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NOTICE: ;&- governwut or ether drawings, speci-fications or other data are used for sny pmrposeother t1a in connection vith a definitely relatedgurernnt procurent operation, the U. S.Govem t thereby Incurs no responsibility, nor anyobli.,oz vhat-oever; and the feat that the Goven-=ert my hwme fomlated, frmished, ur in any vaysupplied the said d--Arngs, specifications, or otherdata is nit to be regarded by icp.lcation or other-vise as in any naer licensing the ho3 A or anyother Person or corporation, or conveying any rigitsor permission to =r2efae-re, use or sell anyptented Inv,-tiom that my in any vay be relatedthereto.

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VNI

130Techniclco Report-----~ WATER VAPOR TRANSMISSION OF

.......... PLAIN CONCRETE

C- 16 May 1%I

.. . . . .LLJ~

.F4.

U.S.NVL..ILEGIERIGLAOATR

Pbr Hueeme Caior

UZA

Sr _

WATER VAPOR TRANSMISSION OF PLAIN CONCRETE

Y-RM1 1-01-025

Type C

by

D. F. Griffin, R. L. Henry

OBJECT OF TASK

To measure water vapor permeability of concrete and relate it to corrosion ofembedded steel; to investigate sa!t whisker crystal growth on cocreMte; and to meas-ure electriial resistivity of concrete.

III

ABSTRACTI

The effects of water-cement ratio, relative h."n idity, aggregate size, concreteslsee positi,, and ccrtain admixturmS such as oleic acid and sodium chloride on thepermeability of plain concrete were investigated. lcluded is a qtorter replicatestatistical experiment for two levels of each of six factors to permit an analysis ofvariawce of different variables in the permeability study. Salt whisker crystal growthon specimens with sodium chloride as an admixture, believed to be reported for thefirst time, is discussed.

Water vapor ir ion values were found to be significantly higher forhither water-cement ratios, .maller oggega~e, and the absence of sodium chloride.Concrete slice position, oleic =cid, and relative humidity were found to have nosignficant effect when compvred w-ith eqerimental variability.

The study demonsmTates that water vapor transmission is not directly proportionalto -water a-pressum differentials between the ends of the flow path.

The investigation of water vapor transmission in plain coi.-.crete will continue,together with studies of the electrical restivity of concrete and the relation of watervapor transmission to the corrosion of steel in reinforced concrete.

j:- i

II

II

CONTENTSpage

BACKGROUND .............................. 1

SSTATEMENT OF THE PROBME•. ...................... 4

APPROACH TO THE PROBLEM ...................... 4

RESEARCH PROGRAM .......................... 4

Phasel . ..... .......... ...... ...... .......... 4

Discuss7io of Phase I (Results) ... .... .......... .... .... 14

Phase if ..................... 0........ . 21

D.scussion of Phase 11 (Results) .................... 23

Comparison of Phase I cnd Phase II ........... * ...... 26

Sodium Chloride Study ........................ 29

Sodim Chloride Whisker Crystals .......... .. *. .. .. 33

FINDINGS . .. ............................ *. 36

CONCLUSIONS ............................. .3

FUTURE PLANS ................. ...... ... 37

ACW•NOWLEDGMENT .......................... 37

REFERENCES ... . ............. ................ 38

APPENDIXES'

A - PLASTIC WET CUP DESCRIPTION ................. 39

B - WET CUP ASSEMBLY ................................. 40,

C - ANALYSIS OF VARIANCE ..................... 42

DISTRIBUi ON LIST .............. o ............ 45

LISARY. CATALOG CARD .......... o .............

£"St'iN - [Na!! i!,- ,,

1I

I I I

L �1 1III

IFiguu I. Galvanized steel wet cup and manometer.

a.

I

InI -rowith a fil .- d of renocc cl o.t stiN tu [IN inJ dII

iT .

I I

t- BA KGl~flL:-'O

S~~in "•. :tion with a *illi v~udy of reinforced coral con•crete structures inStropical ::-.. conducted b"y Pro.fe•_sr C. s. $cho!e• =-nder Contract NBy-3171 of Ir ]~5 Marc: 59,t en in conf-,•'ctk.n -with Task Y-RO07-05-( i2-. core sonples were

Sdrilled frr these struc!~,.res in ord.r to determine their water v•)or permeability.SThe wet- -.-- method v: !-•ee'eJ most suitable for this psrps.

Twenty-six sanples, approximately 3.5 inches in diameter and 1.5 inchesthick, were sealed in galvanized steel cups by using alternating layevs of plasteraf Paris and 3M secler (EC879), as sho in the cron sctrio. of a cup in figre 1.

A few days afttr ie;rng placed in a 2D-p-.tc;--r riy ivr a-ldiy room at73.4 F. several of the specimens showed a •z.--" vh -=- ts. surface(Fi=e 7j. An X--ruy iifrctrion analys:s rxvecied thi- Qti-.j% . e pimarilysodiurm chloride. A setniquatitctive Vec trogaphic m-uty-sim L-i-uc-.4 the principalcation to be No; traces of Ca, Al, Mg, Si, Fe, and Cu wrere i •tected.

thc. wa: no direct conraction between the c-Spaent qiantity of salt whiskergrowth r.id the amount of salt present in the concrete. A cia--nica; - -alysis of the€crex , tv ••- that all chl-wides expes',e4 as a p-ercentage of N•.-!- by weig.htof osue ronged from 0.1,6 to 1.95. Vigorous -qaisker grow4h as well as traces

of gi..r WAf wwe Observed oni Sjscimens to-t!nirdne higk. C* W--* as 'low saltý, k.q'icatinfi that oil- for. s Lnflve.ncin-s ,i'sker gir._w wth ,.e present.

The quantitativ v ar. • pea-oility were incon.clusive because over aperiod of time many a f sov-- imens ware di-l.6dged in the cups by internal pressuresfF'i~re 3). To . .eg -is pher.ommeron, a mercury manometer was placed on an

n.-stu pcd -p t os ,-- Fire 1. it behaved in a repeatable manner, duringthmt fPast -- ý.--4 ý cyzcury vacuum pressure developed and during the follow-ing six w-,.e- c pv- ire of up to 74 -- " e",,-." ;oped. It wasconcluded '-- . invers.iotors tf.-Ai sch pressures cojld . a specimen fromits seal.

Il

rl

I-'

Figure- 2. So iu ch ord wh s e J~go

t n c r l con ret . ] .. ~i .•--i ..

ii

glaie steel cu-cetem ... talt ic cope causin .am reeseomyda

I!j1II

Figurre 2. Sodium chlc~rde whisker crsal growth on cora concrete.

A. moss spect-ometric analysis o' the gas in ,•he cup indicated that .oporoximatety20 percent by volume wos hydoe; no nantccnos~he~ric gas was detected~. One- pos-sible explanation For tho presence of hydroge is that the zinc nd the iron in thegalvanized steel cup created an electrolytlc couple, causing a release of hy/drogen

gas.

T

2

I " --

I.-j-fI �I �

t

Rgure 3. Effects of ntemol pressure coused by generction of Ihy&ooen gas ;n goiv�zed steel cup.

3

ILJ

STATEMENT OF THE PROBLEM

As an outgrowth of the above study, it was desired to explore the subjectfurther. A literature search revealed tfvt very little information exists about water

apor permeability of portland cement concrete. Therefore, a Laboratory SelectedResearch Task was established to determine whether or not significant relationshipsexist btween the spoiling and cracking of reinforced concrete, the effects of"mrlh, chloride incorporated in the concrete, electrical conductivity of concrete,cnd waohm vapor permeability of the concrete. The corrosion of reinforcing stet:sassociated with concrete strictures, spalling and cracking of concrete, and elec-trictal conductivity of concrete will be subjects of separate reports.

APPROACH TO THE PROBLEM

An inert material was needed to replace the steel cup; therefore, acrylicresin tubes and sheets were chosen as the most economical inert materials for fabri-cation of the wet cups.

Concrete cylinders 4 inches in dimneter and 8 inches long were cast, fromwhich 1.5-inch-thick speci.-nens were cut. Thirty cylinders were cast from each2.25-cubic-foot batch of concrete mixed in a Lancaster mixer.

Since the sealer used for previous specimens was inadequate, another materialhad to be found. A sealer was required that would (1) bond to the concrete as wellas the acrylic tube, (2) be inert, (3) be impervious to vapor t!,m.ission, and (4) beable to withstand unpredictable pressures inside the cups., Shell Epon Resin No. 815combined with Shell Epon Curing Agent T-1 was fo'-nd to meet the requLrements.

