P H Y S I C O - C H E M I C A L AND E NGINEE RING

P R O P E R T I E S OF SOME K A S H M I R SOILS

CH APTER : FOUR

Very scanty i n f o r m a t i o n is a v a i l a b l e in the l i t e r a t u r e about

the p h y s i c a l nature, overall c h e mical composition, M i n e r a -

logical and e n g i n e e r i n g c h a r a c t e r i s t i c s of K a s h m i r soils. It

was t h e r efore of i n t e r e s t to i n v e s t i g a t e these c h a r a c t e r i s t i c s

of K a s h m i r soils. In this c h ap ter r e sults of these i n v e s t i ­

gations on f o u r d i f f e r e n t K a s h m i r s o i l s 5viz Pa mpore, H a z r a t b a l ,

Chatta r g a m and L a s j a n have been presented.

The X -r ay a n a l y s e s and t r a n s m i s s i o n e l e ctron m i c r o s c o p y of

these soils r eve al the p r e s e n c e of Kaolinite, i llite and

chlorite as the p r i n c i p a l clay m i n e r als. A t t empts have also

been made to s e m i q u a n t i z e these m a j o r clay m i n e r a l s p r esent

in these soils .

4.1. P H Y S I C O - C H E M I C A L P R O P E R T I E S

The r e sul ts of some p h y s i c o - c h e m i c a l i n v e s t i g a t i o n s such as

pH, salt content, i n o r g a n i c carbon, o r ganic carbon and organic

m atter content are p r e s e n t e d in Table 1.

The soil pH was f o u n d to be n early s i m i l a r in all the four

soils rangi ng from 7.7 to 7.9. The soluble salt c o ntent in

the soils has been f o u n d to be ranging from 0.039 to 0 .120 per

cent. The soils f r o m the P a m p o r e and H a z r a t b a l areas showed

4.2

c o n s i d e r a b l e v a r i a t i o n while as the samples from Chatta r g a m

and L a s j a n had almost s i m i l a r salt contents. The i n o r g a n i c

carbon (c arbonate carbon) express ed as CaCO^ ranged from

2.21 to 4.48 p e r cent. The o r g a n i c carbon in soil is m a i n l y

c o n t r i b u t e d by d e cayed p lant and a n ima l residues. The data

for the o r ganic m a t t e r content g r ouped the four soils into

two and worked out to be a p p r o x i m a t e l y 7 and 11 per cent.

It is of i n t e r e s t to poi nt out here that the v a l u e s obtained

for o r gani c m a t t e r content by ^ 2^2 ^ r e a‘*:men^ are m u c h l arger

than the c o m puted v a l u e s (calculated from the o r gan ic carbon

values) . This d i f f e r e n c e may be a t t r i b u t e d to the d i s s o l u t i o n

of some m i n e r a l s and ca rbon a t e s during ^ 2^2 "treatment in

a c i d i c m e di um.

4.2. E L E M E N T A L ANALYSIS

C o n c e n t r a t i o n s of some m a j o r elements of the f o u r soils studied

are p r e s e n t e d in Table 2 for the origi n a l soils as well as

for the o r g a n i c m a t t e r free soils.

The silico n c o n t e n t ranges from about 19 to 26 per cent for

o r i g i n a l soils and 23 to 29 per cent for organ ic m a t t e r free

soils. From the s i l i c o n - a l u m i n i u m ratio (Table 2), it may be

c o n c l u d e d that all the four soils are composed of a l u m i n o -

s i l i c a t e s .

C o n c e n t r a t i o n of total iron ranges from about 3 to 4 per cent

4 .3

in o r i g i n a l soils and about 3 to 5 per cent in o r g a n i c m a t t e r

free soils. L e a c h i n g of soils (original and o r g anic m a t t e r

free) with n e u t r a l I N - N H ^ O A c did not give a s i g n i f i c a n t

quanti ty of iron as compared to the total iron c o ntent of

the soil. It is p r o b a b l e that m o s t of the iron may be p r e s e n t

in soils in f e r r i c form, p o s s i b l y as h y d r o u s oxides and b a s i c

ferric p h o s p h a t e s .

From the e l e m e n t a l analys is of the o r i g inal and organic m a t t e r

free soils, it is evident that C a , Na, K and Mg are the

m a j o r e l e m e n t s p r e s e n t and as d i s c u s s e d later, these ele me n t s

appear as m i n e r a l c onsti t u e n t s .

