ground improvement techniques (soil cement stabilization)

Name of Ground Improvement by Home assignment AdmixturesOn part of the Ground Improvementsubject: Techniques

Name of the B.MUNI RAJU(PGCEGE007)Participants: B.CHANDRA (PGCEGE008)

SEKHARUnder the Dr. P.BASAK sirGuidance of:Date of Submission: 25th march 2015

TOPICS TO BE COVERED IN THIS PRESENTATION

Types of admixtures for soil stabilization and their requirementsCement stabilization methods and there applications at siteBitumen application methods at siteLime stabilization methods

TYPES ADMIXTURESWater retentive chemicals

Special stabilizers

Miscellaneous chemicals

Calcium chloride and sodium chloride

Cement, Bitumen, lime (CaO)

Molasses, water proofers, aggregants, dispersants

CALCIUM CHLORIDEMostly used as dust palliativesDeliquescent and hygroscopic- absorbs and holds moisture Reduce and evaporation of soil water by lowering vapour pressure and increasing surface tensionReduce loss of strength of fine soils in soakingSmall increase max-densityFacilitates compactionChief disadvantage is washable

PLANT MIX0.5% of calcium chloride is spreaded at road surface at the rate of 0.25-0.50 kg per square metre

MIX IN PLACE

Flake calcium chloride is spread and throughly mixed at an approximately 0.25kg per square metre per 2.5cm thick of compacted soil

SODIUM CHLORIDESimilar to calcium chlorideElectrolyte and crystallising agentForms dense hard mat with stabilized surfaceChecks tendency for the formation of shrinkage speedCan not be used as surface applicationCan be applied to the soil by plant mix and mix insitu

FACTORS AFFECT THE PROPERTIES AND PERFORMANCE SOIL- CEMENT

soil typeCement Pulverisation and mixingCompactioncuring

For more informationhttp://www.cement.org/think-harder-concrete-/paving/soil-cement

METHOD OF APPLICATION AT SITE

DIFFERENT SOIL CEMENT PRODUCTS

(CLASSIFICATION BASED ON THE APPLICATION )

CEMENT MODIFIED SOIL(CMS)CEMENT TREATED BASE(CBS)FULL DEPTH RECLAMATION(FDR)

For more informationhttp://www.cement.org/think-harder-concrete-/paving/soil-cement

CEMENT MODIFIED SOIL

A cement-modified soil (CMS) is a soil material that has been treated with a relatively small proportion of Portland cement – less cement than is required to produce hardened soil-cement. The objective of the treatment is to amend undesirable properties of problem soils or substandard materials so that they are suitable for use in construction.

CEMENT TREATED BASECement-treated base (CTB) is a strong, frost-resistant base for a concrete or asphaltpavement wearing surface. CTB consists of native soils, gravels, or manufactured aggregatesblended with prescribed quantities of cement and water. CTB can be mixed in-place withon-site soils or mixed in a central plant or pug mill depending on the project requirements.Typical cement contents range from 3 to 10 percent, resulting in 7-day unconfined compressivestrengths from 300 to 800 psi.

FULL DEPTH RECLAMATION

Full-depth reclamation (FDR)with cement is a stabilizing pavement solution in which a deteriorated asphalt pavement and the underlying base materials are pulverized then mixed with cement and water to form a cement-treated stabilized base course. An FDR road can be completed with either an asphalt or concrete surface layer.

FULL DEPTH RECLAMATION

BITUMEN STABILIZATIONPosses adhesive, impermeable propertiesSoluble in carbon disulphateFluid consistency easily applicable at site by heatingMainly used in road and air fieldClassification

Asphalts -naturally occurs(cut back, emulsion)Rapid curingMedium curingSlow curing(road oils)

Tars- obtained by condensation process by the destructive distillation of organic materials such as coal, lignite, peat, wood and oil

SOIL BITUMEN STABILIZATION

BASED ON TYPE OF SOIL AND FUNCTION OF BITUMENSoil –Bitumen: used for cohessive soils for water

proof

Maximum size Less than 1/3rd the compacted thickness of stabilized soil layer

Passing 4.75mm More than 50%

Passing 425micron sieve 35-100%

Passing 75micron sieve 10-50%

Liquid limit Less than 40%

Plasticity index Less than 8%

Gradation and plasticity requirements best suited for soil bitumen

SAND BITUMENused for cohessionless soils such sands, gravels, crushed aggregate which are mixed with bitumenFor this the condition is more than 12% of the material should not pass through 75 micron sieveIn case wind blown sand this may be increased up to 25%

WATER PROOFED MECHANICAL STABILIZATION

Well graded mechanical dense stabilized soils which made water proof by uniform distribution of very small amounts(1to3% ) of bitumen

Surfaces which made with water and abbrassion resistant by the application of slow medium curing or road oilsThese road oils penetrates themselves into the earth

OILED EARTH

LIME STABILIZATIONLime is available in two forms

Quick lime Hydrated or slaked lime

Quick lime is more efficient generally hydrated lime is used hence it is safe to handle

Lime is used to treat sub base and base and sub gradesVery successful in clayey soils in water logged areasImproves durability of mud plaster in low cost houses built with un burnt bricks

The percent lime required for stabilisation can be found by penetration resistant considerationsAmount of lime varies from 2 to 10% of the soil weight

MISCELLANEOUS CHEMICALSMolassesFrom sugarcane industry Lignin from paper industry Ground nut husk and oil cake etc., Can be used for stabilisation

WATER PROOFERS•Natural and artificial resigns and other chemicals like alkyl chlorosilanes, siconates, fatty amines and fatty quaternary ammonium salts •Being naturally water repellent these maintain cohesion in fine soils in presence of excess of water•The quantity required is about 1 to 2%

AGGREGANTSThe treatment of soil with aggregants results in reduction of max-compacted dry density ,in an increase in OMC and permeability hence this type of admixtures can be used in active anti seepage elementsUsed for improving drainage or controlling erosion or for frost heave reductionThe soil strength is improvedUsed for flocculation of fine grained soilsSuch anionic polyelectrolyte, copolymer mallets, and corboxylated cellulose

http://alchemypolymers.com/

DISPERSANTSThese are salts of alkali metals such as sodium hexametaphospateRemoval of a mono valent exchangeable ion of soilIncreases fluidity of soil water system hence it will attains maximum dry density at lower OMCAfter drying water absorption is greatly reducedCompressibility, permeability, frost sussecptabilty can be decreased

REFERENCES http://nbmcw.com/articles/case-studies/28479-a-

study-on-soil-stabilization-through-innovative-material-for-construction-of-rural-roads.html

http://www.cement.org/think-harder-concrete-/paving/soil-cement

Soil engineering in theory and practiceBy Alam singh

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