Fyp Reinfbvvcorced Soil

7/25/2019 Fyp Reinfbvvcorced Soil
1/26
1. INTRODUCTIONThe geotechnical engineers design foundations and other structures on the soil after
investigation of the type of soil, its characteristics and its extent. If the soil is good at
shallow depth below the ground surface, shallow foundation such as footings and
rafts, are generally most economical. However if the soil just below the ground
surface is not good but a strong stratum exist at a great depth, deep foundations, such
as piles, wells and caissons are required. Deep foundations are quite expensive and
are cost effective only in the where the structure to be supported is quite heavy and
huge. ometimes the soil conditions are very poor even at greater depth and it is not
practical to construct even deep foundation. In such cases various methods of soil
stabili!ation and reinforcement technique is adopted. The objective is to improve the
characteristics at site and ma"e soil capable of carrying load and to increase the shear
strength decrease the compressibility of the soil.
In the investigation done by # $aeini and % adjadi,&'(()* ,the waste polymer
materials has been chosen as the reinforcement material and it was randomly included
in to the clayey soils with different plasticity indexes at five different percentages of
fiber content &(+, +,'+, -+, +* by weight of raw soil./01 tests are conducted by
0eh!ad 2alantari, 0ujang 0.2. Huat and #run 3rasad, &'((* and their experimental
findings are analysed with the point of view of use of waste plastic fibers in soil
reinforcement. 4ffects of 1andom 5iber Inclusion on /onsolidation, Hydraulic
/onductivity, welling, hrin"age 6imit and Desiccation /rac"ing of /lays
&%ahmood 1. #bdi, #li 3arsapajouh, and %ohammad #. #rjomand,&'(()* * point to
the strength and settlement characteristics of the reinforced soil and compared with
unreinforced condition.
%oreover an environmental concern is also included by utili!ation of waste
plastic materials and they can be made useful for improving the soil characteristics
and to solve problems related to the disposal of waste plastic material.
2. LITERATURE REVIEWS
1

2/26
2.1 CBR TEST
5iber reinforced soil is subjected to /01 test by 0eh!ad 2alantari, 0ujang 0.2. Huat
and #run 3rasad, &'((* and the results are published.
2.1.1 Test materials
3eat soil used in the study were collected as disturbed and undisturbed samples
according to ##HT7 T)89:( and #T% D'(8; &0owles, ;:)< Department of the
#rmy, ;)(* from 2ampung, =awa, western part of %alaysia. 0inding agent used for
this study was ordinary 3ortland cement and its properties are presented in Table
.3olypropylene fibers, shown in 5ig. were used as chemically non9active additive.
Table 1: Proerties o! ol"ro"le#e !ibers &i"a.com, '((:*
3roperty pecification
/olor $atural
pecific gravity (.;
5iber 6ength ' mm
5iber Diameter ) micron
Tensile strength -((9( %3a
4lastic modulus 8(((9;((( &$ mm'*
>ater absorption none
oftening point 8(? /
$i%.1 ol"ro"le#e !ibers& &2alantari, '((;*
2.1.2 E'erime#tal ro%ram
2

3/26
In order to examine the effect of cement admixtures and polypropylene fibers on the
/01 values of peat soil, index properties tests on the peat soil have been conducted.
The tests include@ water content, liquid limit, plastic limit, organic content, specific
gravity and fiber content. hear strength parameters of the undisturbed peat soil has
been found out by triaxial test and shear strength is found out by unconfined
compressive strength. 1owe cell consolidation test has been carried out to evaluate
the compressibility behavior of undisturbed peat soil. The /01 test has been carried
out on the stabili!ed peat soil &mixture of peat cement and polypropylene fibers* to
investigate the increase in strength of the samples. 3eat soil samples used for the /01
tests were at their natural moisture contents and therefore no water was added or
removed from the samples during the mixing process of peat, cement and
polypropylene fibers.
2.1.( Cali!or#ia Beari#% Ratio )CBR*
/01 tests have been conducted on the undisturbed peat soil as well as stabili!ed peat
soil with cement and polypropylene fibers. 5or the stabili!ed peat soil with cement
&mixture of peat soil and cement* the soil samples used were samples at their natural
moisture contents of about '((+. pecified dosage of cement and polypropylene
fibers were mixed well with the peat soil for uniformity and homogeneity, before
molding the samples according to the specified standard. tabili!ed peat soil samples
with cement and polypropylene fibers were placed in the /01 mold for air curing for
;( days. /01 tests were performed on samples under both, un9soa"ed and soa"ed
conditions.
2.1.+ C,ri#% ro-e,re
In order to cure the stabili!ed peat soil samples with cement and polypropylene fibers,
air curing technique has been used. In this technique, the stabili!ed peat soil samples
for /01 tests were "ept in normal room temperature of -(A'?/ and relative humidity
of )(AB+ without any addition of water from outside. This technique is used to
strengthen the stabili!ed peat soil samples by gradual moisture content reduction,
instead of the usual water curing technique or moist curing method which has been a
common practice in the past for stabili!ed peat soil mixed with cement . The principle
of using this air curing method for strengthening stabili!ed peat is that, peat soil has
very high natural water content and when mixed with cement has sufficient water for
3

