eefect of cement on asphalt - emulsion ... journal of scientific research and innovative technology...

International Journal of Scientific Research and Innovative Technology ISSN: 2313-3759 Vol. 3 No. 5; May 2016

159

EEFECT OF CEMENT ON ASPHALT - EMULSION STABILIZED

LATERITIC SOILS

B.D. OLUYEMI – AYIBIOWU

Department of Civil and Environmental Engineering

The Federal University of Technology, Akure, Ondo State, Nigeria

ABSTRACT

The influence of the physical characteristics and chemical compositions of three selected lateritic soils on

their engineering behaviour in the natural untreated state and their response to treatment with asphalt

emulsion mixed with cement in varied proportions was investigated in the laboratory. Asphalt emulsion, Colax

A was added to the collected lateritic samples in their natural state and tested, after which small percentages

of cement in varied proportions was used to modify the properties of the asphalt emulsion treated lateritic

samples to evaluate the influence of cement and to determine the best mix ratio. Test results show that adding

asphalt emulsion to the samples generally increase their strength, the rate of increase depending on the type

of soil. Beneficial results were further obtained by adding small percentages of cement to the asphalt emulsion

for treating all the soil samples especially the highly plastic soils which did not respond favourably with only

the use of asphalt-emulsion, thus bringing to usefulness the technology of improving the strength of locally

available weak soils by pre-treating the soil with small amounts of cement prior to the addition of asphalt-

emulsion for increased strength characteristics.

Key Words: Laterites, Lateritic soils, Soil samples, Stabilization, Cement, Asphalt-Emulsion, Mixes,

Laboratory, Tests, Results, Strength.

1.0 INTRODUCTION

Laterites and lateritic soils have over the years been given increased attention by soil engineers because of

their wide spread distribution and engineering applications. Laterites, though abundant in many countries have

varied properties from place to place. This makes their performance diverse and unpredictable (Gidigasu,

1976). These varied properties have brought limitations to their use on some construction sites. Many of these

Limitations have been overcome by the addition of stabilizing agents to improve their properties or by various

other means of soil improvement.

Some of the stabilization methods include the use of cement, lime, fly ash and bitumen depending on the type

of soil and site condition (British Lime Association Digest, 1999). Portland cement has been used with great

success to stabilize natural soil because almost all soils respond to treatment with cement. However, the

chemical conditions of some soils which can inhibit the normal hardening of cement or lead ultimately to loss

of durability or high construction cost for the highly plastic soils have limited their use. Bituminous

stabilization is also being in use for construction purposes all over the world, and so is hydrated lime.

Hydrated lime in its own case increases soil strength primarily by pozzolanic action with the formation of

cementation materials especially in granular materials or lean clays (Little et.al, 2003, Owolabi et.al, 2004).


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Asphalt-emulsion is a liquid mixture which contains asphalt cement, water and an emulsifying agent for road

construction and maintenance and has received wide acceptance by engineers because of their performance

and economic advantage (Coyne. 1976). Asphalt emulsion does not require petroleum to soften it and no heat

is applied during use, thereby contributing to energy saving. It reduces atmospheric pollution because there are

little or no hydrocarbon emissions from it (Coyne and Ripple, 1975). It also has the ability of coating damp

aggregate surfaces. They are widely available in variety of types and there is potential cost savings by the use

of less fuel (Koch, 2002). In the United States, attention had been directed to fuel savings by using asphalt

emulsion instead of cutback asphalt whereby a huge amount of petroleum solvents could be saved annually by

such substitution (American Virtual Productions, 1997.

Generally, a certain type of stabilization activity may not be very successful for all the soils. A soil may be

mixed with one additive to improve its quality in one phase and in a second phase be mixed with another

additive to achieve desired strength. Mixtures of two stabilizers can therefore be used to stabilize soils in that

one of the stabilizers will compensate for the effectiveness of the other on a certain property of the treated

material (National Association of Australia State Road Authorities, 1986).

