layers and the total thickness of four layers would be 20 cm. After the soil has been compacted the casing is withdrawn slowly to minimize the disturbance to the clay sub grade.
An open mild steel tube of 3.8 cm diameter and 30 cm height are pushed into the clay bed. The tube is turned for two revolutions to shear the sample off at the bottom. Then the tube is removed from the clay bed. The void created by the mild steel tube is filled with the column material in 3 layers. Each layer compacted with tamping rod.
A mild steel plate of 3 cm diameter is placed on the top of the clay bed.For measuring the vertical displacement of bed a dial gauge is placed on the top of the steel plate. Set dial gauge reading to zero or note the initial reading. Then water is added through the sand drain around the clay bed. When the water is available to the expansive clay bed, it starts absorbing the water results in increase in volume. Since the sides and bottom of the clay bed are fixed boundaries the increase in volume results in increase in height of the clay bed which can be measured in the dial gauge. Since the process of absorbing water by the expansive soil bed is a time consuming, hence the dial gauge reading are to be recorded with respect to time till the swelling rate was decreased. The test was repeated with different column material, number of columns and different spacing of two columns.
-
RESULTS AND DISCUSSION
15
10
15
10
GGBS + 4% lime
GGBS +6% lime
GGBS + 4% lime
GGBS +6% lime
Heave(mm)
Heave(mm)
Heave test- results
35
30
25
Controll
specimen
GGBS Column
35
30
25
Controll
specimen
GGBS Column
20
GGBS + 2% lime
20
GGBS + 2% lime
5
5
0
GGBS + 8% lime
0
GGBS + 8% lime
0
200000 400000
GGBS +16% lime
0
200000 400000
GGBS +16% lime
Time(Seconds)
Time(Seconds)
1 Columns
1 Columns
Heave(mm)
Heave(mm)
Figure 4: Variation of heave with different combinations of GGBS and lime
40
35
30
Controll
specimen
40
35
30
Controll
specimen
25
25
20
15
2 Columns
20
15
2 Columns
0 200000 400000
Time(Seconds)
0 200000 400000
Time(Seconds)
10
5
0
10
5
0
3 Columns
4 Columns
p> 3 Columns
4 Columns
Figure 5: Variation of heave with change in number of columns
25
40
35
30
25
25
40
35
30
25
Control
specimen
1D
Control
specimen
1D
20
20
2D
2D
15
15
3D
3D
10
5
10
5
4D
4D
0
0
Series6
Series6
0 200000 400000
Time (seconds)
0 200000 400000
Time (seconds)
20
20
15
10
15
10
Unstabilized
soil
GGBS + 4%
lime
GGBS +8%
lime
5 GGBS + 16%
lime
0
0 0.1 0.2 0.3
Unstabilized
soil
GGBS + 4%
lime
GGBS +8%
lime
5 GGBS + 16%
lime
0
0 0.1 0.2 0.3
Heave(mm)
Heave(mm)
Axial stress(kN/m^2)
Axial stress(kN/m^2)
Figure 6: Variation of heave with variation in spacing between two columns.
Strength test-results
15
15
Axial stress(kN/m^2)
Axial stress(kN/m^2)
Variation in strength of samples by different combinations of ggbs and lime
30
30
25
25
20
20
Unstabi
lized soil
Unstabi
lized soil
0
0
0
0.1
Axia0l .s2train
0.3
0.4
0
0.1
Axia0l .s2train
0.3
0.4
10
10
5
5
Fig 7: Var iation in strength of samples collected from 1D after three days curing
Axial strain
Axial strain
Fig 8: Variation in strength of samples collected from 2D after three days curing
25
25
20
20
0
0
0
0.1 0.2 0.3
0
0.1 0.2 0.3
Axial strain
Axial strain
15
15
Unstabilized
soil
GGBS + 4%
lime
Unstabilized
soil
GGBS + 4%
lime
10
10
5
5
GGBS + 8%
lime
GGBS +16%
lime
GGBS + 8%
lime
GGBS +16%
lime
Axial stress(kN/m^2)
Axial stress(kN/m^2)
Fig 9: Variation in strength of samples collected from 3D after three days curing
70
60
50
40
30
Unstabilized
soil
GGBS + 4%
lime
35
30
25
20
15
Unstabiliz
ed soil
GGBS +
4% lime GGBS +
8% lime
70
60
50
40
30
Unstabilized
soil
GGBS + 4%
lime
35
30
25
20
15
Unstabiliz
ed soil
GGBS +
4% lime GGBS +
8% lime
GGBS + 8%
20 lime
GGBS + 16%
10 lime
0
0 0.2 0.4 0.6
Axial strain
GGBS + 8%
20 lime
GGBS + 16%
10 lime
0
0 0.2 0.4 0.6
Axial strain
10
5
0
10
5
0
0
0
0.05
0.05
0.1 0.15 0.2
Axial strain
0.1 0.15 0.2
Axial strain
0.25
0.25
0.3
0.3
30
30
GGBS + 4% lime
GGBS + 4% lime
Axial stress(kN/m^2)
Axial stress(kN/m^2)
Axial stress(kN/m^2)
Axial stress(kN/m^2)
Axial stress(kN/m^2)
Axial stress(kN/m^2)
Fig 10: Variation in strength of samples collected from 1D after seven days curing
60
60
50
50
40
Unstabilized soil
40
Unstabilized soil
10
GGBS + 16%
lime
10
GGBS + 16%
lime
0
0
0
0.1 0.2 0.3
0
0.1 0.2 0.3
Axial strain
Axial strain
20
20
GGBS +8% lime
GGBS +8% lime
Fig 11: Variation in strength of samples collected from 2D after seven days curing
Fig12: Variation in strength of samples collected from 3D after seven days curing
90
80
70
60
50
40
30
20
10
Unstabilized
soil
GGBS + 4%
lime
GGBS + 8%
lime
GGBS + 16%
lime
90
80
70
60
50
40
30
20
10
Unstabilized
soil
GGBS + 4%
lime
GGBS + 8%
lime
GGBS + 16%
lime
0
0
0
0.2
0.4
0
0.2
0.4
Axial strain
Axial strain
Axial stress(kN/m^2)
Axial stress(kN/m^2)
Fig 13: Variation in strength of samples collected from 1D after fourteen days curing
70
60
50
40
30
70
60
50
40
30
20 GGBS +16% lime
10
0
0 0.1 0.2 0.3
Axial strain
20 GGBS +16% lime
10
0
0 0.1 0.2 0.3
Axial strain
50
45
40
35
30
50
45
40
35
30
Axial stress(kN/m^2)
Axial stress(kN/m^2)
Fig 14:Variation in strength of samples collected from 2D after fourteen days curing
attained. By analyzing the heave pattern of different combinations, an optimum combination of GGBS with 8% lime content was selected for further tests.