RESEARCH PROGRAM

Phase

The first study, hereafter referred to as Phase 1, was = follows:

1. The first factor in the experiment to be varled with respect to thepe'meability was strength of concrete - defined by water-cement ratio. All threeconcretes - high, mediiti, and low strengths - were designed for equial water

4LI

J'll i

i,

contents and a 3/4-inch maximum ogg~rete particle size. The strength was variedby varying the cement content and adjusting the proportions of fine and coarseaggregate. All concrese mixes were designed for equal consistencies without addi-tives or odnixtures; a 3-inch slump was used as the measure of consist!ncy. SeeTable I for the complete mix designs. The cylinders not cut for wet cups were restedfor compm.-•sive strength after fourleen days of fog curing at 73.4 F to obtain basicinformation about the standard deviattons of compressive strengths.

2. The second fator to b varied was the absence or presence of sodiumchloride as an admixture. The Gnount of NaCI to be added was 1.5 percent byweight of plastic concrete, based on the NaCI contert of the coral concrete samples.The NaCI was dissolved in the mixing water before the a,,.mt was cdded ,o the batch.

3. The third factor to be varied was the anbient con1it&,n in vhl;- ibepermeability would be studied. The cups were placed in eithte a 60-perc-nt or a21-perzent relative humidity (RH) room at 73.4 F.

4. The fourth factor to be varied was the Iocation of the spimen (disk) withinthe length of the cylindr. On the bamis of information obtal-ned informalyl from theWaterways Experiment Station that the upper half of a concrete cylinder as cast ismore permeable than the lower half, it was decided to investigate slices taken f-ote upper, middle, and lower portions of the cylinder.

To su.mmarize; all the variablo es invol ID Phase I of this experiment were as

follows:

1. Low QL), medium (M), or high (H) strength of concrete.

2. Absence (A) or presence (P) of NaCI.

3. 261 percent fLV or pcent (M) RH at 7.4 F.

4. Lower (1), middle (M), or upper (U) slice fi-m the test cylln~r of concrete.

Thus, there were four factors, two wIs.h two levels and two with three levels, makinga total of 36 combinations in all. The design v-ariables identified by batch numberappear in Table II.

5 I:

Table L. Summary of Concrete Mix Design Data

A. Characteristics of Materials

Cement: Victor, Type IiAggregate: San Gabriel

Coarse: sp gr = 2.66; 24-hr obs = 1.6 percentFine: sp gr = 2.63; 24-hr abs = 1.8 percentGrading:

Po-nds Retained on Eah Sieve

3/4-inch m-3x 3/8-inch maxSieve H M L . L

3/4 7.4 7.8 6.2 0 03/8 74.1 75.5 73.7 0 0No. 4 46.9 44.2 45.4 103.9 106.2No. 8 27.2 28.6 32.2 38.3 339.8No. 16 24.7 31.2 31.1 27.0 31.8No. 30 27.2 28.6 31.3 23.6 23.7No. 5D 22.2 23.4 28.6 18.7 24.0No. 100 12.4 13.0 14.6 18.4 21.0Pan j 5.0 7.8 7.0 17.2 19.2Total 247.1 260.1 270.1 247.1 265.7

Water:. Port Hueneme tap water a 73.4 F

Chemical analysis (ppm): hydoxlde (0.0); carboncte (0.0);bicarbonate (137.0); chlordles (62.0); caocium (38.0); mag-nesiun (14.6); sulphate (465.0,1 docdiU =d potaj, 1219.0)

Slump: 3 In. (without additives)Additives: Sodi= chloride, U.S.P. ganular; F.W- = 58.45 (1.5 percent

by weight of plastic concrete unless c4-.eiwise noted); olelc acid,U.S.?. (0.25 permct by wele.t of cement)

6

h .

i IIm

Table 1. Sumary of Concrete Mix Design Data (CO.t'd)

B. Batch of 2.25 cu ft consisted of the following: (Phases 1 rid Ii, large ccrev.,4te)

Gravel: 3/4-in. max. particle sizeSand: FM = 3.16

Com.er.z Watera Cement Fac.'o-mix (ib) (ib) (socks per cu yd) WI/C

H 5?.50 26.4 7.62 0.444 lM 46.25 26.4 5.92 0.571L 37.60 26.4 4.81 0.702

C. Batch of 2.25 cu ft conssted of the following: (Phase Ii, small aggmgae)m

GCravel: 3 /8-in. max. particle sizeSandJ: FM = 2.95

mi CemWit Water- Cement Factor

Mix (Ib) (lib) (cs per cuW/C

H 61.9 27.5 7.92 0.444L 39.2 27.5 5.02 0.702

'The quntity of water added at the mixer w*s corrected for moistupresent in the aggregate and moistue req;red for absmptlon.

7

_ _ _ _ _ _ _E__E__ _E__E__ _ E__E

r- C* e

8' 'to) E~~S 3

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-co

-0 z

-C -l C%

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z A batch de•ign sheet was made to include identificatiorn, aaounts ofmaterials, including a&nixtures, to be used, •nd the mixing procedure. Mixinginstructions on the design sheet were as folloss:

1. Add gravel, sand, cement.

2. Mixdyfor 30 seconds.

3. Add water (73.4 F) in shortest time possible with mixer running.

4. Mix for 15D seconds, or a total of 3 minutes including items 2 and ".

5. Take slump test: designed for 3 inches; actual slump - inches.

6. If slump is too low, add water and mix for 30 seconds.

7. Repect slump test. Final slump inches.

8. Place concrete in molds and vibrate with a l-inch stud vibrator.

9. Smooth off tops with wooden float.

10. Cover with metal plctes and place in fog roam.

11. After 24 hours, strip molds, number specimens, and place them in fogroom on shelves.

Although the mix was designed for a 3-inch slump, the NaCI Ircreased the slump toopproW mxtely 7 inches. After the hardened cylindes were numbered, a table ofrando. numbers was used to 6esignate two qylinders from each batch for permeabilitytests.

After 14 days in the fog room at 73.4 F, the 28 cylinders not chosen for thepermeability experiment were tested in compresslco. The compressiv smrengths aswell as their stand•rd deviations were cmputed and appea in Table 1i. Disks weresawed from the two cylinders chosen randomly, then placed in wet cups.

Before being sawed, each cylinder was embedded in plaster of Paris to avoidchipping the edges of the disk at the breakthrough of the saw. A 3/4-In*,,s ikewas removed from either end of the embedded cylinder, then a 1-1/2-inch slice woscut from each end and one from the middle of the cylInder. After sawing, theplaster of Paris was broken away from the disk (Figure 4). The disk was then qcic!&yprepared for sealing in the cup by washing, surface drying, and stamping with w.

identification number.

u7

igure 4. Plaster of Pais casting aound concrete cylinder to,

prevent chipping of concrete at breclcthrough of

A detailed description of the plastic cup and component pm-ts (Figure 5) isgiven in Appendix A. The cup was prepared for assembly by cleaning with ethyl

alohla~nd chckn al ih mt o ih i.Th ikvste di h

wet cup in the up~iiqt position with respect to the as-cast position, aid the cup

1was assembled, it wshalf filled with distilled water. The water inside the cup

was considered to be an infinite source for water Yano at 100-perens- RH.

A mercury manmmeter was attached to the top cutlet. Before placi" themercury, the air inside the cup was washed out with helium in order to eliminateunknown effects of any active gases that migh-t be p.-,sent. Tygon flexible plastictubing was used on the cup system - a short piece- dbout 2 inches long on the bottomI outlet nda l Ionger -p'.-- about 12 inches long conned~ing the top out-let to the man-ometer (Figure 6). All cornections were wrop-sealed with Scotch Plastic EleciricalTape Wo. 33 to prevent leakage, and a showt legth of rmsking tape was applied

m mm

1ver gure 4. tape o pr 'is 10n me on rt e cyl ln .

-- pevet chppig c €onret •' hn~h o

Figure 5. Cormpoent Darts of acrylic Wet CUP.

The wet cup was then placed in the ppropriate RH room. Five to six ors

elapsed from the .. e disk was sawed to the time the wet cup was placed in thIeRHi room. Another twelve hours or so were allowed for the cup and contents to

reach the 73.4 F temperature of +- e RH room before the Initial weight was taken

and the mnercury in tha manometer was leveled.

The wet cup Was 1wcighed in the RH room to the nearest gram (estimated to the

nearest half gramn). At! cups were weighed weekly. Weight losses in grims versustime in days were plotted on agraph like the typical one in Figure 7.

After the first rday each% ctup developed a few miliimeters of vacuum, as

indicated on the m anometer. The vacum increased at a different rate for each cup;offr a month some cups developed a vacu.m of over 200 millimeters of mercury.

