ITIME STABILIZATIQI OF A VIRGINIA CLAI SOIL

tÄ

Syed Iehratali Aarney

Thesis submitted to the Graduate Faoulty of the

Virginia Polytechnie Institute

in oandidaey for the degree of

MASTER OF SCIENOE

in

Civil Engineering

November, 1962

Blaokeburg, Virginia

2VTABLE OF GGNTENT3 2

’ PageLI$T OF FIGURES • • • • • • • • • • • • • • • • • • • • • • •

•LXSTOF TABLES • • • • • • • • • • • • • • • • • • • • • • • • 5

INTRÜEUGTIGN • • • • • • • • • • • • • • • • • • • • • • • • • 6

REVIEE OF THE LITERATURE • • • • • • • • • • • • • • • • • • • 8

HiOtOry • • • • • • • • • • • • • • • • • • • • • • • • • • 8Types of Liüß Usßdu • • • • • • • • • • • • • • • • • • • e 11

V Typßß of 8oi1—Lime 8tabi1izati¤„ • • • • • • • • • • • • • 11Aetio of Lime in SOÄIB • • • • • • • • • • • • • • • • • • 12

g Béhßfitl of Soil-Lime Stßbilizatia • • • • • • • • • • • • 15Laboratory Tßßtß R¢ViCW • • • • • • • • • • • • • • • • • • Ih

Effect cf Lime OD Plastic Limit• • • • • • • • • • • • • 16Effect of Lime and Lime··F1yaah on Strength • • • • • • • 16Ccmpressive Strength of Treated Olaya with

Hydrated LimO• • • • • • • • • • • • • • • • • • • • • 20Effect of Quißklißß Oh äÜt $0ilÜ • • • • • • • • • • • • 21Accclerated Ouring for Lime-·Stabi1ized 30116 • • • • • • 22

Fißld PT01€Ot RBYi¢W• • • • • • • • • • • • • • • • • • • • 26

ANALYEIS OF SGIL U8ED • • • • • • • • • • • • • • • • • • • • • 28

‘ 3011 UBOÖ • • • • • • • • • • • • • • • • • • • • • • • • • 28XbRay Üifffüßtiüh AB&1yÜis• • • • • • • • • • • • • • • • • 28

PTOOOdurO• • • • • • • • • • • • • • • • • • • • • • • • 2BROBultS Bhd Silßußßißß • • • • • • • • • • • • • • • • • 29

Grain 52Plaßtiß Prßpartißß of SÜi1• • • • • • • • • • • • • • • • • 5h

CBR SOAKING TIME STUDY • • • • • • • • • • • • • • • • • • • • 55

. ' Objective • • • • • • • • • • • • • • • • • • • • • • • • • 55ÜUHBÄOY T°$tÜ • • • • • • • • • • • • • • • • • • • • • • • 55California Bearing Rßßiß Teßt • • • • • • • • • • • • • • • -55Rßßultl and Ul¤¤üB8i0B• • • • • • • • • • • • • • • • • • • 57

Relationship • • • • • • • • • • • • • 57GBR Teste • • • • • • • • • • • • • • • • • • • • • • • 59

OCNGLUSIGNS • • • • • • • • • • • • • • • • • • • • • • • • • 5O

5

TABLE OF OONYENTS (oontßd)Pag•

BIBLIOGR„APHY..•„............„•„.„... 51

Aoxxoamummäw . . .....................5§um ...........................51+

« VLIST OF FIGURES

P¤s•

1. X-—Ray3'1i£’f1·aetionDiagrams.................50

2. Grain Size Distribution by Hydrometer. . . . . . . . .V.

. . 55

5. hy Density ·— Moisture Content Relationship . . . . . . . . 56

H. GBR -· Soaking Time Relationship. . . . . . . . . . . . . . . H1

5. Soaking Time ·· Pereent Swell Relationship. . . . . . . . . . H2

6. Peroent Swsll ·- Pereent Lime Relationship. . . . . . . . . . H3

7. Seaking Time - Degree Saturation Relationship. . . . . . . . H5

3. Soeked GBR ·· Pereent Lime Relationship . . . . . . . . . . . H6

9. Sealced GBR ·- Density Relationship. . . . . . . . . . . . . . HB

10. Density ·- Pereent Lime Relationship. . . . . . . . . . . . . H9

5

LIST OF TABLES

Page1• 51

5• Attez·bergLimitReau1ts••••••••••••••••„•• 5llI

h. Effect ef Lime on Density and Moisture Content,

ICompaetive Effort Being Constant • • • • • • • • • • • • • 58

I

5,0BRTestResuJ.te„••„•„„•..••„••„••••••ÄO

‘ Üxsraoauorxow (Soil stabilization may be defined as a modification of the exist-

ing soll so as to increase its bearing oharacteristics• Such an efb

feet may be accomplished by the incorporation within the soll of cer-

tain materials, in particular lime, which provide the desired quality

of permanent stability and waterproofing„ (16) Lime in general re-

duees maximum dry density and inoreases optimum water content. Addi-

tion of lime changes physical properties of soll, makes it more werke-

ble, reduces plasticity index, and increases bearing value of soil•

Strength of soil-lime mixture is greatly enhanced by inereasing

soaking period, The test results show that for a curing period of

sight days, strength is a function of the soaking time• At the end

cf eight days soaking tremendous gaine in GBR values are obeerved•

However, it in doubtful that eight daye is an optimum curing period,

though it euggests that four days curing time remains lnsufficicnt

insofar as strength of the base and pavemsnt is concerned• Lcngcr

curing period than hö hours does not sse tc have affected the volume

change of the specimens• The amount of swell is largest for the

first hö hours, afteruards the swell is almost constant and unotice-able•

As part of this project, it was considered important to deter-

mine the mineralogical content of the soil used in order to explaln

some of the results obtained• The most satisfactory single procedure

for the identification of the clay·minera1s is by means of X-ray

7

diffracticn• It is the only procedure presently available that ls auf-

fieiently adequate to evaluate complex mixturee centaining·mixed—layer

a•semblages• Xbray diffraction analysis would reveal only the charact-

er of the crystalline nuoleus and not of the heterogenecus soating

which is the essence of the cmplex. (7)

The purpose of this project is to determine:l• The effect of increasing seaking time en GBR

values of a Virginia clay soil—lim• mixture•2• The mineral ccmpcsitien of the soil used by

X-ray diffractien ana1ysis•

The procedure for the Xbray diffractien analysis is presented in

suffieient detail in order to serve as a guide for future analysee•

8

y REVIEW OF THE LITERATURE

ggstorg

One of te oldest nonstruetlen.materials — lime - has been ln use

in the United States since 192h when the United States Bureau of Pub-

lic Roads, in cooperation with several states, underteek an investiga-

tion ef the effect of lime on dirt reads, (M) In 1959 the Texas State

Highway Department set up a research project fer the purpose of study~

ing the effect of 1ime•sci1 mixtures,

History reveals a rather extensive use ef this material in read

construction during ancient times, (l) For example, the master read

buildere of their time, the Romane, are known te have used qudcklime

fer base construction, The august l9ä5 issue ef *Amerlean Highways‘

describes briefly the read eonstructio methods and materials used in

building the famous 'Appian Hey', The most advanced stages ef its

construction were asfbllewssl,7*A

layer ef large, flat stenes, ten te tw•¤ty—resr

inohee think, was leid,

2, 'Hext, smaller stenes mixed with lime about nine

inchee think were leid,

5, "'1'he nucleus layer, about one feet think, censist—

lng of small gravel and ooarse sand mixed with het

lime, was leid,

Ä, 'On this fresh mertar was placed the wearing eur-

face of flint-like lava about six inehes deep,' (1)

