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8/11/2019 Engineering Geology Volume 28 Issue 1-2 1990 [Doi 10.1016%2F0013-7952%2890%2990041-x] Jawad S. Al-Sulai
1/11
Engineering Geology, 28 (1990) 191-204 191
Elsevier Science P ubl i shers B.V., Amsterdam - - Pr in ted in T he N ether lands
T e c h n i c a l N o t e
G e o t e c h n i c a l P r o p e r t i e s o f C a l c r e t e S o i l G a t c h )
in K u w a i t
JAWAD S. AL-SULAIMI, MOHA MM AD A. MOLLA H and MU NEER A. MATTI
Kuwait Institute for Scientific Research, P.O. Box 24885, 13109 - - Safat Kuwait)
Government Laboratories and Testing Station, Ministry of Public Works, P.O. Box 8, 13001 - -
Safat Kuwait)
Formerly, Engineering Department, Kuwait Institute for Scientific Research, P.O. box 24885,
13109- Safat Kuwait)
(Received December 11, 1986; acce pted a fter rew sion J an ua ry 1, 1989)
ABSTRACT
A1-Sulaimi, J .S. , Mollah, M .A. and M att i , M .A., 1989. Geo technical pro pert ies o f calc rete soil
(gatch) in Kuwait. Eng. Geol., 28: 191-204.
This pape r presents the resu l t s of a comprehens ive labora tory tes t ing program car r ied out to
study th e geotechn ical prop ert ies of gatch (c alcrete soil) samples. A to tal o f 17 samples col lected
from 17 different s ites in Ku wa it City and i ts suburbs were used for the study. Th e test ing prog ram
included determ inat ion o f physical, index and eng ineering prope rt ies of gatc h samples. The
sensi t ivi ty of variou s geotechn ical propert ies of compacted gatch w as examined b y test ing
specimens a t variou s moisture con tents and also at different soakin g periods.
INTRODUCTION
G a t c h i s t h e l o c a l n a m e o f a p a r t i a l l y c o n s o l i d a t e d s e d i m e n t o f a m a s s i v e
c a l c r e t e t y p e f o u n d i n m a n y p a r t s o f K u w a i t a t v a r i a b l e d e p t h b u t g e n e r a l l y
a b o u t 2 m b e l o w t h e s u r f a c e . T h i s d e p o s i t w h i c h c a n a t t a i n t h i c k n e s s e s o f t e n s
o f m e t e r s , c o n s i s t s b a s i c a l ly o f q u a r t z s a n d s c e m e n t e d p r e d o m i n a n t l y b y
c a r b o n a t e s ( c a lc i te a n d / o r d o l o m i te ) .
S i n c e 1 95 0 a h u g e c o n s t r u c t i o n p r o g r a m h a s b e e n u n d e r w a y i n K u w a i t , i n
w h i c h g a t c h h a s b e e n u s e d p r i n c i p a l l y a s a s u b - b a s e m a t e r i a l f o r r o a d
c o n s t r u c t i o n , f o r t h e f o r m a t i o n o f e m b a n k m e n t s a n d f o r fi l l m a t e r i a l . G a t c h i s
a l so t h e s o i l o n w h i c h m o s t b u i l d in g f o u n d a t i o n s r e s t . C o n s i d e r a b l e f ie ld a n d
l a b o r a t o r y w o r k h a s b e e n c a r r i e d o u t i n t h e p a s t b y e n g i n e e r s e n g a g e d i n
s p e c i f i c p r o j e c ts , b u t s o f a r n o a t t e m p t h a s b e e n m a d e t o c o r r e l a t e t h e r e s u l t s o f
t h e s e s t u d i e s s o a s t o o b t a i n a g e n e r a l p i c t u r e o f g a t c h d e p o s it s . T h i s p a p e r
p r e s e n t s t h e g e o t e c h n i c a l p r o p e r t i e s a n d c h a r a c t e r i s t i c s o f g a t c h e n c o u n t e r e d
i n K u w a i t C i t y a n d i t s s u b u r b s . A t o t a l o f 17 d i s t u r b e d g a t c h s a m p l e s w e r e
r a n d o m l y c h o s e n f r o m d if f e r e n t a r e a s f o r a n i n t e n s i v e l a b o r a t o r y g e o t e c h n i c a l
t e s t i n g . T h e p r o g r a m o f t e s t i n g i n c l u d e d t h e d e t e r m i n a t i o n o f t h e b a s i c a n d
0013-7952/90/$03.50 1990 E lse w er Science Pu blis he rs B.V .
