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)

13

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

23

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

24

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

27

Effects of Cement on Atterberg Limits

28

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

29

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.

32

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.

34

35

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.

37

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)