This paper thus presents laboratory study on the use of cement with asphalt emulsion to stabilize lateritic soils

for use as road foundation and construction materials. This will contribute to sustainable road maintenance and

development.

2.0 MATERIALS AND PROCEDURES

2.1 Materials

The three lateritic soils designated as samples A, B and C used for this work were collected along Ado-Ekiti -

Ikare road, which is a Federal road linking Ekiti with Ondo state in SouthWestern part of Nigeria. Fig. 1 is the

map of Nigeria showing the study area.

For the study, Asphalt-emulsion was used in proportions of 2, 4, 6 and 8% for soil asphalt emulsion mixes.

Portland cement, Type 1 was used in proportions of 1/2, 1 and 2% for the cement modification. The asphalt-

emulsion used is Colax A obtained from Ondo State Asphalt Company, Akure, Ondo State, Nigeria.

2.2 Procedures

The lateritic soil samples in their natural state after collection were stored in polythene bags to prevent

moisture loss. Deleterious materials such as roots were removed prior to their use after which they were air-

dried, broken done with mortar and pestle, and then passed through a No 10 sieve to remove large particles.

To correlate the engineering characteristics of the natural samples with treated ones, laboratory tests such as

Particle size distribution, Atterberg limits, specific gravity, compaction, California Bearing Ratio (CBR) and

unconfined compressive strength, (UCS) were performed on the natural samples.

To improve the engineering characteristics of the soil samples, asphalt emulsion pretreated with cement were

used to mix the soil samples. Mixing of samples was done manually at the optimal moisture content as

obtained from compaction tests. For the cement treated samples, varied percentages of cement were first

mixed with the samples after which asphalt-emulsion with water was added. Specimens were molded in CBR

moulds using the modified AASHTO compaction method for moisture -density relations and CBR values. For

compressive strength determination, unconfined compression test method was used.


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For each percentage of additives, average of four specimens was used to obtain each point on the moisture -

density relation and CBR curves. Nine specimens were used for the UCS; three each for 7, 14 and 28 - day

strength tests. After casting, the specimens were wrapped in nylon bags for curing after which testing for

relevant characteristics were carried out using standard methods. The strength values reported are average of

results of three test specimens for each mixture.

3.0 RESULTS AND DISCUSSION

3.1 Physical Characteristics of Natural Samples

Table 1 shows the Atterberg limits and the textural and chemical composition of the soil samples. The Liquid

limit ranged between 31-55% with plasticity indices between 9 and 26%. The different percentages passing

the number 200 sieves are 34.2%, 32% and 55.5% tor samples A, B and C respectively. The maximum dry

densities are 1.80mg/m3 for samples A and B, and 1.70mg/m

3for sample C with optimum moisture contents of

12.3%, 15.3% and 16.3% for samples A, B and C respectively. The CBR values are 20, 18 and 8% with 28-

day UCS values of 1.20MN/m2, 0.86MN/m

2 and 0.68MN/m

2for samples A, B and C respectively. The low

CBR and UCS values of the three samples indicate their unsuitability for use directly as highway materials

unless otherwise improved.

3.2 Cement Modified Asphalt-Emulsion Stabilized Soils

Addition of cement to lateritic soil samples treated with asphalt emulsion resulted in increased strength over

that of the natural soil samples. This is in accordance with the work of Coyne (1976) which shows that

addition of small percentages of cement will improve the early curing strength of emulsified asphalt mixes.

The results are as shown on Tables 2, 3 and 4 and in Figs. 2 to 10 for samples A. B and C respectively.

3.2.1 Compaction Characteristics

Compaction test results show increase in OMC and MDD of soil-cement-asphalt-emulsion combinations.

Sample A increased from 12.3% OMC at 0 % additive content to 16.3% with 8% asphalt-emulsion modified

with 2% cement. The MDD also increased from 1.80mg/m3 at 0% additive to 1.89mg/m

3 using 2% asphalt-

emulsion with 2% cement content. Further increase in the quantity of additive led to a reduction in the MDD

to 1.78mg/m3 at 8% asphalt-emulsion modified with 2% cement. The OMC of sample B also decreased from

15.3% natural value to 13.2% at 8% emulsion with 0.5% cement but increased with increase in cement

content. Using 8% emulsion with 2% cement gave an OMC of 16.3% and MDD of 1.64mg/m3.

