Experimental Study of Stabilization on Natural Soil Subgrade Using Rice Husk Ash

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I JSRD - I nternational Journal for Scientifi c Research & Development| Vol. 3, I ssue 11, 2016 | ISSN (onli ne): 2321-0613

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Experimental Study of Stabilization on Natural Soil Subgrade using Rice

Husk AshVikash Kumar Singh1 A. K. Saxena2 T. R. Arora3

1M. Tech. Scholar 2,3Professor1,2,3Department of Civil Engineering

1,2,3

Lakshmi Narain College of Technology, Bhopal, India Abstract — The objective of this work is to utilize the

effectiveness of Rice Husk Ash (RHA) material to enhance

the properties of natural soil used for subgrade material in

pavement. The quality of a flexible pavement depends on

the strength of its sub-grade soil. In view of the above the

present investigation has been carried out with rice husk ash

mixed individually and also in combination with locally

available natural soil in different proportions stepped

concentration of 5%, 10%, 15%, 20%, 25% and 30% by dry

weight of the soil individually are used to stabilized of Natural Soil (CL) and to evaluate its properties like Grain

Size Distribution, LL, PL, PI, OMC, MDD, CBR and

Swelling Pressure. The test results indicate that the additionof RHA enhances the percentage of grain size distribution,

but with addition of RHA till 10% the LL, PL, PI andswelling pressure decreases, while these parameters further

increases in this limit beyond i.e. 10% to 30% of RHA while

enhancement is observed above 20% to 30%, Specific

Gravity and Maximum Dry Density (MDD) decrease with

addition of RHA, for all percentage values, whereas OMC

increases in each material. The CBR value increases with

the addition of RHA till 10%, while it decreases beyond the

limit 10% to 30% with addition of RHA.

Key words: Subgrade, Rice Husk Ash, LL, PL, PI, MDD,

OMC, CBR

I. I NTRODUCTION

India has a road network of more than 33 lakhs km which is

the second largest road connecting system in a country in

the world. About 65% of freight and 80% of passengertraffic are carried by the roads. Roads are one of the

strongest measures of economic activity and the

development of any nation. The quality of a flexible

pavement depends on the strength of its sub-grade. The sub-

grade acts as a support for the entire pavement system. In

case of the flexible pavement the sub-grade must be uniform

in terms of properties like index, compaction and strength

etc. Materials selected for use in the construction of sub-

grade must have to be of adequate strength and at the sametime it must be economical for use. If the natural soil is very

soft and weak it needs some improvement for use as sub-grade. It is, therefore, needed to stabilize the existing weak

soil to achieve increased strength and reduced

compressibility.

II. R ELATED WORK

A number of researchers have studies on soil stabilization

for the last few years. Some salient works are as follows; In

1995, Raza and Chandra used were performed used alluvial

soil, Rice husk ash and geo-fabric to stabilize expansive soil.

For this study, they were performed various test such hasCompaction, Swelling, CBR & UCS tests. The result

indicates that soil treated with Rice husk ash gave

considerable improvement in CBR value of soil. With

incorporation of geofabric CBR value further increased. In

2004, Phanikumar and Sharma used expansive soil, Rice

husk ash to stabilize expansive soil properties. For This

study ,the following experimental programme was carried

out such as Free Swell Index, Swelling potential,

Atterberg’s limit, Compaction, UCS, Hydraulic

conductivity. The hydraulic conductivity of expansive soils

decreases when mixed with Rice husk ash .When the Rice

husk ash content increases, there is a decrease in theoptimum moisture content and thus maximum dry unit

weight increases. The undrained shear strength of the

expansive soil blended with Rice husk ash increases with theincrease in the ash content. In 2006, Edil et al. used soft fine

grain soil, Rice husk ash for improvement of soil properties.For This study, atterberg’s limits and CBR test were

conducted. The results indicated that, addition of Rice husk

ash appreciably increased CBR and resilient modulus of

soils. In 2006, J.N. Jha used soft clay soil and Sugarcane

bagasse ash and RHA for the improvement soil properties.

For This study, compaction, USC and CBR test were

conducted. The result shows that addition of RHA enhances

only strength developments but also durability of Sugarcane

bagasse ash stabilized soils. In 2002, Pandian et.al. Rice

husk ash is used for the improvement of soil properties of

black cotton soil. For This study, CBR test was conducted.The results indicated that, addition of Rice husk ashappreciably increases CBR values of expansive soil.

III. MATERIAL USED

The materials used in the present investigation were Rice

husk ash and locally available natural soil. The physical

properties of these materials are summarized in the

following sections.

A. Soil

The Natural soil sample is used in this study were taken

from Lakshmi Narain College of Technology (LNCT)

Campus Bhopal (M.P) from depth of 2.5 m from groundlevel. It contains deleterious substances and of various sizes.

