a research work on cement stabilization of soil
TRANSCRIPT
A RESEARCH WORK ON CEMENT STABILIZATION OF SOIL
PRESENTED BY : 2016-MS-CEG-01
2016-MS-CEG-02 2016-MS-CEG-03 2016-MS-CEG-04 2016-MS-CEG-05 2016-MS-CEG-10 2016-MS-CEG-11
Contents
• Introduction
• Cement Soil Stabilization
• Mix Design
• Mixing Procedure
• Research Work
• Results and Discussion
• Conclusions
2
Cement stabilization refers to the process of changing soil properties to improve strength and durability by adding cementitous material along with water.
Introduction
Cement stabilization is the type of chemical stabilization for the improvement of soils.
This process immediately improves the material’s plasticity, compressibility and bearing capacity.
3
Cement Soil Stabilization …… Why ??
Decreased base thickness compared to unbound aggregate base
High stiffness prevents fatigue cracking and rutting of asphalt surface
Economical pavement base (lesser thickness – High CBR)
Increased durability, stiffness and bearing capacity
Increased resistance to frost and weathering
Increased impermeability
Greater control of swelling
Good performance in hot weather, with no deformation or rutting.
4
Load Distribution
5
Cement Soil Stabilization …… Where ??
Waterlogged site (rapid reduction of moisture content )
Reclamation and remediation of contaminated land
Airport runways, taxiways and aprons
Highway pavement construction
Foundations for floor slabs
Car and lorry parks
6
Factors Affecting Soil Cement Stabilization
Soil
Cement
Pulverization and Mixing
Compaction
Curing
Additives
7
Not every soil suitable
for Stabilization
High Organic
soils
Acid soils
Sulfate soils
8
2nd Presenter
9
Cement Soil Stabilization …… Mix Design
10
Cement Soil Stabilization …… Mix Design
11
Mix Design Step 1 Determine Moisture Density Relationship
Perform standard or modified Proctor test (ASTM D558 or ASTM D1557)
Construct moisture-density curve Determine optimum moisture content and maximum dry density
Mix Design Step 2 Mold specimens for
compressive strength testing
Select range of cement contents (e.g. 4%, 6% and 8% by dry weight of material)
Use percent OMC from Step 1 and Mould two specimens per cement content (ASTM D559/560 or ASTM D1632)
Perform compressive strength testing (ASTM D1633)
Plot cement content versus compressive strength
Mix Design Step 3 Determine moisture-
density relationship of target cement content
Perform standard or modified Proctor test (ASTM D558 or ASTM D1557) Construct moisture-density curve Determine optimum moisture content and
maximum dry density 12
Cement Soil Stabilization …… How ??
Two Methods
Plant Mix Road Mix
(in place)
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Mobilization cost
Usually close or on-site
Plant Mix
High Production
14
Road Mix
In-situ or mixed in place materials
Wider variety of materials
Dry or slurry cement application method
15
Road Mix Method
Spreading Cement
Mixing
16
Grading
Compaction
Curing (Water / Bituminous Material)
17
3rd Presenter
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RESEARCH WORK
Research Work
Objectives of Research:
To study the effect of cement on plasticity and UCS of soil.
To determine the Optimum Cement Content for getting maximum
gain in strength and resistance to swell potential.
Program of Work:
Determining index properties and classifying the soil.
Determining compaction characteristics and specific gravity.
Effect of Cement on plasticity of soil.
Effect of Cement on Unconfined Compressive Strength.