4/26
curing or hydration process to ta"e place and does not need more water &submerging
the samples in water* during the curing process. The technique used for curing
samples will cause the stabili!ed peat soil samples to gradually lose moisture content
during the curing period and become dry and thereby gain strength.
2.1./ Ceme#t osa%es
5or /01 &un9soa"ed and soa"ed* tests, each sample consists of peat soil at its natural
water content added with B, 'B, -(, ( and B(+ cement by weight of wet soil, with
and without polypropylene fibers as an additive. The amount of polypropylene fibers
used for the stabili!ed /01 soil samples was based on the result obtained from /01
tests to be carried out to determine the optimum percentage by weight of the wet peat
soil samples.
2.1.0 Per-e#ta%e o! ol"ro"le#e !ibers
The usual dosage recommended for cement mixes varies from (.89(.; "g m-. In
this study, in order to find the optimum percentage of fiber content for the stabili!ed
peat soil that would provide the maximum strength, peat soil samples at their natural
water content were mixed with different percentages of cement and polypropylene
fibers and were cured in air for a period of ;( days and then /01 test was performed
on them. The samples examined for this purpose were prepared by adding B, B and
'B+ cement and (., (.B, (.' and (.B+ polypropylene fibers. The sample which
showed the maximum value of /01 after ;( days of curing was chosen as the
optimum percentage of polypropylene fibers for further evaluation of strength of the
stabili!ed peat soil.
2.1. CBR test ro-e,re !or soae -o#itio#
#ccording to ##HT7 T;-98- and #T% D))-9:-, the soa"ing period of /01
samples for normal soil is ;8 h or days &0owles, ;:)*. 5or this study, in9order to
investigate the /01 values of the soa"ed stabili!ed peat soil, a set of /01 samples
prepared with different dosages of cement and polypropylene fibers &B, 'B, ( and
B(+ cement with (.B+ of polypropylene fibers* to soil at its natural water content
were cured in air for ;( days and then soa"ed in water for a period of B wee"s. During
these five wee"s of soa"ing period, the soil samples were weighed periodically for
4

5/26
possible weight increase due to increased saturation. >hen the samples attained a
constant weight and no further increase in weight was observed, it was assumed that
the samples became completely saturated. The samples were weighed every day for
the first ' wee"s, every ' days during the next wee" and every Bdays for the last '
wee"s.
Res,lts
2.1.3 Otim,m er-e#ta%e o! ol"ro"le#e !ibers
The results of increase in /01 values for different cement and polypropylene fibers
content are shown in 5ig. '. It appears that the samples with (.B+ polypropylene
fibers gives the maximum percentage increase in of /01 value &ratio of obtained
/01 valueChighest /01 value* after curing for ;( days.
$i%.2 I#-rease i# CBR 4al,es9Di!!ere#t -eme#t a# ol"ro"le#e !ibers -o#te#t
&Ismail, '(('*
0ased on the results obtained, it is possible to that (.B+ of polypropylene fibers as
chemically non9active additive would provide the maximum /01 values for the peat
soil stabili!ed with cement. #lso, based on the result of this test, (.B+ of
polypropylene fibers have been chosen as an optimum amount for the stabili!ation of
peat soil samples.
2.1.5 CBR soai#% test
#ccording to the results shown in 5ig. -, stabili!ed peat soil sample with B+ cement
reached ((+ saturation and therefore constant weight at the end of four days of
soa"ing period. 7n the other hand, the sample with the maximum amount of cement
&B(+* reached constant weight &((+ saturation* at the end of six days of soa"ing.
5

6/26
0ased on the results of this test, all stabili!ed peat soil samples were submerged in
water for at least 8 days before performing the /01 tests under soa"ed condition.
$i%.( 6ei%7t i#-rease ,ri#% soai#% Soai#% time
&. #. $aeini et al., '(()*
2.1.18 E!!e-t o! stabili9atio# o# CBR 4al,e
The results of /01 tests for stabili!ed peat soil samples with cement and
polypropylene fibers after air curing for ;( days are shown on 5ig. . The /01 value
of undisturbed peat soil is (.:)B+. >ith the addition of B(+ cement, it increased to
-+ for unsoa"ed condition and -(+ for the soa"ed condition. >ith the addition of
(.B+ polypropylene fibers with B(+ cement, this increased to -)+ and -B+ for
unsoa"ed and soa"ed conditions. The results indicate that as cement amount in the
mixture is increased, the /01 values also increase and addition of polypropylene
fibers causes a further increase of the /01 values. 3olypropylene fibers as additive
contributes more strength to the stabili!ed peat soil samples.
6