Unstabilized soil
GGBS + 4% lime GGBS + 8% lime
Unstabilized soil
GGBS + 4% lime GGBS + 8% lime
-
By using the optimum combination, number of columns are varied. By providing a single column, only 24% in the heave value was obtained. Heave reduces to nearly 30% by providing two columns in the clay bed. From the results, it was clear that as the number of columns increases, heave value continuously reduces and attains a value of 7.1mm using four columns in the clay bed.
-
The effective spacing between two columns for getting maximum reduction in the heave value was selected by changing the spacing between two columns. 36 % reduction in the heave value was observed when the columns are placed at a distance of 3D. When the spacing between the columns decreased, the effective zone of GGBS columns reduced and thereby heave reduction was less.
The strength test results are
Axial stress(kN/m^2)
Axial stress(kN/m^2)
-
From the three combinations of GGBS and lime, an optimum combination of GGBS with 8% lime content was selected for maximum strength improvement. Only 50% improvement in strength was obtained for GGBS with 4% lime content. For the combination of GGBS with 8% and 16% lime content, nearly 80% improvement in strength was obtained. Hence 8% lime content with GGBS was sufficient for the improvement.
25
20
15
25
20
15
10
5
0
10
5
0
0
0.2
Axial strain
0.3 0.4
0
0.2
Axial strain
0.3 0.4
0.1
0.1
Fig 15: Variation in strength of samples collected from 3D after fourteen days curing
-
-
CONCLUSION
An experimental program was conducted for solving the main problems associated with expansive soils. Heave test and strength test was conducted in unstabilized soil and soil with GGBS column and lime mixed GGBS column.The heave test results are
-
It was observed that by introducing GGBS columns in expansive clay bed, only 18% heave reduction can be attained. Maximum heave of 33 mm reduces to 28 mm by this method. By adding different amount of lime in the GGBS column, further reduction in heave was
ACKNOWLEDGEMENTS
Unstabilized soil
Unstabilized soil
GGBS + 4% lime
GGBS +8% lime GGBS + 16% lime
GGBS + 4% lime
GGBS +8% lime GGBS + 16% lime
I place on record and warmly acknowledge the continuous encouragement, tremendous support, expert and inspired guidance, timely suggestions and motivation offered by my guide prof.K.Soman Head of the department in Civil Engineering, Jai Bharath College of Management and Engineering Technology
,Perumbavoor without which this work would not have been materialised.
I gratefully acknowledge the constant support received from the faculty members, lab staffs, friends and my class mates for carrying out this work successfully.
I owe my profound gratitude to my parents for their unwavering love and unconditional support that has been a constant encouragement to me in all my endeavours.
Last but not the least, I express my obeisance and record my gratefulness before the Almighty God who has showered his blessings on me and strengthened me for preparing this work and who made this work flawless.
REFERENCES
-
Chand,S.K.,Subbarao,C.(2007).In-Place stabilization of Pond ash deposites by hydrated lime columns. Journal of Geotechnical and Geoenvironmental Engineering, ASCE,133(12),1609-1616.
-
Ramu,K.(2009). An Experimental study of fly ash columned bed in expansive soil. Proceedings of Indian Geotechnical Conference,77- 79.
-
Rao,A.S et.al.(2009). Heave studies on Expansive clays with stabilized granulated blast furnace slag cushion. Proceedings of Indian Geotechnical Conference,109-113.
-
Sheeba Kumari ,J.S.,Bindu,J.(2010).Effect of lime on shear strength of Kuttanad Clay.International Conference on Technological Trends Civil Engineering Papers,1-5.
-
M.Rama Rao, G.Sridevi, (2011) Performance of cushions of waste materials in heave reduction of expansive soils Proceedings of Indian Geotechnical Conference December 15-17 (Paper No.D-225)
-
Lambert,S. (2012).Soil-cement columns, an alternative soil improvement method. International Symposium on Ground Improvement,6(2),1-27.
-
Eberemu ,A.O.,Sada ,H. (2013). Compressibility characteristics of compacted black cottton soil treated with rice husk ash. Nigerian Journal of Technology, 32(3), 507-521.