lab sheet - sieve analysis

CIVIL ENGINEERING DEPARTMENT

CC304 GEOTECHNICAL 1

1

NO. PRACTICAL WORK : 2 (a)

TITLE OF PRACTICAL WORK : SOIL CLASSIFICATION AND DESCRIPTION OF SOIL

(SIEVE ANALYSIS)

OBJECTIVE :

The sieve analysis determines the grain size distribution curve of soil sample by passing them through a

stack of sieves of decreasing mesh opening sizes and by measuring the weight retained on each sieve. The

sieve analysis is generally applied to the soil fraction larger than 75 m.

THEORY :

BS 1377 : 1990 allows either wet or dry sieving to be used, but the wet method is preferred. After oven

drying, the test sample mass is determined before being separated into two parts, the first comprises

particles that are retained on a 20mm sieve and the second, that passes 20mm. The particles greater than

20mm is dry sieved, while the smaller particles is wet sieved. The sieves which are used are generally

chosen within the size ranges of (in mm) 75, 63, 50, 37.5, 28, 20, 14, 10, 6.3, 5, 3.35, 2, 1.18, 0.6, 0.425,

0.3, 0.212, 0.15 and 0.063. The mass retained on each sieve is recorded, from which the percentage of the

sample passing of each sieve can be calculated. Material passing the 63 micron (0.063mm) sieve is retained

for a fine particle analysis are plotted on a semi logarithmic graph of the form shown in figure 1.0, to produce

a particle size distribution curve, hence allowing the type of soil to be determined.

Having plotted the results of the particle size analysis, the shape of the curve and its position on the chart

can be used to indicate the nature of the soil.

Figure 1 shows the grading curves of a typical soil. Thus a well-graded soil has a curve which was evenly

spread and indicates a wide range of particle size. A uniformly graded soil has a near vertical curve

indicating that the soil particles are approximately the same size. A poorly graded soil is one having a wide

range of particle sizes but in which there is a lack of particles in one or more of the intermediate size ranges.



2

Figure 1

This deficiency, or gap, is indicated by near horizontal section of the curve.

Two additional piece of information can be obtained to define the curve, the effective size and the uniformity

coefficient. The effective size of a soil is defined as the particle size of the ten percent passing fraction of

that soil and is denoted by the symbol d10. The uniformity coefficient is defined as the ratio of the sixty

percent passing fraction size to the ten percent passing fraction size and denoted by the symbol Cu where;

Cu = d60 / d10.

Another quantity that may be used to judge the gradation of a soil is the coefficient of curvature, designated

by the symbol Cc.

Cc = d302 / (d10 x d60)

d10 and d60 have been defined, while d30 is the grain diameter corresponding to 30 percent passing on the

grain-size distribution curve



3

Criteria for Grading Soils

The following criteria are in accordance with the Unified Soil Classification System:

For a gravel to be classified as well graded, the following criteria must be met:

Cu > 4 & 1 < Cc < 3

If both of these criteria are met, the gravel is classified as well graded or GW. If both of these criteria are not

met, the gravel is classified as poorly graded or GP.

For a sand to be classified as well graded, the following criteria must be met:

Cu > 6 & 1 < Cc < 3

If both of these criteria are met, the sand is classified as well graded or SW. If both of these criteria are not

met, the sand is classified as poorly graded or SP

APPARATUS :

The following apparatus are required.

i. Series of standard sieves with opening ranging from 75m to 75mm,

including a cover plate and a bottom pan.

ii. Rubber hammer

iii. Soft wire brush

iv. Mechanical sieve shaker

v. Weighing machine



4

Figure 2 shows photos of the sieving equipment to be used in this test.

PROCEDURE :

Dry Sieving

1. Oven dry a tray of soil sample in approximately a mass of 250g. Allow it to cool.

2. Select a stack of sieves suitable to the soil being tested. A stack of six or seven sieves is generally

sufficient for most soil and applications. The top sieves soil should have an opening slightly larger

than the largest particles. Arrange the stack of sieves so that the largest mesh opening is at the top

and the smallest is at the bottom.

3. Attach a pan at the bottom of the sieve stack. Pour the sample on the top sieve. Add the cover plate

to avoid dust and loss of particles while shaking.

4. Place the stack of sieves in the mechanical shaker and shake for about 5minutes or until additional

shaking does not produce appreciable changes in the amounts of material retained in each sieve.

5. Remove the stack of sieves from the shaker. Measure the weight of soil retained in each sieve.

6. Record the data and plot the passing vs sieve size on a semilog graph.

7. Determine the uniformity and curvature coefficients and the type of soil.



5

RESULT :

Mass of sample: ________________

Sieve size

(mm)

Mass of Sieve + soil

(g)

Mass of empty

sieve

(g)

Mass of

retained soil

(g)

Percentage of

retained soil

(g)

Percentage of

passing soil

(g)

7.5

5.0

2.360

1.180

0.600

0.425

0.300

0.212

0.150

0.075

Pan

Total of retained soil :

From the distribution curve on semilog graph,

Cu = ____________

Cc = ____________

Type of soil = ___________________________________________



6



7

CONCLUSION :

REFERENCE (S) :

lab sheet - sieve analysis

Documents