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Bachelors Theses Student Theses and Dissertations

1931

The transmission of pressure in the dry pressing of typical The transmission of pressure in the dry pressing of typical

building brick and fire brick mixes as affected by the variation in building brick and fire brick mixes as affected by the variation in

grog size grog size

Henry Rickel Herron

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Department: Materials Science and Engineering Department: Materials Science and Engineering

Recommended Citation Recommended Citation Herron, Henry Rickel, "The transmission of pressure in the dry pressing of typical building brick and fire brick mixes as affected by the variation in grog size" (1931). Bachelors Theses. 304. https://scholarsmine.mst.edu/bachelors_theses/304

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~- TRANSMISSION OF PRESSURE IN THE DRY PRESSING

OF TYPICAL BUILDING BRICK AND FI}iE BRICK I~:IXES .AS AFFECT:ED

BY TffE VARIATION IN GROG SIZE

A

THE-SIS

submit.ted to the faculty of the

SCHOOL OF MINES AJn) bLETALLURGY OF THE UNIVERSITY OF MISSOURI

in partial fulfilLment of the work re~uired for the

De-gree of

BACHEL6R OF sc rENeE IN CERAMIC ENGINEERING

Rolla. Missouri

1931

A.pproved by --------------------Pro:ressor of Ceramic Engineerin.g-

TABLE OF CONTENTS

Title Page

ACKN OVVLEDG1\rENT • • • • • .. • • • • !

INTRODUCTION • • • • • • • • • • • • • • • 3

MATERIltLS USED .. • .. • '. • • • • • • • • • • 6

SIZING OF lVIATERIp...LS • • • • • • • • • • 6,

MIXING .AIm TEMJ?li,EING • • • • • • • • • 7

FORMING. • • • • • • • • • • • • • 8

TEST SPEC I:MEl~S • • • • • 9

DRYING .. .. • • • .. • • .. • • • • • • • ~o

APPAli.ENT POROSITY DETEilliiINATION. • • • • • • 10

CALCUL.A.TIONS • • • • • • • • • • • • • • 11

GRAPHICAL REPRESENTATIO~I ,OF DJ~TA • • • • • l~

DATA .. • • '. • • • • .' • • • • • • .. • 12

CURVES • • • • • • • • • .. .. • • • .. • 23

DISCUSSION OF RESULTS. • • • • • • .. • 24

RESUME .. • • • • • • • • • • • • • • • • 28,

ACDJOWLEDGIVfENT:;:

The wri ter wishes· to aeknow~edge his· indebtedness to the

Dry Press· Commi ttee of the National Bricl{ }[anufacturers

Association fo~· the priviledge of us ing its dry press in

~arrying out the investigation.

Special IlPI>reciatiorl is Que to Doctor ]I. .E.Holmes and to

Professor C.M.DodCL for their many helpful comments and

criticisms throughout ~he entire research problem.

The writer wishes to thank and congratulate his

Qo-investigat,or, ·S.J. Tompach t for his hearty ~oo:peration

in all the work encountered.

I~rTROlJUCTION

In the :tormation o:r dry pre'sse<l ware. the transmission of

pressure is of' vital import.anc.a t.o the quali t.y and eharac"t-e·r

of' the finished proQuct, as regards the resistanee· to spalling.

load at high. temperatures. slag aetion. abrasion anQ other

physieal propertie-s·. Furthermo're·,. the· transmissi.on of pressure

is a limi ting :rae'tor as regards the s·ize and. irregularity of

shape o~ a pro~Qct manufaetured by the dry press process.

Prior to the time of' this. investigation several companies

have sucaeed.ed. in producing ware. up to· six (6) inches in dept·h;

but an inerease over six inehe. has resulted.. in every oase. in

failura iiue to lam~ations, so:rt. eanters t andair crack.s~ which

were c.aused by entrapped air.

An id.ea~ mater'ial :for' dry press,ing' would. be one. which

possesses the J,nherent characteristies of' water. i.e •• trans­

mi·ts pressure equally in al~ direc.tions. C·~ay» unf'ortunately.

does not possess this clesirab:le property and. it is the aim of'

dry press inves.tigators to a:pproaC'h tlle. ideEtl pressure trans­

mission. whie;h water ::Possess.es to such a marvelous clegreeOl

The cause for unequa~ d.is·tribution of pr"essure in a clay

mix is Que to differences. in grain sizes. ~riction be~een the

grains. abs:ence of lub·rication between tha grains. and the

di:r:fere'nce in phys1.c.al ]ropartie's of the various grains.

!fh.e Ceramic InQus.tries or -the United States have dec1d..ed

to concluct a series. of inTes.~igations concerning the d.ry press

p,r'oblems of manufaeturing bigger ana. better ware. 50 tile

a.tiona1 B 1ek Ian~acture,r8Ass{)c.1ation ha$-" appo.inted a

Commit"5ee on the Dry Presa Proe:ess to work in coordination nth.

3

the Ceramic Departrnent of the hl[issouri School of Ivfines and

Metallurgy on a series of investigations relative to the im~­

ortant prob16:ms of the' dry press process. T.his Comnli ttee~ has.

secured. a hyclraulia· press. which is established at the M1ss,ouri

School of Mines and Metallurgy.

The first 1")robl.em investigated. by the d.ry press Commi ttee·

was eondueted by C. M. Dodd.; G. A. Page; F. F. Netzebancl3 on

uThe Transmission of Pre:ssure in the 'Dry Pressing o~ Typical

Building Brick and Fire Brick Mixes As Affected By the Degree

o~ Pressure.• Physical Charaeter of the Mix Ingredients t and

the Moisture Content of the Mix. 1t.