9

Thur, lime was used in three of the five layers of this road which,

to this date, rmains one of Italy's principal highway artcries,

Ldme, in the fhrm of quicklime, has been used in both China and

India, In China, lime has been used both hy itself and in conjunctlon

with burned elays; in India lime ws used in base construction,InChina,according to Y, F, Hau, vice director of Engineering D•part—

ment, National Highway Administration, lime is and he been oommclyused for years in the conetructio of upaved earth roads in village:and rural sections, Lime was used in China mcstly by judgement and

experience, and without the benefit of laboratory teste, (1) Also,

methods and equipment employed were completely primitive, Deepite all

these, according to Y, F, Hau, soc of these unsurfaced lime reads are

proving tc be eurprisingly durable and eccnmical providing they are

not subjected to hevy traffic,

In the United States, the use of lime in road construction is not

entirely new; For several years lime has had limited usage ae an ad-

ditive to concrets, (8) In this connection, hydrated lime was substi—

tuted for portland cement in concrete mix in quantities ranging from

5 tc 15 percent by volue• Fer years, the State of Delaware has used

hydrated lime in this manner in virtuslly all of their concrete high-

wy construction, (l)(8)The first known experimentation n lime in hase construction oc-

curred at the niversity of Missouri in 192h and 1925 under a National

Lime Association fellowshp, (1) This research project was supervised

10

by Dean E. J, Mcüanstland, Director, Engineering Experiment Station,

who presented the results of this work before National Lime Associa-

tion Conventions in 192ä-25, he research project largely consisted

cf field tests, Test sections treated with various percentages cf

hydrated lime were established near St, Joseph, South Cedar City, Oc-

lumbia, and Jefferson City, Missouri, During the course of this pro-

ject, the then United States Bureau cf Public Roads became eufficient·‘ ly interested to collaborate on this work by supervising soe test

sections of their own located in Iowa and South Dakota, (1)

Results of these experiments proved that the addition cf 5 tc 6

percent hydrated lime made clay reads, containing small amounts cf

aggregate, reasonably stable for one to two years, (1) In addition,

lime changed the physical properties of th eoil from a plastic to a

relatively friable condition which greatly facilitated compactic,

Other than s few tests made with lime by the Public Roads Admini—

straticn on some Alabama solls, at Purdue University by the Joint High-

wy Research Project, and at Ohio State niversity, little was heard

about lime in base construction until about 1958, (l) At that time,

the Texas Highway Bepartment initiated some rather extensive laboratcry

tests on lime in varying percentages with different southwcstern soils,

The program of lime—soil stabilization ws halted during world wor II

until l9ä5• (8) However, in l9ä5, two percent of hydrated lime was

used to reduce the plasticity index of a caliche gravel in connection

with the construction of a base course for the runways and taxiways at

Oase Field, Beeville, Texas, This is probably the first large scale

use of‘lime in pavement oonstructio in this country, (1)

ll ·

Lime stabilization ie slowly spreading in the United States and

each year is being used in ever greater qusntities by more states• (1)

(8)Emsa 22. lem. Hasi

Much of the lime that is currently used in connection with seil-

lime stabilization is hydrated lime (caleium and/or magnesium hydroxide)

(15), though some quick lime (calcimm and/or calciuxmmagnesitex oxldc)

is also used. mate lime has also been used with success to stsbilise

eoi1s• (8) This type of lime is usually a by·—product of different

menufacturing processcm Hydrated lime is formed when quick lime reacts

with water to produee calcium hydroxidc which is also ccmmenly known as

elalced lime• (8) Hydrated lime hae been used in powder as well as in

slurry form, while quick lime when used in powder form has been known

to injure some werkmcm In order te evercome this difficulty quick

lime could be slurried eufficientlm (8)

ggg; gg §g;l_—y_ StabilizationIn general, there are two principal types cf lime stsbilizatiom

(1}) One consists of treating granular material for final base course

upon which a wearing surface is to be placed• Such mixturcs usually

contain less than 50 percent soil binder and are treated with from

2 to Ä perccnt lime based on dry weight of soil aggregate material•The other type consists of treating soil materials to serve as subbasc•

A Usually clay solls are treated for this purpose by the addition ofV

from Ä tc 8 percent lime based on dry weight of soil• (15)

12

The treatment of granular ecile which do not react well with lime

alone can be enhanced by the addition of flyaeh, expanded shale finee,

voleanie aeh, portland cement, and bitminoue materials. (15)

£—.1&.i.;•=..1 ai 9.21 .%.2 .529.1Several types of chemical reactions take place when lime is mixed

with a meist coll. (15) Ueußlly, a number of reaetiene take place at

the same time in the lime—eoi1 mixturee which.make it difficult to

separate and analyle each of th. Hewever, the following three reac-

tions have been identified and are underetoed to a certain extent.

These, incidentally, are known to be the most important ones for eta•

bilisaticn. (15)

1. ‘The first reaction ie of a base exchange nature

p which lowere the plasticity index of the eoil and

gives the eoil a leeee friable appearance.

2. ‘The eeend reacticn coneiste of ealcium reecting

with available silica and alumina (collcidal sizes)

to form complicated oempounds of non—e1aking mono~

calcium silieatee and aluminatee. This is a form

of slow setting cement which zcntinuee to gain

etrength over log periode of time, and ie comonly

referred to ae ‘pezzelanic reactien'. The rate of

thie cementaticn varies a great deal with the type

of eoil being treated and with climatic conditions.

15

j. ‘The third reaction is the slowest and involves

the abaorption of carbon dioxide from the air sol

as to reaet with the ealcium hydroxide to form

calcium carbonate or limestoue. For either of

these last twe reactios to produce effective

hardening by cementation, the mlxture must be

thoroughly cempacted prior to time of reactions.‘ (15)

Beuefits gg §_o_g_l__—I_=_i_gg_ Stabilization

Follcwing are some properties cf lime that make it a good etabi·

lizers (15)

1. It eau be eaeily·mixed with soll, especially

with plastic or clayey soils.

2. It quickly reduees the plastic charaetoristics

of soll when wetted.

5. It sets slcwlyg the time interval between mixing

and ccmpaotion is not critical, especially if the

mixturo is not allowed to remain spread in a thin

_ windrow for long periodc of time.

h. Oompaction can be done over a period of two or

three days, baees need not be rolled all at once

allowing time fer base to adjust te eubgrade.

