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JOB#6

Tittle: Stabilization of soil using commercially available OPC

Objective: to study the behavior of soil by mixing of ordinary Portland cement.

Apparatus:

unconfined compression test divices remoulding devices weighing balance and oven.

Test meterials:

Ordinary Portland cement Soil studied in compression test Water

Related theory:

Stabilization:

Improving the engineering properties of soils by chemical, mechanical , physical or physio-

chemical methods is called stabilization.

Engineering properties:

Compaction/density, shear strength,void ratios,and drainage characteristics ets.

Stabilization techniques:

Mechanical stabilization:

In this technique mechanical energy is used to improve the soil mass and the method, in

general ,is known as compaction for the construction of embankments for roads, railways,dams

and levees etc.

generally rollers, vibratory plates,and tampers are used for compaction.

Physical stabilization:

In this technique, the physical properties of the soils are improved by blending two or three

soils, together so as to improve the graduation of mixture to well graded material.this

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technique is usually used in the construction of roads when more then one type of soils are

readily available at or near the site.

The method of stabilization is named after the name of the additive being added to the soils to

improve its characteristics for stability.

Chemical stabilization:

Chemical stabilizers also known as soil binders or soil palliatives, provide temporary soil

stabilization. Materials made of vinyl, asphalt, or rubbers are sprayed onto the surface of

exposed soils to hold the soil in place and protest against erosion from runoff and wind.

chemicals used for stabilization are easily applied to the surface of soil, can be effective in

stabilizing areas where vegetative practices cannot be established, and provide immediate

protection.

Applicability:

chemical stabilization can be used in areas where other methods of stabilization such as

temporary seeding or permanent vegetation are not effective because of environmental

constraints .they can also be used in combination with vegetation or perimeter practices to

enhance erosion and sediment controls.

Cement stabilization:

Cement stabilization is quite frequently used in road construction to improve the stability to the

sub-grade. any soil which can be economically pulverized can be stabilized with cement.

Heavy clays are difficult to pulverize and are not suitable for cement-stabilization.the best soil

for cement stabilization are well graded sand gravel mixtures with at least 10% of the material

passing #200 sieve, and a uniformity coefficient of less then ar equal to 5.

The presence of sulphates and organic matter in soil may make the soil unstable for cement

stabilization.

Cement stabilization prefer in case of non-cohessive soils.

Lime stabilization

Lime stabilization is also a sort of chemical stabilization. Both hydrated lime or quicklime

(unslaked lime) may be used for lime stabilization but the material cost of stabilizing with quick

lime is generally less then with hydrated lime. Handling of quick lime ,however ,is difficult due

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to safety reasons and usually causes health hazards.When unslaked lime is mixed into the soil

the following four reactions take place:

Hydration of lime Ion exchange Cementation(pozzalonic reaction) carbonation

lime stabilization prefer in cases of cohesive clay soils.

Bitumen stabilization:

Certain granular soils, may be stabilized by adding bitumen, such as asphaltic bitumens,cut-back

bitumen, and bitumen emulsions. The bitumen seals the pores of the soil,reducing itspermeability , and may also increase the shearing strength by providing cohesion between the

particles.

Bitumen stabilization is used in places where moisture are very less.

Procedure of test:

1. If density and moisture content of the soil is known, calculate the weight of the dry soilneeded for preparation of three soil sample of 1.5 inch diameter and 3 inch height.

2. add 5% moisture content to the dry soil and mix thoroughly. put some of the soil formoisture content determination.

3. add 3% of OPC to the soil.4. prepare three soil sample of required density by packing the soil in the specimen mould.5. if the sample specimen crumbles easily or a good bearing surface for the platen cannot

be obtained.it is permissible to cap the end using plaster of paris.

6. carefully align the specimen in the compression machine.7. set the load dial gage to zero load and set the deformation dial to zero at this time a

very small load should be on the sample .

8. turn on machine and take load and deformation dial readings as follow10,20,30,.,until the soil fails.

9. compute the unit strain ,the corrected area, and the unit stress, for enough of thereadings to define the stress strain curve adequately. Plot the results on the graph paper

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from the test results, show qu as the peak stress of each test and show the average

value of qu for three tests.

10.draw a mohr,s circle using average qu and show the soil cohesion. If this is not drawnwith a compass the report is unacceptable.

11.perform the test at the same day, one day later and one test after 7 days later.