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J S AL-SULAI MI ET AL
stre ngth properties. The effect of sa tur at ion of various degrees on soil
properties was also examined.
GEOLOGICALSETTING AND CLIMATE
Kuwa it is a small country located in the northe aste rn edge of the Arabian
peninsula, bordered by the Ara bian Gulf in the east. The eastern part of the
Arabian Peninsula, known as the Arabian Shelf, consists of a sedimentary
succession in which the most common rock types are sa ndstone and carbonate
rocks (Powers et al., 1963).
The area of Kuwa it con stitutes a part of the interior homocline of the
Arabian Peninsula. The rocks exposed range in age from Eocene to Recent.
The Dammam Limestone Formation, of Eocene Age, crops out along the
Ahmadi Ridge abou t 40 km sou th of Ku wa it City and is the oldest rock exposed
m Kuwait. The Dammam Limestone is overlain by a sequence of terrigenous
sediments that range in age from Miocene to Recent. These sediments are
exposed in the Jal Az-Zor Escarpment northwest of Kuwait City. The rock
sequence of Ja l Az-Zor consists of three main formati ons named, from bottom
to top, Ghar, Fars and Dibdibah (Fuchs et al., 1968). The Dibdibah Formation
covers most of the n orthe rn area of Kuwa it and consists mainly of a fluviatile
sequence of cross-bedded sands and gravels usually cemented by gypsum and
carbonates. The rest of Kuwa it is covered by other Quat erna ry deposits.
The climate of Kuwa it is characterized by a typical desert environment, with
prolonged hot dry summers and mild to cool, relatively wet winters. Annual
pan evaporation is about 3500 mm per yea r which increases graduall y from a
minimum value of 2.1 mm/da y in winter (Januar y) to a max imum of 13 mm/day
in summer (June and July).
PETROGRAPHY OF THE GATCH
A typical fully developed simple soil profile m the study a rea can be divided
into five zones or horizons. In descending order t hese are: (1) aeo lian soil 0.5 to
10 m thick , but commonly less than 2 m; (2) up to 3 m thi ck of friabl e sand wi th
powdery calcrete or tightly cemented calcrete lumps (nodules) up to 30 cm m
diameters ; (3) massive calc ret e 0.2 to 2 m in thi cknes s (gatch); (4) a mottle d
calcre te zone up to 2 m in thickness ; an d (5) una lte red pare nt material.
Detailed accounts of the diagenesis and formtion of the different calcrete
zones have been published by A1-Sulaimi (1988).
The massive calcrete (gatch) is a white to light-yellowish, porcellaneous,
carbona te rock. It consists of variably c emented and replaced sand particles.
The car bonate in the massive calcrete (gatch) represents a su bstantia l replace-
ment of the original material. Mineral grains such as quartz and feldspar are
etched and replaced to varying extents by carbonate. The dominant cementing
materia l is largel y low-magnesium calci te (1-4 mole ~/o MgCO3) and]or micro-
crys talli ne dolomite. Mod era tel y coarse (up to 0.6 mm) dolomite usual ly
occurs as subhedral or small euhedral rhombs whereas the low-magnesium
8/11/2019 Engineering Geology Volume 28 Issue 1-2 1990 [Doi 10.1016%2F0013-7952%2890%2990041-x] Jawad S. Al-Sulai
3/11
GEOTECHNICAL PRO PERTIES OF CALCRETE SOIL GATCH) IN
KUWAIT
I
*
A
~ ~ ~ ~ = = ~ ~ l ~ . u = , . , = ,
~ w ~ ~ ~
\ ~ ~
Fig.I. Map of Kuwait City and its suburbs showing sampling locations.
pp.