7/26
$i%.+ CBR )* 4al,es o! ,#ist,rbe eat a# i!!ere#t er-e#ta%e o! OPC a#
ol"ro"le#e !ibers !or t7e stabili9e eat soil -,re !or 58 a"s &. #. $aeini et al., '(()*
The air curing technique of peat soil stabili!ed with cement and polypropylene fibers
increased the general rating of the in situpeat soil from very poor &/01 from (9-+*
to fair and good &/01 from : to above '(+* &0owles, ;:)*. #lso, visual inspection
of soa"ed /01 samples depict that the polypropylene fibers not only increase the
/01 values but also contribute towards the uniformity and intactness to the stabili!ed
peat soil samples, as compared with the soa"ed samples with cement only.
2.2 S;EAR STREN

8/26
fibers used in this study were obtained from polymer west materials. The scrap tire
rubber fibers were supplied by local recapping Trac" Tyres producer in Fa!vin city of
Iran.
$i%./ Waste lasti- stris $i%.0 Waste T"re R,bberC7is
&. #. $aeini et al., '(()*
These fibers reproduced by shaving off the old tires into B( mm and smaller strips
and then ground into scrap rubber. The product specifications of the polymer fibers
are given in Table -.
Table 2: E#%i#eeri#% roerties o! -olle-te soils
&. #. $aeini et al., '(()*
8

9/26
Table (:P7"si-al a# e#%i#eeri#% roerties o! !ibers
&. #. $aeini et al., '(()*
2.(.2 Testi#% ro%ram
This experimental wor" has been performed to investigate the influence of 3lasticity
Index and percentage of waste polymer materials on the shear strength of waste
polymer materials on the shear strength of unsaturated clayey soils. 5or this purpose,
clayey soils with different plasticity Indexes were used and mixed with different
percentage of waste materials to investigate the shear strength parameters of
unreinforced and reinforced samples in terms of direct shear test.
In order to determine the shear strength parameters &/ and G* of unreinforced
and reinforced samples, a series of shear box tests at vertical normal stresses of ((9
-(( 23a and strain rate of (.'+ mmCmin were carried out in accordance with
#T%D -()(.shear stresses were recorded as a function of hori!ontal displacement
up to total displacement of : mm to observe the post failure behavior as well.
erification tests were also performed in order to examine the repeatability of the
experiments.
2.2.3 Results and Discussion
The shear stress9hori!ontal displacement curves obtained from the tests for reinforced
and unreinforced soils with the fiber content of '+ at normal stresses of '(( are
shown in 5ig.:. It is seen that initial stiffness at the same normal stress for reinforced
and unreinforced soils remains practically the same. Therefore fiber reinforcements
have no discernible effect on the initial stiffness of the soils. It can be also seen that
the pea" shear stresses are significantly affected by fiber content especially at high
normal stresses.
9
Type polymer
6ength &mm* :9' mm
/ross9section rectangular
Thic"ness &mm* (.'B mm
>idth &mm* (.-B mm
Density &gCm-* .B

10/26
$i% s7ear stress=7ori9o#tal strai# !or ,#rei#!or-e a# rei#!or-e Soil B
6it7 2 !iber -o#te#t.&. #. $aeini et al., '(()*
The values of shear strength &J* cohesion &c* and internal friction angle &G* for both
unreinforced and reinforced soils obtained from tests showed that the addition
amounts of fiber have the significant influence on the development of cohesion and
internal friction angle and similar trends are found in three suit type with different
3lasticity Indexes.
It is indicated from 5ig.) that the variation of cohesion with percentage of fiber
content is a non9linear variation. The cohesion of fiber specimens increases while
increasing fiber content up to '+ and then decreases slightly with addition amounts of
fibers.
$i%.3 E!!e-t o! !iber -o#te#t o# -o7esio# o! soils A& B a# C.
&. #. $aeini et al., '(()*
10