For soil sample C, 4% asphalt-emulsion mixed with 0.5% cement gave the highest MDD value of 1.69mg/m3

at OMC of 16.3%. Increasing the quantity of emulsion led to a reduction in the degree of compaction with an

OMC of 16.6% and MDD of 1.56mg/m3 at 8% emulsion mixed with 2% cement.

3.2.2 Strength Characteristics

To determine the effect of cement on asphalt-emulsion stabilized samples, CBR and UCS tests were carried

out to ascertain the responses of the materials to stabilization. The results are shown on Tables 2, 3 and 4 with

the variations shown in Figs. 2 to 10 for the treated samples.

Addition of 0.5% cement to each percentage of asphalt-emulsion for sample A improved the strength

characteristics. With 2% asphalt emulsion, the CBR value increased from 85% to 145% at 6% emulsion

content. This later reduced to a CBR value of 100% at 8% emulsion content. Adding 1% cement to the varied


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percentages of emulsion brought the CBR value to a maximum of 150% with 6% emulsion, but reduced to

120% at 8% emulsion. Mixing 2% cement for the modification gave CBR values of 120% and 200% with 2%

and 4% emulsion contents respectively. On further addition of asphalt-emulsion, reduction in CBR values

resulted gradually to 125% with 8% emulsion.

For sample B, the CBR values also increased on the addition of cement to asphalt-emulsion mixes. With 0.5%

cement, a maximum CBR value of 95% resulted with 6% asphalt-emulsion, and later reduced to a CBR value

of 80% with 8% emulsion content. Adding 1% cement to modify the asphalt-emulsion gave maximum CBR

value of 119% at 6% asphalt-emulsion and 80% at 8% emulsion content. Pre -treating the emulsion with 2%

cement led to CBR values of 100% and 140% at 2% and 4% emulsion contents respectively. Mixing 2%

cement with 6% and 8% emulsion led to reduction in CBR values to 125% and 115% respectively.

Due to the high plasticity of sample C, maximum CBR value was obtained by using 2% cement with 8%

asphalt -emulsion. The result gave a maximum of 120% CBR value.

Considering Unconfined Compressive Strength test (UCS), the treated samples were tested at 7, 14 and 28

days to determine the effect of curing age on the strength of samples treated. The result is as shown on Tables

2, 3 and 4. For sample A, the result gave UCS strengths of 1.02 MN/rn2 at 7-day and 1.34 MN/m

2 at 28 days

for 2 % asphalt-emulsion modified with 0.5% cement. Treating with 4% emulsion gave a 7 and 28-day UCS

of 3.9MN/m2 and 4.32MN/m

2 respectively. Increasing the emulsion content to 6% reduced the UCS to a 7 and

28-day values of 3.0 MN/m2 and 3.6MN/m

2. At 8% emulsion, a further reduction in UCS to 2.2MN/m

2 7- day

strength and 2.53MN/m2

28-day strength were obtained.

Modifying sample A with 1% cement added to 4% asphalt-emulsion gave a maximum UCS of 4.0MN/m2 at 7

day and 4.66MN/m2 at 28 day strength. With 6% asphalt-emulsion, this decreased to 3.5MN/m

2 at 7-day and

3.80MN/m2 at 28-day; and with 8% asphalt-emulsion, it further reduced to 2.7MN/m

2 7-day and 2.88MN/m

2

28-day strength. Varying emulsion contents with 2% cement with 4% asphalt-emulsion yielded a maximum 7

and 28 - day UCS of 4.85MN/m2 and 5.12 MN/m

2. At 6% emulsion, the result gave 7-day strength of

3.8MN/m2 and 28-day strength of 4.21MN/m

2. While with 8% emulsion and 2% cement, the UCS reduced to a

7- and 28- day strengths of 2.86MN/m2 and 2.98MN/m

2 respectively.