4.3. B A S E E X C H A N G E CAPACITY

It is well known that the i o n - e x c h a n g e p r o p e r t y of soils is

due a lmost e n t i r e l y to the clay f r a c t i o n s and o r ganic m a t t e r

present in them. A v a r i e t y of t e c h n i q u e s for the base e x c h a n g e

c a p a c i t y ( CEC) d e t e r m i n a t i o n gives a wide range of CEC v alues

for the same soils. The CEC of soils, on the other hand, is

largely d e p e n d e n t on the amount of o r g anic m a t t e r and the

44type and c o n c e n t r a t i o n of the m i n e r a l present.

The values of base e x c h a n g e capac i t y (meq/gm) are p r e s e n t e d

in Table 1 for the f o u r soils studied. These range from 0.27

to 0.61 for the o r i g i n a l soil and 0.23 to 0,50 for the soils

free from o r g a n i c m a s t e r .

It is known that the CEC for K a o l i n i t e ranges from 0,03 to

0,15, for illite and chlorite it ranges from 0,10 to 0.40

and for h a l l o y s i t e 41^0 it ranges from 0.40 to 0 t50 m e q per

gm. The o b s e r v e d v a l u e s of CEC for the four s oils studied

depict that the clay m i n e r a l s p r e s e n t in these soils are

domina n t l y Kao lin i t e , illite and chlorite. The values

obtained for P a m p o r e and C h a t t e r g a m soils also p o i n t to the

presenc e of h a l l o y s i t e m i n e r a l s in these soils.

4.4. L E A C H A B L E ELEMENTS

It is well known that in the d y n a m i c p r oc ess of d i s t r i b u t i o n

of elements in d i f f e r e n t m a t r i c e s of an e n v i r o n m e n t , labile

compon ents are inv olved at any p a r t i c u l a r time. The labile

componen ts may be t h o ught to consist of the b a s i c c h e m i c a l

componen ts or ele ments of the m a t r i c e s that b e c o m e a v a i l a b l e

for p a r t i c i p a t i o n in b i o l o g i c a l , p h y s i c a l and c h e m i c a l i n t e r ­

actions in an e n v i r o n m e n t . ^

The data of the leach ing e x p e r i m e n t s conducted on the o r i gin al

and o r g a n i c m a t t e r free soils are p r e s e n t e d in Table 3. The

p e r c e n t a g e s of the l e a c hable e l e ment s of the total p r e s e n t

in the soils as c a l c u l a t e d are p r e s e n t e d in Table 4 for

or i gi nal and o r g a n i c m a t t e r free soils. It may be p o i n t e d

out that the total l e a c h a b l e elements obtained for four soils

studied are much m o r e than that can be e x p l ai ned by base

exchange c a p a c i t y ob tai n e d for the same soils. The CEC is

4 ,4

4 .5

lower by a f a c t o r 1.2 to 1.9 for all the soils s tudied. The

h igher v a lues may be a t t r i b u t e d to the p r o g r e s s i v e s o l u b i ­

lization of the m i n e r a l s p r e s e n t in the soil. It is known

that the p r o c e d u r e adopted for base e x c han ge capacity

d e t e r m i n a t i o n i n f l u e n c e s the s o l u b i l i t y of the m i n e r a l s , as

a r e s u l t of which some soluble m i n e r a l s get l e ached out and

do not p a r t i c i p a t e in the cation e x c h a n g e process .

Fu rthermore , it may be said that in leaching p r o c e d u r e

e x c h a n g e a b l e eleme n t s and the s o l u b i l i z e d clay m i n e r a l s

appear in the l e a c hates along w i t h the s o l u b i l i z e d h y dr ous

oxides, a r a g o n i t e and dolo mite.

CALCIUM

The data for the l e a c h a b l e calcium ranges 'from 6 .443 to

12.492 m g/gm for the o riginal soils and from 5.48 to 5.96

mg/gm f o r o r g anic m a t t e r free soils. Calcium a c c o u n t e d for

about 13 to 25 per cent of the total l e a c h able p r e s e n t for the

original soils and for about 15 to 22 per cent of the total

from o r ganic m a t t e r free soils (Table 4). This suggests that

calcium is the p r e d o m i n a n t l e a c h a b l e element and as much as

65 to 84 per cent of the total l e a c h a b l e elem ents is calcium.

Thus, it may be c o n c l u d e d that c a lcium may be p r e s e n t in the

soils as a m i n e r a l c o n stituent.