From this problem it was discovered that the more fines

present. the less uniform is the pressure transmission. The

bUilQing brick contained more fines that the fire brick. and

the bUilding ~rick mix, with its excess fineSt transmitted

pressuIlle less uniformily than the fire brick mix <lid. It was

als.o established that the. most, pra0tioal water content far dry

pre:ss work was ?-Sro • The most et:r'ieient I>re~ssure was found

to be 2000 pounds per square ineh for good pressure trans-

mission.

(1) C.M.~odd - Assistant Professor of Ceramie' Engineeringa& the. Missouri Sahool of Mines ana. Metal~u.rgy.

(2) G.,A.Page - S~enior Student of Ceramie- Engineeringat the Missouri School of ~nes and Metallurgy in 1930.

(3) F.F·.Net.ze·b.and - Senior Student o:f Ceramic Engineeringat the Missouri School of Min,es" and Metallurgy in 1930.

This paper maybe obtained. at the TeohniealLibrary of

The Missouri School of Mines and Metallurgy at Rolla.• Missour1.

The second :proble,m stuclieQ was~ ltThe Ef:tect o:r Occluded

Air in Dry Press Mixes lt by W. R. Powel11 From this :problem

it was clisc:overe.a that the e:f:fect of a vacauum on the reIna,val

o~ occluded air increased. trl6 porosi ty. This was :round to be·

true between 500 and 2000 pounQS, per s~uare in~h on~y. Above

these ~ressures there was no Qecided effect proQueed by a

vacuum",

The third problem investigated concerned. ffT'he Ef:reo.t of

Grog on Pre,ssure Transm.i.ssion in Dry Pressing. tt Tha in­

vestigators were C.M.:Dodd.1 and. M.E.H.olmes5• It was deter-

minecl that the adclition o:f grog increased.. the pressure. trans-rn

mission, ancl near 5ar; add.i tion of grog gave the. max~um effect.

although small. additions· aid-a.a.. materiall.y. The more fine,s

prese-nt in a mix~ aueh as the. building briek mix. the more

grog was re~uired to give good. pressure transmission. The

smaller the pressure~ the mere grog was required. It was eon­

eluded that thro·u.gh the use of a substantial amount, of grog.

shapes as· thick as tan (lO) inehes eoulQ be formed with a min­

imum loss through physi ca~ defects arising' f:ronl clifferential

shrinking.

The foregoing stUdy has a tiirect bearing on this paper,the

ai.nee both are aoneerned with grog. Sineej\ optimum amount of'

grog was :found. fl prob!lem in direct coordina tion with the

abo,va would. b·e the optimum size of grog. lfhe·refore,. this

:paper originatecl :from the ab.Qve rela ti onship anci co·ncerns the.

(4) ·W.R.Powel~ - Se·nior St.udent o~ Ce.ramie Eng'ineeringat the: Missouri Schoo1 of Mines and. Metallurgy in 1930.

(~) M.E.Holmes, .. Professor of :Ceramic Engineeringat the lfisSQuri Schoo1 a,f" Mines and Metall.urgy.

size of grog and ~he best pressure transmission.

MATERIALS USim

The clays use·d ax~e· repI.le-sentativa: of the various types

of clays employed· in dry ~ress work. A mixture of 30~ grog

and 7·0/~ clay was used in eacl1. case. The grog used throughout

the eJq>eriment was obtained from Cheltenham Briek.

The foll.owing· list gives the- clays used and. the sizing

t,Q 1ih1.ch they we-re' ground:

(1) North Missouri Semi-flint Clay ~ S- Mesh

(2) North Missouri Plastio Fire Cla-y ... 8 Mesh

(3) Cheltenham Fire Clay - 8 Mesh

(4) St. "LoUis Sur~aoe. Clay - 10 Mesh

SIZING OF MATERIALS

CLAY:

The primary crushing was performed in a J·aw crt1sher and the

lumps re-duc-ad to a maximum of one (1) ineh. ~hen the seeond.ary

crushing was done by dry :panning in a three foot. C3onvertible.

~et and dry ~an.running at a speed o~ sixty (60) R.P.M. The

openings in the sereen :plates of the dry pan were l/e inehes

.in width and: 6 inches in length. The milled material was

sereened. through the <lea.ired- mesh on at Great Wes,tern Manufac·t­

urLng Company Gyratory Ridd1e. ~he tailings were returned to

the· dry pan and. reground until the entire ba:tch passed through

the desired-mesh.

Grog.:

ftte cr- « was ,sizad. in eJEact:Ly the same manneraB the clay.

ne gQg was ground. i:~ the dry pan ana $creened through six. (6)

different meshes) which were:

Through 2,.5 M'eshn 4 "11 8 It

tt' 20 t

tt 40 It

It 60 IT

It must be: emph.asi zed that the grog was ground to the

de-sire·d fine 5S so that i t all passed through the reflUireo.

mesh. There::rore. the rna te.ria1. that pass.ad. through 2.• 5. mesh

eontaine<l all the d.i:fferent .size grains whi~·h range below the

siz'e of the 2.5 mesh openings. while. the grog whioh p.assed thru..

~.he' 60 mesh openings eontaine:d on~y the grain Biz,es below t.he 60

mesh openings.