For sample B, using 0.5% cement for modifying the soil samples treated with 2% emulsion content gave 7-

and 28-day UCS of 0.87MN/m2 and l.02MN/m

2; Maximum UCS was obtained with pre-treating with 6%

asphalt-emulsion. This gave 3.01MN/m2 28-day strength, which reduced to 2.41MN/m

2 with 8% emulsion

content. Mixtures of asphalt-emulsion with 1% cement increased the UCS from 7-day strength of 0.96MN/m2

with 2% emulsion content. Further increase in emulsion content to 8% led to a reduced 7-day UCS of

2.5MN/m2 and 2.75MN/m

2 28-day strength. Using 2% cement with 2% emulsion gave a 7-day UCS of

2.9MN/m2 and 3.34MN/m

2 at 28-day. This increased with 4% asphalt-emulsion to a UCS of 3.5MN/m

2 at 7-

day and 3.80MN/m2 at 28-day but later reduced with 8% asphalt-emulsion to 2.60MN/m

2 7-day strength and

2.80MN/m2 28-day strength.

The UCS of sample C also increased on addition of 0.5% cement to the asphalt-emulsion mixes but with a low

range of increment due to its high clay content. It increased from a 7-day strength of 0.58MN/m2 to

1.60MN/m2 by using 2% and 8% asphalt-emulsion contents respectively. Adding 1% cement to 2% emulsion

gave 7-day strength of 0.75MN/m2 and 1.70MN/m

2 with 8% emulsion. Mixtures of emulsion with 2% cement

and 2% asphalt-emulsion gave 7 and 28-day UCS of 1.86MN/m2 and 2.54MN/m

2. This increased to 7-day

UCS of 2.80MN/m2 and 28-day UCS of 3.40MN/m

2 with 4% emulsion and 2% cement. With further increase


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in asphalt-emulsion content, an increased UCS resulted to maximum values of 3.70MN/m2 at 7-day and

4.21MN/m2

28-day values with 8% asphalt-emulsion content.

4.0 CONCLUSION

The results of the investigation presented in this paper showed that beneficial effects were obtained by adding

small amounts of cement to soil-asphalt-emulsion mixes, and specifically the results led to the following

conclusion,

(i) Pre-treatment of fine grained soils with cement facilitates mixing in of asphalt-emulsion and hence

improves workability

(ii) Addition of cement increases the strength of soil-asphalt-emulsion mixtures.

iii) Curing of treated samples increases their compressive strengths.

(iv) For treated samples, there is an optimum amount of additive which gives a maximum compressive

strength depending on the type of soil.

(v) Addition of cement to asphalt-emulsion highly favours soils of high plasticity that does not respond

appreciably with only asphalt-emulsion.

(vi) Modification of asphalt- emulsion with small amounts of cement will lead to reduction in cost of

stabilized soils especially the clay soils which will require a high quantity of cement for their treatment.

(vii) It has been possible to obtain samples of soils stabilized with small percentages of cement added to

asphalt-emulsion and possessing strengths as those of samples stabilized with higher amounts of cement.


164

Table 1: Characteristics of Natural Soil

Soil A B C

Textural composition %

Gravel 3.4 5.8 0.5

Sand 62.4 62.2 44

Fine 34.2 32 55.5

Classifications:

British Soil Classification System, BSCS Very clayed

Sand

Clay of intermediate

Plasticity

Highly Plastic Soil

American Association of State Highways and

Transport Officials, AASHTO

A-2-5 A-2-7 A-7-6

Physical properties:

Liquid limit, % 31 46 55

Plastic limit, % 22 31 29

Plastic index, % 9 15 26

Max Dry Density, Mg/m3 1.8 1.8 1.7

Optimum Moisture Contents, % 12.3 15.3 16.3

Chemical Composition:

pH 5.6 5.4 4.8

Si O2 56.81 56 50.5

Al O3 26.22 26.11 30.93

Fe2 O3 0.88 0.1 0.11


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Table 2: Summary Results of sample A Treated with Asphalt-emulsion and Cement