The vacutu continued to inchease, but as the mercury ia ched its limit of travsel,

clamps were placed on the Tygond tubing and the manometers were removed without

distRroin the interior of the cup. A likely explonatien for the vacutan in the wet

cups is that the helium has a diffusion coefficient through most substances grtater

than that of the atmosphere; therefore, a dsp in internal pressure developed in

each cup as the helium diffused through the nsemabled cup system.

nret al ga.) Al up wr wigedwekl.Wegh lsss ngrmsvesu1

trn ndy ee'ote nagahlk h apcloei iue7

I SiJ

Fiur 6.ArlcwtcpLIldwihseie n cn tr

12j

__-_.. •0 _ _.. . . _ ._ _. ._i ,I i

Wi Cup No. P344T, Botch S-16

- 1 73.4 F. 50 patc-1t RH

V 60 1, - -

I I

40

I Ia3t

:40

-J

10

* -i

h. i mn fssd. slt , fl- w

Figure 7. Typical weight iloss vem-s timne for wet cup.

13

10 1 Iie e1 -'_fl• 1 I II'I I I 1 1 I nlI

Discussion o. Phase I (Results)

Cotnpiessivc Strenth. The curv-e in Figure 8 were plotted from Table fl.The tep twc crves, representing compessive strengo plotted with respect to water-cement rati:, relate concrete without NoCI to concrete with 1.5 percent NoCI by

weight of pl-3stic concrete. These cu-ves show that concrete without NaC! has ahigher 14-d 3y compre"sive strength than concrete with 1.5 percent NaCI. Thisrelation helJ true for all the watw-ce€ent ratios used - 0.444, 0.571, and 0.702for high-,fedium-, and low-tranth concretes, re ly. r'S"'Melation wasalso verifi"<4 later ;n PhI ases Ill . i1

The -.--tram two curves of Figure 8, representing standard deviation ofcompressiv, strength vetsus water-cement ratio, relate concrete with 1.5 percentNodC and v ithm-t NcCL. The standard deviation for concrete with 1.5 percentNoC! is cefinitely lower than the standard deviation for concrete without NaCI.There also eefs to be a m~nimum -standrd deviation -t a tL -c.r--ntratio; i;n .,.me plots the minietum standard deviation occurs at a wdar-cemnt ra(0o10of 0.61 fL- b~tb concretes. At each of these water-cement ratios there is the leastdeviation -.- variation of compressive strength among samples.

Peru eability. The equation, based on a form of Fick's law, that generallyhas been ued to calculate water vapor permeability (WVP) coefficients for concrete

W9Atz•P

where: W = total weight of vapor transmitted, grains (1 gram = 15.43 grains)

I = length of flow path (or thickness of specimen), inches

A = arec of cross section of flow path, square feet

time during which the vapor transmission occurred, hours

t.P = difference of vcpor pressure between ends of flow path, inches ofmercury (at 73.4 F: 100-0 percent RH,, AP = 0.82948; foi100-2D percent RH, A? 0.8 (0.82948) = 0.66358; for I00-50percent RH, AP = 0.5 (0.82948) = 0.41474) k

Wf W'P permeability coefficient, grain-inches p-- square foot per hourper !nch of mercury vapor pressure difference

14

IIIi:- ii iii i l il'm " "i' 1 i'l , , r

0-O-- 1.5 percent NOCI Helium

Each point represents 23 Fettaod c mentconcreftecylinders, 4-in. diont by a au.

70M________ ___________ ___________ __________

60M NI__ _ __ _ __ _ _ L_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

0%0

O.4 0.5 0U 0.7 O

water-ce-ne-V ratio - Phase I.15

SI I

Wisng Euction I to calculate WVP gave Eg!er values for wet cup ;n .he0-percent .RH room than for companion cups in the 20-percent RH room. After

examination and comparison, it was decided that such calculated WVP values wereincompatible. For specimens of identical mix design, A was constant and I wasvirtually constant; for equal values of t, W was measureed and found to be nearlyconstant; therefore, the only variable thought to be significant was. AP the =tivatingforce.

The Building Research Advisory Board Report No. 14 to the Federal HousingAdministration3 has sumrnmarized the current professional thinking about the ve'; inwhich water moves in =oncrete as follows:

"The Committee (Advisory Committee of BRAS) believes that moisture is

transferred through partially dry concrete in the absorbed or condensedstate by surface diffusion and does not move as vapor through concrete.Also, where good practice has been followd.- in the design and curingof concrete, ;t is be!.ev.d that moisure does not move throngfh the con-crete by capillarity as it is usually understood. The transfer process isconsidered to be the some where either liquid water or water vapor arepresent directly beneath a slob-on-ground. However, other conditionsbeing similar, there is believed to be a much slower transfer to theaborb-d state when vapor rather than liquid water is in contact withthe slab. This results in a slower rate of moioture transfer through theslab where oniy vapor is present."

Further, "Due to the hygroscopic nature of concrefe it is believedincorrect to consider the rate of moisture transfer pr hOtiol!e t.avapor pressure differential between a moist anr -. dry side of a slab.This is because moisture moves through a mature concrete in an absorbedor condensed state cnd not in a vapor phase. For water moving throughconcrete in a condensed state, the driving force is not comptoed from.the difference between the two pressures but from the ratio between thetwo relative humidities.

Moreover, 9The Committee reommends against expressing results interms of pemeeonce as defined in ASTM Designation: E96-53T,Appounix 2. Computation of permeance is based on the assumptionthat moisture travels through partially dry concrete as v:aor, whereas,tnder the conditions of these tests., it is transferred in the absorbedstate by surface diffusion. Motive force is proportional to the loga-rithm of the ratio between the vapor pressure on the moist side andthat on the dry side; it is not equol to the difference between the twovapor pressures as assumed in the ASTM definition."

16

tI

According to Babbitt, 4 Fick's law states that the concentration gradient isthe driving force for diffion and, since concentration is independent of the phys-ical state of the molecules, Fick's law does not distinguish absorbed moisture from

£ maisture in the gaseous or liquid phases, and therefore is not applicable to* hygroscopic materials such concrete.

Babbitt4 further points out that "...movement of moisture through porous orgranular solids is a complicated ".enomenon that cannot be solved completely byany single approach." Moreover, "...any satisfactory explanation of the movementof moish-w-e not only must consider. the physical state of the water molecules "vithinthe solid but also must include all possible modes by which t'e mnolecules mightmove. He distinguishes six possible states: vapor, liquid, ice, chemical compound,aix-'bed, crd dissolved; and adds: "In each of these states, the woter molecules,imder certain conditions, are capable of movement, and all six states may contri-

bute to the migration of the moisture. He then presents a form of the Stokes-Navierequation as a generalized equation of flow, since "...any movement of * fluid mustcbm•an - eqation of transport of the form of the Stokes-Navier eqtlotton-:

6P6x. Ax = 0

In the absence of a numerical evaluation for concrete of the pressure gradient6P/6 x, and the resistive force A the foliowing expression for water vapor trans-mission (WVT) was arbitrl•l!y adopted for this study:

WV = _w (2)At

where: f = length of flow path (or thickmess of specimen), inches

W = weight of vapor traniitted, grains (I gram = 15.43 grains)

A = area of c.-oss section of flow path, square inches (11.12 squareinches for specimens reported herein)

t = time during v•tch the vapor transmission occurred, days (100 daysfor this study)

WVT = water vapor transmisslor, inch grains per square inch p day

17

• •.I.

Equation 2 can be reduced to the following simple w-rking form:

WVT WC (3)

whare C = 0.13876, an S and V1W e;e used in units of inches and grams, respectively.

The weight of water loss for erch cup for a period of 100 days was interpolated

from the straight-line portion of a graph like the typical one in Figure 7. Subsestutingvalues of W and z from Table Ill into Equation 3, the ViT values were computedfor each wet cup. All three cups (top, middle, and bottom slice) of the same designwere averaged because there was no appreciable difference in their values ( le i;•

It is interesting to note that the WVT values are a!most equal for identicalspecimens In the different RH rooms, it must be remembered that all specimens hadnearb-y eqiiotiren'on; therefore, W is the only significant variable in Equation 3for this study. Since meas-red values of W were almost equal for identical speci-

mens, it is apparent that ambient relative humidity hod no significant effect withreference to WVT. Therefore, ambient relative humidities used in this study seemto have little or no effect on the transmission of moistuwe .I-.ough a concrete disk.This condition can be better understood by examining Figure 9. This fIgure showsthat the upper two curves representing concrete without NaCi lie very close to eachother, as do the lower two curves for concrete with 1.5 percent NoCi. The WVTincreases with an increase in water-cement ratio (lower strength concrete).