4.6

MAGNESIUM

leachable m a g n e s i u m values were found to be ranging from about

0.5 to 1.40 m g / g m f o r origi nal soils and 0.5 to 1.22 for

organic m a t t e r free soils. M a g n e s i u m a c c o u n t s for n earl y 6

to 23 p e r cent of the total p r e s e n t in the o r i g i n a l soils and

for about 6 to 14 per cent of the total l e a c h a b l e e l e ments

from orig i n a l soils.

POTASSIUM

Values for l e a c h a b l e K from the soils studied lies in the

range of a bout 4 to 12 per cent of the total K p r e s e n t in the

original soils. However, l o w e r values were obtained for

organic m a t t e r free soils for l e a c h a b l e K. N e a r l y 4 to 13 per

cent of the total l e a c h a b l e P o t a s s i u m in all the four soils is

accounted for K. Thus, it may be c o n c l u d e d that p o t a s s i u m

appears as a c o n s t i t u e n t of clay m i n e r a l s .

§ILIC0N

Silicon may be p r e s e n t in the soils as a h y d r o u s material,

amorphous or s o l u b l e silica. The v a l u e obtained for silicon

ranges from 0.17 to 0.24 per cent of the total p r e s e n t in

soils. This may be a t t r i b u t e d to the surface d i s s o l u t i o n of

the s i l i cate m i n e r a l s by the extra c t a n t . M o r e o v e r , much

deviation was n o t observed for the values of s i l i c o n for

organic m a t t e r f r e e soils sugges t i n g that s i licon is not

4.7

p r e s e n t as soluble silica in these soils.

IRON

The amounts of iron obtained were only 0.04 to 0.15 per

cent of the tot al Fe p r e s e n t in the or iginal soils. 0.10

to 0.68 per cent only of the t otal l e a c h a b l e e l e m e n t s in

the soils s t udied is a c c o u n t e d for by iron. This s u g gests

that a small p e r c e n t a g e of iron may be in the a v a i l a b l e

form and the rest of it may be c o m p lexe d with soil organic

m a t t e r , as h u m i c and f u l v i c acids c o n t r i b u t e g r e a t l y to the

a b i l i t y of soil organic m a t t e r to remove m e t a l l i c ions such

n <1as F e (111) and A 1(111) from solution. The u n a v a i l a b l e

iron may also be a s s o c i a t e d with the clay m i n e rals.

4.5. THE CLAY M I N E R A L S

The clay m i n e r a l s of the four soils studied were c h a r a c t e r ­

ized by using X-ray diffra c t i o n , D i f f e r e n t i a l thermal

a n a l y s i s and T r a n s m i s s i o n e l e c t r o n m i c r o s c o p y . Attem pts have

been m a d e to s e m i q u a n t i z e the m a j o r clay m i n e r a l s p r e s e n t

in soil. The s e m i q u a n t i z a t i o n of v a r i o u s clay m i n e r a l s is

b a s e d on the p r i n c i p l e that the i n t e n s i t y of X-rays d i f f r a c t e d

by a m i n e r a l is related to the amount of that mineral,

p r o v i d e d the o p e r a t i n g c o n d i t i o n s are kept c o n s t a n t t h r o u g h o u t

92 93the sc ann i n g p e r i o d of the sample. B r o w n and B i s c a y e

s u g g e s t that the peak areas in the d i f f r a c t o g r a m s give a

, - 94b e t t e r e s t i m a t e of the clay m i n e r a l c o n c e n t r a t i o n . G r i f f i n ,

.95 96V e m u r i and K unze and Scaffe have shown that the use of

peak h e i g h t s in c a l c u l a t i n g the relative clay m i n e r a l4'

co n c e n t r a t i o n is e a sier and faster. Howev er, H a r l e y at

al (1963), H a r l o n ( 1 9 6 6 ) and A w a s t h i ( 1979) c o n c l u d e d that

for the e s t i m a t i o n of rela tive a b u n d a n c e of clay m i n e r a l s

e i t h e r of the m e t h o d s can be used. The peak h e i g h t m e t h o d

has been used in the p r e s e n t study for the e s t i m a t i o n of

r e l a t i v e c o n c e n t r a t i o n of m a j o r clay m i n e r a l s such as illite,

c h l orite and Kaol in i t e .

The X-ray d i f f r a c t o g r a m s for these four soils are p r e s e n t e d

in Fig. 4 and thei r DT curves are p r e s e n t e d in Fig. 5. The

t r a n s m i s s i o n e l e c t r o n m i c r o g r a p h s for all the four soil samples

are p r e s e n t e d in Figures 6 to 9. The e l e c t r o n m i c r o g r a p h s

of the soils confirm the p r e s e n c e of the m i n e r a l K a o l i n i t e

and illite in them. However , the p r e s e n c e of h a l l o y s i t e has

been c o n f i r m e d in the soils from H a z r a t b a l and L a s j a n

areas .(Figures 7b, 9a and 9b).