11/26
The increase in cohesion of soil9fiber matrix may be due to the increase in the
confining pressure because of the development of tension in the fiber, and the
moisture in the fiber helps to form absorbed water layer to the clay particles, which
enables the reinforced soil to act as single coherent matrix of soil fiber mass.
The decrease in cohesion of soil9fiber matrix with addition amount of fibers
&more than '+ fiber content* may be due to separation of clay particles due to the
addition of fibers. The maximum cohesion is observed at '+ fiber content as ( "3a
for soil9# which is .' times more than that of unreinforced samples, and 8) "3a
for soil90 which is a.(B times more than that of unreinforced samples and ; "3a for
soil9/ which is .( times more than that of unreinforced samples.
These results showed that fiber reinforcement have more effect on soils with
low 3lasticity Indexes. The variation of internal friction angle with fiber content,
illustrated in 5ig.; #s seen, the variation of internal friction angle with tire rubber
fibers contents in showed a non9liner variation.
In general the internal friction angle value of each reinforced samples increased, and
these values in soil9# ranged from ':.-? to -:.?, in soil90 ranged from '(.-B? to
'B.8?, and in soil9/ ranged from :.B? to 'B.-?.
$i%.5 E!!e-t o! !iber -o#te#t o# !ri-tio# a#%le o! soils A& B a# C.
&. #. $aeini et al., '(()*
11

12/26
The effects of scrap tire rubber fibers on shear strength values of clayey soils
are given in 5igure (.for soil #, 0 and / respectively. The contents of fiber played an
important role in the shear strength. 5igure ; indicate that the shear strength values of
clayey soil9fiber mixtures have a tendency to increase first, after a pea" value, the
shear strength values of these mixtures decrease. It was found that the shear strength
values of unreinforced samples increased due to the raise of '+ tire rubber fiber
content from ' to :: "3a, from ); to '( "3a, and from '(.: to ''; "3a for the
clayey soils #,0 and /, respectively.
The maximum shear strength value of soil9# &soil with lower 3lasticity Index* being
:: "3a is .' times more than that of unreinforced samples. These findings
indicated that the optimum tire rubber fiber content based on shear strength values is
'+.
$i%.18 E!!e-t o! !iber -o#te#t o# s7ear stre#%t7 o! soils A& B a# C.
&. #. $aeini et al., '(()*
>aterials ,se !or -o#soliatio#& s6elli#%& s7ri#a%e& esi--atio# a#
7"ra,li- -o#,-ti4it" tests
Mahmood R. Abdi, Ali Parsapajouh, and Mohammad A. Arjomand,
2008! "#p"rim"n$all% in&"s$i'a$"d $h" "(")$ o* +as$" pol%m"r
b"rs in $h" soil s$abili-a$ion o* soil b% )ondu)$in' )onsolida$ion $"s$,
s+"llin' $"s$, shrina'" limi$, d"si))a$ion )ra)s and h%drauli)
)ondu)$i&i$% $"s$.
12

13/26
Soil T"e:# soil comprised of a mixture of "aolinite and montmorillonite was used in
this research. 3reliminary investigations conducted by the authors showed a mixture
of :B+ "aolinite and 'B+ montmorillonite to be suitable. $ot only it was wor"able, it
also showed pronounced consolidation settlement, swelling, hydraulic conductivity,
shrin"age limit and desiccation crac"ing characteristics. In order to be brief, instead of
referring to the above composition, the word soil is used here after. #ll soil particles
passed $o. '(( sieve and hydrometer test data indicated ;)+ passing (.(:mm,
)'.8+ passing (.(-8mm, :8.8+ passing (.('mm, B(.+ passing (.((;mm and
B.-+ passing (.((mm. #tterberg limits T% D@ -)9):* and specific gravity
T% D@ )B9):* tests were also carried out on representative samples. The soil had
a liquid limit of (&+*, plastic limit of ';&+*, plasticity index of )&+*, shrin"age
limit of '&+* and specific gravity of '.8).
$iber T"e:%ost of the researches carried out on fiber reinforcement of soils have
made use of polypropylene fibers. This is the most commonly used synthetic material
mainly because of its low cost and the ease with which it mixes with soils K;, ', '-,
'L. %iller and 1ifai K'BL also reported that polypropylene has a relatively high
melting point & 8(?/*, low thermal and electrical conductivity, high ignition point
&B;(?/*, with a specific gravity of (.;. It is also hydrophobic and chemically inert
material which does not absorb or react with soil moisture or leachate. Therefore, to
be consistent with earlier researches carried out, bearing in mind the foregoing
characteristics, polypropylene fibers having B, ( and Bmm lengths and contents of
, ', and )+ by dry weight of soil were adopted in this research. 3reliminary
investigations showed that longer and higher fiber contents could not be effectively
mixed with the soil and therefore were not investigated.
2.( CONSOLIDATION TEST
2.(.1 Test ro-e,re
In order to assess the effect of random fiber inclusion on consolidation settlement,
swelling and hydraulic conductivity, oedometer tests were /onducted according to
#T% D'-B9;8. 4arlier research conducted by $ataraj and %c%anis K'L, #bdi and
4brahimi K'-L and %iller and 1ifai K'BL had shown that fiber addition has little or no
effect on compaction characteristics. 5or that reason, in the current investigation all
13