The reason for' grinding the· gro·g through the various meshes

ma~e explaine~ by the ~aet that in the manufacturing operations

o~ the industry. a separation of the tiifferent grain sizes is

very seld.om macle. An a t tempt was mad.e to approximate as nearly

as possible the actual operative conditions in praatiee.

MIXING AIm TEMPERING

The first step was; to we'igh out. the grog and. elay in the

c·orre~t. prop'ortions - 3~and '10% respective·ly. In each ease the

total'mixture weighe~ 35 pounds. as this weight gave a plentiful

a.llowanaa :tor' each test bloc·k. Then the mixture was plaeed in. a

small kneading machine. ana a.ll.owed to mix dry. for on.$ minute.

An. eight '8) per eent. ad.Qition of water was adcleo. to the mixture.

and th,emixer a,11oweii to run for fiva minutes in artier to pro-

7

viae an equa1. distribution of ater. eigh~ of water ~ded

in e~ch case .as 2 poun .s.... 2.8 Q·unc·es. ftla r'esu1ting mixtur

as dumped. f:rom t.he'kneatiing machine onto a 2.5 mesh se:reen~ and

rushe hrough in orcler to ramo e a11 lumps Qf' coagulated (I.lay.

Each batch was covered with a damp cloth and al~owed to

age for twenty-four hour's before being formeci in orcler to insure

a homogeneity of the mix.

Samples for moisture determillations were take·n from each

bateh before forming into blocks.

FO·RMING

A/hydrauliC dry press made by the Hydraulic Press Manufact­

uring Company of' Mount Gilead." Ohia, was used for :forming all

test blocks.

~he operating s:peci~ications of this press are as follows:."

The maxium pressure obtainable on this :pre.. is 684.0 pounds perA

sQ..uare inc-h. whic'h gives a total pre-ssura of' 135 Tons on the

mo,ld box surface of 9: inches by 4; inches. ~he maximum cle·pth

of the mold box is 22 inches. which permitteQ blocks to be

forma·a.. up to 10 inehes in d.e:gth. The possible:: lower ram travel

was 22 inahes~ and the mold. box itself traveled 1i ·inches•.

A gaatge. was locatecl between the electrie plunger pump and

the compression aylind.er of the dry .press. ind.icating at all times

of compression the, :pressure on the clay column. ~e forming

pre:ssure an al~ blocks in thi 8 investigation was 500 pounds per'

s.~uare inah.•

In the actual. formation of the blooks the lower ram was

first ra.ised to within two inches of the topot the mol.d gax.

~hen a weighe~ amount of the aged mixture wasintroQuced into this

two· inch. depres·s,ion. and a f"linted tissur& towel was p1acad on

top as a s$parating medium between la~ers. ~e; ram as 1Q~ered.

another two inehes t ancl the same operation repeated until th~

co~umn o,t clay was buil.t up into eight 2 inch I.ayers.

s

Since· each l.ayer was of the same weight and thickness. the test

blook was ke.pt uniform throughout.

A:fter the reqUired. number of layers had been placed in the

mold. box. the aompress.ing maahiner:}r was se.t into operation. and

the reqUired pressul'e of 500 pounds :per square inch was apl?lied

for two seconcls and instantly released.. The resultant block

was removed flrom the mold. "box anti its total height measured..

rES T SPEC IME:NS

There were severa~ proposed methods o~ obtaining the

pressure transmission in the whole bloak. but Que to labaratory

linli tations. lack of time ~ ancl lack of finanoial 'backing 1 twas

:finally decided upon to measure the pr~ssure transmission by

means of the variation in Apparent Porosity between the ~ayers

throughout the entire bloek.

The next item to consider was a method of obtaining rep­

resentative samples from each layer. 9n which to measure the

Apparent Porosity. ~is was solved by breaking each layer into

four equal parts. and selecting two opposite eorners,on which

an average porosity could be obtained for the entire layer. The

flinted tissure· towel permitted the layers to be separated easily.

Then each layer was broken into i ts fo,ur quarters by striking

sharply over a kni:fe e~ge.

! I23-4 I £3-4X, .

~-_._---t---------

Z3-4'1 23-4X

!he above illustra"tiqp·illustratss the method. employ-ed. in

numbering the tes specimens. This diagram piQtures layer

number 4 in block number 23. The' specimens. used. were 23..4 and

23-4x. the other two being reserved in case of' a necessity of

repetition in measuring the Apparent Porosities.

DRYING

After the test specimens. were selected anti trued. up. in

order to eliminate all loose corners, th&y were placed on a

p·allet. boarCl and allowed to dry at room temperatures for five

days. A.t. the end of' this time the spee-ime:ns were: meahanica11y

dried for 14 hours or more at 2Z50F.

A~ the end o~ the drying period the samples were taken out

of the dryer and allowed to cool in a dessica:tor. Then they

were removed from the dessicator anQ given a. thorough brushing

to remove all loosely adhering particles.

The test specimens were then ready for the final. operation•

.APPARENT POROSITY DETERMINATIONS

The first ate'p' in the de·termina tion of Apparent Porosity

was obtaining the dry weight of the s~eaimens.