It is most important to note that the WVr" for concrete without NaCI Is abouttwice that for concrete with 1.5 percent NaCI. The following is a summary of theeffect of 1.5 percent NaCI in concrete with a high water-cement ratio:

1. The slum-p 's increased from 3 inches to 7 inches.

2. NaCi whiskers develop on the wet cup specimens.

3. The compressive strength is reduced.

4. The WVT is reduced.

A faint growth of whiskers was first detected after the low-strength specimensc,-ta!ning NaCi were in the RH room for three days; the higher the concrete strength(the lower the water-cement ratio), the longer t+e tL-ne that was required for theinitial growth of whiskers to begin. A discussion appears later in this report underthe heading 'Sodium Chloride Whisker Crystals.a

18

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Ii i - I II II I I I I I I I i l I I II I I I II

04 C14

t 1 ,4 1 1 M 1 1C14 1_ _ _ _ _~ ~~ ____ _ 0_ ___ ___ ___ ____,4

10m3I "1%"I0- ."t . . 9

- 000l .)W 00 006 C;a

0 CN0 N C4 , CI C 14CJ

C.

W.__ zzzzzzzzzzzzzzzzzzI .

a Z

a za

c N.co- C-4 -0 ttco'oN r Rr ooD .I 0-

ro C4' rý V! -u! t% .4O

rD - - -- - - 0

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zz-33zzzzzzzzzzz co~-J -J - -

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19

20- Sptrcso RH, 73.4 F

Larg. AW.got. Helium. each palut is aw for 3 tests

0.70__ _ _ _ _ _

4 1

0.0 petcmit NCI

0.10

a.~0.5 - 060. .

-c~i

£ _ _ _ _ / _2D

Phase If was initiated to cosnsid&- tw oddithona fctors. ',r- cw~~iffitht Laborctory's "Hydrophobic Cem~ent" TaskI- No. Y-MV0-05-0e6t ~!c -- Id I.Swead ca an addliiiye to make cement .'es twt tz, sakhdonlng, prticuhirly intropical locattonw, 'hsrefore, it was dccidad :c frnckze o-!e.c o--d as a a~-in t-Aition, *-e efect of mai-w awgegcde sime w-,. of tnter123t. it v:,s d~iec'..

th .e res-,-ts ef Plioe I t.at thie me)u c4~ntoa conxretv h nt e skFi - th~e ira cylizgra v,-;r noti nwvý-; P1~ zz1 rn Wy Hh voii-mwinvolved in Mhae 11 of this e.Trhent wee9 as fotlow--

i~Law (L) or hish 00i stren~1h * onf rsz

2. 3/8-inch (S) or 3/-4-Inch WL gaxi.ý csav.cateb zle.

3. Absence (A) or prsence oP f N*Ck.

4. -Absence (A) orpraec-e(P) of ofle 1dc.

S. Lower (L.) or uvper(% ic i h e hefndr f on e

Thus there were tvg* PE~io eo+cof six f~o~ ~~~ a total o! 64com~bhxnat-ios !n al I. A c~jter r-e-cote- :ieý ;I;, one ?-a$vin 16cowiibinations - was msd cz Phase fl. This pAhee badsnr- 'Ws~~ - Phaise Ibut took le.- thtm halF the nt.Ybr oa wet cu-ps, afewuoh It crid no., r--- the %spapsof the trend cu~vrs a- deflned by 4-4=& polnr4. T-hr vn~wiables identiffied bybatch nmxber appe= in T~ka IV.

The proced=-e* Far Phot. It W-me Tho ue --- S l~h=s for Phase I except thetnitrogen gas was use4 in p~tae of helium gms -,3 ar-d develolmet, of aOleic ocdd artd dry cement ý.- mi'X64ed a pabble mill (wti-hout the *ebbles) fbr25,000 revolutions.

After a wert cup was assamnbled, D~ %*= ;4z if- its designo!id RH jo~ andpeeliadic weight anzd mameter reaw%,.% Ywvt& *. as In 1h we 1. The rmercuy

rees revealed little zz, r,- avi~i. Afý*r six weeks it wvas 4teided the %immm~zmeters. wer.: of no Finfrthr cas~quexmce and thyw re= re ed ft~ alltewe- cupz.

The NoCI -Aiijce devreloped, as pfewtcusly 4escribed, on. oil thasa *vckisnswhiich cormtalned 1.5 perent Na~i,

21

C

C- a0 -4.

4 * . U 0 v s V I - --- 4 % n

x ii

CM A

4-

0

0 0% Co 0 r Q

** C% r- m M m_

*~~~~I . I______I. 0 "U

-"I V -4-C4 C4.-9 9 t-q 4 it I&," " C O C

c a~

30 2 .1 -I- ME

e ooi

'I 22

To cscertain if the cup assmbly system was impervious to moisture, threetypes of control cups were assembled 2s follows:

1. In place of a concrete disk, an acrylic disk was cemented to the top ofthe cup, the cup half-filled with water, the air flushed out with. helium,and the small access tubes clamped tight.

2. Some as (1), but flus-hed out with nitrogen.

3. A =p w cocr"•- ie disk was sealed across the top with a 1/4-inchlayer of epoxy.

One of each of the above assembiles was placed in the 5)-percent RH roomcpd • _,-v e w=P ..l ace 2D-perceist RH oron. After six months there was no

detectable weight loss, $.us showing thai the system was impervious to moistuhe.

Discussicn of Phase I! (Results)

The curves for small ond large aggregate with and without NaCi were plottedfrom Table IV ard appear as the top four curves in Figure 10. Here again, it isshown that the presence of 1.5 percent NoCi in concrete lowers the compressivestrength. Figure 10 also relates the effect of aggregate size and strength. Withand without NaCI, the concrete containing small aggregate had a higher compressivestre-ath than the concrete containirg large aggregate. (The designation of 3/4-inchaggegote as "large aggregate" is a relative term within this expe-iment.)

Figure 10 also contains curves for star•drd deviation of cacnpesive strengthversus water--cement ratio fc- oncrete containing small as well as large aggreggrewith and without NoCI. Here again, the standard deviution foi concrete with1.5 pe•r•et NaCi is less thcm concrete wi.•tho NaCI. For some unexplainable rea-son the spread of the curves is greater for icrge ag.--regate with and without NoClthan for small aggregate with and without NoCI. The NaCl seemed to have slightlyless effect on the small than on the large aggregate concrete.

As in Phase I the weight of vapor loss for a period of 100 days was taken Fromtihe straight line portion e. týh weight-time ggaphs for each cup. Cmputed valuesof water vaor t isson ppea in Table V.

23.4

I I

~IC,

a.6 ~ 0.7?~eeeI ~.~ ~Tat Ceam Ras;~ff* 4i.d

g£rt and ii-s -£ w Lv ci n v rt

wt -ennraio hs It

I 24

SV 734F I~

==- 3. ••.

_• i ll I II II I I ii i l iI ; ; ]

•-•l~llll NO ini. ii

I 73.4 F, W]/ •c, w•

_ 1percent In.

S11 N-972B D3. .9 0.714S 2 P24T 2 14.0 i.3 0.292

IS :3 N T 5D 13.2 1.491 0.274S i P41803 15.5 1.5 0.329

S6 j P22485 50 18.3 1.9 0:38115 7I NI52T I 5D 27.1 1.481 0.558s S P•-T j 20.7 1.539 0.443S 9 4•-"7T 18.6 1.503 0.389

S I P-214S 2D 28.3 146 0.8SI1 -4.910 17.9 1.513 0.376Si2 Pi POT 5D 7.7 1.497 0.160

S !a 13.4 1.5D9 0.281SU1 P-9,6 2D 10.8 ,.520 0.228$ i5 P17T 2D 19.6 1.499 0.408$i6 P344T 5D 38.6 1.522 0.817

i • •~s..'T,Mr e •- U, M, Lon Table iI.

.,'Welght of water toss for 100 days on straight-lime portion of groah.Z £ Leng•h of flow pt (or thlckmess of specimen).

4-~e~per sQuare inch per dlay.

Note: A.-eG of cross section or flow path 11.12 square inches.

t

25

. ... ,

3 - -

a¶ i 4'l!i~ ! f i!' i! l! ,

IIi

These vczues of WVT were plotted wilh respect to water-cement ratio forsnail and large aggregate with and without NaC! (Figure 11). The shapes of thesetwo-point curves were based on the three-point curves of Figure 10. Again thefact that the presence of 1.5 percent NaCI lowers the WVT value is demonstrated.The top two curves, representing concrete without NaCI, clearly show that thesmall aggregate concrete has a higher WVT value than the large aggregate •ancrete.Unfor.turzcly, because of a condition referred to as a "random deviate" bystatisticians, .the curves representing small and lrge agwegate concrete with1.5 perc•.t NaCI in.- rsect, and therefore do not allow any direct conclusion to bedrawn, without benefit of analysis of variance. The "expected" rates of WVI,plotted on Figure 11, demonstrate the probable relationships. These two curve-, iidentified by a triangular symbol, help to explain these variables in that they followthe same pattern as the o*.tr comparative curves. All the curves show that higher jwater-cerent-ratio concrete has a much higher WVT value than tow vwter-cement-

ratio concrete.