5. Oosts are reaaeuably 1ow•1

l6. It is found in abundanoe in uderdeveloped

coutries. (1})

lk ,Laborator g‘_g_e_t_g_ gp_g_i__g__p_

Taylor and Armen of the Louisiana Department of Highway! conducted

tests cn soil•1ime mixtures, (15) They observed that there is a reac-

ticn cf lime with soll which takes place during first #8 tc 72 hours

after mixing, It in called the initial reaction, while the sscondary

reaction starts after a period of 72 hours, Also, it was found that a

ccnditioed soil produced higer densities at lower mcisture contents

after stabilizing the soll, (15)

During a study in 1957 undertsken by the Louisiana Department cf

Highways, it was observed that the primary reascns for the failure cf

lime in stahilized bascs were due to poor mixing becaue cf high clay

content and delay in compacting the soll after it was mixed with lime,

(15) All these factors, ccncluded the Louisiana Department of High-

ways, pointed out the fact that when a soil—1ime stabilized base is

compacted within hö hours after mixing, cementation takes place, and

the entire base results in a homcgenecus base, (15)

Addition of small amount! cf lime to clayey eoils improves the

werkability, but the increase in strength is not substantial (9),

whereas larger amouts of lime increase the strength and bearing eapa—

city cf sells, This is suggestive that soll must first satisfy the

affinity towards lime which ie termed 'lime fixation*, Test results,

condueted at Iowa Engineering Experiment Station, showed that when

plastic limit increases, with small amounts of lime, strength reine

constant, whereas with larger ameunts of lime the plastic limit rs·

meins constant and strength increases, (9) Thus, plastic limit is

”——__”__—-—_——_——_——————__———————————————————”'9999999“———————'*"'————————“—“““’“““’“’““’“"“’“""’l

A

15

indieative of the amount of lime fixation in clayey solle. Also, it

was obeerved that the amout of fixation is proportional to the type

and amout of two-micren clay preeent•

The National Lime Association report: that when lime ie added to

over-wet clayey soils it dries them out and improve: the workahdlity•

(9) Fuller and Ehbney reported that when highly elayey solls of Texas

were mixed with lime additive and water, pulverizing of clay belle be—

came easy, the material was friable, and ehowd many eharacterietios

of a non—plaetie mix• In these teste reduetien in plaetisity index

were noted when treated with loss than 5 peroent of lime, (9)

The Iowa State University Engineering Experiment Station Soil Re-

search Laboratory has been oonduoting experiment: on treatment of sollI

with lime and lime·£lyash• (9) The basic meehaniem involved is exe

plained by Davidson and Handy• (9) °Pirst, the eoheeive soll: beeeme

friable due to reduetio in plasticity index, The meehaniem is either

a catie exchange er a crowding of additional cations onto the clay•

Both processes change the electrioal charge donsity around the clay

particlee• Clay partiolee then become electrieally attraoted to one

another · caueing floeculation or aggregation• The olay particlee,

now eating ee aggregatee, behave es a eilt which has a low plaeticity

er oohesi¤¤• A second chamical reaction is carbonatio of lime by

carbon dioxide of the air, producing caleium earbonate, a week oement

which is deleterioue to overall strength gains• A third claee cf re—

ecticne, termed pozzclanic reactione, results in a slower, long—term (

oementation of compacted mixturee of lime and eoil•‘ (9)

h

e ...ini.....rAi................................_...._._._____________________________J

16

when lime ie added to eoil, changes in soil characteristics depend

on the caticn absorbed cn clay eurfaces, and on the type cf clay. (9)

The montmorillcnitic solle are more susoeptible to the nature of ex•

changeable catio than kaclinitic ecils. Expansive clays like montmor—

illonitic reset more readily with lime lcsing plasticity and gaining

pczzclanic strength than illite, chlcrite, vermiculite, and kacliuite

which are less effective when treated with lime. (9)

Effect cf Lime on Plastic Limit

with sall additives of lime to ecils it was obcerved that plastic

limit increased; the largest increase occurred in clays containing

montmorillcnite as principal clay minerals. (9) Also, the increase in

plastic limit depended upon the clay—eize material while the illite·

chlcrite clayey scils did not show such an increase in plastic limit.

Kaolinite rich soils ahowed the emallest increase in plastic limit.

Effect of Lime and Ldme·Flyaeh on Strength

In order to determine the effect cf lime cn the unccnfined com-

pressive tests, three soils with clay·minerale, i•e. montmorillonite

(M-67), illite·chlorite (IO·&4), and kaolinite (K—§0) were selected. (9)

Additio cf lime inereased the unecnfined compressive strength of

mcntmcrillonitic soils by the largest amount. Strength of kaelinitic

solle was quite substantially inereased, while illitic—chloritio eoils

shewed only a slight increase in strength. (9) On the other hand,

addition of 20 percent flyash plus lime produced gaius in unconfiued

compreseive strength of illitic—chlcritic soil (lO—#ä) while

17 “

montmorillonitic eoile (M-67) and kaolinitio soile (K-50) were little

affeoted insofar as strength is concerned, The increase in strengthof illitic-ohloritic soll was by 28 peroent, Thun, it appears that

montmorillonitie (M-67) end kaolinitic (K-50) soils are both natural

pczcolans and reaot with lime to produoe cementing materials, However,

since the addition of lime docs not help illitic-chloritic soils in

its strength, it may be concluded that either illlte cr chlorite er

both are not effective natural pozzolans, It becomes necessary, there-

fore, to add a poazolsnic material auch as flyash to obtain signifioent

increase in strength, (9)H, F, Barnes and D, T, Eavidscn (5) reported that lime in cabl-

nation with an incrganic chemical may be a useful and economic alterna-

tive to stabilization of clayey solls for highway construction, Three

Iowa elayey soils with water contents from 55 to 1h percent were select-

ed fer determining the effects when mixed with varying Eßüühtl of both

hydrated oalcitic and hydrated dolmitic lines, and three inorganie

chemicals, i,e, sodiu phoephate, eodium carbonate, and sodium hydroxide,

The test reeulte showedg ‘Addition of 1 to 5 percent of eodiu hydroaide

doubled the strength of soil—lime mixtures, Addition: of sodium phoe-

phate to soil-lime mixtures actually deoreaeed the strength, and addi-

tions of sodium carbonate gave inooneistent results,' (5) It, however,

seems to have proved the theory that sodiun hydroxide can be a success

in the stabillzation of sol1•

In the northern part of the United States where high curing tem

perature cannot be obtained in the fall and winter eeasons, alternate

18 ;cycle: of freesing and thawing may bring eonniderable damage to lime

stabilized elay solls, The gaius in strength in soil-lime mixtures may

be too small to meet baee course requirements, It ws also suggested

that ohemioal additives could be a beneficial answer to cement produc-

ing (pozzolanlo) reactions in clayey soil-lime mixtures, produeing

higher strength, (5) Another alternative to harden lime-treated solls

is by·means ef heating artifieially, though it may not be an economi-

eal procedure at present to eure a eoil-lime base course, The fo11ow—

ing eonclusions were derived:1, 'Addition ef a small amout of sodium hydroxide

to mixtures ot'montmoril1onitic olay soils andl

lime ast as an effective aoeelerator fer the

hardening meohanis of the eompacted mixture,

The cptimum sodium hydroxide treatment is aboutt 1 to 2 peroent, based on th dry weight of the

_ eoil eompenent,2, ‘Sediu¤ carbonate and sodium phesphate are not as

promising ae eodium hydroxide fer improving lime

stabilisation of‘montmorillenitie clay soils,

partisularly when the lime is doloitic monohy-

drate (N type),5, ‘The magnituds of strength improvement up te 28

day: due to the use of sodium hydroxids, varies

with the compesition of the lime and olay soils;

ealoitie (high caleium) hydrated lime may give

I19

somewhat better results than dolmitic meohydrate

(N type) lime, but the presence of sand size quarta

in the soll is definitely benefloial•”