193 196
KUWAIT SUBURBS
;r
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I
II
I
II
I
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8/11/2019 Engineering Geology Volume 28 Issue 1-2 1990 [Doi 10.1016%2F0013-7952%2890%2990041-x] Jawad S. Al-Sulai
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GEOTECHNICAL PROPERTIES OF CALCRETE SOIL (GATCH) IN KUWAIT 197
c a l c i t e o f t e n o c c u r s a s m i c r o s p a r i t e a n d s p a r i t e . T h e c a r b o n t e f r a c t i o n i n t h e
m a s s i v e c a l c r e t e a v e r a g e s 6 0 % ( r a n g e 1 5 - 9 0 ~ / o ) w i t h t h e d o l o m i t e c o n t e n t
a v e r a g i n g 4 0 % ( r a n g e 5 - 9 0 % ) . G y p s u m i s a l s o o b s e r v e d in a fe w g a t c h s a m p l e s
a n d i n s o m e c a s e s i t e ff e c t i v e ly c e m e n t s t h e a s s e m b l a g e a s a r e s u l t o f i n t e n s i v e
r e p l a c e m e n t o f t h e c a r b o n a t e . T h e m a i n e f f ec t o f t h e d i a g e n e t i c p r o c e s s e s o n
t h i s h o r i z on i s a n o v e r a l l d e c r e a s e i n p o r o s i t y a n d e f f e c ti v e p e r m e a b i l i t y o f t h e
g a t c h z o n e d u e t o c e m e n t a t i o n b y c a r b o n a t e ( A 1 -S u la im i , 19 88).
SAMPLING AND TESTING PROGRAM
T h i s s t u d y f o rm s a n i n t e g r a l p a r t o f t h e K u w a i t I n s t i t u t e f o r S c i e n ti f i c
R e s e a r c h p r o je c t e n t it l e d S t u d y o f t h e G a t c h D e p o s i t s i n K u w a i t C i t y a n d
S u b u r b s ( A 1 -S u l ai m i e t a l. , 19 84). O v e r 20 0 s a m p l e s o f g a t c h w e r e c o l l e c t e d
f ro m d i f fe r e n t lo c a t i o n s o f K u w a i t C i t y a n d i t s s u b u r b s t o s t u d y t h e g e o l o g i c a l
c h a r a c t e r i s t ic s . O u t o f t h e s e a t o t a l o f s e v e n t e e n m a s s i v e g a t c h s a m p l e s t a k e n
f ro m v a r i o u s l o c a t i o n s ( F i g . l ) w e r e m a d e a v a i l a b l e f o r g e o t e c h n i c a l a n a l y s is .
T h e s a m p l e s w e r e c o l l e c t e d f ro m d e p t h s r a n g i n g b e t w e e n 1 .0 a n d 6 .5 m f r o m
o p e n t e s t p it s a n d a l s o d u r in g v i s it s to v a r i o u s c o n s t r u c t i o n s i te s .
U p o n r e c e i p t o f t h e s a m p l e s i n t h e s o i l l a b o r a t o r y a v i s u a l c l a s s i f i c a t io n w a s
m a d e f o l lo w e d b y th e d e t e r m i n a t i o n o f t h e n a t u r a l m o i s t u r e c o n t e n t. A
s y s t e m a t i c l a b o r a t o r y t e s t i n g p r o g r a m w a s c a r r i e d o u t i n w h i c h f i r s t l y t h e
b a s i c a n d i n d e x p r o p e r t i e s o f a l l t h e s a m p l e s w e r e d e t e r m i n e d . T h e c o m p a c t i o n
c h a r a c t e r i s t i c s o f g a t c h w e r e d e t e r m i n e d e m p l o y i n g b o t h s t a n d a r d (2 .5 k g
r a m m e r ) a n d m o d i fi e d (4 .5 k g r a m m e r ) e n e r g i e s. A n i n t e n s i v e t e s t i n g p r o g r a m
w a s u n d e r t a k e n t o s t u d y th e s t r e n g t h p a r a m e t e r s i n t e n d e d f o r f o u n d a t i o n
d e s i g n a n a l y s is , a s w e l l a s s u i t a b i l i t y o f c o m p a c t e d g a t c h a s a s u b g r a d e
m a t e r i a l u s i n g f iv e s e l e c t e d s am p l e s . T h e s e t e s t s i n c l u d e d p e r f o r m i n g d i r e c t
s h e a r , C a l i f o r n ia b e a r i n g r a t i o ( C B R ) a n d p e r m e a b i l i t y t e s t s u s in g s p e c i m e n s
c o m p a c t e d b y b o t h e n e r g i e s . T h e e f f e c t o f s o a k i n g o n s t r e n g t h c h a r a c t e r i s t i c s
w a s s t u d i e d b y p e r f o rm i n g t e s t s a t d i f f e re n t s o a k i n g c o n d i t i o n s .