Immediately after each sjle'cimen ha<l been weighed dry', it

was immersed in kerosene. to prevent the moisture in the air from

entering into the pores. of each sample. !he next ste:p was t.o

place the s~eeimens. immersed in kerosene. in an evacuating

chamb,er and to apply a vacuum of 2.9 inehes of mereury. 'lhese

s;peeimens were subjected to this. treatment for two hours. They-

were., then, removed from. the eonta:Lne,r and plaeea in k·erosen

unti~ th.ey were needed. ~e:n. the saturated and suspende.d weigh:tB

o,:r. each specimen were obtained and tabul.ated.

lit:'

C:ALCULATIONS

From the d.ry" sat·ll.rated and suspended weight s obtained on

the test specimens, the Apparent Porosity for each sample was

calculated by use of the following formula:

Saturated wt - Dry ~t

II

~ .. S1>. Gr. of Kerosene

Saturated wt ~ SuspendeQ wtSp. Gr. of Kerosene

x 100

Since· the Specific. Gravity of the K.erosene remains constant

throughout. the formula was reduced to the following form:

%AIlP. PorSaturated wt - Dry wt r 100

• • ;;;to..Saturated wt - SusHended wt

GRAPHICAL REPRESENTATION' OF DAT.'A

The draWing of conclusions and discuss1onof results was

faeilitated by transforming statistieal data to graphical

represe,ntation.

On' the follOWing page,s are the data ancl curves obtained,.

Onl.y one block was run on each grog size. with the exception

ot blocks, Nos. 4. 6) lOt and 14. where it was found n~Q:essary

to run ()heclk bl,acks. The curves plotted were taken as an average

of both the original and eheick blocks.

In order to observe the effect· in variation of grog size.

i t was necessary to kee.p everything constant except the: s.ize,

of grog.

CONSTRUCTIVE DATA ON .ALL BLOCKS

Jz'

No.--I,2

3

4

5,

6

7

8

9

10

~l

1.2

13

l4.

15,

~6

1.'1

~8

19

20

2.1

22

2Z:

24

Grog 'Size- 2.5

.- 4.0

- 8.0

-20.0

-40.0

-60.0

- 2.5

- 4.0

- 8.0

-20.0

-40.0

-60.0

- 2.5

- 4.0

- 8.0

- 20.0

-40.0

-60.0

- 2.• 5

- 4.0

- 8.0

-20.0

-40.0

....60~O

LayerWgt

3#-140·z

3/-12oz

3i-lloz

3ii- 60z

3#-11oz

31- 60·z

3#- 40Z,

3#- 6oz·

zl- 10z

3#- 30-z

3#- Ooz

3#,- :J.o'z

1J:/f- 80z

3#-l.Ooz

'lJ#- 60z

3#-lOoz

31- 50z

3#-50z

3#-11oz

3#-11oz

3#- 90z

3#- 80z

'li#- 90S

z1-iOoz

T-otal H'eight

8-9/1&lt

a-511GB

8-Z/16 tf

'l-lQj16tt

8-6/'16 ft

7-13/16rt

7-1.4j~6t1

8-4/l61'

7-8/16"

7-~o/16n

7-9/15"

7-~2/16tl

a--6./1&"

7-10/16

7-11/16

7-11/16f.'

7-9/16tt

8-3/16rt

8-4!16ft

8-1/16"

8-5/1.6

8-12/16

10 Moisture8.65

8.78

9.00

8.46

8.65

8.8.6

8.88

7.86

8.36

8.49

B.28

8.21

B.6~

8.06

8.4Q

'1.80

8.1tS

8.63

8..26

8.40

8.1'1

8.43

8.40

8.38

ClayNo.Mo.Semi-Flint

n

It

'··St.Louis Surface

It

n

n

ft

Che:ltenham

1t

n

n

11'

No.Mo.Plastie Fire

n

It

COMPLETE DATA ON ALL~BLOCKS

21,.49­2%'~19

22.'0~.45

23.19f;1.'5~1.61

!,0.182

21.~4G

22.~

22.88az.3''l2&.49'21.6,5,21.~

20.9·4

Ayar.Po;r

22.~2

21.4,02.2013Zl.8G2&.42.­226012.1.5720.98

22.2.0~46

&4:.0023.Z623.9923.9422.9922.,&620.66a20092:L.7S~.fJ8

20'.9819.4619.6119.2J..

22.92230-4524.2325.1826.,092S. 92~.·08

22.26~~,O~·

2a~92n~'i'7, .0..,.';.

20•. ""',':'2O.1~

19.17

~ For.

·25·.5.02.2:.86a4.0024.142Z.74~.oa

as.062.2.482,0 0 2.519.9:420.2.619.5'21..0916.7120.0719.48

~1.,5

3~.O

35.032.035.53.5.531.531.5:;1 ... 5~8.0

36.038.0~2·.O

3~~O'ZG.O29.0'

33.034:.031.5M.SIZZ.5Zl,.Oao.o~O.5

.. :n..,Q3,2'.0,31:.5_·;',.,,54If:,., .

Sat-Dry;

Z,8.0M.5a3..oS5.0'/)-7.536.0Z~.7

3S.632~.5

~1~O

51.030.5~Q..O

34.029.5W.O

~4 .6·1.42.5157.5137.0148.0140·.a13rr~o

1~9.0

152.5~72.0

165.5162~5152..5~64.5

Q2.~·

l.~l..o

144..0145.0

00.013'1~O13Z.Q1Z2.0110.01Z·,.01S .0

>5 .-m~·a1. .51:" •',5%.·56.,55, ."

Sat..sus

l.49.0161.0lZ7.~,

145·.0108.01Q;G.O137.514:9.0160.5155,.5153>.018,6.5

66.0203.514.7.01Q.4.0

246.0248;.0258.5239.0­254~O

M~.O

2040.02:4:3:.526ti.a301.028G~O283.()·2,62;.52,88.0267~O2&£1.0

aw.oM9.•~5222.02Z3.0228.5228.~O

225.5'24.l...0274.0264-.'02"..2;,.5aM~i26' .02'1Z.0,;278.,6

Sus

261.5263.02Z'1.Q.24'.0­2'12·.6~70.0

241.5260.Q278:.D·270.5264,.5284.S284.52,9·2.0253.~

270;.0

• .. I.