It may be noted on Figure 11 that there isan mpparent inconsistency in datasources for ambient RH, NaCl, and aggregate cures. Because of the quarter repli-

cae c' hosen to be investigated, there was neither a specimen with small aggregateand without NaCl in the s-percent RH room nor a specimen with large aggregateInd without NaC! i. the 20-percent RH room. The opposite situation existed forspecines• i with 1.5 percent NaCI. But since it has been concluded that RH has nosi•nificrnt effect on WVT, the curves can be compared on a sound basis.

The resultin-% values of WvIT, as found in Table V, were subjected to ananalysis of variance. Results of this analysis are presented in Appendix C. Waterv'por transmission values were found to be significantly higher for hight wafer-cement ratios (lower concrete strýgths), the absence of NaCI, and, to c lc Iextent, the smaller aggregate size. Concrete slice p•iJian, oleic acid, a:ld RHwere found to have no s;9nii~ican1 effect.

Comparison of Phase I and Phase 11

Phases I rd If were similarly conducted except for the gas used to flush theinside as' the wet cups and the kind and number of va-iables st.died. The curvesin Figure 12 represent IWW valures fr both ph.ass plotted with repect to water-

S III =,cement ratio for nitrogen and helium gases for concretes with and withot NaaCI.The top two curves, representing conc.rete without NaCI, show the effect of nitrogenrelative to helium to give a higher 'iVT. The sane relation holds true for concretewith 1.5 percent NaCl. This is sh-ow further by the following exomple. By takingthe WVT value for a wet cup containing helium fro Phase I ad adding to it thecorrection factor taken from Figure 12 (The ordinate value between two curves withSsimilar variables), it was found tit the new point falls on or very near the curverepresenting a wet cup with similar variablet containing nitrogen from Phase IU. Theeffect of different gases was not intended to be a variable in this exeriment, butinteresting devepmeats have come from their use.

S26

O-- O Let Aq, 9 0 ,, 47 * Tamp 73.4 F. each point te,.wwents one fts?

lip0 1ec r RH _ _

I I 0.0 Percent mCe

IIa.1 _ _ _ _ _ _

Cc

C

(L20

Ex$*de Curves

0.10 ______ &IOAJ 0.5 0.6 0.7 0-8

Water - Cceent Ratio

Figure I1I. Wazter vopor transmission versus water-cementrot~o - Aggregee size effect, Phase 11.

27

I

e i for tests

S I o.Io

I0.70-1t

I i

W Percen RH

SI -S PercenteNt.

0-"I

o !1 1 IIo,,, ,,, ,. , , _____._. ,,;,,,,,__. . __ _

3-0 1GA 0.5 0src6 0-7CI

Wwa( 20 Comm Rati

0202_

iii ii II Il lI I ll II] i ir i " i/ i 'i ii .n . - . . ..

I" I I I0 I I ! 1 ; ; ; ; -i ,

Sodrium Chloride Study

AatfromPhases Iand11, but asnoutgrtoftho+e effectof NaCt'on thecompressive strength of the concrete of those studiies, cm investigation was conducted

* varyihig the percent of NaCI in the concrete. Additional specimens were modefollowing the some procedure as !n Phase 11 but varying the percen! NaCI between0 and 1.5. Trhe design variables. compressive strengths, and standard deviationsappear in Table V1. Some specimens r1i.. Phae I and 11 are listed in Table VI forcomparison arzi convenience.

A graph of coompressive strength plotted with respect to percent Nod- (11=*!e f)cpoears-x- a: the top curve in Figure M3 Note that with an increase of NoCi fromo to 0.6 percent there is an increase of comp~resise vtrength; with additional saltthe compressive strength decreases to the limit of the experiment. The bottomn curve,though inconclusive, represents the standwd deviation of compressive strength(Table VI) also plotted wilth respect to percent Nodl. 8o" -uryes in Figure 13 crefor low-strength :oncrete (water-cement ratio, 0.702). Table VI1 summairizes the'A"%.CI stud data a is included for informational and comparative purposes.

As small an amount of sadhxn chlord'e as 0.075 percent by weighit of plasiticconcrete xcisdthe slun-. from 3 to 6 inches. Increasing the camounts of salt upto 1. 5 percent further ;ncreased the slump to 7 inches. The data in Figure 13 arefor a constant water-cament ratio of 0.702. If the water-cement ratios were reducedto provide equal consistencie-s (slunips), the cur-e dhold shicw significantly highercom pressive strength values.

Nothing was found in the liteafture to =ither verify or nullify the finding of anoptimum salt content for moximum strength; however, IKleinlogel 5 reported that experi-ments mode by the building department of ti-e city or S.-lin-Charlottenburg and byDieckmnsann resz),'ed in an increase in strength in most cases when sodium chloridewas added- to concrete. He finrther added that American publications reported a lossin strength. of from 7 tr- 40 percent when 1 to 20 ppercant sodium chloride solutionswere o_..A to the concrete mix. He also mode the following interesting observaions:Sodium chloride may cause effloresence;d it will cause reinforcing steel to rust; w-dcot Aaretz ec with chloride absorbs muah moistgre from the air.

1r-.ie results of the present study point out the net d for further investigationa620 .he effects of NaCo on concrete. At present a detailed investi ran of salt-waivr concrete is being conducted under Task Number V-RG07-05-012.

Mis may have been san t whisker crystals.

29

-1 0 o0_prettee sanraoo•rsi•••rt;wlho~ilnlsl

0 -_

22 _ _ _ - I

0-0

-Is-

>1 M

.2 =0qj~ ~~~~ _ _ _Z;__ _ _ a- -

c- -a

E CQ~0 _Z *-

0 '3 0 m

4;~~% 0 4C 4 O fC

Ij_ -i <-

in - n n ~ - - - ----- 4

* 00

1' C

I= co 4 4 4c

E .2 00 c 2 c

10~go 0!fta

-~IA

00 u

a C*

- 0-E4

i-o

________o 4.!L~

Ua 0

S 0

00)

I NC312

WMW irnw.4i.dcsb n41C

[ 4 StT~ gI~* WjC 0AD2D

4z0

C6

36 2___ 00

aw-2

320

_: I

Sodium Chloride Whisker Crystals

a IWhisker crystal growth on portland cement concrete incorporating sodiumchloride is believed to hove been first reported in this study. Within three daysafter being placed in either of ;he test envirenments, the high vwer-cement r-atioor low-strength concrete containing NoCI developed ,visible whiskers. The rate ofgrowth appeared to be somewhat more rapid in 20 percent than in 5D percent RH;in general, however, the ultimate amount of growth over three or four mon.hsappeared to be about the some.

One of the authors (Griffin) observed the sane type of growth in an air-conditioned building on .Y.i•.crdy, where the external temperature ranged between70 and 100 F and the relative humidity ranged between 100 and SD percent. On6 July 1960, in an air-conditioned room inside the b--ilding the tempercture was69 F and the RH was 51 percent. In a non air-conditioned room, where whiskerswere a!= growing, the temperature was 80 F and the RH was 54.5. These whiskersemerged through a layer of paint and the surface of the walls had floked off to adepth of 1/32 inch. The whiskers were fine enough to move cbout in the room onair currents and thus damage the large amount of electronic equipment that washoused in the building. It is not known whether the whiskers had the same ultimatedeteriorating effect on this equipment as do metal whiskers that develop short circuliton microminiature electronic devices.

Many articles about whisker crystals have appeared in various journals andmagazines in recent years. Reference 6, an authoritative and comprehensive singlevolume deaiig with the growth and perfection of crystals, describes whiskets ofmany substances, including sodium chloride. The description of these whiskers cor-responds very closely with observations mode by the authors in this study.

On some of the Labore!ory' s specimens the whiskers wer like lamb' s wool,on others they w.-.:. -ubb-y and coarse. Figure 14 shows _he whisker grwh on low-strength concrete after 5 .months. Figure 15 sh-4 s growths magnified 15 times.Individual whiskers were obse'ved to be as !ong as 4 centimeters and ca small as0.025 miillimeter in diameter. Geometric configurations on a single concrete diskincluded spirals, helices, and noncurvlinear shapes. In addition to individualwhi4er;, dense mats of closely pocked parallel whiskeLs emerged, usually separatedfrom c-•h other near the tips.. ndiv-Mual whiskers were striated longitudinally andhad the appecronce of having been extruded from a die as they continued to growfrom iust under fhe Surface of the concrete. They definitely appeared to have groimnfrom the base. In fact, if viewed at the proper time tnder G low-powered.microscope,they may be observed breaking thxi h a crust in the matrix that has been fifted aboveits original psitimm by tho formation of the whiskers.