The peaks in the X-ra y d i f f r a c t i o n p a t t e r n s for v a r ious

m i n e r a l s were i d e n t i f i e d by their b a s a l r e f l e c t i o n s . The

r e l a t i v e c o n c e n t r a t i o n of K a o l i n i t e , illite and c h l orite in

the soils s t u d i e d are given below:

4 . 8

Soil K a o l i n i t e (K ) I l l i t e (I ) Chlorite K/I

P 28.91 53.00 18.07 0,54

H 42.01 44.19 13.77 0.95

CH 43.04 44.94 12.01 0.95

LAS 23.30 52.43 24.25 0.44

A b r i e f d e s c r i p t i o n of the m i n e r a l s found in the four

samples studied is gi ven below:

K A O L I N I T E

The r e f l e c t i o n s of 7 .1A°(12.3°), and 3.58A° (24.9°) from the

001 and 002 p l a n e s in the d i f f r a c t i o n p a t t e r n s ( F i g . 4) for

all the f o u r soils i n d i c a t e the p r e s e n c e of K a o l i n i t e . A

2.52A° (35.5°) r e f l e c t i o n was also obtained for K a o l i n i t e

(Fig .4-P ,H &. CH ) . The e l e c t r o n m i c r o g r a p h s c o n f i r m the

p r e s e n c e of K a o l i n i t e m i n e r a l in all the four soils. Well

formed, six sided f lakes (Figures 7b, 8a, 9a and 9b) show

that the m i n e r a l is well c r y stalli zed.

The c o n c e n t r a t i o n of K a o l i n i t e for the soils from H a z r a t b a l

and C h a t t a r g a m areas was found to be n e a r l y the same and

showed c o n s i d e r a b l e v a r i a t i o n both for L a s j a n and P a m p o r e

soils .

ILLITE

It is the d o m i n a n t m i n e r a l p r e s e n t in all the four soils.

The m i n e r a l is i d e n t i f i e d by its peaks around 1 0A° (8.8°)

and 5.0A° (17.7°) due to the 002 and 004 r e flections f or

all the four soils. A 2.42A° (37.0°) reflection was also

o b s e rved in all the d i f f r a c t i o n p a t terns except f or H a z r a t b a l

soil. The small i r r e g u l a r a g g r e g a t e s of poorly d e f i n e d

flakes as o b s e r v e d by e l e c t r o n m i c r o s c o p y (Figures 7a and 8b)

confirm the p r e s e n c e of illite. However, l a r g e r and thicker

4 .9

4.10

flakes with b e t t e r defined edges have also been observed

(Figures 6a, 6b and 9b).

The p e r c e n t a g e of illite v aries from 44.1 to 52.9 per cent

for all the soils.

CHLORITE

Various peaks for chlorit e m i n e r a l were c h a r a c t e r i z e d by its

reflections from 003 ( 4 . 7 B A 0 ) and 004 ( 3 . 5 3 A 0 ) planes. It

is r a t h e r d i f f i c u l t to i d e n t i f y chlorite m i n e r a l in a mixture,

with the help of 002 (7.0A°) b asal reflect ion. Since, both

Kaolinite and c h l orite give this refl ection. In the case of

Chattargam soils a peak at 19.9°(28) was also observed for

chlorite. The p e r c e n t a g e of chlorite was found to be nearly

similar for H a z r a t b a l and Chatta r g a m soils, . Of the four soils

studied, L a s j a n soil was found to have the largest p e r c e n t a g e of

chlorit e .

HALLOY SITE

The 4.42 and 2.50A° re f l e c t i o n s from 11- and 20- planes

indicate the p r e sence of h a l l o y s i t e m i n e r a l in the soils from

H a z r a t b a l and L a s j a n areas (Fig. 4, H &. LAS). No r e f l e c t i o n s

have been observed for this m i n e r a l in the case of C h a t t a r g a m

and P a m p o r e soils. The presence of h a l l o y s i t e as t u b u l a r

particles was also c o n f irmed by e l e c t r o n m i c r o s c o p y (Figures 7b,

9a and 9b ) .