4l.7,.i8.,5

~,'...o

410.5414.0375,.0392.0400.5426.0379·.0409.5439.0426.041~.5

451.0450.54Q·9.o400.6424.0

38'.5Z90.5376.0375.0402~O

383.5~'l .0382.5419·.04'13. ;451..5445.•_415.0452.5­419.54.1'1'.0

394.0Z9~.5

~52.0

370.0Z62..0S60.0355,.5Z7S.043,1.0417.54l"'~

4i~

:Dry

3:72.5Z79.fi342--.05L1'1.0~93.0

~90.•0347.~

~76.0

406.5~95.0

~8&.5

414.54:15.5425.53'l~.O

Z94~O

S5Gt.O35705:34~.O

343.03;6'1.~·

350.0346.5.351.038'.0143~,.O

4J.5.~;

407.5383t O'420.5389.5388.0

~61..0360.5~2,O.5

:i,~.5

Z28~5~29.0

~o5K7'.5'~99~5\$~,~ 5.,Q..3$S~O.~'6~·6':S'I~tl'

1$,' •.0,

5.

B10ek

1 ...11-21...Z1-41 51 61--'1--81-lx~...2x1--ZX.1-4%1.-ax1-6%1-7x~8x

~"1Z...~2~3

~-4

2-5~&

2...72-82-1%Z-2X2-k2-4x2"'5%2-6x2-'1xa-ax3-1~-2

3-ZZ-45..5,S-63-7.3~a:

3;-.1%3 ...k,~":'b~~,

,~ 'ax'$-:6x,3~7x

3-8%

/4

Blo'ck Dr;r Sat Sus Sat-Sus: Sat-Dry 1&- Por. Aver.Por

4-1 31.0.fi. 3~9.0 214.5 124.5 28.6 2Z.89 21.4t)-4-2 311.5 33.9.Q 216.5 124.0 28.0 22.Q8 21.544 ..3 Z64.0 3·98.6 253.0 146.B 34.B 22.03' 21~81

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1'1-2 199.5 2~,.O 13900 84,.0 23.5 2?98.(out)25.4917...~ 1.92.0 2~3.0 ·132.Q· 80.6 2:1.0 2.&.09 26.66 '

7-4 208.0 232.5 144.0 8·8.0 24.5 2.7.84 2,8.8711-5. 200.5 225.5 139&Q 86.0 25'.0 Z9.07 28'.ti517-6 203,.0 22~.5 41.0 SZ.6 21.Q 25.71 20.6717-7 178.5 197.0 12Z. 74.0 18.Q 2~.OO ~.94

1.7-8 184.• 0 20~.5 2'l.fi '14.0 1 rz .5' 23.6ti 25.0417-lx 197.6 21.7.0 13'7.0 ,80.0 19.6 24.381'1'-2x la6.0 200.L5 1.29:.0 ·76.5 19'.5 2.5.4.9I7-~x 201.6 224.5 40.0 84.5 23.0 2'.22~7-4x 202.0 228.0 141.0 87.0 26.0 29~89

1'l-5x 185.0 207.,0 1.28.·5 '18.5 22~O 28~ .~

1.7-6x :t90.t> aU·.o 132.6 80.5, 22.5 Z7.~9

1.'1-7x 1.9:2.5 2,· 4.•:0 1H.~O SQ,.O 21.•5 26.88'7..8X 169.6, 188.,0 1.8'.0' 70.0 18.6 26~4~

Block D·ry; S'at Sus S·at-Sus. Sat-Dry fi Par Aver Por18'-1 21.9.0 241.0 l52.5 88.5 22.0 24.86 25.66~8-2 214.5 237.0 149.,0 88.0 22.5 25.51 25.6118...3 218.0 243.0 151.0 92.5 20·.5 27.5'7 27.081.8-.4 215.5 '244.0 :150.5 93.5 28.5 30.48 30.9Q18-5 ~93.0 217.5 134.5 83·.0 24.5 29.52. 28.0518-6. 192.0 2·14.5: l33.5 81.0 22.5 27.'78 27.6418-7 200.5 2.20.5 139.0 81.5 20.0 24.54 25.43l8-8 2.06.5 226.0 143.0 83.0 19.5 23.49 25.0'1l8-Ix 229.5 254.5 160.0 9'4.5 2.5.0 26.4618-2x 236.0 262.0 164.6 97.5 25.0 25.64.18-3x 208.5 231.5 14~.O 86.• 5 23.0 26.591.8-4x 216.5. 246.• 5 151.0 9Q.5 30.0 31.41~8-5x ~88·.5 209.5 130&5 79.0 21.0 2.6.5818-6x. 1.89.0 211.0 131.0 80.0 22.0 27.5018-?x, 231.0 2.fi6.0 161.0 96.0 25.0 26.32la-ax 22~.O 2.45.0 IB4.5 90.6 24.0 2.6.52

19-1 290.0 316.5 201.5 115.5 26,.5 2Z;·.04. 23.2719...2 27'1.0 296.0 198.0 98.0 25.0 25~J51 (out) 23.'1119-3 254.5 278.0 176.0 102.0 23.5 23.0,4 23.4519-4 283.5 3~O·.D. 196.5 114.0 27.0 23.68 24.131.9-n 2.71.5 297.5 187.0 l10.5 2·6.0 23.53 2~.72