33Iit

r

--'" " -- ' ( " '"" " :=i -

0

CL

C-4

-14

i(

t

x

0

I-

-r*1

-ii1��

0

V-aE0xLu

IL

35

I

3.

FINDINGS

Water VCPGr PermeabI Iity,

1. The formn of Fickss law which is co-ranonly used to determine water vaporpermeability for concrete was not verified.

2. An equation for a WVT (water vapor transmission) quantity equal to W

is mo~re suitable for the observed pherxnomnon. than Fick's law At

Strengtsfh, * Concrete

1. There is an *:otinu~m concentration of NoCI for maximum, compressive,strength of c-onacrete with2 a given high water-cement ratio.

2. Cancrere --iiih 1.5 percen.t NaClI-has !ess, strength than concrete wi thoutNaCi, other foc-lors being equal.

3. Concre-te containing srall aggregate is strcnger than concrete contcIningVlarge aggregate for I'identical water-cernent ratios.

Water Vapo Transjnission

1. WWV increases with an increase in water-cement ratio.

2. WPVT increases wifCi a decrease in maximum partitcle size of aggregcte.

3. WWT dpecrec-.*s with the presence of 1.5 percent NaCI in the concrete.

4. WV'T decreases with the presence of helium inside wet cups.

5. WVT is independen~t of the location of segments in a con~crete cylinder.

6. WVT, is independent of the presence c.f absence of oleic acid.

7. VJVT cte appears to increase slightly in a majority of cases as ombientPM dec.'-eases (partial vapor pressure increases), but for the range of thetests, 2D and 5D percent RH at 73.4 F, thie trend is not significant when

~ compared with the experimental variability.

r

I 36

General

1. Salt whisker crystal gr ieteriorates the surf•ce of the concrete wherethe whiskers form.

2. Acrylic cups, whiic are Inert, proved to be imper'Aous to vapor leak asindicated by the control cup tests.

23. The results of Phase ii (Wqarter replicate) were verified by results of

Phase I (full replicate).

CONCLUSIONS

1. Acrylic cups, as used in this investigation, are completely satisfactorycar stding VW.

2. A fractional foctorial design for est.mating WVT for several variables isnot only reliable but also L. econoc-..-cal.

3. A well-founded mthematical expression is yet to be estblshed for- I predicting WVT for a given concrete. In the meontime, straight-line

portions of the weight-loss-time curve provide a practical solution.

RFIJURE PLANS

All the wet cups will contir,.,e to be weighed for on indefinite time, andadditional information will be sought.

A Phase Ill study is planned to investigate the effect of water vapor trcnsmisslonon steel erbedded in concrete disks placed in 6-inch-dicameter wet cups. This willprovide ct least 48 additional wet cups from which water vapor trasmission cod theeffect of specimen size can be -tud-cd. It is ais planned to sudy the electricalresistivity of concrete.

ACKNOWLEDGMENT

The aut4ws gratefully acknowledge the contributions of Samue! H. Brooks,Sc. D., the Labortory's statistical consultant on this "aork.

37

~~-|

REFERENCES

I. Rand owPrporatkn. A Million Rmndom Digits With 100,000 N=r=a Deviates.Free Press, Glencoe, Illinois, 1955.

2. American Society of Heating, Refrigerating and Air-Cond itioning Engine=r, Inc.Heating, Vertilicti.ng, Air-Cor~dilrionin -Guide, Val. 37. New Yotk, ;-959.pp 127-138.

3. National Academy of Sciences - National Research Council Publicatijon 576,Building Research Adviisory Board, Report No. 14 to the Federal HousingAdministration. Effectiveness of Concrete Admixtures in Controiling the Transeissionof Moisture Through Slobs-on-Ground. Prepared and edited by William S. Brown.Washington, 0. C., 1958.

4. Babbitt, J. 0. "The Movemient of Moivture Through Solids.' ASTM BulletinNo. 212, FebIuary I m1 , pp 58-60.

5. Kleiniogel, A. Influences on Concrete, toranfated from the revised German.edition of i941 by F. S. Morgenroth. frederick Unigar Pub. New York, 1950,p 102.

6. Doremus, R. H., B. W. Roberts, and David Turnbull, eds. Growth andPerfection of Crystals. Proceedings of en Internaitional Conference on CrystalGrowth held at Cooperstown, New York, August 27-29, 1958. John Wiley & Sons,New Yormm, 19m58.

38

A4Vendfix A

PLASTiC WET CLUP DESCRIPTION

The following is a detailed description of the plastic wet cup and cor.ponentparts. Reference should be --od-- to Figures 5 and 6 in the main text of the report.

The main body of the cup, which is cut from Codco polis-he-d colorless widdtronsparert cast-acrylic-resin tubing, is 5-1/2 inches Iong w; h oS-in.ch oumridediameter andoa 4-1/2-inch inside dkmeter. The tubing is machined wiooth on bothends, cut with three circumferen-.el gaging grooves on the inside near the top withinthe dimension of the thickness of the s-pecimen,, and drilled fo, The access tubes.The purpose oa the grooves is to offer the rnax'nmum seal with the epoxy.

The top ring is cut and machined to size from 1/4--inch Plexiglas 'G' -heets.The outside diometer is 5 inches and the inside diameter is 3-3/4 inches *1/,64 inch.

The annulor ring with the counterbore is cut and machined fro-M 3/8-inchPsle)Gglas to fit tightly inside the main tubing body. The outside diam~eter is approxi-mately 4-1/2 inches and the inside dianieter is 3-3/4 inches *1/64 inch; thecounterbore, is 4 inches +1/16 inch in diameter and 3/16 inch deep. It is impartantthat this ring fits tightly in order to have a perfect seal.

The bottom plate is cut aid machined to size, from 3/8-inch Plexiglas, witha diameter of 5 inichets*1/32 inch. A shoulder 1/8 inch deep and qapproxiniately1/4 inch wide i indto fit the eotm ofech section eof he main tubina.

The access tubes are cut 1-1/2 inches long frcm ext~ruded acrylic tubing witha 3(8-inch oue iseter z-.d a L14-irsch inner dianeter. Thbe tu-bes and boes inthe main body are tapered slightly to provide a tight fit.

39

E ~Appendilx 8

WET CUP ASSEMBLY

The followiroi is a detailed description of the step-by---ep procedure for"mssnb~ling thehwettcup. Reference should be mode to Figures 4, 5, nd 6 in the

* main body of the text.

1 1. Measure the thickness of the concrete disk in fou7 different places with amicrcrz•.; and record the average thickness.

2. Clean all plastic parts of cup with ethyl alcohol and allow to dry.

3. Fit counterbore of annular ring onto bottom of concrete disk.

4. Mix the desired quantity of epoxy -nthe proportion of four parts ShellEpon Resin 815 with one part Shell Curing Agent T-1 by weight and thicken toconsistency of paste with a thickening agent, *Cob-O-Sil, " and seal the ring tothe disk by constructing a fillet of paste on the top surface of the ring oadacent tothe concrete.

5. Place the main body of the cup (4-1/2-inch id tubing) over the inverteddisk-ring component and press it down so that the concrete disk is flush with the topof the plastic main body '-n the inverted position.

6. Seal the disk-ring component in the main body with Cadco-94 GeneralPurpose Acrylic Cietmrt (conzsency of water,. At the some time, seal the access.tes in place. Allcw to dry 15 minules.

7. Mix the desired quantity of epoxy in the some proportions as in step 4without thickener. Set the cup upright on a level surface and fill the arnulor space.

8. Allow ths epoxy o se until hw-ened. Thismay take asmuch as fvehours.

9. Seal the top ring onto the cup with a thin layer of epoxy. Place a pressureple and weight (12-!5 pounds) on top of the ring to hold it in position. Allow toset.

401:!

I°

10. Seal the bottom plate to the cup with a thick acrylic ce.n---nt. Place apresure plate and weight (12-15 pounds) on top of the cup to hold it in place.Allow 30 to 45 minutes to set.

I. Attach a 2-inch length of Tygon flexible plastic tubing (FormulaNonR-3M'M; V8/4nch id, 1/2-inch od) securely to the bottom access tube.