4.11

Intense r e f l e c t i o n s from 101 and 100 p lanes (26.8° and 20.8°,

26 r e s p e c t i v e l y ) have been observed for quartz. A r e f l e c t i o n

at 2.43A° (36.5°) c o r r e s p o n d i n g to quartz has also been

observe d for H a z r a t b a l and L a s j a n soils. A r e f l e c t i o n at

3.17A° (28.1°) has been observed for all the f o u r soils.

This may be a t t r i b u t e d to the m i n e r a l f e l d s p a r which m a y be

as s o c i a t e d with quartz.

The peaks at 23.0° and 39.4° (20), i n d i c a t e the p r e s e n c e of

a n o n - c l a y m i n e r a l c a l c i t e . A r e f l e c t i o n from basal (104)

plane (30.2°, 20) has been observed for calcite in all the

four soils. The r e f l e c t i o n s around 22.0° (4.03A°) and 30.8°

(2.89A°) a p p e a r e d in all the soils e x cept for P a m p o r e soil,

i ndica t i n g the p r e s e n c e of d o l omite in these soils.

It is well known that the c h a r a c t e r i s t i c e n d o t h e r m i c rea ct i o n s

are m a i n l y due to the d e h y d r a t i o n and loss of l a t t i c water.

Whereas, e x o t h e r m i c r e a c tions are due to the f o r m a t i o n of

44 9 78,9 8new p hase s at e l e v a t e d temper a t u r e s . ’

A f airly well d e fined e n d o t h e r m around 100 to 1 1 5°C

(Fig. 5 - H ,CH and LAS) but for P a m p o r e soil which showed

poor e n d o t h e r m i c r e a ction at 95°C (Fig. 5,P), i n d i c a t e the

loss of h y d r o x y l w a t e r p r o b a b l y from the m i n e r a l illite.

The shift of e n d o t h e r m i c r e a c t i o n towards l o w e r t e m p e r a t u r e

in P a m p o r e soil e x h i b i t p oo rly c r y s t a l l i n e n a t u r e of this

m i n e r a l .

4.12

An e n d o t h e r m i c reaction appe aring b e t w e e n 550 to 650°C in all

the four soils may be a t t r i b u t e d to the loss of OH l att ic

water from K a o l i n i t e and illite. It is i m p o r t a n t to point

out that this peak also s i g n ifies the phase t r a n s f o r m a t i o n

of quartz m i n e r a l from alpha to beta form.

The e n d o t h e r m near 880°C in all the f o u r soils i n d i c a t e s the

presence of illite. A r e l a t i v e l y flat e x o t h e r m i c peak near

950°C i n d i c a t e s the p r e s e n c e of K a o l i n i t e m i n e r a l .

A broad and s h a l l o w e n d o t h e r m b e twee n 200 to 550°C is observ ed

in all the four soils which may be due to the d e c o m p o s i t i o n

of organic m a t e r i a l s p r e s e n t in the soils.

4.6. THE E N G I N E E R I N G P R O P E R T I E S

A complete s p e c t r u m of the nature and b e h a v i o u r of soil can

be prepared only when its en gine e r i n g p r o p e r t i e s are also

investigated. The u n d e r s t a n d i n g of e n g i n e e r i n g p r o p e r t i e s

of the soil is also e s s e n t i a l both for the a p p l i c a t i o n of

the p r esent m e t h o d s of soil s t a b i l i z a t i o n for p r o d uc ing

durable e a rthen s t r u c t u r e s and for achieving f u r t h e r p r o g r e s s

in this field.

Some of the e n g i n e e r i n g p r o p e r t i e s such as G r a i n size,

Atterberg i n d i c e s , c o m p r e s s i b i l i t y and shear s t r e n g t h are of

primary i m p o r t a n c e from a p r a c t i c a l standpoi nt. The results

of the p h y s i c a l and some of the engine e r i n g p r o p e r t i e s of the

four soils i n v e s t i g a t e d are p r e s e n t e d in Table 5.

4.13

4.6.1 THE G R A I N SIZE

The soil c o m p o n e n t s have been c l a s s i f i e d as sand, silt and clay

The grain size d i s t r i b u t i o n curves of the four soils i n v e s ­

tigated are p r e s e n t e d in Figur es 10a and 10b. It is c l e a r from

these curves that the four soils have high silt content, ranging

from 67 to 77 per cent. This fraction has been found to be

almost the same for C h a t t a r g a m and L a s j a n soils. P a m p o r e soil

contains only 5.5 per cent clay. H a z r a t b a l soil has been

found to contain a bout 14 per cent clay. The sand f r a c t i o n

ranges from 16.5 to 23 per cent in the case of all the four

soils .