14/26
samples were prepared using the same dry density and molding moisture content
equal to :(+ of the liquid limit. Initially several "ilograms of "aolinite and
montmorillonite were weighed and thoroughly mixed in dry form by appropriate
proportions of :B and 'B percent respectively. The soil was "ept in a container and all
samples were subsequently made using the same mixture. 5or each particular mixture
initially enough soil and appropriate amount of fiber were weighed and thoroughly
dry mixed. Then, water was gradually added and mixing continued until a uniform
mixture was obtained. amples were then molded directly into the confining ring and
tested according to #T% standard procedure. 3ressure increments of B(, (( and
'(("3a were used and verification of the results was assessed by randomly selecting
and testing duplicate samples of some mixtures. # maximum difference of B+ was
observed in results of duplicate samples tested which were considered acceptable.
2.(.2 Co#soliatio# Settleme#ts Res,lts
4ffects of random fiber inclusion on consolidation settlement of soil samples were
evaluated as function of fiber length, content and consolidation pressure. These
relationships are shown in 5igures , ' and - for fiber lengths ofB, ( and Bmm
respectively. 3rior to the fiberinclusion, consolidation settlement ofunreinforced soil
sample was determined. Thissettlement is also shown in the above figures to be used
as a reference behavior for comparisonwith those from different fibrous samples. It
canbe observed from 5igures , ' and - that at a/onstant pressure, increasing the
fiber contents from to )+ resulted in reducing consolidation settlement of the
samples. This is a common trend with all fiber lengths examined. %aximum and
minimum consolidation settlements of :.B and '.8 mm were respectively measured
for the unreinforced sample and the sample reinforced by )+ fibers having Bmm
length &e.g., M5ig. N*. This shows a reduction in consolidation settlement of
approximately 'B+. #lthough increasing the fiber length from B to (mm resulted in
slightly higher consolidation settlements, but in general this soil characteristic did not
appear to be very sensitive to the fiber lengths. It can be speculated that random fiber
inclusion resulted in increasing stiffness of the samples and subsequently reduced the
consolidation settlements.
14

15/26
$i%.11 Variatio#s o! -o#soliatio# settleme#t 6it7
$iber -o#te#t )$iber le#%t7?18mm*.
&Mahmood R. Abdiet al., '(()*
To support this speculation, laboratory triaxial compression tests conducted by
/onsoli et al. K'8L on fiber reinforced soils also showed a greater than '(+. In
contrast, unreinforced samples demonstrated an almost perfectly plastic behavior at
large strain. Their field plate load test results also showed a noticeable stiffer response
with increasing settlement. This potential applications of fiber reinforced soils in
shallow foundations, emban"ments over soft soils, and other earthwor"s that maysuffer excessive deformations. 5rom the above figures it can also be seen that at
constant fiber contents, for all fiber lengths investigated, higher pressures resulted in
greater consolidation settlements. This is mainly attributed to the higher excess pore
water pressures initially generated and subsequently dissipated. Higher pressures also
grant greater potential for soil particles to slip and rearrange relative to each other,
resulting in greater deformations or settlements.
2.+ SWELLIN< TEST
7edometer was used for swelling saturated on molding< they showed no affinity for
further water absorption after flooding the oedometer water bath. Therefore, they did
not exhibit much free swelling in order to be able to assess the effects of fiber
inclusions on this characteristic. Therefore, volume changes during the unloading
stage of the consolidation tests were measured and used as an indication of the
possible effects of fiber inclusion on swellings. The swellings presented were
measured after unloading the maximum consolidation pressure of '(("3a.
15

16/26
2.4.1 Test result
The relationship between swelling and fiber content and length are presented in
5ig.'. It can be seen that by increasing the fiber content, the amount of swellings
decreased. The unreinforced sample produced the highest swelling of about -.mm.
This was reduced to approximately .Bmm for the sample reinforced with )+ fibers
having Bmm length which is a substantial reduction in swelling. 5or constant fiber
contents, an increase in the fiber length from B to (mm resulted in a slight increase
in swelling.
$i%.12 Variatio#s o! s6elli#% 6it7 !iber -o#te#t a# le#%t7.
#s a whole, however, the increase in the fiber length did not have a significant effect
on swelling reduction. This was particularly true when the fiber contents remained
constant. It can therefore be concluded that with the increase in fiber contents and
lengths, the soilCfiber surface interactions were increased. This resulted in a matrix
that binds soil particles and effectively resists tensile stresses produced due t swelling.
1esistance to swelling is mainly attributed to cohesion at the soilCfiber interfaces.
3uppala and %usenda K''L have reported that fiber reinforcement reduces the
swelling pressures in expansive soils. 1educed swelling pressures result in less
volumetric changes, which is exactly what has been observed in this investigation.
16