The cup assembly is now completed and the cup ;s ready to be_ filled withwater, washed with gas, and to have the •-•--m-eter c..toched o thc upper accesstube, if one is desired. If a manometer is not required the upper access tube is notneeded.

41

IiI

I-

6 S

S -

'Water vapor trw=r&_*on values were found to be significantly higher for !he* high water-cement ratio, the absen-c-e of sodiun- dhorýcde, cnd, to a lesser extent,

the •-•ler amqragcote s•_e, Ccicete slice position, oleic acid, and reiative humid-I- were factois found to have no significant effects.

It ;s interesting to note that the small residual eror indicates that much of thevariabillty has been accounted for in the experimental procedures and in thisanalysis.

mnplied in the abo-.e an=lysis is this linear statistical nzodel for the "ex;.cted"rate of the water vapor transmission:

"Expeced' rate = 0.401 - 0.127A + 0.017B - 0.052C - 0.101D + 0.003E - 0.004F

The following table shows tie experimental design, the resulting observationsof the rates of water vapor trantission for the indicated combination of factors, the'exected' rate as computed above, and a check colwnn to show that:

z (c•b•sred - "expectedn) = 0

443

3-t

A,

ii

Table IX. Experimental Design and RGwuiting Observed and "Expected"Rates oF Water Vapor Transmission

Factor Factr- Levels Observed "xpectedu (Observed-Coam;±ior. A B C D E F Rcxteg/ Rateg/ NExpectedm)

S 1 -1 -1-1-1-1-1 0.714 0.665 0.049

S 2 +1 +1 +1 -1 +1 -1 0.292 0.347 -0.0m5

S 3 +1 +1 -1 +1 -1 +1 0.274 0.235 0.039

S 4 -1 -1 + +i +1+1 0.329 0.357 -0.028

S 5 +1 -1 +1 +1 -1 -1 0.185 0.105 0.080

S 6 +1 -1 -1 -1 +1 +1 0.381 0.409 -0.028

S 7 -1 +1 +1 -1 -1 +1 0.558 0.587 -0.029

S 8 -1 +1 -1 +1 +1 -1 0.443 0.503 -0.05 I0

S 9 -'& +1 -1 -1 -i -1 0.389 0.445 -0.056

S 10 -1 -1 +1 -1 +1 -1 0.581 0.567 0.014

s11 -1 -1 -1 +1 -1 +1 0.376 0.455 -0.079

S12 +1 +1 +1 +1 +1 &1 0.160 0.137 0.023

S 13 +1 -1 +1 -1 -1 +1 0.281 0.299 -0.018

S 14 +1 -1 -! +1 +! 41 0.228 0.215 u.u13

S 15 -1 +1 +1 +1 -1 -1 0.408 0.393 0.015 m

S 16 -1 +1 -1 -1 +1 +1 0.817 0.697 0.120

z (observed - "expected) = 0.0o0

2/ Inch-grains per suore inch per day.

44

- • ._- =- _- =- . __- _

IkI:I

* DISTRIBUTION LIST

No. of SM0L

]0 Ch;ie. Buea of Yards and Doc.ks

Bauocks; -Cedr DistrbutionI 23A Kvl Forcs Coanders Oi Only)

2 39 sobe Construct ion Battalions9 -M M~obie Construction Botlions

39E Amphiibious Consuruction Battlions

A2A ciu -- ..... . Research. Only

2 A3 Chief of No Il Opet.ons (Op-07.

S AS Bueaus

3 83 Colleges

2 F4 Laboratory ONR tashingt-n. D. C- Only)

1 E16 Trainrg Dei•c. Center

F F9 Station - OKO (Boston; Key vaest New Orlecots; Son Juaw Long Beach; Son Diego;

Traszure Island; and Rodmian. C. Z- Only)

5 F17 Coun.ication Station (Son Juan; San Fra0cisco; Pearl Hairbor Adak. Alaska; and

Gq-o- only)

1 F21 A.-minisi-r-ion Command and Unit CNO (Sai•an o-ly)

I F40 Cocwunication Facility (PWt. Lyouty cad Japan only)

2 F42 Radio Station (Oso and Cheltanham only!

I F43 Racdo F=slity (Londondeny only)

1 43 14 ,ecrsaty Group Activities Mbinter Harbor only)

8 O3 HIspital (Chelsea; St. Albans; Portsaovth. Va; 8eutalon; Great Lakes; San Diego;Oakland; and Coup Peod!ftn only)

I H6 medicoa Center

2 A1 Adimint*raso C===,cud and Unst-BaPes (Great Lakes and Son Diego only)

z "U. ,. Fleet Anti-Air Wcar'ar Taining C.wer (Vir•;ial Beach only)

2 J4 Amphibious Bases

1 J19 R lceiving Static,- (Brclklyr =Jly)

j3.4 S1*t6o0 - BUFa7rs (fas•"ington D. C. onlyt1 J37 Training Canter (Bainbridge only)

1 J46 Persennel CeIt*r

I J*! Construction Training LUnit

I J60 School Academy

45

IL

Distribution List (Com'd)

No. OF SNDL

copies Cod*

I J65 Schol CEC Officers

.IaA SzhooI Past•duare

1 j93 SchIo Supply Corps

1 .195 oWar College

I J" CLos==-n; €tion Training Cener

11 Li VSitipyods

A L7 LBu•htoy - (,N.ep {sw L.t&dn; Panam* City; Carderoa; and Annapolis only)

5 L26 Naval Faclities - BuShips (Antiguo; Turks Island; Barbados; Son Salvodon andEleuthera only)

I L30 s5bgm-ne Base (Gron Coon. only)

2 L32 Naval Support Activities (London & Naples only)

2 L42 Flee Activities - BuShips

4 hG7 Supply Center

7 AM2 Supply Depot (Esi~ept Guontonaimo Bay; Subic Boy. and Yakotuko)

2 LS1 Aviation Supply Office

3 NI Buoocks ODrector, Overseas Division

42 N2 Pawic Eoks Offices

7 Ns Ccnstructon Bttolion Center

5 U6 Construction Ofr fcer-ln-Quorge

I N7 Construction Resident.Officer-in-Charg9

12 N9 Public Marks Cenftr

1 NUd Howsing Acj.y••.

2 R9 Re'crui Depots

2 RIO SulyI, bIzallations (Albany and Barstow only)

1 R20 JMrmne Corps Schaýv. QVentico

3 R64 Uft~rW Cors Sate

I R66 Marine Corps Camp De•-ac•tnt (Te.a.n only)

7 VIA1 Air Station

35 W1A2 A: Smtion

WIB Air Station Auxiliary

5 WIC Air Facility (•hoeniz; Mmntei-Y, Oppag; .•5ha; and Naples only)

3 ME Livine Corps Air Stttion (Exrept Quaonico) II WIF marine Corps Awuxliery Air Station

8 V114 Station - BuWsps (Excep Rota)

46!a

* Distribution List (Cort-tlc)

No. ofcopies

Chief of Slaff, Ii. S. Armay, Chivi of Research orif Deveiapawmnt 0-oprtz-nt at the Arm-y.Washington 25. 0. C.

Offic, of the Chief of Engineer:, Asst. Chlief of Engineening for Civil Works, Deport-ment of thcArmy. Washington 25, 0. C.

1 Chia; of Engin'teroz, Daportuarrt of the Army, Attn.- Enginoerin2 R & 0 Division. Washington 2S. 0. C.

1 Comme ing Officer. Engiz serang R & 0 Loboratories. -A.m: Tocir-ical intelligence brcn-ch.FotSeliroir, Yilginin

1 Commarding General. Wrigiht Air Developmen:t Center Air Rasearcht and Davaisopam.ent Co=I--nd.Weight.Prtteison Air Force Base. Oiu

I Demcty Chief of Stoff. Deivelopmrent, Director of Research -j-4 Developmen. ODporta--i of ihe

Air Forcec. Washitngton

I Pu;sadent* Mairie Corps Ea&upntpert Board, UDA-ie Co.ps !'0%is. 00ontico, Virginia

I Director. MPeatic;a Bureot, of Standards. Dep~artm~ent of Commer-ce, Cecritecticut Avenue.Wozhingto~n. 0. C.