A. 'Heat also eeoeleretes the hardening of eempaoted

mixtures of mentmorillonitic slay solls and lime,

and temperature: around 100°F or higher during the

early curing period are extremely benefioial to

strength and durabllity, the benefioial effects

apparently supplementing those obtainable from the

use of sodium hydroxide as an additive•5• *Ibl¤mitis monohydrate (N type) lime should be used

fer lime steblllzetlon of montmorillonitis cley solle

tor road base courses in Iowa or regions of similaror more severe climste, unless an additlve of eodium

hydroxidn is specified, in which case either the

dolomitie lime or ealeitie hydrsted lime may be

used• In Iowa, without eodiu hydroxide edditive,

ealcitio lime appears sstisfaetory only for subbase

or subgrade stebi1izatie„' (5)

The reaetion of hydrated lime with sell has been under research

at the Uiversity ot Il1inoie• (6) hith the help of Xsray diffraction

and diffsrential thermal analysis, it has been possible to study and

identity the reaetions• The first reaetlon that is brought soo

after adding lime sonsists of replacement of absorbed lens by ealeium

20

ions; second, a series of newrminerals are formed; third, the oarbonae

tion of hydrated lime. (6)

Oompressive Strength of Treated Olays with Hydrated Lime

The hyeming montmorillonite showd a reduetion in its eopressive

strength when 2 per sent lime was added. (6) Speeimene with 4 peroent

und 6 peroent lime showed slight increase in strength. The Fithian

illite elay had the highest eompressive strength in the utreated con-

ditio, but when 2 pereent lime was added its strength was greatly

lowered. Test results show that kaolin samples inoreased signifieant-

1y in strength with the additie of the first inerement of lhme, where-

as in other olay*minerals there is little increase in strength until

4 pereent er more lime is added. From experiments it is observed that

kaolinite and lime reaet easily and only small amount of lime is needed

to start the reaetien, while montmorillonite end illite require greater

amount of lime befbre development in strength begins. (6)

For the past three years much research he been eondueted at M.I.T.

on soll-lime stabilization. (6) The soll-lime mixtures tested con-

sieted of pure minerale, ranging from quertz to keelinite, plus lO

pereent Ca0H; and natural eoile ranging from a uniform eilt to an er-

ganio elay, plus 5 pereent ealclum lime. The test results showd

that:l. Addition of lime reducee the eompaeted density

of soils but increeses the seeked strength of

21

solle after curing period of from 7 to 26

days,

2. Small percentages cf quicklime (1 to 5)

increase the strength of wet soil 5 to 10feld in two hours.

Seven scil samples from the Republic cf Honduras eere sent to

H.I.T. research labcratcry fer classification tests. (10) Of these

two samples cf low and high plasticity were selected for so11—1lme

stabilization. Test results showeds‘—

l. A large decrease in strength due to soakingfer utreated soil.

l2. Maximu dry density reduced with incrsssing

percentage of lime.5. Oonsiderable increase in soaked strength

with incressed percent lime. (10)

After obtaining these results, soils in Honduras were treated

with lime during constructic cf 1000 miles of reads. (X3 An econo-

mic study showed that a sisainch sci1·lime base course proved to be

less then one—ha1f as expansive as a crushed stone base course.

Effect of Quicklime c wet Seile

Four solls, i.e. Massachusetts Glayay eilt, Vicksburg loess, Heu

Hampshire eilt, and Vieksburg buckshot clay were selected fer testingst H.I.T. scil stabilizaticn laboratcry. (10) Test results showed

22

that a small peroentage ef quieklime, i,e, 2 to 5 pereent, inereaeed

the dry density ef all the sells, Gempressive strength ef eilt and

elay inereaeed from 2 psi to 5 psi to 75 and #5 psi, respeetively in

100 hours, (10) The effect of ealoium oxide on the strength„ef'Massa•

ohusette elayey eilt ie more due to the greater hydratability of sal-

cium oxide than magnesium oxide, The strength ef this eilt after 1,5

hour euring with 2 peroent ealoium oxide ie about twiee that with

2 pereent oaleium quioklime, (10)

Aoeelerated Guring For Lime—Stabi1ized Seile

Two eoile, i,e, olay grevel and mioaeeeue eilty soil, were ee-leeted fer testing uneenfined eempreesive strength and GBR values

when mixed with 5 pereent lime es the stabilising additives, (2)

Experiments were eendueted at the Investigation and Research Labora-

tory of Seile at Oharlottesville, Virginia, The fellowing oonelusions

were derived:1, 'The uneonfined sempressive strength ef epeeimens

field oured fer appreximately ne daye at summer

temperature could be predieted by an aeeelerated

leberatery euring for either 18 hours at 1h0°Fer two days et l20°F, Hwever, 120°F euring is

perfhrmed fer the following reaeons:a, Lese oondeneation between the epeeimen

and the preteotive eoating during euring,

25

b. A lower, therefore, a more realistic

temperature.

c. Oenvenisnee of ouring time.

d. Increased aecuracy obtained with small

slopes of the etrength-time curve.

2.‘The strengths of these stshilized soils will be

a function cf their maturities, when subjected

to field curing.

5. ‘The solls' GBR values will increase many feld.

However, these values are sometimes so high as to

be unrealistic. Also, due to the size cf the

specimens and the amount of scil involved, not

enough 0BR test specimens can be made for statisti-'

cal evaluation:. Therefbre the attempted field-

moist roo curing correlation for the GBR epecimens

proved unsuccessfu1.V (2)

Soi1·1ime stebilization ws cxperimented on a section of Northeim-

Hanover, Autoban, Germany. (5) The lime used was calcitic quicklime.

In order to study the poesibilitiee cf soil property modification,

the raw soil was mixed with 1,5, and 5 percent respectively of the

calcitie quicklime. lmmediately after mizing lime with the raw soil,

a significant flocculaticn was observed which proved to be water re-

sistent. The reason for this behavior could not be satisfactorily

explained. (5) The plastic limit rose from 16.0 to 22.0. The liquid

l

2h

limit rose from 22,8 to 2h,O which reduced the P,I, from ä,8 to 2,0,

Maximum dry deneities were somewhat reduced by lime, whereae the opti·

mum water contents were noticeably increaeed, After curing period of

28 days the soil samples ehowed an increase in compreesive strength

when mixed with one poroent lime up to 98 psi, Upon further ouring

the comprescive strength remained constant, The specimens treated

with 5 percent lime showed a eteady increase in immersed copressive

strength up to 500 psi after a period of six months, (5) The test re·

sults clearly showed that loose may he improved considerably by adding

small amoumts of lime, In particular, the fhllowing properties can

be improved: a) soil structure, b) plaeticity, c) compactibility,

d) water resistance, and e) strength and bearing capacity, (5)

In 1956 the Nebraska Department of Roads perfermed an experiment

in which hydrated lime in the stabilization of plastic eoile was used,

(12) The scil used was a plastic reddieh—brown glaoial clay AASHO

soll elaeeification A—7•6 (16), The laboratory test results show

that six percent lime reduced the plaeticity index from 50 to l in one

hour, and zero in two days, Ehen greater percentages of lime were

added the maximm dry density deoreaeed while optimum moisture con·

tsnts lnoreased, (12) From the data collected it was concluded that

the pavements in the limc·treated sections have perfermed as well er

better than the pavement in the standard control sections, (12)