PRESENTATION AND DISCUSSIONSOF TEST RESULTS
Class i f i ca t ion tes t s
T h e s e t e s t s w e r e p e r f o r m e d a c c o r d i n g t o A S T M s t a n d a r d s , a n d t h e r e s u l t s
a r e s u m m a r i z e d i n T a b l e I. T h e g r a in - si z e a n a l y s i s i n d i c a t e s t h a t s a n d s i z e
d o m i n a t e s t h e p a r t i c le c o m p o s i t i o n o f t h e g a t c h , w i t h g r a v e l c o n t e n t v a r y i n g
b e t w e e n 0 n d 4 % . T h e p e r c e n t a g e o f f in e m a t e r i a l s h a v i n g t h e s i z e o f c l a y a n d
s i lt p a r ti c l e s v a r i e s b e t w e e n 8 a n d 3 3 % . T h e m e a n g r a in - si z e d i a m e t e r a n d
s p e c i f i c g r a v i t y o f s o i l s o l i d s v a r y f r o m 0 .1 5 t o 0 . 8 r a m a n d 2 .6 3 t o 2 .7 0,
r e s p e c t i v e l y .
T h e p l a s t i c i ty o f t h e g a t c h s a m p l e s w a s d e t e r m i n e d o n m a t e r ia l f r a c t i o n s
p a s s i n g U . S . s i e v e s iz e o f 4 25 pro. T e n o u t o f s e v e n t e e n s a m p l e s w e r e f o u n d t o
b e n o n -p l a s t ic ( N P ), a n d t h e r e m a i n d e r s h o w e d a l o w p l a s t i c i ty i n d e x ( P I)
8/11/2019 Engineering Geology Volume 28 Issue 1-2 1990 [Doi 10.1016%2F0013-7952%2890%2990041-x] Jawad S. Al-Sulai
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8/11/2019 Engineering Geology Volume 28 Issue 1-2 1990 [Doi 10.1016%2F0013-7952%2890%2990041-x] Jawad S. Al-Sulai
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GEOTECHNICAL PROPERTIESOF CALCRETE SOIL (GATCH) IN KUWAIT 199
between 2 and 10%. When plotted on the Casagrande chart, the gatch samples
lie at or slightly above the A-line in the low plasticity region. Accordingly, the
United Soil Classification System (USCS) designation of the gatch is SM-SC.
For road works, the gatch belongs to a soil group of A-2-4. The results are in
full agreement with those reported by Riedel and Simon (1973) on samples from
three locat ions in Kuwait City, and by Ismael et al. (1984) on samples from the
A1-Andalus area about 20 km southwest of Kuwait City. The shrinkage limit
(SL) which is the moisture content of the soil below which little or no volume
change is to take place is recorded to vary from 12.5 to 21.0% with an average
of 17.0%. An examination of Table I reveals tha t the natu ral moisture conten t
(NMC) is well below the shrinkage limit at all locations indica ting a general
moisture deficiency. Upon saturation, these soils are liable to swell; this
explains why gatch soils at the surface crack once subjected to drying.
Compaction characteristics
Test results summarized in Table II show the maximum dry density together
with thei r corresponding optimum moisture content. The results obta ined are
similar to those reported by Riedel and Simon (1973). In constructions,
TABLE II
Summary of results of compaction tests
No. Loc ati on 2.5 kg ram mer 4.5 kg ram mer
and 305 mm drop and 457 mm drop
OMC ~dm.x OMC ?din.,
(%) (kg/m a) (%) (kg/m 3)
1 G-1 11.0 1950 9.0 2060
2 G-2 11.0 1915 9.0 1995
3 G-3 13.0 1860 11.5 1970
4 G-4 13.0 1880 9.5 2030
5 G-5 13.0 1825 9.5 1940
6 G-6 12.5 1870 11.5 1940
7 G-7 10.5 1985 9.5 2040
8 G-8 13.0 1895 8.0 2025
9 G-9 15.0 1810 12.5 1965
10 G-10 8.5 1880 7.5 1975
11 G-11 12.5 1940 10.0 2040
12 G-12 12.0 1850 8.0 1935
13 G-13 13.0 1850 10.5 1970
14 G-14 9.5 2000 7.5 2095
15 G-15 12.0 1910 8.5 2065
16 G-16 12.5 1880 9.0 2035
17 G-17 13.0 1875 10.5 2025
Av er ag e 12.1 1880 9.4 2005
OMC = optimu m moi stu re c ont ent ; ~dm.x= maximum dry density.