17/26
2./ S;RIN@AITS
hrin"age limits of fiber reinforced and unreinforced samples were investigated using
the test procedure outlined in #T% D;-9('. 0ecause of standard sample si!e
limitations and the difficulty in soil9fiber mixing to obtain uniform distribution of
fibers within the soil, shrin"age limits of specimen reinforced with )+ fibers and
varying lengths could not be determined.
2.5.1 Test result
ariations of the shrin"age limits as function of fiber content and length are shown in
5ig. -. It can be seen that increasing fiber contents and lengths resulted in increasing
the shrin"age limit of the samples. The resulted increase in the shrin"age limits
became more pronounced by increasing fiber length from B to (mm as compared to
when it changed from ( to Bmm. The shrin"age limit determined for the
unreinforced sample was approximately '+. This was increased to --+ for the
sample reinforced with + fibers having Bmm length. This significant increase
means that samples reinforced with random inclusion of fibers experienced less
volumetric changes due to desiccation. Increase in the shrin"age limits means that
longer fibers having greater surface contacts with the soil have shown greater
resistance to volume change on desiccation. It can be said that random fiber inclusion
improved the soil tensile strength very effectively, thus resisting shrin"age on
desiccation.
$i%.1( Variatio#s o! s7ri#a%e limit 6it7 $iber -o#te#t a# le#%t7.
17

18/26
2.0 DESICCATION CRAC@S
7edometer rings were used to investigate the effects of random fiber inclusion on
desiccation crac"ing of the soil. #fter molding, confining rings containing the
specimen were placed inopen air in the laboratory at a temperature ofabout -(?/.
amples were regularly weighed and when no changes in three consecutive
measurements were observed, they wereconsidered completely dried. Then, samples
wereused for observational examination of the extentof crac"ing.
2.6.1 Test result
7bservational examination of samples after desiccation showed that by increasing the
fiber contents and lengths, the extent and depth of crac"s were significantly reduced.
#s an example, in 5ig. surface crac"ing features of the unreinforced sample and the
sample reinforced with )+ fibers of (mm length are shown for comparison.
$i%.1+ Desi--atio# -ra-i#%:
)a* U#rei#!or-e samle )b* Rei#!or-e samle
It can be seen that extensive, deep and wide crac"s were formed in the
unreinforced sample. The reinforced sample, however, has mainly experienced
separation from the metal ring with no visible sign of crac"s forming within the
sample. This clearly shows the effectiveness of random fiber inclusion in resisting and
reducing desiccation crac"ing which is of paramount importance in surface crac"ing
of clay covers used in landfills. Therefore, it can be concluded that random fiber
inclusion seems to be a practical and effective method of increasing tensile strength of
the clayey soils to resist volumetric changes.
18

19/26
2. ;DRAULIC CONDUCTIVIT
The relationship between hydraulic conductivity and fiber content is presented in
5ig.B. The hydraulic conductivity of the fibrous soil is dependent on the fiber
content, generally increasing with fiber content increase. The slight decrease of
hydraulic conductivity noted around (.'+ fiber content is within the limits of
experimental error, and should not be used to infer that minor fiber additions improve
the hydraulic conductivity. The increase in hydraulic conductivity was most
significant for fiber contents exceeding +.
$i%.1/ : ;"ra,li- -o#,-ti4it" !or 4ario,s !iber -o#te#ts.
&Carol J. Milleret al., '((*
( LITERATURE REVIEW ON >ODEL ANALSIS
/ush%an$ umar hard+aj and ..Mandal )ondu)$"d a mod"l
anal%sis on $h" b"r r"in*or)"d soil +h"n subj")$"d $o )"n$ri*u'"
mod"lin' and $h"ir r"spons" +as no$"d.
3.1 PREPARATION OF THE ODE!
/entrifuge tests were performed on fly ash without and with fiber reinforcement at
slope angle, O P :).8?. 5ront and bac" sides of the container were covered with glass
plates. silicon grease was applied in the inner sides of the glass plates to minimi!e
the effect of friction. 5igure '( shows the dimensions of the slope model used in the
test for O P :).8?. >idth of the model ta"en was :.B cm. 1emaining portion was
covered using geofoam pieces. To minimi!e the friction in between the soil and
geofoam, plastic sheets were used, after applying silicon grease. #ll samples were
made at optimum moisture content. 0ecause the height and the base width of slope
19