At Iowa State College Laboratory, a study of the effect of vari-

ous peroentages of lime and portland cement was conducted on the engi-

neering properties of a heavy, eticky, gubc soil which is found in

25

southeastern Iowa, The eoil is very old, highly wathered mcntmoril—

lcnitic material of Nebraskan or Kansan age and contains #5 percent

of five—micro clay, (1#) It is an A-7·6 (20) soil in the Bureau of

Public Roads Classification system, The lime used was USP calcim

oxide obtained from the ehemistry department of Iowa State College,

It oorresponded roughly with th commercial nslaked or lump lime for—

merly used widsly in mascnry and plaster work, It has a specific

gravity from 5,15 to 5,#, The lime was pulverized and passed through

a lO0·mesh eieve before it was added to soil, (l#)

In general, the engineering properties of gumbotil soil were im•

proved after adding lime and cemsnt admixtures, (l#) There was a

‘ marked decrease in plasticity index, However, as the peroent lime

added increased, the lime produced a much more rapid decreaee in

plasticity than the ccmcnt, For example, two percent of lime reduced

the plaeticity index to 8, whereas two percent cement only reduced it

te 27,5, Both lime and cement improved shrinkage factor and strength ·

of soil as revealed by GBR tests, Lime provod to bc more effective

of the two for equal amount of admixtures, The addition cf four per•

cent lime to the soll dccreased the standard AASHO density from 97,5

pdf for the natural soil to 92,8 pdf, (1#)

This labcratory study indicates that it ls possible to modify

favourably the gumbotil soils of eouthcast Iowa, Also, the indica·

tion! are that lime is more effective than portland cement and pro·

duoes more extensive modification for the same amount of added

material,

26

The soll conditions in Red River Valley in North Dakota are most

uneuitable fer road construction. (ll) The coll ie called gumbo which

ie four to five feet deep. In order to overeme the difficult problem

cf providing an all weather road without spending too much money, it

ws decided tc run standard soil tests to determine the relative quali-

ties of the native soll with hydrated lime. The experiment: hegen in

March 1958. Samples were taken from the depth of O to 6 inchee and

from 6 to 12 inohes. The teat results lndioated that soll reaetedT

very favourably with lime: l) the drop in plaeticity index valued frm

21.5 without lime to 1.8 with lime, 2) GBR reached a value of 128 afb

ter curing in a temperature of l#0°F for seven days. A speoimen pre-

pared for the GBR test was kept under water fer 15 days and showed no

sign of dieintogration. (11) The test uder water indicates the poten-

tial cf lime stabilization in the resistance of capillary water, which

ls one of the most deeirable characteristice in any type of base

construction. (ll)

Durlng l9ü8, two sections in State Highway District III, Head-

quarters at Marysville, Oallfornia, were constructed using lime. (18)

The first project wae located near Truckee, Oalifernia. In this

two percent of agriculture lime of the type sold comercially in 100-

poud bags was added to a for inch layer of granular base material

by the road mix method. (18) The construction hegen in August l9Ä8.

27

An inspectio on April 20, l9h9, showd that the section was in good

condition, Samples of the treated base material were non•p1astic and

when tested in the stabilmetcr gave satisfactory stability values,1 Te preliminary test indicated that the addition of two pcrcent cement

rcduesd the plasticity index to 5, The lime treatment showed satis-

factcry results and produced a stable base which has carrisd compare,

tively heavy traffic during one of the wetteet winters in that locality,”

Another inspeotion in 1950 showed the treated section to be in excel-

lent condition, (18)A second project coneisted of the construction of a test section

which was made of impcrted base material to which was added approxtmat—

ly four percent hydrated agriculture lime on a road between Oool and

Georgetown, Galifornia, (18)

Preliminry samples submitted prior to start of construction

showed e GBR in exoess of 100, Plasticity index ranged from 7 to 9 per-

cent• (18) Laboratory test results indicated that the addition of four

pereent agriculture lime would render the material non-plastic, Ernest

Zube of the Oalifornla Highway Department concluded that lime stabili-

zaticn treatment for bases and subbases permits greater flexibillty

during construction as it is not essential for the material to be com-

pacted soo after mixing, In areas where oparatively inexpensive

egriculture lime may be obtaincd in bulk, a eonsiderable saving may

be possible as against other comparable types of treatments, This

saving would amout to approximatcly $1500,00 per mile for a bass

course six inchee think and twenty feet wide, (18)

28

ANALYBIS OF SOIL USED

äsél Peas.The sample ef the elay eoil used in this study was taken from

the exeavation fer the foundatio of the new Givil ngineering Build»

ing at the Virginia Polyteehic Institute campus. The clay eoil used

was reddiehpbrown with a plastioity index (P.I.) ef jo and liquid lim-

it (:..1,.) er 67.

§:§gg_Hdffraotlon Analygis

Procedure

A meist speoimen of soil, approximately 50 grame dry weight, was

mixed with 500 oc. of dietilled water to which a teaspoonful of de—

floeeulating agent, the detergent 'dalgon", was added. The auepeneion

was agitated with a high speed electric mixer. The suspeneion was

mixed and then allowed to rest. Partielee with a size of lese than

0.002 mm. effective eettling diameter, ae oalculated using Stoke‘e

Law, were oarefully siphoned fro the diepereed suspension after ma-

terial of eilt size had eettled to the bottom of the eontainer. Pull

recovery of the less than 0.002 mm. material from the original sample

was not attempted. The solide in the siphoned suepension are here•

after referred to ae clay.

The pH of the clay suepension was adjueted with HQI to about 2.0

and the colloide allowed to flccculate and settle• The supernatent

liquid was decanted, dietilled water added, and the mixture ehaken•

29

with four repetitions of this floceulationedeeantation process, the

exoeee HC1 was removed from the sample; subsequently about 50 mg. of

solide in 2 ml. of suepension were traneferred to petrographic slidee

and allowed to dry slowly eo as to form an oriented clay film on the

surface of the glass. The epeeimene were then treated with ethylens

glysol, heated to 500°O, heated to §oo°o, er left untreated es re·

qudred fer diagnostlc Xeray diffraetion analysis. The analysis was

oondueted using a G.E. XRD5 Zeray diffraetien machine with attached

epectregoniometer and employing Cu Koi radiatlon.

· Results and äascusslon

Curve A, Figure 1 is an Xeray diagram of the untreated clay at

roo temperature. The i1l—deflned, asymetrical, and hrend ‘peaks‘

characteristic of these patterns suggest that the elay is poerly

orystallized. The first portion of the diagram suggeste that the

clay·minera1 may be allophan which are amorphous to Xeray diffrae-

tion, or it could be a mizture of poorly cryetallized montmorlllonite

and illite. This, hoever, does not mean that auch materials have a

eomplete_absenee of any etruotural organization. Rather it means

that the arrangement of tetrahedral and octahedral uits with respect

to each other is not sufflciently regular to permit diffraction, or

the individual uits are too small in eine to yield diffraotion efb

feste. At l2.l0°, the olay minerals belong to the kaolinite group.‘

These kaolinitic minsrals seem to be of low eryetallinity, i.e. poor-

ly erystallised kaolinite. This suggeste that there may be some

.E.„‘§.9.B..€--1><—P«AY- DIAGRAMS OF CLAY SOIL USED

' >··E BU) .ZLI.!I-Z

C

A ..uI~ITR6ArE¤B - TREATED WITH GLYCOL,

C- HEATED TO 500C

I3 I2- II I<> 3 8 7 6 5 4 52-S

\

501l

randcmaess in the distribution of aluminum atoms amog octahedralpesitions, which point cut the fact that there may be some froquent