8/11/2019 Engineering Geology Volume 28 Issue 1-2 1990 [Doi 10.1016%2F0013-7952%2890%2990041-x] Jawad S. Al-Sulai
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J S AL-SULAIMI ET AL
c o m p a c t i o n i s d e e m e d a c c e p t a b l e w h e n i n - si t u d ry d e n s i t y e x c e e d s 9 5% o f t h e
d e n s i t y o b t a i n e d i n th e l a b o r a t o r y f o r t h e s t a n d a r d o f c o m p a c t i o n a p p l i e d . T h e
i n - si t u d r y d e n s i t y o f g a t c h s h o u l d b e a b o v e 1 90 0 k g / m 3 f o r t h e m o d i f ie d
P r o c t o r (4 .5 k g r a m m e r ) a n d 1 7 9 0 k g / m 3 f o r t h e s t a n d a r d P r o c t o r (2 .5 k g
r a m m e r ) .
T h e d e n s i t y o f g a t c h i s v e r y s e n s i t i v e to c h a n g e s i n m o i s t u r e c o n t e n t . O n c e
t h e o p t i m u m m o i s t u r e c o n t e n t i s e x c e e d e d , t h e r e i s a s h a r p d e c r e a s e i n d e n s i t y ,
a s t h e m a t e r i a l b e c o m e s r a t h e r s p o n g y a n d d i ff ic u lt t o c o m p a c t . F u r t h e r
i n c r e a s e s i n m o i s t u r e c o n t e n t w i ll c a u s e t h e m a t e r i a l t o fl ow u n d e r c o m p a c -
t i o n .
Strength characteristics
T h e s h e a r s t r e n g t h o f a s oi l c a n b e u s e d to d e t e r m i n e i t s u l t i m a t e b e a r i n g
c a p a c i t y . T h e t e s t r e s u l t s o f u n d r a i n e d s a m p l e s ( G - l , G -2 , G -5 , G - 8 a n d G -1 4)
c o m p a c t e d a t o p t i m u m m o i s t u r e c o n t e n t a r e g i v e n i n T a b l e II I . R e s u l t s s h o w e d
t h a t s o a k i n g f o r 2 4 a n d 9 6 h h a s l i t t l e e f f e c t o n s h e a r s t r e n g t h . T h e a n g l e o f
i n t e r n a l f r i c ti o n (~b) r e m a i n e d u n c h a n g e d a f t e r s o a k i n g f o r s a m p l e s c o m p a c t e d
b y 4 .5 k g r a m m e r a n d f o r s a m p l e s c o m p a c t e d b y 2.5 k g r a m m e r i t d e c r e a s e d b y
1 o n l y , w h i c h i s i n s i g n i fi c a n t i n p r a c t i c a l e n g i n e e r i n g w o r k . I n c r e a s i n g t h e
c o m p a c t i o n e f f o rt c a u s e d a n i n c r e a s e o f 3 to 4 i n t h e v a l u e o f , w h i c h
i n d i c a t e s i m p r o v e m e n t i n t h e s h e a r s t r e n g t h o f p r o p e r l y c o m p a c t e d s o il s. T h e
c o h e s i o n (c) v a l u e s w e r e v e r y s m a l l a n d r a n g e d f ro m 0 to 1 6 k N / m : f o r l o w
c o m p a c t i o n e n e r g y a n d f r o m 0 t o 2 8 k N / m 2 f o r h i g h e r c o m p a c t i o n e n e r g y .
I t is in t e r e s t i n g t o n o t e a n i n c r e a s e i n t h e v a l u e o f c w i t h s o a k i n g . T h i s c o u l d
b e d u e t o t h e w e t t i n g e f f e c t o f t h e f i n e r f r a c t i o n s o f t h e g a t c h w h i c h a l s o
c a u s e d t h e m a t e r i a l t o s w e l l .