The nature of the slope of the grain size d i s t r i b u t i o n curve

99indicates the g r a d a t i o n of soils. B azen p r o p o s e d that the

gradation of soils can be expre s s e d as u n i f o r m i t y c o - e f f i c i e n t

(Cu) as:

Q ~7according to M I T classi f i c a t i o n .

The size ranges are as

5and 2.0 to 0.06 mm

Silt 0.06 to 0.002 mm

Clay less than 0.002 mm

where, Dgg is the e f f e ctive d i a m e t e r of the soil p a r t i c l e of

which 60 per c e n t of the soil weight is fine r and is the

4 . 1 4

corresponding v alue at 10 per cent finer. The u n i f o r m i t y

coefficient v alues for the four soils, viz; P,Hs,CH and LAS

are 7.11, 10,20 and 27.5 r espec t i v e l y . These values clearly

indicate that C h a t t a r g a m and Lasjan soils fall under the

category of well graded soils. ^

4.6.2. ATTERBERG INDICES

The liquid limit values for the four soils i n v e s t i g a t e d have

been c al culated from their respe c t i v e f l o w curves (Fig. 11a

and 11b) and were found to be ranging from 25.5 to 36.7 per

c e n t .

The p l as tic limit varies from 14.3 to 25.2 per cent for all

the four soils. The p l a s t i c i t y index for the four soils have

been found to range from 5 to 15.4. It is. evident from the

plasticity index that P a m p o r e soil exhi bits much lower de gree

of plasti c i t y whereas a m o d e r a t e p l a s t i c nature is shown by

Chattargam and L a s j a n soils.

The p r o p e n s i t y of soils for u n d e r g o i n g changes in volume in

the p resence of varying m o i s t u r e contents has been d e f i n e d

as Activity N u m b e r (A). The quantity of water involved in

effecting the change in v o l u m e is d e p e ndent largely upon the

type and q u a nt ity of coll o i d a l clay 'fraction. This r e l a t i o n -

101ship is e s t a b l i s h e d with p l a s t i c i t y index (PI) ass

A = P i / p e r cent less than 0.002 mm

4.15

In general, the more active a clay is the g r e a t e r will be

the change in its v olume when it p asses from the liquid

limit to the s h r i n k a g e limit.^

The a c t ivi ty n u m b e r for the soils in question, have been

calculated from their p l a s t i c i t y indices and clay f r a c t i o n

concentrations. The v a l ues obt ained for all the f o u r soils

show n o rmal clay be havi o u r .

4.6.3. P E R M E A B I L I T Y

The rate of f l o w of water through the soil was d e t e r m i n e d on

remoulded samples p r e p a r e d at optimum m o i s t u r e conte nt and

maximum dry d ensity. The p e r m e a b i l i t y of the f o u r soils

studied has been found to range from 1.07 x 10 ^ to 7.B9 x

10 ^ cm/sec. The p e r m e a b i l i t y of the soi'l is much effected

by compaction. The soil co mpacted to the same d e n s i t y on

the dry side of the optimum is u s ually found much more

permeable than when compacted on the wet side. This is

because of the p r e s e n c e of more randon or f l o c c u l a t e d

structures in the soil, when c o m p acte d on the d r y side of

the optimum than wet side. H o w ever, the pore v olume is same

4.16

in both the cases.

4.6.4. C O M P A C T I O N AND C O M P R E S S I V E S TRENGTH

The c o m p a c t i o n s u b s t a n t i a l l y i n f l u e n c e s the f ut ure b e h a v i o u r

such as st rength, p e r m e a b i l i t y , s e t t l e m e n t and erosion

resistance of any e a rthen s t r u c t u r e . The i n i t i a l m o i s t u r e

content in soil g r e a t l y i n f l u e n c e s the c o m p a c t i o n of the

dry soils and therefore, d e t e r m i n e s the e f f e c t i v e n e s s of

the contact p r e s s u r e applied. The optimum m o i s t u r e content

has been d e t e r m i n e d by p l o tting the i n i t i a l m o i s t u r e content

and dry d e n s i t y of soils and is shown in F i gures 12a and 12b.

The per cent optimum m o i s t u r e content and m a x i m u m dry d e n s i t y

of the four soils studied ranges from 12 to 17-4 per cent

3and 1.63 to 1 .82g»n/cm r e s p e c t i v e l y .