interlayers of water between the eilicate units, Dehydration curve O,

Figure 1, tende to confirm the preeence of such water• It is quite

possible that there may be sos light eubstitution of titanium er iron

for aluminum in the pcorly erystallized kaolinite• It may be that the

presence of auch replacoment ie a cause ef the lower degree of crystal-

linity• Alec, it could be halloysite which has the basic kaclinite

structure but contains layered water in the etructure•

Ourve B, Figure 1, which is the X·ray diagram of ethylene glyeol

treated elay, shows that the mixture tends to separate into more die-

tinct r•flections• At 5° it suggeste the presenee of poorly crystal-

lised mcntmorillcnite, At 8,6P and l2•6° the mixture, poesibly, con-

tains minerals which belong tc illite and kaolinite group, respec-

tively•

In Ourve 0, Figure l, the first part suggests that ae the sampleI

is heated to §o°o the pri refleetions lose their sharpnese and in-

teneity• The refleetions for the montmorillcnite were reduced in in-

teneity from a peak to a haggered band, suggesting a general, gradual

dehydration of’montmorillcnite etructure• At lO•2° it shows the pre-

eenee of illit••

One-half of the sample is 1:1 type clay, kaclinite group, poorly

crystalline kaolinite cr hal1cyeite• ne-half of the sample is 2:1

type clay, of which: one—fburth is illite (l0A° uderall mcisture andl

temperature), one-eighth ie montmorillonite (l7•6A° with glycol), and

l51

one-eighth is interetratified 2sl type minerals•

Table I eummarizes these eonolueions•

TABLE 1 (

0lay·Mineral Oopositien

50 Kaolinite group, either hallcysitecr poorly crystalline kaclinitemineral

10 Illite

10 Montmcrillonite

10 Interstratified illite — montmori1—lonite or illite « chlorite

ho Amorphous Fe and Al oxidea andhydroxiden

The Xaray analysen, including the diagras of the samples treated

with ethylene glycel and when heated to various critical temperatures,

suggest that the clay fractien sf the soll has the epproximate ccmpesi-

tina given in Table I, Interpretation: of the Xeray data were based

en published material sunmarized by Grim, (7)

Ooneidering the large amount ef amorpheun material thought to be

present in th elay samples, it is difficult to draw eonclusive rela-

tie to the elay behavior on the basis of the X»ray diffracticn analy-

sis, Hbwever, Grim gives engineering data on samples ef variou clay

minerals which suggest that if the elay in this study were oonpared

to these results, it would have properties about midwey between the

montmorillonite and kaollnite group•

52 Eggg; §g,_gg_ Determination

The results obtained from grain size analysis by standard hydro•

mster (ASTM Dssignation ·· D¢+22··5öT) are shown in Table II, and the ga-

dation ourve plctted on the basis of results obtalnad ls shown in

Figure 2. The following modiflcations tc the standard procedure were

made:1. Instead of soaking for 16 hours and mixing for

5 minutes, the soll sample was stirred in an

electric mixer for 20 minutes.2. Tap water instead cf distilled water was used.

The sample of soll was so fine···gra1ned that only 2.} peresnt of the

total sample was retalned an slave eine Ro. 200, while 97.7 percentpassed through lt.

TABLE II

Q Grain-·S1z• Analysis

D Finermm. H ä

0.018 96.500.0125 95.1+0 Q0.0092 95.20 ¤0.0061+ 90.05 :0.001+5 66.00

T 10.005561.200.002665.50 '0.0016

t65.70

55

PEIÄCENT FINER BY VVEIGHT

co oo oo ¤o ko ko kv ‘¤ ‘°O N A GN N O N -‘* m °°Ö „01

GNDI>

’ ZU3

" N· ¢Tl

U(B·—lD

CZ E TIO •-•2 ·· "m 6 C

-4 Q Z ]°FTI 9. mD m u

~<Z I

~<E 0K DO

3W}-{H1Do

9 ‘

9kb

P 5 112 1

Plastic Prcgcrtics gg §_•:_;_;_l__ ‘

Attsrberg limit test results arc tabulatcd ae fcllcwm

TABLE IIIAttsrberg Limit Results

0 67 57 av5 61+ 1+1 25

10 68 115 25

‘

GBR SOAKING TIME STUD!

Ojeetive

The objective of this part of the investigation is to study the

effect of inereasing soaking time en GBR values of clay soil~lime mine

tures• Haring this study eoaking time and lime content were kept as

variables,Density Lg};

Th standard AASH0 oompaotion tests ere run on air dried sollwith natural water content of five percent in aecordanee with ASTM

designation 698·58T (Moisture·density relations of solls using 5,5 lb,

hamsr, having a drop of 12 inches) method A. Three samples, each

with 0, 5, and 10 peroent lime by dry weight of soil, were prepared•

Gompaction was done soon after mixing, Gurves plotted on the basis

of these results are shown in Figure 5,

California Bearing §g};g_QgggThe Galifernia Bearing Ratio tests (GBR) determine the bearing

ratio of soll when compaotsd in the laboratory by eoparing the pene-

tration lead of the soll te that of a standard material, The stan-dard material selected is a high quality crushd stone, This method

is mployed to evaluste the relative quality of subgrade solls hut

ie also applicable to subbase and some base course material, (17)

Gelifernia bearing ratio tests were run on natural eoil and

soil·lime mixturee campaeted at optimum water contents in asoordance

with ASTM designation D 188§—61T, in order to study the effect of

w

I

66 I

FIGURE31;>R9 DENSITY-M0ISTuI2E CONTENT RELATIONSHIP

/0

98

96

94oV I

92 O\° IO I

zwu *1Ä) 90 Y} O I\J I9 I>,I.; 8* ,,98 IU3 __ 9 _______ IZ 6 6/‘ I ' " IIII“ 8 >< I I QG _I>~

{ ICf 84 I I YpQ I I O

I I 782 I I 3I ' T-I I OI \80 I II „.I I378I III I076I‘ II I IIO II I @68 : .74 I‘JDPIV‘V I I

%IPII// I72. I25 28 55 58 43 48

MOISTURE c0MTEmT<I>sRc6~T>

57

inereasing soaking time on strength, dry density, degree of saturatio,and swell potentials. The peroentages of lime added were O, 5, and 10

by dry weight of soll. Three samples were prepared each for O, 5, and

10 peroent lime and soaked for 1, A, end 8 days reepectively. Gompae-

tion was done soon after mixing. Due to an inedequate quantity of

available soll, only one sample was prepared for each eoaking period.

Observation: were made to caloulate the following:

1. Dry density of sample before scaking

in lb. per eu.ft.

2. Moisture content of sample, in peroent

a. During oompaction

b. Top one-inch layer after soaking

o. Representative after soakingA

5. Pereent swell

A. Percent degree ef saturation (average

after eoakingö

5. Bearing ratio of sample (unsoaked and soaked),

in pereent.

Results ggg_Discussion

Moisture—Density Relationship

Reforring to Figure j, it is eeen that the maximum dry density

obtained is a function of moisture content, eompaetive effort being

constant. Ao the soil molsture content is inereaeed, the dry deneity

increasee because of a breakdown of solid clode and soo other factors

55 Ü

influenolng werkability cf the soil. The ourves shown in Figure 5

slcpe upward until at a certain moisture content (hereafter optimum

moisture content) the density begins to decrease. The decrease ie

caused by the vcids of the soil becoming partislly fllled with moie—I

ture, with the result that with further increasce in moisture ootent

water replaces a portion of soll solide.