10 Armed Services Tsclvincal lnformarnon Agency, Arlington 1'loll Station. Arlington 12. Virginec

I Deputy Chief of Staff. Research at a Development JIL-dquztncrs, U. S. Marine Carps

Z t~6 uA.AF. a ; Civ,, Engineerng. Attn: AFOCE-ES. Washington 25, D. C-

2 Co-nmonr. pv.d.irartors. Air Research cnd Develop=*%.t Commanrd, Auvire-, Air Ilarc* Base,Washington 25. 0. C.

2 Office, of the Detector. U. S. Coast and Geodetic Survey, Washington 25, D. C.

2 Library of Congtess. Washington 25. D. C.

10 Director. Office of Tecfoimczl Sarvices, Da-partimenT of Commerce. iashingion 25, 0. C.

NCEL Stondord Distribution

2 Director of Defense Research and Engineiering, Deportment of Defense. Washington 25, D. C.

2 Daoctor. Divi~sion of Plans and PoliciezHaqure, U. S. MariYne C---=, Washington 25. 0. C.

2 D-rector, Bureau of Reclamation. Washington 25. D. C.

2 zowma...jn officer. U S Na-af Construrction Battolton Certer. Attn: Technical Division.Code 141. Part H.enzme, Co!.ornmo

2 Coaonei"n~~ Olfcer. U- S. tfovoi Construction 8Bttalion Center, Attn: Material Deportment.Cod* 142, Port ffuename. California

IComanding.n Officer (Patent Dept' ). Office of Naval Researce. Branich Office. I0= E. Green Street,Pasadena. C4l ifon.:z

I Coic~ldng Officer. Yards and Docks SMIrpY Office. U. S. Waald COM--%. flaitlic. cen.ter,Por? HUeneme. Calif.

L 47

Me c

14CEL Su~,eralsaw L-s.&Amiohz*a

I D~tor, Illrine PhiYsio' - .---- 469, UJ. S. Navy Elecismca Labcmoiery San tiege

1Co==dc4i-'. Pacific ~ .sz li~ga. Mt* An Tedahoh! Discitor. Pv'dat &&V,p Calit.I Ccow-a6rw U. S. 14-vol S~karrd, AM; Meforiae3 and 0.mlcal ;.ok., S~ Absa

1 Office 12f Novel Svzeck~ Grwa: Office, Nevy Sz. 100, S= 39, FP0, Nww Ycrc

02o Chi DF* a~~ of Srof1, FeSasao6i,~ DoeeM. 4tdqc tee U. S. Uplcef C- ' -,

M 2- 1;w.At iet of Reýhocd 0vv&!*Vwvw Goa~p. Vaalhingtuoe, 0. C.

1 A*ý Cortcete Division. Wctarways Experiment Statien, P.. MOrawar 2131, Jockst--. i&ts.

1 lr.iscl lHowiiq Aminir-aa. VosItoan. D. C.Clim.f Ekcree- zf Y*74ds and Docks. Cois D-23OM Wesi-irrt-. D. C.

I 91,. P. R Mosoz, Director %C-4001 &=ertials Ttsting mraA &-rohveriz Division, Diz±rict PL-IlicVIOAS Offc&. 14 N9. No-ri No- 1M3 FPO, S-m Fiedc

1 V. E. ktRoyw~rmo (0-2;5EAR). moe..?lO Division. -hitirct Pubfic Works Cffice, 1AND, NavyMe- 12t, FPO. Son, Froncizc.,

1 Direcuir, ". Bureau of Standards* Dwp=t2Wc:-xh Commrca, C*-wc~x Avs.. W~azltnvnD. C-* AM^': mr. Mebvr 2 IOanff

I Cfic*, gA Giate.. U. S. ifaval Sipply Reseachcl anid DewIlopwors: FacilityF. Hez~dSgpy ClworeAt=- Library, Bc-vanne. M. J.

1 Offics. rn Chvce. u.. &. Navy Lmit, Raensselaer fta,#Icht c boolt'aft. Troy, N. Y.

01MOffr $na Ch*'gv, U. S. FocI-- Sups17 ResGerti ad Dv.-ioA'.az Faelity, Iaa Sply Cs~sc

Conioa.Aini Orficer FleIot Training Cows:. Nevy He. 122, Mo ?PO, S"n Srsc~itco

1 CoavsnAider, Li. S. t-2vCA Shkýrd Aftft UMetr~iel o~asbrraa Srooalcy;% M. Y.

3U. S. Nava-l Re-aecrzh Lhobearao, Cameisivr D.4;on. VaaWtigoaoa. 0. C.I C*=w;A-ont, 1sz Ravel OtrcAmo: CEC Naval Poser" Programi Officer, 49-5 Sczxv -St..a.

Bort, U-~r

Cowcwndauaq. 3rd Naval 0tec*A"ij E oe sv Provwen aficr. 91) lwth w:H--w YTor

ICcemadenf th X"ti Nva Distuic:. Am,: CEC Navel Rasara. Rogucis Officer, Nava-l Base.PhMladiphio Penn.

ICowvmandorip. Sth Naval Dsrc.A!-In: CEEC llavzl Rezov. Propcim Officer. Norf~k, Va.

I onau daadnt. 6e Na-al Disitic-, Attn: CEC Noval Res*e,%a Progeci. Officer, U.I Pi cv. base.Charfeston. S C.

Couamedont, Mi Novel Distuics. Ann- CEC Navel Reserve Pra=ra Olrf;cer. U. S. Navel StSortn.Hww Q:oorasý, La.

I Ccmanwwazrj Mef Novel Distr~c*, Athr. CEC Noval Resorre Progirce. 01fiwr &.xi~ing 1.Great Lokozý fil.

L

Distributtion List (coned)

Ho. ofcopies

1 Ca===oaa. 11th HavaI District. Ann: CEC loie. Reserve Pmomam Officer. 9ý-7 N- H~rb-r Drive-

1 ~ ~Conumuinw 12ib Koale District. Aitu, CEC Naoval Rmserve Prc Vffi-rer, F*66oI OficSui'4imz Scm Ftrw~isco

1 U. S. Aswey C-0s of Enginscr_ Off; c, of the Distrtc E aee. St. Port Distrct. 1217 U. S. P.O0.and Cava=a Hoc"s. St. Pool. Minn.

1 PCA. %esoorch oftd DevloreaI Lots, 512 Old Orchard Rood. Skokie, Ill.

M U S. -Am Vctmvwags Ezpesimai SIsi;*, coeps 0. eptirmose~. jo,4CMo Installation. C4Cnrr4eDiv~xian* P. 0. Dicwe? 2131. Jackson. Miss-

1 Library. Eawv*mrn" D*Pwtnwt,. le-o Smet Ljci ersi". Ame. Io--

I Labrory, tow-j Srct. Urwavrsl?, Aames. towa

i Comm.-aider Air Research & Develpeat Comamd. Attn: Library. An*sws A-it Force Base.etzkLttfa. D. C.

1 Libray. University of Alaska. Fairbanks. Aleske

1 Columbia Umiveusary. Lewmoo Geological Ohmavwtary. ATno Libr-y. Pclisoics. N- Y.

I De-o wtime of Mecbzicel Engineig- Most Visrgia. Uu,.uerity. Morgatown. W. V*..

1 Chief, Physicel Research Branch. Research Divisiori, U. r. Oepertment of Comic,. Bureau ofPtvblk Rowds. Wosuhimo,. 0. C.

I Library. Enineing~ Deatwt Stmfr unvrmy Stso Colif.

1 Library. Harvar e: vriy rdaeSho f ~ore.Coed es

I Director. Engingermi; Qsect-cl. Imt.ute. Uosversuty of Abckigms. Aaw% Arbor. Mich-

a Lebrcry. Engwwwwrft D..i fsc. M.szty of CO1Af--nio. 405 Kdard Avefsue. Los Amgele

I Library. Betucile Insutvtce. Col==6w. Ol6o

-~I Labrary. Uutrversty of Seotar!n Colo farwtie. Lh iversit7 Park. Los Axmgetes.

0 Dieck,* to. Sai reyu.zz L=Ltary. Dever=meat of Engietering. Ann:c Library. Princetoe University,

1 Lil~wy. Vest V c.vi-a University. Worgcant Iwt. V. Ye

I Library. E-iftg.eering Deportmart. West Virginia 13%wivorsity. blargemlemn. W. Vo.

I Lsbrary. BSae* Coflse. Berea. Kty.

1 Mstiic, The- Tsa3cl-zcdI-- lastiTsior. N:=r-uwaste=ic Liverzity'. Evonstait. 191.

I Laibrary. tsit.of Tcivmcfog,. University of '1zeor. V~wcacnis. Wonn.

1 Library, Colifamra Isoliulttt of Tedhsoneoy. Pasodeito "~;f.

I Oie of Eaggmeers Dwp~townt '- 11e Army. wrsua-aa D. C.

1 *. j. 0Swlpviv, The Miere Coqetetiom. P.O0. Box 209, Lexism~, aboc.zz

I Codm~s.13!S Novel Disriac twz= Ckuit. .v R..... :w,-,, Of fmcet Seanlie, VWsI,.

49

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Z.Z C £0SA

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