Laboratory Studies on BioLaboratory Studies on Bio--Enzyme Stabilized Enzyme Stabilized Lateritic Soil as a Highway Material Lateritic Soil as a Highway Material

Dr. I.R.Mithanthaya Dr. A.U.RavishankarProfessor Professor & Head

Dept. of Civil Engineering Dept. of Civil EngineeringNMAMAIT, Nitte . NITK-Surathkal.

Lekha B.MResearch Scholar

Dept. of Civil EngineeringNITK-Surathkal.

ContentsContents• Introduction• Objectives of the study• Literature survey• Experimental Investigations• Fatigue Analysis• Field Study• Conclusions• References

STABILIZATION MECHANISMSSTABILIZATION MECHANISMS..

• Mechanical stabilization, whereby the stability of the soil is increased by blending the available soil with imported soil or aggregate, so as to obtain a desired particle-size distribution,

• Mixing or injecting additives such as lime, Cement, sodium silicate, calcium chloride, bituminous materials and resinous materials with or in the soil can increase stability of the soil. Chemicals stabilization is the general term implying the use of chemicals for bringing about stabilization.

CHEMICAL STABILZATIONCHEMICAL STABILZATION

• Mixing or injecting additives:

• Two typesStandard stabilizers :

lime, Cement, sodium silicate, calcium chloride, bituminous materials and resinous materials.

Non standard stabilizers:Sulfonated Oils, Ammonium Chloride, Enzymes,

Mineral Pitches and Acrylic Polymers.

Selection of stabilizerSelection of stabilizer

• Selecting the stabilizer type depends on number of factors including:

• 1. gradation,• 2. plasticity index (PI),• 3. Availability and cost of the stabilizer and

appropriate construction equipment• 4. Its long term effect on strength etc.

Concept of Enzyme Soil StabilizationConcept of Enzyme Soil Stabilization

• Demonstrated by the termites and white Ants –Build the shelter by Ant Saliva- which are rock hard and stand firm despite of heavy rainy seasons.

• Enzyme –Natural , Non toxic , non flammable, Non Corrosive liquid enzyme formulation fermented from vegetable extracts that improves the engineering properties of the soil.

Clay Particle Clay Particle ––Water RelationWater Relation• Behavior influenced by ability

to absorb exchangeable cat ions and the amount of water.– Negative charge on the

surface of clay particles attracts positive (Hydrogen) end of water molecule.

– Water molecules are arranged in a definite pattern-Adsorbed layer

Removal of absorbed water by enzyme Removal of absorbed water by enzyme

• Absorbed water in the structure of soil • Elimination of absorbed water

in he soil

Mechanism of Enzyme StabilizationMechanism of Enzyme Stabilization•Enzyme catalyze the reaction between the clay and the organic cations and accelerate the cat ion exchange process to reduce the adsorbed layer thickness.

Enzyme replaces adsorbed water with organic cations, thus neutralizing the negative charge on a clay particle.

Mechanism of Enzyme StabilizationMechanism of Enzyme Stabilization

The organic cations also reduce the thickness of the electrical double layer. This allows enzyme treated soils to be compacted more tightly together.

Enzyme promotes the development of cementatious compounds using the following, general reaction:

H2o + clay Enzyme Calcium Silicate Hydrates

Net Effect of EnzymeNet Effect of Enzyme

• Film of adsorbed water is greatly reduced.• The soil particles acquire a tendency to

agglomerate• As a result of relative movement , the soil

get condensed which in turn reduces the swelling capacity

Need for present InvestigationNeed for present Investigation

• Recently developed technique.• Produced by number of private agencies• More attention is given in foreign countries• Rigorous technical investigation is very

essential• Unclear how these product will work and

under what condition.• To better understand their potential value

for road construction

Objectives of the InvestigationObjectives of the Investigation

• To study the change of geotechnical properties of the lateritic soil by stabilizing with enzyme.

• Study of quantitative changes in CBR values of blended lateritic soil with different dosage of enzyme.

• Study of fatigue behavior of enzyme stabilized lateritic soil.

Objectives of the Investigation (ContinuedObjectives of the Investigation (Continued))

• To evaluate the influence of various parameters such as dosage of enzyme, curing period, on stress level and frequency of stabilized soil subjected to repeated loading

• Field experimental investigation to study the performance of road constructed using stabilized soil.