Soil is a highly variable materiaJ•espeoially highly plastic

soll; the inter—relationshlp of soll textue, deneity, moisture con-

tent, and strength are complex. Because cf this eomplexity, it ie

not possible to set down rules as to the exact behavior of the soll.

Table IV and Figure 5 show that addition cf five percent and ten per-

cent lime decrease the dry dcnsity from 95 lb./cu.ft. to 66.6 lb./cu.

ft. and 76.6 lb./cu.ft. respeotively. This tends to eonfirm the gen-

eral belief that lime generally bringe about a decrease in soll densi~

ty. Also, 10 percent of lime increaeed the optimum moieture content

from 55 peroent to ä5.8 perocnt, while 5 percent lime in fact appears

to have deoreased lt from 55 percent to 52 percent.

TABLE IV

Effect of Addition cf Lime on Ieneity and Meisture Content,Gompactive Effort Being Constant

Pcrcent Lime Br Densit MolstureContent0

95.0 55.0

N5 66.9 52.010 76.6 A5.6

lN

---——---—....................................._.__..______________________________g_j

59

GBR Testsgg__f_ggt_ gg __L5_g_g ggg Increasing Soalcing gi_.gg gg gg ggg. Table

V and Figure Ä show that as the lime content and soaking time increase,

ecaked GBR inoreaees from l2•5 perocnt (natural coil, one~day cooking)

to 5l•66 (soll treated with 10 pcrcent lime, 8-day eoaking period)•

The increase in strength by addition of lime may be du to ooncentra•

tion cf calclum lens. Figure Ä also suggeets that soil—lime mixtures

cured fer a period of eight days result in greater strength• The ex-

planation may be that immediate increase in soil strength is brought

about by changes in the water films surrounding the clay partiole:•

Ouring the speoimens fur an increasing period (from one to eight days)

bringe about further increase in strength•

Soaking gggg_- §gggg_Percent - gggg_Pcrcent Relationship. Ourveein Figure 5 are plotted far three samples, l•e• 0, 5, and 10 percent cf

lime fur soaking periode each of 1, Ä, and 8 days, respectively• un-

treated coil samples show a gradual increase in swell, though swell po-

tential is not sppreciable• This may be dus to the fact that since th

soil possibly contains large amounts of halloysite or poorly crystallised

kaolinite minerals, the structure does not have capacity to abscrb great-

er quantity of water. aith additio of 5 percent lime the magnitude of

suell gradully increases• In case of 10 percent lime the suell poten-

tial gradually increase: for a period of Ä days; afterwards swell re-

main! ¤onstant•From Figure 6, it ls clearly evident that in all three cases, i•e•

l, Ä, and 8 day soaking period, the amount of swell at ten percent lime

ho

1 21002 v

Q2!}.2.9.9.*:.Scaking

in lb./0u.f‘t. % ·Period % Lime % Lime 1% Line % Limav Lime 1% Lime1 day 65.50 77.50 60.0 19•ÄO 19.66 17.706 day 65.50 77.00 79.70 16.20 21.55 läaäß6 day 66.00 76.00 79.80 16.55 20.00 1#•0O

.;*0:14 957 Limo 7,% Lima •1*7~ 7 ·7 7 •;7 1..1010 Lima Lime1 day 12.50 10.00 25.00 1.50 1.25 0.150 day 9.65 11.00 27.55 1.60 1.26 0.226 day 11.66 12.5§ 151.66 1.65 1.56 0.22

Periad Lima jä Lima 1%. g1g .1 day 99.60 66.50 95.001 day 99.50 192.20 95.506 day 96.00 67.00 95.0

I#1

I

FIGURE 4I

SOAKED CBR — $oARaNG TIME -REL/ÄTIONSHIP

55

IQ sc aeg LamaluUS 450.U

40CDU0 35ILIX

. ( 30Okh

25

2

I5 SZ LIME

IOooé Lama

5

° 1 4 2SOAKING TIME (DAYS)

1:,2 .

FIGURE 5SOAKINC-3 TIME —PERCENT SWELL. RELATIONSHIP

2.~0

F 183 OZ umeQ I·6I! Iä 1-4J 523;///**4;* 1-2UI

I·O

O·8

o-6

Omj, LIMEQ.2°

1 ”””TÄ_T—_ 3SOAKING TIME (DAYS)

I

/+3 .

F IG U R E 6

SWELL PERCE/VT—LIME PERCENT RELATIONSHIP_____ -_,„.-..-......._.;.——..— -———--—-——-— M-—————~——— i~—··— -—-^ —-~- ---—-—·4- -—·—--—•·····t— ——§·—·*‘-I

I _

IIIII

I II II I

I· 8 II- IIII I 6 I,·—¢(-\?ÄII-P---$4 Q3äwIII

I 4 I IE \x—· ILU I- ZI-xx2I \_ \ IIII I II II I0-8‘-

II0-6

II0- 4O

O —-—-—-—·-·——·~w·—·———-TTT—§”TTIT·---- - ——··· IT "‘”"’

I. I M E P E RC E N T

hh

is mueh less than that at five and zero pereent lime, which tends te

eonfirm the theory that addition of greater quantlty of lime deereaees

the swell potential irrespeetive of soaking period. The explanation

may be that since oaleixmx has greater ionic charge than water,

claypartieleslose their affinity towards water and become attraeted to

ealeium powerful lens. It ie this attraction that possibly is respon-

sible for deorease in swell, thus making the eoil sample more permeable•

Also, it was observed that almost all the swell takes place within the

first #*+8 hours in all the cases•

Soaking ggg ··_Q_•_gz_j_e__e_ Saturatig Relationship Figure 7 shows

the relation of inoreasing soalcing time (1 day to 8 days) and degee

of eaturation, which was calculated on the basis of specific gravity

of solide equal to 2•67• Untreated soll sample shows a eontinuous,

gradual downward slope• Five and ten percent lime show an increase -·

more sharp in five pereent lime than with ten pereent lime —- in eatu-·

ration up to a eoaking period of four days. Afterwards, the eatura-·

tion deereases, This suggest! that lime additione reduce the degee

of saturatiom§_ggk_gg g — Pereent ggg Relationship, From Figure 8 it is

seen that with iaswsaslwg amount of lime a sharp increase in eoaked

VV

V

1+5FIGLJRQ Z _

SOAKING TIME—DEGREE SATURATION RELATIONSHIP

/00

¤»98I-Zu.a 96 ¤‘ä ao/, Lama

Q95ua

ZO 94I·—

E3 95I-<‘^ 9:.auua

af! 9'K')LuC) 90

sg LIME89

88

87

86O 1 4 8

SOAKING TIME (DAYS)

46

F-IGURE B

SOAKED CBR — L.INIE PERCENT RELATIONSHIP

52A

48 VOA MQ 44LUU<I 40LUO.COi 36 l

ci)U —\ //Q 32.

