267 Effect of Lime on Engineering Properties of Cohesive Soil

Soil is a unique natural material and the propertie s of soils can be altered by adding stabilizing agents s uch as lime. Lime is t he oldest traditional stabilizer used for soil stabilization. Lime is one of the several products that can be used in the improvement of the engineering characteristics of soils. This research presents the effect of lime on engineering properti es of cohesive soil. In order to identify and classify this soil, at first physical properties of soil are dete rmined. And then, mechanical property tests are conducted. Next, lime is added to natural soils. Lime contents are selected as 4%, 6% and 8% by weight of na The plasticity index decrease with increasing the percentage of lime content. Soil is mixed with selected lime contents at their maximum dry density . In cohesive soil, the more the lime content, the mo re the cohesion. The lowest value of cohes kg/cm2 at lime 4% and it increases according to lim e content. The percentage of lime increased, CBR valu e is also increased. KEYWORD: Cohesive Soil, Stabilization, Lime

Soil is a unique natural material and the properties of soils can be altered by adding stabilizing agents such he oldest traditional stabilizer used for soil stabilization. Lime is one of the several products that can be used in the improvement of the engineering characteristics of soils. This research presents the effect of lime on engineering properties ive soil. In order to identify and classify this soil, at first physical properties of soil are determined. And then, mechanical property tests are conducted. Next, lime is added to natural soils. Lime contents are selected as 4%, 6% and 8% by weight of natural soils. The plasticity index decrease with increasing the percentage of lime content. Soil is mixed with selected lime contents at their maximum dry density. In cohesive soil, the more the lime content, the more the cohesion. The lowest value of cohesion is 0.59 kg/cm2 at lime 4% and it increases according to lime content. The percentage of lime increased, CBR value

Cohesive Soil, Stabilization, Lime
Cohesive soils are those possessing cohesion. They have a higher water content and a natural tenancy to "ball" together when squeezed. Under pressure from loads these type of soils settle and consolidate over a number of years. These soils contain sufficient quantities of clay to render soil mass virtually impermeable when properly compacted. Such soils Cohesive soil is available everywhere in Myanmar and this is not suitable for engineering construction works.
tion of lime to clayey soils to improve their established practice. Lime used in stabilization is the product of calcining limestone. Lime is most commonly used as a modifier of cohesive soils. The quantity of lime used stabilization of most soils usually is in the range of 2% -10%. The main benefit from lime stabilzation is the reduction of the soil's plasticity, and the soil becomes more rigid. It also increases the strength and workability of the soil, and reduces swell. Soil lime stabilization is more suitable in warm region than in cold region. Soil base course for low traffic roads. It cannot be used as surface course as it has little resistance to abrasion and impact.

II. TESTING OF SOIL METHODS
The following tests are performed to determine the engineering properties of cohesive soils.

Effect of Lime on Engineering Properties of Cohesive Soil
, Technological University, limestone. Lime is most commonly used as a modifier of cohesive soils. The quantity of lime used for stabilization of most soils usually is in the range of 10%. The main benefit from lime stabilzation is the reduction of the soil's plasticity, and the soil becomes more rigid. It also increases the strength and workability of the soil, and reduces the soil's ability to swell. Soil lime stabilization is more suitable in warm region than in cold region. Soil-lime can be used as base course for low traffic roads. It cannot be used as surface course as it has little resistance to abrasion

TESTING OF SOIL METHODS
The following tests are performed to determine the engineering properties of cohesive soils.
Water Content Determination

California Bearing Ratio (CBR) Test
Water Content Determination Water content is defined as the ratio of the weight of water to the weight of solids in the soil. Table 1 shows the specific gravity for various types of soil.