Emulsion:

Cement (%) OMC % MDD Mg/m3

CBR % UCS 7days USC 14 days UCS 28days

0 12.3 1.8 20 0.85 1 1.2

2:0.5 14.8 1.86 85 1.02 1.2 1.34

4:0.5 15 1.84 120 3.96 4.19 4.32

6:0.5 15.2 1.82 145 3 3.25 3.6

8:0.5 15.4 1.79 100 2.2 2.41 2.53

0 12.3 1.8 20 0.85 1 1.2

2:1 15 1.83 105 2.81 3 3.25

4:1 15.4 1.81 125 4 4.25 4.66

6:1 15.8 1.77 150 3.5 3.72 3.8

8:1 16.1 1.76 120 2.7 2.81 2.88

0 12.3 1.8 20 0.85 1 1.2

2:2 14.8 1.89 120 3.56 3.73 3.9

4:2 15.6 1.83 200 4.85 5 5.12

6:2 15.8 1.82 150 3.8 3.98 4.21

8:2 16.3 1.78 125 2.86 2.9 2.98


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Table 3: Summary Results of Sample B Treated with Asphalt-emulsion and Cement

Table 4: Summary Results of Sample C Treated with Asphalt-emulsion and Cement

EMULSION:

CEMENT %

OMC

% MDD Mg/m3

CBR

% UCS 7days USC 14 days UCS 28days

0 15.3 1.8 18 0.5 0.72 0.85

2: 0.5 13.4 1.74 50 0.87 0.92 1.02

4: 0.5 13.8 1.73 85 2.35 2.79 2.85

6: 0.5 13.1 1.72 95 2.7 2.87 3.01

8: 0.5 13.2 1.7 80 2 2.36 2.41

0 15.3 1.8 18 0.5 0.72 0.85

2: 1 13.6 1.72 75 0.96 1.02 1.16

4: 1 15.4 1.7 98 3.19 3.3 3.46

6: 1 14.2 1.63 119 2.8 2.93 3.01

8: 1 15 1.6 80 2.5 2.61 2.75

0 15.3 1.8 18 0.5 0.72 0.85

2: 2 14.4 1.7 100 2.9 3 3.34

4: 2 15.3 1.68 140 3.5 3.65 3.8

6: 2 15.8 1.66 125 3.01 3.3 3.38

8: 2 16.3 1.64 115 2.6 2.72 2.8

EMULSION:

CEMENT ( %) OMC % MDD Mg/m3 CBR % UCS 7days USC 14 days UCS 28days

0 16.3 1.7 8 0.41 0.5 0.68

2 15.2 1.63 25 0.58 0.95 1.2

4 16.3 1.69 45 0.9 1.16 1.28

6 16.6 1.63 50 1.5 1.65 1.8

8 16.3 1.54 80 1.6 1.8 1.87

0 16.3 1.7 8 0.41 0.5 0.68

2 15.6 1.61 30 0.75 1 1.18

4 15.6 1.6 50 0.95 1.07 1.29

6 16.1 1.58 70 1.2 1.38 1.5

8 16.5 1.55 90 1.7 1.83 s1.95

0 16.3 1.7 8 0.41 0.5 0.68

2 15.8 1.65 40 1.86 2 2.54

4 15.9 1.63 90 2.8 3.15 3.4

6 16.3 1.59 105 3.05 3.2 3.5

8 16.6 1.56 120 3.7 4 4.21

International Journal of Scientific Research

Figure 1: Map of Nigeria Sho

ch and Innovative Technology ISSN: 2313-3759

167

howing Ondo and Ekiti State, Nigeria

Vol. 3 No. 5; May 2016


FIG.2: Variation of OMC, MDD, CBR a

Modified with ½ % Cement

Fig. 3: Variation of OMC, MDD, CBR a

Asphalt Emulsion M

0

2

4

6

8

10

12

14

16

18

0 2 4

0

2

4

6

8

10

12

14

16

18

0 2 4


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and 28-day UCS of sample A Stabilized with 0-8