20/26
models were fixed due to restriction of container dimensions, therefore other
dimensions of the slope models were ta"en in such a way that the inclination of slope
will remain :).8?. #ll three potentiometers were adjusted in such a manner that their
locations were '.B cm, .( cm and B.B cm respectively from the bac" face of sample.
$o surcharge was used in this case< the sample was allowed to fail under self weight,
by increasing the 13%.
$i%.10 Dime#sio#s o! t7e sloe moel ,se i# -e#tri!,%e test& !or ? 3.0.
&Dushyant 2umar 0hardwaj et al., '(()*
3.2 TE"T PRO#ED$RE
To observe the effect of fiber reinforcement in fly ash slope models all the centrifuge
tests were performed at )( + compaction effort and all the necessary properties of fly
ash were calculated at )( + compaction. 3olypropylene fibers were mixed in the soil
+ by dry weight of soil and water was ta"en according to the optimum moisture
content. #fter mixing the fiber in the soil at optimum moisture content, samples were
ta"en in three different and equal parts. 4ach part was compacted such that its width
should remain '.B cm to ma"e the total width as :.B cm.
3.3 #ENTRIF$%E ODE!IN%
mall centrifuge present in IIT 0ombay was used for the experiments. It is a
balanced beam type centrifuge. 3otentiometers were used in the experiments to
measure the vertical displacements of the slope models.
1eading obtained from these potentiometers were not the actual displacements of the
slope models. To find out the actual displacements of the slope models, first these
potentiometers were calibrated.
20

21/26
Unreinforced Soil
$i%. 1 )a*Be!ore $ail,re )b* A!ter $ail,re
$i%.1 Sloe moel !or ,#rei#!or-e soil& be!ore !ail,re at ? 3.0.
5igure : &a* and &b* show the unreinforced fly ash slope model before and after
failure &at O P :).8?* respectively. Data obtained from the centrifuge test, shows that
unreinforced slope fails at an angular velocity of ( rpm and after )B seconds from
the beginning of the test. cale factor of unreinforced slope at ( rpm was B(.
Reinforced Soil
)a* Be!ore $ail,re )b* A!ter $ail,re
$i%.13 Sloe moel !or ol"ro"le#e !iber rei#!or-e soil&
Be!ore !ail,re at ?3.0.&Dushyant 2umar 0hardwaj et al., '(()*
5igure ) &a* and &b* show the polypropylene fiber reinforced fly ash slope model
before and after failure &at O P:).8?* respectively.
Data obtained from the centrifuge test, shows that polypropylene fiber reinforced
slope achieves the angular velocity equal to that of unreinforced soil i.e. ( rpm after
)'B seconds from the beginning of the test. #nd finally polypropylene fiber reinforced
slope failed at :'' rpm after )-- seconds from the beginning of the test. cale factor
of polypropylene fiber reinforced slope at :'' rpm was -.
21

22/26
)a* U#rei#!or-e )b* Rei#!or-e
$i%,re 15 Variatio# o! ote#tiometer reai#% 6it7 time.
>ith the help of potentiometer reading vCs time graph, reading of first potentiometer
at )B' seconds was .- mm. 5rom the calibration curve of first potentiometer, actual
displacement of model was '.;( mm. 5or reinforced soil, with the help of
potentiometer reading vCs time graph, reading of first potentiometer at same scale
factor as that of unreinforced soil was (.BB mm. 5rom the calibration curve of first
potentiometer, actual displacement of model was .; mm. #fter multiplying this
model displacement with the scale factor, prototype displacement was ;B mm. 1esults
of centrifuge tests and maximum vertical displacements for unreinforced and
reinforced soil are given in Table ) and Table ; respectively.
Table 3. Ce#tri!,%e test res,lts at ? 3.0.
Qg P 4arthRs gravity< 1e P 4ffective radius< S P #ngular velocity< $ P cale factor
Table 5 >a'im,m 4erti-al isla-eme#ts obtai#e !rom -e#tri!,%e tests.
22

23/26
3.4 FA#TOR OF "AFET&
5actor of safety of the slope models were found out by using student version of
software 476734. This software uses the limit equilibrium theory to compute the
factor of safety of earth and roc" slopes. implified 0ishops method was used in
analysis the factor of safety. 5or the comparison of factor of safety between
unreinforced and reinforced slopes, factor of safety of all slope models were found out
at the same scale factor as that of unreinforced slopes. alues of minimum factor of
safety obtained from 0ishopRs %ethod are given in Table (.
Table 18 $a-tor o! sa!et" )$OS* obtai#e !rom Bis7os >et7o.
23