The soil was air dried and pulverized manually. This natural

soil is grey and black in colour.

B. Rice Husk Ash (Rha)

Rice husk ash is basically agricultural waste products

obtained from the rice milling. Rice milling generates a

byproduct know as husk. During milling of paddy about

78/% of weight is received as rice, broken rice and bran, and

rest 22% of the weight of paddy is received as husk. This

was obtained from local rice mill at Sawstik krishi farm in

Mandideep (Near the Bhopal).



Experimental Study of Stabilization on Natural Soil Subgrade using Rice Husk Ash

(IJSRD/Vol. 3/Issue 11/2016/004)


IV. METHODOLOGY & TEST PROGRAMME

All the tests of soil before and after stabilization with

different mixtures of NR Sample were carried out as per the

Indian standard. For laboratory tests specimens of soil with

and without admixtures were prepared by thorough mixingthe required quantity of soil and stabilizers in pre-selected

proportions in dry state and then required quantity of water

was added and mixed thoroughly to get a homogeneous anduniform mixture of soil and RHA. There are various test

performed in laboratory as per IS code standards like test

Grain size distribution, LL,PL,PI, specific gravity,

compaction, OMC, MDD, swelling and California CBR and

their result are discusses by graph and tables which are

given below.

The samples used in the research work are Natural

Soil, Rice Husk Ash (RHA) and Natural Soil stabilized with

varying percentages i.e. (5, 10, 15, 20, 25 & 30%) of RHAindividually for the construction of sub grade soil. These

parents samples i.e. Natural soil, Rice husk ash are named as

N and R notation respectively in further research work. The

artificial Mix Samples i.e. NR which are mix of Natural Soil plus Rice Husk Ash, The details of the prepared samples andtheir notation are discussed below in Table No.1:

S.

No

Details of Prepared

Samples

Notation used for

samples

1 Natural Soil (NS) N

2 Rice Husk Ash (RHA) R

3 Natural Soil + 5% RHA NR-1






Table 1: Details and Notation used for Prepared Samples.

Fig. 1: Natural Soil with RHA Mixture.

V. LABORATORY TEST RESULTS

The laboratory test results for different parameters of NR

Sample are presented in Table No.2 below:

S.N. Properties Natural Soil N NR-1 NR-2 NR-3 NR-4 NR-5 NR-6 R

1

Grain Size Distribution

Gravel (%) 18.4 14.89 15.45 12.35 15.36 12.42 12.48 0.27

Coarse Sand (%) 7.2 7.08 15.43 16.3 15.3 17.3 17.1 4.53

Medium Sand (%) 52.6 50.37 46.84 47.4 46.3 31.6 46.1 40.40

Fine Sand (%) 20.3 22.38 20.08 21.12 19.94 19.82 20.6 46.60

Silt and Clay (%) 1.5 1.74 2.2 2.83 3.1 3.36 3.72 8.20

2 IS Classification CL CL CL CL CL CL CL --

3 AASHTO Classification A-6 A-6 A-6 A-6 A-6 A-6 A-6 --

4 Liquid Limit (%) 26.00 21.00 19.00 22.00 24.00 27.00 31.00 NP

5 Plastic Limit (%) 17.40 14.80 13.20 15.90 17.80 18.60 21.20 NP

6 Plasticity Index (%) 8.60 6.20 5.80 6.10 6.20 8.40 9.80 --

7 Specific Gravity 2.63 2.59 2.54 2.48 2.42 2.36 2.28 1.64

8 OMC (%) 12.18 13.88 16.55 19.90 21.70 22.90 25.78 66.57

9 MDD (gm/cm3) 1.88 1.78 1.68 1.64 1.56 1.47 1.43 0.76

10 CBR (%)Unsoaked 7.04 11.73 13.36 11.19 9.93 8.12 6.68 11.19

Soaked 4.21 6.86 7.58 6.50 5.78 4.69 3.79 6.6811 Swelling Pressure 2.15 1.65 1.40 1.72 1.88 2.06 2.18 1.49

Table 2: Laboratory Test Results for Index, Compaction and Strength Properties of NR Artificial Sample.

VI. R ESULTS AND DISCUSSION

The different properties of soil like Liquid Limit and Plastic

Limit, Maximum Dry Density and Optimum Moisture

Content and California Bearing Ratio are obtained aftercarrying out tests and different change of these soil

properties with addition of RHA Mix are studied as follows.

The different properties of NR Sample like Liquid Limit and

Plastic Limit, Maximum Dry Density and Optimum

Moisture Content and California Bearing Ratio are obtained

after carrying out tests and different change of these Natural

soil (N) properties with addition of RHA (R) are studied as

follow.