Ca lifornm bearing ratio C BR )
T h e C B R t e s t s w e r e p e r f o r m e d o n f iv e s e l e c t e d g a t c h s a m p l e s ( G - l , G -2 , G -5 ,
G - 8 a n d G - 1 4 ) p r e p a r e d a t o p t i m u m m o i s t u r e c o n t e n t ( O M C ) . T h e t e s t r e s u l t s
a r e s u m m a r iz e d m T a b l e IV . T h e a v e r a g e C B R v a l u e r a n g e s f r o m 4 % t o 3 2 %
f o r u n s o a k e d s p e c im e n s c o m p a c t e d w i t h 2 .5 k g r a m m e r w h i l e t h e s o a k e d C B R
v a l u e s f o r s i m i l a r s p e c i m e n s r a n g e d f r o m 4 % t o 2 8 % . T h i s i n d i c a t e s t h a t t h e r e
i s a s li g h t d e c r e a s e i n s t r e n g t h d u e t o s o a k i n g b u t n o t s o s i g n if i ca n t . H o w e v e r ,
i n c r e a s i n g t h e c o m p a c t i v e e f f e c t r e s u l t e d i n 3 00 % i n c r e a s e i n C B R v a l u e a n d
t h i s e x p l a i n s w h y c o m p a c t i o n h a s t o b e c o n t r o l le d .
T h e s w e l l i n g o f t h e g a t c h w a s a l s o i n v e s t i g a t e d . I t w a s f o u n d t h a t t h e v a l u e s
r a n g e d f r o m 0 t o 0 .2 6 % , a n d t h a t s w e l l i n g d e c r e a s e d w i t h i n c r e a s i n g c o m p a c -
t io n . T h i s il l u s t r a t e s t h a t i f a s a t i s f a c t o r y c o m p a c t i o n c a n n o t b e g u a r a n t e e d ,
t h e g a t c h i s u n s u i t a b l e u n l e s s i t s p ro p e r t ie s a r e i m p r o v e d b y m e a n s o t h e r t h a n
c o m p a c t i o n a l o n e .
T h e g a t c h i s r e p o r t e d t o b e v e r y s e n s i t i v e to c h a n g e s i n t h e m o i s t u r e c o n t e n t
( B i s s a d a a n d Q a b a z a r d , 1974). A c c o r d i n g l y , t e s t s w e r e c a r r i e d o u t i n w h i c h t h e
m o l d i n g m o i s t u r e c o n t e n t a t t h e t im e o f c o m p a c t i o n w a s v a r i e d f ro m 4 t o 1 6% .
8/11/2019 Engineering Geology Volume 28 Issue 1-2 1990 [Doi 10.1016%2F0013-7952%2890%2990041-x] Jawad S. Al-Sulai
8/11
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8/11/2019 Engineering Geology Volume 28 Issue 1-2 1990 [Doi 10.1016%2F0013-7952%2890%2990041-x] Jawad S. Al-Sulai
9/11
2 0 2
T A B L E I V
R e s u l t s o f C B R t e s t s 1
J S AL-SULAIM[ET ~L
S a m p l e
U n s o a k e d , 2 4 h s o a k e d 9 6 h s o a k e d
C B R ( % ,
a v e r a g e o f C B R ( % , s w e l h n g C B R ( % ,
2 t e s t s ) a v e r a g e o f ( % ) a v e r a g e o f
2 t e s t s ) 2 t e s t s )
s w e l l i n g
(%)
U s i n g s t a n d a r d r a m m e r (2 5 k g )
G-1 8 6 0 6 0 15
G-2 32 28 0 11 28 0 07
G - 5 3 0 2 5 0 0 2 2 5 0 0 4
G-8 5 5 0 04 6 0 07
G-14 26 19 0 11 20 0 11
U s i n g h e a v m r r a m m e r ( 4 5 k g )
G-1 58 25 0 02 22 0 0
G-2 57 61 0 03 62 0 0
G - 5 6 6 5 2 0 0 9 5 4 0 1 6
G-8 93 50 0 11 43 0 20
G - 1 4 5 6 5 1 0 0 7 4 1 0 0 2
* 1 S p e c i m e n s c o m p a c t e d a t o p t i m u m m o i s t u r e c o n t e n t t o m a x i m u m d r y d e n s i ty
T h e s e t e s t s w e r e c a r r i ed o u t u s i n g 4 .5 k g r a m m e r o n 2 s e le c t e d s a m p l e s G -5
a n d G - 8 ) o n l y a n d t h e s o a k i n g c o n d i t i o n s w e r e v a r i e d a s u s u a l . T h e r e s u l t o f
t h e t e s t c o n t a i n s w h o l l y t h e fi n d i n g s o f B i s s a d a a n d Q a b a z a r d 1 97 4).