Effect of Curing Time on Unconfined Compressive Strength. 20
21
Original Soil
GSD + Hydrometer
Atterberg Limits
Specific Gravity
Modified Proctor
UCS
WORK METHODOL0GY
Phase 01
22
14 days
2% Cement 4% Cement 6% Cement 10% Cement
Atterberg Limits UCS
0 day 7 days
Soil
21 days
WORK METHODOL0GY
Phase 02
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Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.010.1110100
Per
cen
t P
assi
ng
Grain Size (mm)
Sieve Analysis and Hydrometer
No
. 4
No
. 10
3"
No
. 40
No
. 200
No
. 100
No
. 16
1 1
/2"
3/8
"
3/4
"
SAND SILT & CLAY GRAVEL
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Compaction Curve
O.M.C = 10 % Max. dry density = 19.5 g/cc
1.87
1.88
1.89
1.9
1.91
1.92
1.93
1.94
1.95
1.96
0 2 4 6 8 10 12 14
Dry
De
nsi
ty (
g/cc
m^
3)
Moisture Content(%age)
Moisture Content vs Dry Density
25
Unconfined Compression Test
0.00
10.00
20.00
30.00
40.00
50.00
60.00
0.00 0.20 0.40 0.60 0.80 1.00 1.20
Stre
ss (
KP
a)
Axial Strain (%age)
Stress (kpa) vs Axial Strain (%age)
Sample#1
Sample#2
Index Properties of Original Soil
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Gravel 7 %
Coarse Sand 2 %
Medium Sand 2 %
Fine Sand 23 %
Silt & Clay 65 %
Liquid Limit 30 %
Plastic Limit 17 %
Plasticity Index 13 %
Soil Type CL-ML
Maximum Dry Density 1955 kg/𝑚3
OMC 10 %
UCS 55 kpa
Specific Gravity 2.63
4th Presenter
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Effects of Cement on Atterberg Limits
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0
5
10
15
20
25
30
35
0 2 4 6 8 10 12
Mo
istu
re C
on
ten
t (%
)
% Cement
% Cement Content vs Atterberg Limits
LL
PI
PL
Plasticity chart showing the original and cement treated soil
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0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100 110
PL
AS
TIC
ITY
IN
DE
X (
PI)
LIQUID LIMIT (LL)
Plasticity chart
0%
2%
4%
6%
10%
CH or OH
CL or OL
ML or OL
MH or OH
CL-ML 4
7
"U" LINE "A" LINE
Comments
• Plasticity Index of Soil is slightly increased with the increase in
cement content.
• Hence potential for volume change/swelling is decreased.
• Maximum reduction in Plasticity Index is achieved with 10 %
cement trial, although no more trials were performed due to
time constraints.
• Great practical significance, especially for sub-grade soil
improvement in road construction.
30
31
Effects of Cement on UCS
0
500
1000
1500
2000
2500
3000
3500
4000
0 2 4 6 8 10 12
UC
S (k
pa)
% Cement
% Cement Content vs UCS for Different Days
0 Day
7 Day
14 Day
21 Day
Comments
• The UCS of soil is increasing almost linearly with the increase of cement content.
• Although no increase in UCS is observed when samples were tested immediately (0 days UCS) after cement addition. Not enough time for setting of cement.
• Maximum gain in strength is achieved with 10% cement content. • No further trials were tested due to time constraints. • The possible mechanisms behind this remarkable strength gain have
been suggested to be: Either due to formation of strong nuclei by cement distributed
throughout the soil mass. Or due to formation of a skeleton of hydrated cement throughout the
voids. Nucleated structure at low cement contents might change to a skeleton
structure at high cement contents.
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33
0
500
1000
1500
2000
2500
3000
3500
4000
0 5 10 15 20 25
UC
S (K
pa)
Time (days)
Time (days) vs UCS for Different % of Cement
2% Cement
4% Cement
6% Cement
10% Cement
Comments
• Graph shows that the gradual increase of strength with the age of
curing is in accordance with the established trends.
• Maximum strength is achieved for curing period of 21 days.
• Rapid increase in strength with curing time is observed for 10 percent
cement content.
• Unconfined compressive strength of soil cement samples tended to
develop rapidly in an early curing stage and the development of
strength tended to slow down afterwards.
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Based on the results obtained from unconfined compression tests carried out
on soil-cement samples prepared with different conditions, the following can
be appropriate;
1. The given soil sample had inadequate strength, and addition of cement
will increase the strength and bearing capacity if to be used in construction.
2. Soil-cement samples with higher cement content showed more brittle
failures.
3. The cement content has more influence on unconfined compressive
strength than curing time.
4. To conduct test on 0 days with % of cement it should be tested at least
after the initial setting time of cement.
Conclusions and Recommendations
36
Conclusions and Recommendations
5. According to test results obtained, addition of 10% of cement should be
added for this particular soil to achieve maximum gain in strength and
resistance to water softening.
6. Although more trials with increased cement content are recommended to
attain the optimum cement content which could not be done due to time
limitations. Too high a cement content can cause problems due to shrinkage
and thus this must be taken into account while selecting the cement content.
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References
SOIL IMPROVEMENT & STABILISATION (European Concrete Paving Association).
http://civilengineersforum.com/soil-cement-stabilization/
Zeena Tariq Jaleel Eng. & Tech. Journal, Vol.29, No.6, 2011 “Effect of
Admixtures on the CBR-Value of Sub-base Soil.
Notes on “Soil Improvement Techniques” by Sir Sardar Babar.
Thesis by Hafiz Muhammad Anas, Waseem Waheed and Danish Farooq on
“Stabilization of Problematic Soil using Cement as an Admixture” UET Taxila
(2008)