A. Index Properties (Grain Size Distribution, LL, PL, PI

and Specific Gravity)

The results of Index Properties tests on the Natural Soil with

the different percentage of RHA are shown inTable.1. The

nature of changes of LL, PL, PI and Specific Gravity with

the different percentage of RHA also presented in Figure

No: 1 to 4 respectively is given below:






Fig. 1: Variation of Liquid Limit with Natural Soil and RHA

Combinations.

Fig. 2: Variation of Plastic Limit with Natural Soil and RHA

Combinations.

Fig. 3: Variation of Plasticity Index with Natural Soil and

RHA Combinations.

Fig. 4: Variation of Specific Gravity with Natural Soil and

RHA Combinations.

B. Compaction Properties (OMC And MDD)

The variation of OMC and MDD with the different

percentages of RHA combinations as shown in Figure No: 5

and 6 respectively shown by below and their details are

given in Table No.1.

Fig. 5. Variation of Optimum Moisture Content with Natural

Soil and RHA Combinations.

Fig. 6: Variation of Maximum Dry Density with Natural

Soil and RHA Combinations.






C. Strength Properties (CBR and Swelling Pressure)

The results of California Bearing Ratio tests on the Natural

Soil with the various mix proportions of RHA in Unsoakedand soaked conditions as shown in Table No: 2.The

different changes of CBR values with different mix

proportions in Unsoaked and soaked conditions are also

presented in fig.7 and fig.8. The comparative Effect in CBR

value of NR Sample towards Natural Soil are also presented

in fig. 9.

Fig. 7: Variation of CBR Value with Natural Soil and RHA

Combinations.

Fig. 8. Variation of Swelling Pressure with Natural Soil

RHA Combinations.

Fig. 9: Variation of Percentage Increase in CBR with Natural Soil and RHA Combinations.

VII. CONCLUSION

The following conclusions may be drawn from the present

investigation on the basis of the laboratory test results of

RHA stabilized with the Natural Soil:

– In Grain Size Distribution, major part of the soil

belong to sand, it has been observed that increasing percentage of RHA decreases the gravel content and

increases the silt and clay content in soil mixture.Investigation also shows that all soil mixture belongs

to CL Class according to IS classification and A-6

Class under AASHTO classification.

– The results of Liquid Limit tests on CL soil goes ondecreasing from 26 to 19%, when RHA Sample is

increased from 0 to 10%, increase in from 19% to 31%

when RHA Sample is increased from 10 to 30% and

further increase of value for 100% RHA is sample

shows non plastic behavior.

– The results of Plastic Limit tests on CL soil goes ondecreasing from 17.4 to 13.20%, when RHA Sample is

increased from 0 to 10% and increase from 13.20 to

21.20% when RHA Sample is increased from 10% to30%.

– The results of Plasticity Index tests on CL soil goes on

decreasing from 8.60 to 5.80 %, when RHA Sample is

increased from 0 to 10% and is increases from 5.80 to

9.80% when RHA Sample is increased from 10% to

30%.

– The results of Specific Gravity tests on CL soil goes on

decreasing from 2.63 to 2.28 with increase in

percentage of RHA from 0 to 30% and 1.64 for 100%

RHA.

– The results of OMC of CL Soil continuously increases

from 12.18 to 25.78% from 0 to 30% of RHA and for

100% RHA its value is 66.57% and MDD decreasesfrom 1.88 g/cc to 1.43 g/cc from 0 to 30% of RHA and

0.76 for 100% RHA.

– The results of Unsoaked CBR of CL Soil goes onincreasing from 7.04 to 13.36% when RHA is

increased from 0 to 10% and is decreases from 13.36

to 6.68% when RHA waste is increased from 10% to

30% and for 100% RHA is 11.19% and in Soaked

CBR of soil goes on increasing from 4.21 to 7.58%

when RHA is increased from 0 to 10% is and is

decreases from 7.58 to 3.79% when RHA Sample is

increased from 10% to 30% and for 100% RHA is

6.68%. In Soaked and Unsoaked CBR test on soil

sample it has been observed that Natural Soil with 10%RHA mix gives maximum value of CBR in both

Soaked and Unsoaked condition.

– The results of Swelling Pressure on CL Soil goes on

decreasing from 2.15 to 1.40 when RHA is increased

from 0 to 10% and is increases from 1.40 to 2.18 when

RHA Sample is increased from 10% to 30% and for

100% RHA is 1.49.

– The results of percentage increment in Unsoaked CBRgoes on increasing from 66.62 to 89.77% with respect

to Natural Soil when RHA is increased from 0 to 10%

and is decreases from 89.77 to -5.11% when RHA

Sample is increased from 10% to 30% and for 100%

RHA is 58.95%. However in Soaked CBR it increasesfrom 62.95 to 80.05% when RHA is increased from 0to 10% and is decreases from 80.05 to -9.98% when






RHA Sample is increased from 10% to 30% and for

100% RHA is 58.67%.

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Experimental Study of Stabilization on Natural Soil Subgrade Using Rice Husk Ash