Permeability tests
P e r m e a b i l i t y t e s t s w e r e c o n d u c t e d u s i n g f iv e s e l e c t e d s a m p l e s ( G - l, G-2 , G -5,
G -8 a n d G -14). T h e s p e c i m e n s w e r e p r e p a r e d b y c o m p a c t i n g a t O M C b y b o t h
e n e r g ie s . T h e t e s t s w e r e c o n d u c t e d u s i n g t h e f a l l in g h e a d m e t h o d .
T h e r e s u l t s a r e s u m m a r i z e d i n T a b l e V . T h e p e r m e a b i l i t y c o e ff ic i e n t (k )
T A B L E V
R e s u l t s o f p e r m e a b l h t y t e s t s 1
S a m p l e
P e r m e a b l h t y ( m / s , 1 0 - 1 )
2 5 k g r a m m e r 4 .5 k g r a m m e r
G - 1 8 0 2 2
G - 2 4 2 0 3 0 5
G - 5 3 4 0 0 7 4 0
G - 8 4 6 0 6
G - 1 4 3 4 6 . 3 0
* 1 S p e c i m e n c o m p a c t e d a t O M C t o ydm a x
8/11/2019 Engineering Geology Volume 28 Issue 1-2 1990 [Doi 10.1016%2F0013-7952%2890%2990041-x] Jawad S. Al-Sulai
10/11
G E O T E C H N I C A L P R O P E R T I E S O F C A L C R E T E S OI L G AT CH ) I N K U W A I T 2 0 3
v a r i e s b e t w e e n 4 .6 a n d 3 40 0 1 0 - 1 m / s f o r s p e c i m e n s c o m p a c t e d b y 2 . 5 k g
r a m m e r , a n d 0 .6 a n d 7 40 1 0 - 1 m / s f o r s p e c i m e n s b y 4 . 5 k g r a m m e r . T h i s
i n d i c a t e s a f iv e -f ol d d e c r e a s e i n t h e p e r m e a b i l i t y f ig u r e s j u s t b y i n c r e a s i n g t h e
c o m p a c t i v e e f f o rt . T h e a v e r a g e p e r m e a b i l i t y c o e f f i c ie n t o f U n i t e d S t a t e s
B u r e a u o f R e c l a m a t i o n ( U S B R , 1 977) f o r s il t y a n d c l a y s a n d s v a r i e s f r o m 7 20 t o
4 8 0 . 1 0 - 1 m / s a n d t h e s o i l s a r e d e s c r i b e d a s : (1 ) i m p e r v i o u s w h e n k i s
< 1 0 0 . 1 0 - 1 m / s ; ( 2) s e m i - i m p e r v i o u s w h e n k i s 1 0 0 t o < 1 0 0 0 10 - 1 m / s ; (3 )
p r e v i o u s w h e n k is > 1 0 0 0 -1 0 - 1 0 m ] s.
A c c o r d i n g l y , g a t c h s o i ls a r e c o n s i d e r e d a s i m p e r v i o u s , c o m p a r i n g t h e
f ig u r e s w i t h t h e e x c e p t i o n o f t h o s e f r o m G - 2 a n d G -5 a r e a s w h e r e t h e g a t c h i s
s e m i - im p e r v i o u s . T h i s im p l i e s t h a t t h e u s e o f g a t c h r e q u i r e s p r o p e r d r a i n a g e
a r r a n g e m e n t s w h e n u s e d a s fill m a t e r i a l .