Materials UsedMaterials Used

• Lateritic soil • And one commercially available enzyme

Literature ReviewLiterature ReviewLacuoture et al. 1995

Germany The reactions of the soils treated with the enzyme was observed and recorded and compared to the untreated samples

The variation in properties was observed over a period six months

Hitam et al. 1998

Malesiya Road constructed for a length of 27 Km using enzyme stabilized soil

The sections were then monitored for two rainy seasons for erosion due to rainwater and wear due to usage.

Yusof et al. 1998

Brigham Young University

Laboratory experiments with two types of enzymes

Studied for variation in strength and maintenance cost

Brazetti et al. 2000

Thailand Field experiment with six difft. Types of soil mixture with pieces of recycled pavement

The field stretches were periodically tested with DCP to evaluate variation in CBR

Santoni et al. 2001

USA Lab. experiments on two types of soil with two types of enzyme

Variation in Unconfined compressive strength was observed

Literature ReviewLiterature Review(Andrew et al. 2002).

USA The objective was to study the potential applicability of tested enzyme for unpaved road in-situ stabilization.

Evaluated on the basis of statistical measurement of change in CBR strength, soil stiffness and soil modulus

(Isaac et al. 2003).

India 3 types of soil with varying clay content from Kerala were tested

Significant increase in CBR as curing period increases

Manoj et al. 2003).

India Six difft. Types of soil with varying clay content

The field stretches were periodically tested with DCP (Dynamic Cone Penetrometer) equipment.

Mihai et al. 2005

India Practical application for roads

Major district roads in Maharashtra are constructed with enzyme stabilized soil and are working very well.

Variation of CBR with time for soil with very high Plasticity .

Variation of CBR with time for soil with medium Plasticity .

Increase in CBR values is of the range from 130 to 1800 times of the original value(Isaac et al. 2003).

I

Manoj Shukla et.al Manoj Shukla et.al 20032003

• Effect of Bio-Enzyme use on soil stabilization was conducted at Soil Mechanics Laboratory, Thailand (1996) to determine the effects on CBR

• Increase in CBR is more than 100% as compared to 28% -Untreated

• Investigators also reported reduction in gravel loss, road roughness, dust levels on the Enzyme treated road sections.

• Bio-Enzymatic soil stabilization in Road Construction

(Everyman’ Science VOL XLI No.6 March 06 Page No.60-69- Dr. C.Venkatasubramnyam School of Civil

Engineering SASTRA Tanjavur.)

• In this study 5 types of soil (From low to high clay content) are considered.

• Based on strength variation study has been done on cost saving by the use of enzyme stabilized sub base.

• The overall saving in the total cost of construction is 30-40%

• Field study : Prof. Hitam & Yusof-Palm oil research Institute Malaysia (1998)– 27 Kms of road was constructed with enzyme treated soil.– The section of the road was monitored for four monsoons.– No surface damage was observed

Geotechnical propertiesGeotechnical properties

Sl No. Property Lateritic Soil

1 Specific gravity 2.45

2 Grain size distributiona) Gravel, % 19

b) Sand, % 50

c) Silt, % 29d) Clay,% 2

3 Consistency limits (%)Liquid limit 35

Plastic limit 25

Plasticity index 10

4 IS Soil Classification SM-GM

Geotechnical properties of SoilsGeotechnical properties of Soils

Sl No. Property Lateritic Soil

5 I.S standard Compactiona) Max dry density, γdmax (kN/m3)

19.32

b) O.M.C 13.5%I.S modified Compactiona) Max dry density, γdmax(kN/m3)

19.95

b) O.M.C 11.4%6 CBR Value (%)

I.S Standard Compaction

a) OMC condition 10.0 %

b) Soaked condition 4.0 %

I.S Modified Compaction

a) OMC condition 14.0 %

b) Soaked condition 8.0 %

Geotechnical properties of SoilsGeotechnical properties of Soils

Sl No. Property Lateritic Soil

7Un confined compression testI.S Standard Compaction( kN/m2)

108

I.S Modified Compaction (kN/m2)

142

8 Co-efficient of permeabilityI.S standard Compaction (cm/sec)

4.78x10-8

I.S modified Compaction (cm/sec)