The soils c o m p a c t e d on the dry side of the o p timum sw ell when

water is made ava ila b l e . This is p r o b a b l y due to the i n c rea se

in the t h i c k n e s s of the double layer as the soil p a r t i c l e s

try to a t tract more w ater and i n c r e a s e the pore water t e nsion

in the pore spaces, and therefore, incre a s e the i n t e r g r a n u l a r

pressure and result in g r e a t e r s t r ength in the as m o u l d e d

99s t a t e .

The co mpre s s i v e strength was d e t e r m i n e d on soil remoulded, to:

its m a x imum dry d e nsity and o p t imum m o i s t u r e c o nte nt level.

4 . 1 7

The m e a s u r e m e n t was carried out on c o m p a cted c y l i n d r i c a l

samples of 3 s' height and 1.5" base diameter. The UCC

strength has been found to range from 32 to 51 N / c m 2 for

all the soils studied.

4.18

P h y s i c o - C h e m i c a l . r o p e r t i e s of some K a s h m i r V a l l e y soils

5 oils

P a r a m e t e r £ H CH LAS

1. pH v a l u e 7.8 0 7.90 7.70 7 . BO

(7.65) (7.85)

2. E l e c t r i c a l 0.268 0.851 0.474 0.504C o n d u c t i v i t y(m mho/cm.)

3. Salt content 0.039 0.120 0.070 0.074(W'/o)

4. I n o r g a n i c carbon 2.21 2.69 4.48 3.79as CaCO^tWTi)

5. O r g a n i c carbon 2.51 2.57 3.0 4.0

(2.95)

6. O r g a n i c M a t t e r 5.08 4.43 5.17 6.89

-

Table-1

U r q a n i c H a t t e : (\d% ) (C o m puted value)

7. O r g a n i c M a t t e r 7.17 7.91 11.23 11.74(Vi%) (e s t i mat edvalue)

8. B a s e e x c h a n g e 0 . 6 1 0 * 0.276 u.454 0 .310

g m ? aC;Lty(meq/ 0 . 5 0 9 * * 0.233 0.398 0.271

V a l u e s in b r a c k e t s are d u p l i c a t e v a l u e s

* O r i g i n a l soil

** O r g a n i c m a t t e r free soil

4.19

E l e m ental Analysis of somt K a s h m i r Vallej soils (on dry weight basis)

ELEMENT SOILS

T able-2

(Mg/gm)