CONCLUSIONS
(1) M a s s i v e g a t c h i s p r e d o m i n a n t l y s a n d y w i t h t h e p e r c e n t a g e o f m a t e r i a l
f in e r t h a n 7 5 t an r a n g i n g f r o m 8 % t o 3 3 . I t i s e i t h e r n o n - p l a s t ic o r h a s a l o w
p l a s t i c i t y i n d e x , a n d c a n b e c l a s s if i e d a s S M - S C i n t h e U n i f i e d C l a s s i f i c a t i o n o r
A -2 (0 ) i n t h e A A S H T O c l a s si f ic a t io n . T h i s m a k e s i t s u i t a b l e f o r u s e i n r o a d
s u b g r a d e s . T h e a v e r a g e s h r i n k a g e l im i t i s 17~/o, w h i c h i s c o n s i d e r a b l y a b v o e
t h e n a t u r a l m o i s t u r e c o n t e n t . T h i s i s c r it i c a l, b e c a u s e it m e a n s t h a t t h e s o i l s
a r e l ia b l e t o s w e l l w h e n s a t u r a t e d a n d t o c r a c k w h e n d r y , a n d s u i t a b l e
d r a i n a g e a r r a n g e m e n t s m u s t b e m a d e t o e n s u r e t h e ir s t a b i li ty .
(2 ) T h e a v e r a g e v a l u e s o f t h e C a l i f o r n i a b e a r i n g r a t i o ( C B R ) f o r u n s o a k e d
s a m p l e s r a n g e d f r o m 5~/o t o 3 2 ~ w h e n c o m p a c t e d a t O M C u s i n g l o w e n e r g y ;
t h e s a m e s a m p l e s c o m p a c t e d a t h i g h e r e n e r g y g a v e a C B R v a l u e b e t w e e n 5 6%
a n d 93/0. T h i s i n d i c a t e s t h a t c e r t a i n t y p e s o f m a s s i v e g a t c h c a n b e u s e d a s s u b -
b a s e o r e v e n a s a b a s e c o u r s e f or r o a d c o n s t r u c t i o n . S o a k i n g o f g a t c h s a m p l e s
c o m p a c t e d a t t h e i r o p t i m u m m o i s t u r e c o n t e n t h a s l it t le e f f e c t o n t h e C B R
v a l u e . T h e C B R v a l u e i s v e r y s e n s i t iv e t o t h e m o i s t u r e c o n t e n t o f t h e g a t c h a t
t h e t i m e o f c o m p a c t i o n , a n d t h i s w i l l d i c t a t e t h e n e e d f o r g o o d q u a l i t y c o n t r o l
d u r i n g c o m p a c t i o n .
(3) T h e c o h e s i o n o f g a t c h i s v e r y l o w a n d a t t i m e s n e g l i g i b le , w h i l e o n t h e
o t h e r h a n d t h e a n g l e o f f r i c ti o n h a s b e e n f o u n d t o i m p r o v e c o n s i d e r a b l y w i t h
p r o p e r c o m p a c t i o n . T h e p e r m e a b i l i t y i s c o n s i s t e n t l y l ow ; t h e m a s s i v e g a t c h i n
t h e s t u d y a r e a i s e i t h e r i m p e r v i o u s o r se m i - i m p e r v io u s .
ACKNOWLEDGEMENTS
T h e a u t h o r s e x p r e ss th e i r g r a t i t u d e t o D r . A b d u l m a j i d J e r a g h , H e a d o f t h e
G o v e r n m e n t L a b o r a t o r i e s a n d T e s t i n g S t a t i o n f o r a l l o w i n g t o u se t h e s o il
l a b o r a t o ry . T h a n k s a r e a l s o d u e t o D r. H a m e d S a e e d y o f K u w a i t I n s t i t u t e f o r
S c i en t if ic R e s e a r c h f o r r e v i e w a n d u s e f u l c o m m e n t s o n t h e m a n u s c r ip t . T h e
K I S R p r o j e c t E E S - 4 6 s t a f f a r e a c k n o w l e d g e d f o r f ie ld a n d l a b o r a t o r y a s s is t -
a n c e .
8/11/2019 Engineering Geology Volume 28 Issue 1-2 1990 [Doi 10.1016%2F0013-7952%2890%2990041-x] Jawad S. Al-Sulai
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204 J s AL-SULAIMIET AL
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Rmdel, G. and Simon, A.B., 1973. Geotechmcal properties of Kuwait gat ch and their improve-
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