and 28-day UCS of Sample A Stabilized with 0-

Modified with 1% Cement

6 8 10

OMC %

MDD Mg/m3

UCS 28days

CBR %

6 8 10

OMC %

MDD Mg/m3

UCS % 28days

CBR %

Vol. 3 No. 5; May 2016

8% Asphalt Emulsion

-8%



Asphalt Emulsion M


Asphalt Emulsion M

0

2

4

6

8

10

12

14

16

18

0 2 4

0

2

4

6

8

10

12

14

16

18

0 2 4


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and 28-day UCS of Sample A Stabilized with 0-


and 28-day UCS of Sample B Stabilized with 0-


6 8 10

OMC %

MDD Mg/m3

CBR %

UCS 28days

6 8 10

OMC %

MDD Mg/m3

CBR %

UCS 28days

Vol. 3 No. 5; May 2016

-8%

8%



Asphalt Emulsion M


Asphalt Emulsion M

0

2

4

6

8

10

12

14

16

18

0 2 4

0

2

4

6

8

10

12

14

16

18

0 2 4


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6 8 10

OMC %

MDD Mg/m3

CBR %

UCS 28days

6 8 10

OMC %

MDD Mg/m3

CBR %

UCS 28days

Vol. 3 No. 5; May 2016

8%

8%



Asphalt Emulsion M

Fig.9: Variation of OMC, MDD, CBR an

Asphalt Emulsion M

0

2

4

6

8

10

12

14

16

18

0 2 4

0

2

4

6

8

10

12

14

16

18

0 2 4


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and 28-day UCS of Sample C Stabilized with 0-


and 28-day UCS of Sample C Stabilized with 0-8


6 8 10

OMC %

MDD Mg/m3

CBR %

UCS 28days

6 8 10

OMC %

MDD Mg/m3

CBR %

UCS 28days

Vol. 3 No. 5; May 2016

8%

8%


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Fig.10: Variation of OMC, MDD, CBR and 28-day UCS of Sample C Stabilized with 0-8%

Asphalt Emulsion Modified with 2 % Cement

5.0 REFERENCES

American Virtual Productions (1997); Specialty Emulsions, Site Re-built and Maintained, American Virtual

Productions Co, USA

British Lime Association (1999): Improving Poor Ground Conditions, Lime and Cement Stabilization of weak

soils, Aggregates Advisory Services, Digest No, 058

Coyne, L.D (1976): Emulsion Stabilization Mix Design, Technical Paper No. 172, Chevron Asphalt Company,

San Francisco

Coyne, L.D and Ripple R.M (1975): Emulsified Asphalt Mix Design and Construction, Technical Paper,

Annual Meeting of Association of Asphalt Paving Technology

Dallas N. Little, Eric H. Males, Jan K, Prusmski and Barr Stewart (2003): Cementitious Stabilization, Report

of Committee on Cementitious Stabilization, A2J01, Transport Research Board.

Gidigasu M.D (1976): Laterite Soil Engineering, Pedogenesis and Engineering Principles, Elsevier Scientific

Publishing Company, Amsterdam.

Koch Materials Company (2002): Emulsified Asphalt, Koch Pavement Solutions, USA

National Association of Australia State Road Authorities (1986): Guide to Stabilization in Road works, TRRL,

Technical Information and Library Services, Sydney.

Owolabi, A.O, Oluyemi-Ayibiowu, B.D and Aderinola O.S (2004): Effect of Moisture on the Strength of

Lime Stabilized Lateritic Soils (A Case Study of Ojota, Lagos), Journal of Civil Engineering, Pp 10-15

0

2

4

6

8

10

12

14

16

18

0 2 4 6 8 10

OMC %

MDD Mg/m3

CBR %

UCS 28days

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