19-6 24,7.5 270.Q 171.~ 99.0 2:5.0 23·.23 2Z.0819-' 285.5 312.0 198.5, 11.~.5 26.5 23.35 22.2619-8 269.0 294.0 18'1.0 197.0 2~.O 23.36 231419-1x 26~.O 274.5 174.5 ~oo 23.5 23.5019-2:x 243.0 266.0 169.0 97.0 23.0 23.7119-3% 2:73.0 299.0 190.0 109.0 26.0 23.8519-4:x: 22.2.0 244.0 154.5 89.5 22.0 24.5819-5x ~25.5 247.0 156.D 90.5 21.5 23.7619-6:x:. 240.0 262.0 1,66,.0 96.0 22.0 2Z.921.9-1x 24~.5 261.5, 167.0 94.5 20.0 21.1619-8x 227'.5 2,48.0 158.5 89.5 2-0.5 22.91

20-1 261.0 2.84.0 181.0 1.QZ.O 23.0 '~2.~3 22'·.452,0-2 266.5 291.0 1.8·5.0 106.0 24.• 6 23,.11 23.5020-3 262.•0 287'.0 181.5 105.5 25.0 2,3.70 23.5020-4. 272.0 299.0 188.5 ll0.5 21.0 2.4.43 24.Q920,-0 24,2·.Q ~65.0 16,8.0 97.0. 22·.6, 23.20 22·.9020-6 2~·4.• 5 261.5 166.0 945.5 22.0 2~3..04 22,.9920-' 243,.Q 2.6.5 .5 168.B 91.0, 22.•0 2.2:.68 22.4~

20-8 2,20.5 247.0 157.0 90.0 20.5 22.78' Z2.•13'2.0-1x 245.0 267.0 16.9.6 974!'5 22,.0 22.562,O-2:x: 249.5 2'13.5 175.0 100.5 24 .. 0 23, ..88·20~3x. 2'12.•6 298.0 189'.0 109.0 25.5 2.3.3920-4x 23·7'.0 2.61.0 164.0 97.0· 24.0 24.7420-5x. ~a,2.• 5 199,.0 1~6.0 13.0' 16.5 22.• 6020-Gx ~~f .0· 14.9.0 95.0 Q4.~, 1%.5 22.'94,20-'% E~4.0 1~5~O 14'.6· 8.~:.5, l~.O 22':2a'20-8x 224.0 24.3.0 lli4.5 8S.0 19.0, 21.41

B:look Drl Sat, Sus Sat¥Sus Sat-Dry: PO Po,r :l.ver Por21-1 286.0 312.0· 198.0 1l4.0 27.0 23.68 23.272l-2 169.0 1.86.0 ll7.0 69.0 l7.0 24.64 24.3421-3 2,93.5 322.0 204.0 1l8.0 28.5 24.15 24.202l....4 290.5 320.5 200.5 l20.5 30.0 25.00 25.1321-5 1.99.5 219.0 138.0 al.O 19.5 24.0,7 23.5521.-6 214.0 234,.0 l48.0 86.0 20.0 23.26 23.452l-7 214.5 234.0 148.5 85 •.-5 19.5 22.• 81 23.082,1...8 242.5 263.5 l68.0 95.5 21.0 21.99 21.9521.-1x 264.0 288.0 18,3.0 105.0 24.0 22.8621.-2x 267.0 282.0 178.0 104.0 25.0 24.042~-3x 20~.5 221.5 139.0 82.5 20.0 2'4.24.21.-4x 240.0 265 •. 0 166.0 99.0 25.0 25.2521-5x 188.5 206.0 l30.0 76.0 17.5 23.052~-6x 218.0 238.5 151.0 87.5 20.5 23.4321-7x 225 ..0 245.0 155.5 89.5 20.0 23.352~-8x 226.5 246.0 15·7.0 89.0 19.5 21.91

22-1 278.0 305.0 194.6 111.0 27.0 24.3Z 24.3022-2 2.70.0 298.5 l87.5 lll.O 28.5 2..5.68 25.6~

22....,3 270.5 300.5 188.0' 1~2.5 30.0 26.67 26.2Z22-4 259.5 288-.5 180.5 108.0 29.0 26.85 26.752G-5 25~.5 278'.0 174.0 1.04.0 26.5 25.48 26,.1822-6 267'.0 284.L5 194.5 110.0 27.5 2.5.00 2.4.8122-7 267.5 284.0 194.0 ~l.O.O 26.5 24.90 24.1222.-8 254.5 279.0 1.76.0 103.0 24.5 23.79 23.6022--lx 2n6.0 281.0 178.0 lO3.0 25.0 24.272Z-2x 24.8.5 274.5. 173.0 I_Ol.o 26.0 25.62.22--3x 2,73.0 302.0 189.5 :J.12.5 28.0 25.7822.-4x 255.6 284.0 1'17.0 :107.0 28.5 26.64.22-5x 235.0 259.0 162.6 96.5 24.0 24.8722-6x 24.6.0 270.5 17l.0 99.5 '24.5 24.6222-7x 255.0 279.5 174.Q 105.0 24.5 2303322.-8x 236.0 258.0 1.64.0 9'4.0 22.0 23.40