P

OS OFS

H

OS OFSCH

os OFS

LAS

OS OFS

Si 24 5.12 286.67 194.88 237.67 261 .35 294 .0 265.51 291 .08

Fa 36.03 40.58 43.28 48.10 35.61 36.36 35.19 3 6 .79

Al 74.61 79.0 75.64 80.37 81 .08 83 ,24 67.09 71 .71

Ca 4 3.24 33.63 44 .53 38 .40 36.99 25.18 4 6.23 34 .83

l\! a 16.86 21 .86 20.72 24.96 18.72 26.69 20.34 24 .36

K 17.49 22.49 14 .63 19.97 13.23 18.71 14.18 13 .11

Mg 14 .84 19.69 12.06 17.21 7.41 14.74 6.10 1 1 .07

P*

1 .46 1 .54 1 .78 .J .87 1 .68 I .81 1 .32 1 .4 6

Si/Al 3.28 3.61 2.64 2.95 3.22 3 .53 3.91 4 .05ratio

O S - O r i g i n a l soil

O F S - O r g s n i c m a t t e r free soil

4 .20

Leachable elem e n t s obtained on leachin g of some K a s h m i r Valley soils

ELEMENT SOILS

T able-3

(Mg/gm) P H CH LAS

OS OFS OS OFS OS OFS OS OFSCa 11.105 5.575 6.868 5.960 1 2.492 5.767 6.443 5.480

Mg 1 .039 1 .002 0.844 0.890 0.524 0.519 1 .406 1 .225

Na 0.649 0.699 0.799 0.049 0.689 0.749 1 .005 0.974

K 2.110 1 .974 0 .049 0.946 0.624 0.749 0.4B0 0.599

Si 0.472 0.509 0.4 76 0.504 0.458 0.495 0.44 9 0,436

Fe 0.016 0. C 1 6 0.066 0.063 C .023 0.024 0.025 D.C27

OS-Original soil

OFS-Organic m a t t e r free soil

4.21

T able-4

Percentag e of l e a c h a b l e el ements of the total p r e s e n t in soils

ELEMENT SOILS

H CH LAS

OS OFS OS OFS OS OFS OS OFS

Ca 25.86 16.57 15.42 1 5.52 33.77 22.90 13.93 1 5.73

Mg 7.00 5.08 6.59 5.17 7.07 3.52 23 .04 11 .06

Na 3.84 3.19 3.85 3.40 3.68 2.61 5.33 3.99

K 12.10 8.77 5.80 4.73 4.71 4 .00 5.38 3 .30

Si 0.19 0.1 Q 0.24 0.21 0.18 0.17 0.17 0.17I

Fe 0.04 0 .04 0.15 0.13 0.06 0.07 0.07 0.07

OS-Original soil

O F S-O rganic m a t t e r free soil

4 .22

E n g i n e e r i n g p r o p e r t i e s of some K a s h m i r V a l l e y soils

Ta b l e - 5

P a r a m e t e r Soils

P H CH

1. S p e c i f i c g r avity 2.709 2.670 2.7 51

2. G r a i n size

a. Sand(^) 18.0 16.5 22.0

b. Silt(/'j) 77.0 69.5 68.0

c. Clay(/a) 5.0 14.0 10.0

3. Activ i t y Number(A) 1 .0 1.1 0.87

4 . Atter b e r g L imits

a. L i q u i d l i m i t ( r/i) 30.30 36.70 27.45

b. P l a s t i c limit(/j) 25.28 21 .27 18.74

c. P l a s t i c i t y Index 5.02 15.43 8.71

5. C o m p a c t i o n ( s t a n d a r d - proctor)

a. 0MC(W%) 17.4 13.7 12.0

b. dry d e n s i t y ( gm « cm’■3 )

1.6 6 1 .63 1 .31

6. P e r m e a b i l i t y 5.11x10 4 7 . 89x1 0 ^ 4 . 1 1 x 1 0(cm per sec.)

7. UC strength 50.91 3 2.57 50.72(N p e r cm )

LAS

2.871

23.0

67.0

1 0 . 0 1 .0

25.50

14 .39

1 0 .1 1

13.2

1 .82

4 1 . 0 7x1 0

4 5 . 2 2

RADIATION-Cu KcT

X« 1.S405A*

423

FIG

4 X-RAY

DIFFRACTION

PATTERNS

OF

THE

SOILS

STUDIED

4.24

o

FIG.5

DIFFERENTIAL

THERMAL

PATTERNS

OF THE

SOILS

STUDIED

4.25

A . 6 3 0 0 X

B . 1 8 0 0 X

FIG* 6 T r a n s m i s s i o n E l e c t r o n m i c r o g r a p h s ofP a m p o r e Soil

4 .26

A. 780QX

B . 2200X

FIG. 7 T r a n s m i s s i o n E l e c t r o n m i c r o g r a p h s of H a z r a t b a lSoil

A. 2200X

B. TBODX

FIG. 8 T r a n s m i s s i o n E l e c t r o n m i c r o g r a p h s of C h a t t a r g a m Soil

4.28

A. 1 7 0 0 X

B .5 1 0 0 X

FIG. 9 T r a n s m i s s i o n E l e c t r o n m i c r o g r a p h s ofL a s j a n Soil

4.29

QZ<

*3

oz<

hia

22<6.'

Zop

2m$-m

fl̂Q VdN

S i

m se

3 ?1 5

2 S

> —< 9-8 ^ o 2

© o<@ * w

{% M > tf S N IJ I N J D M ld

HAZR

ATBA

L

4.30

oz<<$

O 8 8-

utN55

biJO

oe

M

OO

o o« <0

&3NIJ

± X

li.o

V)5 .

s?o §H zo <S- “> at <o < <a. -i

o o* wI N 3 083d

_ Oo oO

> 9

d * w u.

431

34.0

NO. O F BLOWS

P IG.

NO. O F B L O W S (6)

11a 4 b L I Q U I D L I M I T C U R V E S O F P A M P O R E , C H A T T A R G A M , H A Z R A T B A L A N D L A S J A N

S O IL S -

DRY

DENSITY

6m.

Peft

C«/432

8 0

i.s

s.7

1.4 X I ± ± ±6 12 1® 24 30

COMPACTION W A T E R C O N T E N T ( W> */•}C

FI 0.1X0) S TA N OAR O P R O C TO R 'S COMPACTION C U R V E S 6 l PAM PORE AN O C H A T T A R O A M S O I L S .

DRY

DENSITY

Gm.

PER

Cm

4 33

F!G1?(0> s t a n d a r d proctor's compaction curves o p hazratba_ a n d lasjan soils.