B. Specific Gravity Test
Specific gravity is defined as the ratio of the unit weight of a given material to the unit weight of water. Organic soil Variably but may be under 2

C. Grain Size Analysis
Grain size analysis is the determination of the size range of particles present in a soil, expressed as a percentage of the total dry weight. Two methods are used to find the particle size distribution of soil. 1. Sieve Analysis is used for particle sizes larger than 0.075 mm in diameter, and 2. Hydrometer Analysis is used for particle sizes smaller than 0.075 mm in diameter

D. Atterberg Limit Test
The Atterberg limit tests provide measurements of the water content of clayey soils. Atterberg limit test includes; Liquid Limit (LL) -Liquid limit is defined as the moisture content, in percent, at which the soil changes from a liquid state to a plastic state.
Plastic Limit (PL) -Plastic limit is defined as the moisture content, in percent, at which the soil changes from a plastic stage to a semi-solid state.
Shrinkage Limit (SL) -The moisture content, in percent, at which the volume of the soil mass ceases to change, is defined as the shrinkage limit.
Plasticity index (PI) -Plasticity index is the difference between the liquid limit and plastic limit.

E. Free swell Test
Free swell test is performed to determine the increase volume of the soil. Table2. Shows soil classification based on free swell ratio.

F. Standard Proctor Compaction Test
Use to obtain the maximum dry density of the soil sample and the optimum moisture content. Compaction reduces in soil void ratio by expulsion of air from the voids or by expulsion of water from the voids.

G. Triaxial Shear Test
Triaxial shear test is one of the most reliable methods for determining the shear strength parameter.

H. California Bearing Ratio (CBR) Test
The determination of the potential strength of subgrade, sub-base, and base course material, including recycle materials for use in road and airfield pavement. Classification system on the basic of CBR number is shown in    Fig. 5 shows the variation of consistency limits with lime content. It decreases the liquid limit and increases the plastic limit of cohesive soil resulting in a decrease in plasticity index. The plasticity index decreases from about 45% to 8% for lime contents varying from 0 to 8%. The consistency limits with various lime percent are shown in Table.10.  Fig. 6 and 7 show the comparison of compaction characteristic untreated and lime treated cohesive soil. It can be observed that, the maximum dry density is increases when the lime is added. But the increase in percentage of lime, maximum dry density goes on decreasing. The more the percent dosage of lime, the higher the OMC, the maximum OMC is found at 6% of lime, and at 8%, the OMC is decreased.  Table.12 shows the value of cohesion and angle of internal friction of cohesive soil with and without lime. The percentage of lime from 4 to 6%, the value of cohesion is decreased. It is increased nearly about the value of natural soil at 8% of lime content. The maximum value of angle of internal friction, φ is found at 4% of lime, after that its value decrease with increasing percent dosage of lime.  Table.13. The CBR samples are treated with 4, 6 and 8% of lime are tested under unsoaked condition. The value of CBR increase, the lime content increase. According to Table.3, CBR samples are treated with 4% of lime, the general rating is changed fair to good condition. At 8% of lime, the general rating is very good.   This research deals with the effect of lime on engineering properties of cohesive soil. In this study, to identify and classify the studied soil, physical property tests are firstly carried out. Soil sample is taken from the depth of 3ft. It is used for the water content determination, specific gravity, grain size free swell test, compaction characteristics, triaxial and CBR test. According to the test results, the natural soil can be concluded that; silt, 5.5% of sand and 0% of gravel. And then, the studied soil has specific gravity of 2.71, free swell ratio of 1.83, liquid limit of 74.3%, plastic limit of 28.81%, plasticity index of Shrinkage limit of 6.71%, cohesion of 0.89 10° and CBR of 15. According to Table.1 and 2, the studied soil is inorganic soil and the degree of expansion is moderate. The general rating of studied soil is fair To know the effect of lime gineering properties of cohesive soil, consistency limit, compaction characteristics, triaxial and CBR test are performed. Lime contents are selected as 4%, 6% and 8% of lime by weight of natural soil. From the result of consistency limit, it can be observed that decrease in liquid limit and plasticity index with an increase of lime contents. When the lime contents are increased, the optimum moisture content and maximum dry density is slightly increased. From the triaxial test results, the more percentage of lime, the cohesion is increased but the angle of internal friction is decreased. Not only the CBR value but also the general rating is increased when the dosage of lime increased.