23-l 17~.O 189.0 118.5 70.5 18.0 25.53 '26.0623-2 195.0 21.5.0 135.0 80.0 20.0 25.00 (out. ) 26.1923-3 199.0 22,1.0 138.0 8.~.O 22.• 0 Z6.51 26.5l.23-4 206, • .0 231.0 143.5· 87.5 24.5 28.00 2.7.7623-5 ~92.5 214.5 133.5 81.0 22.0 2.7.~6 26.8'423,-6 ~8o.0 202.0 126.0 75.0 19.0 2.6.33 26.2823-7 ~9'l.fi 21.7.5 137.0 80.5 20.0 24.85 24.78·23-8, l89.fi, 209.0 131.0 78.0 19.5· 25.00 25:.002Z-U 2~6.Q 238.5 150.0 89.5 23.0 23.~·9

23-2% 2,03.5 225.5- 141.5 84.0 22.0 2,6.1923-3:x- 21~.O 22.9.5 146·.~ 84.0 ~8.5 22:.29 (out)23-4x 218.6 245.0 150 • .Q 94.5 26.0 2'1.512,3-5x: 198.0 220.0 137.0 83.0 2: -.0 Z6.,§12D-6x 13~.S 140.0 91..5 53.5 13.5 25.232Z-1x 219.0 24~.O 15 .0 89.0 22.0 24.7423,-8x 226.0 249.0 lS'l.O 92.0 2Z,.O 25.00

Block Dry Sat Sus Sa~Sus Sat-Dry 10 Por Aver Por

24-1 104.0 11.6.0 72.5 43.5 12.0 27.59 26.0024-2 207.5· 232.5· 144.0 88.5- 25.0 28.25 28.4024-3 213.5 240.5 148.0 92.5 27.0 29.19 29.1924.-4 193.0 217.5 134.0 83.0 24.5 28.34 29.4724-5 1.8'0.5 203.0 125.0 78.0 22.6 .28.86 29.12,24-6 178.0 200.5 123.6 77.0 22.Q 29.22 (out) 28.0924-7 189.0 210.0 131.0 79.0 21.0 26.58 26.952498 201.0 223.0 139.5 83.5 22$0 26.36 26.6124-lx 208.0 233.0 145.0 88 •.0 25.0 28.4124-2:x 208.0 233.5 144.5 89.0 25.6 2.8.6624--3x 172.0 ~95.0 119.0 76.0 23.0 30.26(out)24-4:x: 226.0 155.0 157.0 98.0 29.0 2.9.5924..-5% 206.0 2,32.0 143.5 88.6 26.0 29.3824-6x 211. •. 0 236.0 147.0 89.0 2,~.O 28.0924--7x 217.fi 242.:5 151.0 91..6 25.0 27.3224-8x 211.0 234.5 147.0 87.5 23.5 26.86

DISCUSSION OF I{ESULTS

, All- curves obtaine<l are-· based on Apparent Porosi ty t which

give·s all indicationa of being directly proportional to IJressure

ilransmission. The smaller the differenoe between the extremes

of Al)parent Porasi ty the more uniform p·ressure transmission

throughout eaeh block. The ideal curve would. be a st,raight line­

where the ]tQrosi ty would. be equal_ for all layers. which would

indicate that the :pressure· had been equally distri'buteCi to each

layer of the block. Such a curve would be obtained with water

as the traxlsferringmed.ium. while clay would not giva this ideal

pressure transmissio,n clue to its heterogeneous arrtangment of the

grains.

It may be easily seen from the curves that the size of grog

p~ays an important part in the d.egree- of pressure transmission

throughout a test block.

It would. appear to.be reasonable that there would be more

pressure at the to~ ,~and at the bottom than in th~ center of the

block.. whi:ch was :found to be true in this investigation.

PLOT' A

Nort-h Missouri Semi-Flint Clay 70% and Fi~e Brick Grog 30%

From thistset of ourvEis i t was easily conoluded tha t, the

larger the gro:g size the better the pressure transmission, i.e.,

approxi.mating the ideal straightlina of water.

The 2.0 mesh ourve was a curve being nearest to a straight

line. as di sc'ussed above. There was, not, a large difference

between the ext,raffias of poros1ties of this curve - the t,otal

differ.~Qe being ~.4~.

As the grog size· deo'rea'sed. which is illustrated by the

· 4. and. 8 mesh curves,,, tIle difference in the e-xtrenles becomes

greater. There i's very Ii ttle difference in the 4 and 8 rnash

ourves. the two being very nearly parallel to each other. The

'total differenoe between the extremes of these two curves was 2.5%.

As the size of grog decreased to a greater extent,. the

oontrast betweell the extremes becomes more evident~t until the size

of grog had been reduced to 60 mesh, where the largest difference

in the extremes'was disoovered. It was 2.8%.

In each o:f tile six CllrVeS J' with the exception of the 2.5

me sh curve. the highest pora sity was obtained i.n the fourth

layer. T.his is reasonable because' the fourth layer is in the

e,Jtaot center of tIle block and the.oretically receives. the least

amount of pressul~e clue to uneg:Llal pressure transmissio'n. When

the ~ressure is less in the center of the block. a soft core and

a n'shellylf structa.re will result.

There are several proposed reasons for the unequal distrib­

ution of pressllre throughout a piece of war·e. Some of the mor~e

probable are as follows:

(1) It is apparent that the pressure exerted on tIle to]? and

, bo·ttom of a clay col"umn has been absorbed. before reaching the

center of the column because the pressure in the center is less

than that on the ends.

This nlay be logically eX111ained by the ass'WllIJtion that the

press'are is lost in transmi tting itself from one grain to another.