2.87x10--8

Experiments on enzyme treated Experiments on enzyme treated soilsoil

• Enzyme is used for stabilization. (Nature Plus-USA).• Physical/Chemical Characteristics of Enzyme• Boiling Point: 212° F • Specific Gravity (H2O = 1): 1.000 - 1.090• Vapor Pressure (mmHg): As Water • Melting Point: Liquid• Vapor Density (Air = 1): 1 • Evaporation Rate : As Water• Solubility in Water: Infinite pH: 3.10 - 5.00• Appearance and Odor: Brown clear liquid

Enzyme DosageEnzyme Dosage

• Enzyme is to be added to water before mixing maintaining the OMC

• It is in terms of ml per m3 of soil• Four dosages are selected• The enzyme is to be mixed with • 200 ml/3.5 m3 to 200 ml/2m3

Enzyme dosage for lateritic soilEnzyme dosage for lateritic soil

Dosage Amount of dosage

Amount required /Kg of soil

1 200 ml/3.5m3 0.029 ml

2 200 ml/3m3 0.0338 ml

3 200 ml/2.5m3 0.0406 ml

4 200 ml/2m3 0.050 ml

UNCONFINED COMPRESSION TESTUNCONFINED COMPRESSION TEST

CP ED1 ED2 ED3 ED4

Lateritic Soil -142 (kN/m2)(Untreated)

1 205 272 343 447

2 262 324 398513

3 330 434 532716

4 428 513 607782

CBR values for treated soilCBR values for treated soil

CP ED1 ED2 ED3 ED4

Untreated 08%

1 17 20 21 23

2 20 23 25 27

3 23 25 27 29

4 25 27 29 31

Variation of Coefficient of PermiabilityVariation of Coefficient of Permiability

CP ED1 ED2 ED3 ED4

k m/sec (10-8)

1 2.87 2.87 2.63 2.63

2 2.63 2.39 2.392.39

3 1.91 1.91 1.911.67

4 1.91 1.67 1.671.67

CBR Values of blended soil with enzymeCBR Values of blended soil with enzyme

Soil-sand(%) CP 1 CP 2 CP 3 CP 4

100-0 25 29 30 31

90-10 27 30 31 32

80-20 24 29 30 31

70-30 22 27 28 30

60-40 21` 24 27 28

Fatigue Behavior of materialsFatigue Behavior of materials• Term FATIGUE refers to premature failure

under the action of repeated loading.• Push-Pull type (Repeated) of loading

system is adopted in Lab.• Depends on :

• Nature of loading• Magnitude of max. load• No. of cycles to failure• Surface finish of test specimen• Temperature

Fatigue AnalysisFatigue Analysis• Fatigue behavior of stabilized soil

under repeated loading.• Test has been performed using

fatigue testing machine.• A cylindrical specimen of length to

diameter ratio of 2 is used.• The Fatigue test equipment that is

capable of applying the repeated loads at a frequency 0 to 12 Hz is used in the present investigation.

Effect of Enzyme content on Fatigue life of Enzyme Effect of Enzyme content on Fatigue life of Enzyme

treated soil specimens at different stress level treated soil specimens at different stress level Lateritic SoilLateritic Soil

Effect of load repetitions on residual static UCSEffect of load repetitions on residual static UCS

•

Effect of load repetitions on Ultimate UCS strengthEffect of load repetitions on Ultimate UCS strength(Lateritic soil)(Lateritic soil)

Effect of curing period on Fatigue lifeEffect of curing period on Fatigue life

Effect of loading amplitude on fatigue lifeEffect of loading amplitude on fatigue life

Fatigue life Vs UCSFatigue life Vs UCS

Stress level Correlation equation of Lateritic soil for Enzyme dosage 2 R² value

30% Fatigue Life=272.2 UCS- 743.7 0.98

40% Fatigue Life =199.6 UCS- 1975 0.98

50% Fatigue Life =161.0 UCS - 5942 0.99

60% Fatigue Life =132.3 UCS- 7916 0.98

80% Fatigue Life =99.68 UCC - 10732 0.98

FIELD EXPERIMENTAL STUDYFIELD EXPERIMENTAL STUDY

• The road selected for the experimental investigation is at Nancharu-Kokkarne Road,Udupi District.

• The construction of road segment for a length of 1.35 Km was done under “Pradana Manthri Grameena Sadak Yojana” scheme.