Q? —\/

un°‘ vv

K N

Ö 28 2 /° LO

24 '

20

I6

’ IZ € •

8 0 5 no

LIME (PERCENT)

1

*47

GBR ie noted• Strength of eoil inereaeee most after 8-day noaking

with ten pereent lime content, with five peroent cf lime, strength

in feet deereaeee after 1 and k~day eoaking periods• The sudden jump

after 8-day eoaking period auth ten pereent lime in obviou• Thin

peeeihly points out an important fact that with inereaeee in lime

content and ncaking period, strength of thin fine•grained noil in

ereaeen many fold•§ggggg_Qg§_- Benoit; Relationship. Pigure 9 shown that eoaked

GBR lncreanee with an increase in dennity frm five pereent lime eon—

tent to ten peroent lime content, and then elepee downward eharply

from ten percent lime content to zero peroent lime ccntent• Thin

holds true fer 1, b, and 8-day ncaking periode• Also, it beocee ap-

parent that greater peroentagee of lime content do increase the Astrength of the ecil eamp1e•

£ggg;tgyPereent gggg_Relatlonehip• In all the caeen, i,•• 1, k,

and 8—day noaking periode, deneity ehowe a sharp drop frm zero to

ten percent lime, (Figure 10) Afterwardn, an inereane in deneity ie

seen an percent of lime ie added• This, however, does not agree with

Figue 5 where additionn of lime content gradually deereaee the maxi»

mum dry densitien•

48

FIGURE 9SOAKED CBR —1>6Ns1T>¢ RE1.AT10Ns1-11P

10701.1ME52

6 48

” 44

C 40ZIUQ 36ME

O .

U 1Q / °

G},1, 24 ‘ U.,

.L< JÖ 2

Oqvs ° *16 >

¤ O 07LlM7 1 ¤·,1 5/1.1ME '• Q.1.\*

5/, 1.1ME o/° 1.1545I]

47/

g 6/ ume

4

o75 76 77 78 79 80 Sl 82 85 84- $5 86

DENSITY ( Pc?)

II

I49

FIGURE IO

DENSITY — PERCENT LIME RELATIONSHIP

86 ¤‘

Q3 85Q\/

>~ 84I—thZ 85LuQ

82

G I.gl y 'O P_‘I.//V OQ ~¢ 's/

so V2

79

78 ••

77 1*-..,-O 5 IO

PERCLENT LIME

50

OGNGLUSIGS

n the basis cf the results presented in this study, it is feltthat addition of lime hs definite and dietinct bearing on maximum dry

denaity and strength. Deoreaee in optimum moisture content with the ad—

dition of five peroent lime may not be very signifioant. Inereaeing cur-

ing time has resulted in a eubstantial increase of seaked GBR. It appear!that a four·day soaking period is insuffieient insofar as bringing outth maximum strength of a lime stabilized soil. Swell potential was

net affected by inoreaaing the ouring period, while degree of saturationmay be among the factors which are influenced by the addition of hydrated

lime and the inoreasing cooking period.1

The most important conolusione of this study are as followss1. The addition of lime deereaeed the maximum dry deneity,

compactive effort being oonetant.

2. Soaked CBR increaeed many feld at the end of the 8—day

soaking period with 10 peroent lime content. Strengthgained after 8-day soaking period was almost double the

strength of Ä•days curing.

5. Percent swell ehowed a graduel increase in the oase of

untreated soil and with the addition of 5 pereent lime,

while addition of 10 pereent lime shewed a elight, in-significant increase in ewell potential for a period of

Ä days; afterwarde it remained constant.

I

1

51

BIBLIOGRAPHY

1. Aaron, Henry, 'Report of Committee on Lime··Soi1 Btabiliscation."

washington, D. C., ABBA, Tech. Bull. Ho. 1b7, 19bB.

2. Anday, M. 0., ‘Acce1erated during for Line·8tabilized So1ls.'

Virginia Council of Highway Investigation and Research,

Charlottesvills, HRB Bull. No. 50h, 1961.

5. Brand, R. and R. Schoenberg, *Impact of Stabilization of Leess

with Qnioklime on Highwy Construetion.' Autoban—Neubauaat•

Northeim, Germany. HRB Bull. Ho. 251, 1959.

b. Carter, H. C., ’Lime Stabilisation In District Fourteen, Texas

Highway Department.* ABBA, Tech. Bull. Ho. 185, 1952.

5. Davidson, D. T., Manuel Matces, and Barnes, H. F., “Improv¤mcnt

of Lime Stabilization of Montmorlllonite Clay Scils with

Chemical Additives.' HRB Bull. H0. 262, 190.

6. Endes, James L., and Ralph B. drin, ‘Reaction of Hydrated Lime

with Pure Clay Minerals in Beil Stabi1izati0n.* HRB Bull.

ae. 262, 19607. drin, Ralph E., *2+Ray Diffraetlon Data.* Chapter 5, Clay Miner·

alogy, 1955.8. Herrin, Moreland and Henry Mitchell, *Lime·Soil Mixtures‘ HRB

1Bull. as. ach, 1961.

9. Hilt, G. arrison and D. T. Davidson, ‘Ldme Fixation in Clayey

211.11..* aus sau. se. 262, 1960.10. Ladd, C. C., Z. C. Mob, and T. R. Lambe, ‘Recent Soil·Lime Re-

, search st the Massachusetts Institute ef Techno1ogy.' HRB

52

11, Luim, E, L,, "Red River Valley Experiments with Lime Stabiliza-

tion} Better Reads, Nov, 1958,

12, Lund, 0, L, and N, J, Bamsey, "'Expsri¤snta1 Lime Stabilization

in Nebraska} HRB Bull, No, 251, 1959,

15, McDonell, Chester, "Stabilizstion of Seile with Lime, Lime•

Plyash, and Cther Lime Reaetive Materials} HRB Bull, No, 251,

1959,lb, Spengler, M, C, and G, H, Pate}., "M¤d1f‘ieat5.en ef a Guubotil

Seil by Lime and Portland Cement Admixturee} HRB Prooeeding

Vol, 29, 19!+9,15, Taylor, äf, H, and Ara Arman, ‘L1ms Stabilization Using Pre-

5conditioned Seile} HRB Bull, No, 262, 1960,

16, Reed, J, Eldridge, "Lime··F1yash Seil Stabilization in Maryland}

ABBA Tech, Bull, Ro, 199, 1955,

17, Yoder, E, J,, "'8ubgrede•," Chapter 9, Principles of Pavement

5 Design, Riley and Son, 1959,

18, Zube, Ernest, Experimental Use of Lime for Treatment of Highway

Base Courses} ARBA Tech, Bull, No, 181, 1952,

l

_ l

55

AOKNOWLEDGMENT

_ L

A B 8 T R A O T

Lime Stabillzation of a Vlrginla Ulay Sell

The fact that when lime is added to slayey solls same very bene-

ficial results are produced dates back into the remote past• It ls

net a new development• In the United States lime has been in use

since l925•

The objeetive of this study was to determine the effect of in-

creasing soaklng time ef soil—lime mixtures on the strength, swell

potential, and degree of saturatlon• In order to ascertaln the exact

cempositlon ef elay mlnerals, X+ray dlffraetion analysis was rn an

the sell sample• The analysis showed that the clayey soll contained

a large amount of water with a greater pereentage of halloyslte miner·

« als. The sell, lt was concluded, was pocrly crystalllne and was feud

to be mldway beteen mcntmorillonite and kaollnite group• Frm the

test results obtained ln the laberatory, the following obeervations

were made:l• ith inereasing ecaking tlme, strength of the soil

sample increased many fold• “

2• The effect of increasing soaklng time on the swell

was not slgnifieant• Almcst all volume change took

place in the first hö hours•

5• Degree of saturation remalned constant with increase

in curlng perlod•

It is felt that feur—day euring period may be conservative in-

sofar as strength of subbase and pavement is conoerned• By increas-

i

ing the curing time from feur days to sight days or langer, failure

of subbase er pavement may not oecur•