Fro,m thi·sreasoning it would be natural to e.x:p8ct that with a

certain height of column there would be no'"pressure transmitted

to the center.

hom the previous deductions it would seem that to inarease

the numberot grains would redllce the degree o,:r pressuretra.ns~

mission towards the oenter. ' This~is the exact condition whioh

arises frofn the fine grinding of the grog and as o'ur c'urves

indicate. this theory is tenable •.

(2) When ~arge size gr"og is used. similarity is approached.

. to that of an ideal medium of pressure tran~nission because there

are ':rewer contacts ·between the grains t as explained above t and.

the grog cannot be compressed to any such degree as c18Y due to

its immobility caused by its dense structure.

All honlogeneous materials transmi t,..~ressure equally in all

directions. Large grog is a homogeneGus mixture because of its

vitrifieQ structure due to the formation of a binding glass when

fired. while fine grog, although bound within itself. is too

finely disseminated to act as a single transmitting medium.

T.he curves in Plot A were studi.ed wi th the above considerat­

ions in mind and were found to bear out the theories in a very

remarkable manner.,

The total difference in the high porosity ~etween the 2.5

and 60 me sh amounted to 4.•5%.

So it may be ooncluded that course· grinding gives the best

pressure transmission with the North MisS.ouri Semi-Flint Clay.

PLOT B

North Missouri Plastio Fire Clay 70~ and Fire Brick Grog 30%

The curves in this graph were very similar to those in

Plot A. with the 2.5 mesh again giving the. b;est pressure tans,­

mission. A.s· the grog size decreased. the l,)orosity rose'; 'With the

mazi.~ porosity in the fourth layer.

. All theourves were slightly more jagged than the CUITes

in Plot -L. his maybe e'xplained by the mowlefige tha·t the

!Ia,rth lfissouri S'emi-Flin"t approached more nea.rly the character­

istics of the grog t sf.nee ~t oontained more grains of a· flinty

:1,0

nature. which produced a more ev·en :proleSSUl-·e transTIlission.

The tcDtal variation between the highest p·orosi ties of the

2.5 and 60 mesh was 5.5~

PLOT C

Cheltenham Fi:re Clay 70)~ 2~nd. F,ire Brick Grog 30)'0

This clay gave the best anQ the worst exapmles of pressure

transf11ission. The 60 mesh .curve made a very decided jump to a

high I>0rosi ty in tile center of the block which W8JS very und.esir­

able. But the 2.5 mesh curve was more n~arly a straight line

than any of the curves obtained and gives the best pressure

transmission of any o~ the clay mixes.

n·u.e to some tlnexplainable cause t the 4 Inesh curve fell into

a nl'uch higl1er region than was expected.. This was probabl.y clue

to experimental error.

The total variation between the high porosities of the 2.5

and. 60 mesh was 8.3Jo which was tIle largest difference obtained.

PLOT D

St. Louis Surface Clay 701~ and Fil"e Brick Grog 30~v

This plot gave the best set of curves of any obtaineQ in

the investigation.

Each curve was ··clearly defined and the CUi"ves followed each

other in an orderly sequence from the lowest mesh (2.5) to the

highest (60). !I!'his graph differ.s from the three previo'usly

discrussed in possessing a much higher :porosity throughout the

entire set of blocks on this building brick. mix.

From screen analyses. previously made by the other invest­

tigstors t it was found that this clay possessed an unusual

amount of fine.s through 20·0 mesh about 46~. Compared wi th the

other clays this is an exce.edingly high figure. This clay

27

possesses a v'er~l lttrge 8,ffiourlt of frtee silica) vvhich J?!~ogably

contributed a large portion of the fines.

It has been defini tely proved that fine n'lateria·l has a

much gr~eater ~ur·:race tllan large rnaterial, bo·th being originally

of ~.he san1e volume. and this obviously increases the porosity of

a prod'llct com.posed mainly of ftines. This shovvs why the curves

obtained :from the bUilding brick clay have such B,n exceedingly

high porosi ty. T'he large amount of free silica in this clay

seemeQ to have a positive effect on the pressure transmission

beCa"llSe it had a sonlewhat simila:r effect as the grog i tsalf.

Onoe more the 2.5 mesh gave the best pressure transmission

curve with a variation o~ 1.5~.

The total variation between the high porosities of the 2.5

and. 60 mesll CUl--ves \vas 6 •. 07b•

This clay shovvs a e;:reater res:ponse to any variations in the

manipulations of its ~hysieal charaoteristics than any of the

other clays. It is the onJ.y bUilding 'brick mix in this invest-. ..

igation~ the' other tllree being fire brick mixes.

RESUlvIE

From the above investigations it may be conclutied that in

every case the large grog gives a much better transmission than

the fine grog.

The reason for selecting50Q pound.s per squal"e inch form.ing

pressure wa:s b,ecause it aaaentuated thediffareht variations. i.e.,

grog a1 ze. used through.Qutthis investigation.

It is suggested that the followingtopxcs be aarried dnin

fUtureresearoh:

(1) ~e grog' size be made l~rger than 2.•5 mesh.

(2\) IncI~ea.sa the forming pressure to. 20·00 :m:ounds ,per square

inch and inorease the amount of grog to 5oal>

(3) T-he re:S:Lll ts obtained in this inves.tigation be more

l)ractically proved by using the best mixtures~ as clecideu' from

this study~ by making standard 9 inch briak and testing them for:

a} MOQulus of iu~ture in Doth the green and fired state~

b) Hot Load test...

c) Spallimg test.