Index properties of the soil at the site before the Index properties of the soil at the site before the application of Enzymeapplication of Enzyme

Dynamic Cone Penetration Test Dynamic Cone Penetration Test (Treated soil)(Treated soil)

Long Term Effect of enzyme on Long Term Effect of enzyme on soilsoil

• Field CBR was conducted during the month of Feb. 2009 after allowing the road for one rainy season.

• The results were shown that the CBR value is more than 80%. This clearly indicates the long term durability of enzyme treated soil.

ConclusionsConclusions• Soil properties have been improved with

dosage 4.• CBR value increased by 400%• UCC value increased by 450%• Permeability decreased by 42%• Improvement in soil properties by adding

sand ( 80-20).• Effect of enzyme is less for cohesion less

soils• CBR values of enzyme treated soil decreases

with increase in sand content

ConclusionsConclusions• Fatigue Analysis

– Effect of Dosage :For different stress level (30-80 %) it is observed that the fatigue life of the stabilized soil increases with increase in dosage and beyond the dosage 2 the increase is marginal.

– Effect of Curing Period: Showing considerable increase in fatigue life up to 4 to 6 weeks of curing. Further it is marginal.

– Effect on residual UCS strength: Ultimate UCS strength (after repetitions) are higher than the original UCS strength for the specimen cured up to 4 weeks.

ConclusionsConclusions• Fatigue Analysis

– Effect of Dosage :For different stress level (30-80 %) it is observed that the fatigue life of the stabilized soil increases with increase in dosage and beyond the dosage 2 the increase is marginal.

– Effect of Curing Period: Showing considerable increase in fatigue life up to 4 to 6 weeks of curing. Further it is marginal.

– Effect on residual UCS strength: Ultimate UCS strength (after repetitions) are higher than the original UCS strength for the specimen cured up to 4 weeks.

ConclusionsConclusions• Experimental field study

– The road constructed with enzyme stabilized soil has monitored for its performance at regular interval for 8-10 months. The road is performing well and field CBR test indicates that stabilized soil can be used as sub base material very effectively. But prior laboratory study is necessary to get the good result in the filed.

Concluding RemarkConcluding Remark

• Based on experimental analysis, study of fatigue behavior and field study it can be concluded that there is improvement in geotechnical properties of lateritic soil and can be effectively used in the design of flexible pavement with the replacement of WBM layer

ReferencesReferences• Andrew,R., Fadi,S.M., Nicholos, E. and Elahe, M.(2003): “An

Evaluation of Strength change on Subgrade soils stabilized with an Enzyme Catalyst solution using CBR and SSG comparisons”, Report submitted to University Transportation Cente South Carolina State University Orangeburg, SC, USA .

• Andromalos, K.B., Hegazy,Y.A. and Jasperse, B. H. (2000): ”Stabilization of Soils by Soil Mixing,” Proceedings, International Conference on Soft Ground Technology, ASCE, Noorwijkerhout, Netherlands, pp, 194-205.

• Beena, S.(2000): “Suitability of using CBR test to predict Resilient modulus” paper presented for the federal aviation administration airport technology transfer conference Rowan University,201 Mullica Hill Road, Glassboro, NJ 08028.

• Brazetti, R., and Murphy, S.R.(2000): “General usage of Bio-Enzyme stabilizers in Road Construction in Brazil”, 32nd annual meeting on paving, Brazil.

• Boateng P. Y. and Johnson, P. T. (1990): “Estimation of subgrade resilient modulus from standard tests” Journal of Geotechnical Engineering, Vol. 116, pp.68-78.

• Dhinakaran, C. and Prasanna K.R. (2007): “Bioenzyme soil stabilization in road construction”, Everyman’s Science, Vol.XLI No.6, pp.397-400

• Gidigasu, M.D. (1976): “Lateritic Soil Engineering Pedogenesis and Engineering Principles”, Elsevier Scientific Publishing Company, New York .

• Gireesh, B.G. (2008):“study on geotechnical properties of laterite and black cotton soils with Bioenzyme as a stabilizer”, M.Tech. Thesis, National Institute of Technology, Srinivasanagar, Karantaka , India.

• Ganesh, C. (2008): “ Fatigue Behavior of enzyme stabilised soil “,M.Tech. Thesis, National Institute of Technology, Srinivasanagar , Karantaka ,India.

• Hitam, A. and Yusof, A. (1998): “Soil stabilizers for plantation road”, Proceedings, National seminar on Mechanisation in Oil Palm Plantation, , Selangor, Malaysia, pp.124-138.