24/26
+. CONCLUSIONS
5rom a critical receiver of literature on the use of randomly distributed waste plastic
fibers for the stabili!ation of soil which are having very poor strength characteristics,
the following conclusions are drawn@
. The soils are reinforced with randomly distributed polypropylene fibers
and the /01 values obtained for this type of soil is around -)+ high than
the unreinforced soil. 5or the /01 test we have used cement as a binder,
even though the percentage of cement is very high fiber content is
responsible for the increase in /01 value.
'. The value of cohesion also increases due to the inclusion of fiber. The
variation of cohesion with percentage of fiber content is observed to be
non9liner . The value obtained for cohesion &c* indicates that soil obtained
is of very stiff nature.
-. In general angle of internal friction increased with fiber content. The
variation of with percentages of fiber contents leads to a conclusion that
the behavior of the fiber included soil can be non9liner variation because
the reinforcement materials exhibited a distribution with hori!ontal and
vertical directions to the shear surface.
. The shear strength of fiber reinforced soil is improved due to the addition
of the waste polymer fibers and it is a non linear function. Ep to a critical
fiber content shear strength increased considerably and later small
reduction is observed. However shear values are greater than unreinforced
soil.
B. The soil stabili!ation with waste fibers improves the strength behavior of
unsaturated clayey soils and can potentially reduce ground improvement
costs by adopting this method of stabili!ation.
8. The addition of randomly distributed polypropylene fibers resulted in
substantially reducing the consolidation settlement of the clay soil. 6ength
of fibers had an insignificant effect on this soil characteristic, where as
fiber contents proved more influential and effective.
:. >ith increase in fiber content the swelling after unloading is reduced to
almost half of the unreinforced situation. #t constant fiber content the
length of fiber does not have much effect on swelling.
24

25/26
). The shrin"age limit is showing a rising graph with both the increase in
fiber content and fiber length. It indicates that the soil is susceptible to less
volume change and it has got enough tensile strength with reinforcing.
;. 5iber reinforcement significantly reduced the extent and distribution of
crac"s due to desiccation as observed by the reduced number, depth and
width of crac"s. These results show that it can be used for covering waste
material in containments and also can be used for canal slopes.
(. Hydraulic conductivity is increasing with fiber content up to particular
limit.
. /entrifuge modeling gives a clear idea about the performance of the fiber
reinforced soil and it points to the vast scope of this method of reinforcing
soil with waste plastic fibers.
'. The most important point is the environmental concern regarding the
effects of waste plastic in soil and the problems and threats that is related
with their excessive usage and disposal. This gives an effective solution to
waste treatment with the advent of soil reinforcement.
B. 145414$/4
25

26/26
. /arol =. %iller and ami 1ifai, &'((*, M5iber 1einforcement for >aste
/ontainment oil 6inersN, /4* =ournal,&9B*.
'. 0eh!ad 2alantari, 0ujang 0.2. Huat and #run 3rasad, &'((* ,N 4ffect of
3olypropylene 5ibers on the /alifornia 0earing 1atio of #ir /ured tabili!ed
Tropical 3eat oil N , #merican =. of 4ngineering and #pplied ciences,&98*.
-. %ahmood 1. #bdi, #li 3arsapajouh, and %ohammad #. #rjomand,&'(()*,N
4ffects of 1andom 5iber Inclusion on /onsolidation, Hydraulic /onductivity,
welling, hrin"age 6imit and Desiccation /rac"ing of /laysN, International
=ournal of /ivil 4ngineering, ol. 8, $o. , &')9';'*.
. . #. $aeini and . %. adjadi ,&'(()* ,N 4ffect of >aste 3olymer %aterials on
hear trength of Ensaturated /laysN, 4=4 =ournal, ol -, 0und ",&9'*.
B. Dr. D 3rasad, Dr. 1 3rasada 1aju and % #njan 2umar,
&'((;*,MEtili!ation of Industrial >aste in 5lexible 3avement /onstructionN,4=4
=ournal,vol -,0und d,&9'*
8. 3radip D. =adhao and 3.0.$agarnai", &'(()*,N 3erformance 4valuation of 5iber
1einforced oil9 5ly #sh %ixturesN, The 'th International /onference of
International #ssociation for /omputer %ethods and #dvances in eomechanics
&I#/%#*. oa, India,&9(*
:. Dr. 2 1 #rora ,Nsoil mechanics and foundation engineeringN, published by
tandard 3ublishers Distributors , Delhi.

Fyp Reinfbvvcorced Soil

Documents

FYP Report

FYP finalh

FYP Briefing

Malaysian FYP

TrabajoFinal FyP

Banner FYP

FYP Dissertation

FYP Ornithopter

FYP presentation

FYP Complete

Fyp Huang0min

Fyp Manual

FYP reportl

Fyp Present

FYP guidelines

How did the policies work? What are the challenges ahead...