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I 7.- MISCELLANEOUS PAPER C-70-1

THE EFFECT OF TEMPERATURE ON CREEP OF CONCRETE; A LITERATURE REVIEW

by

~. G. Geymayer

January 1970

Sponsored by

Office, Chief of ~ngineers u-. S. A.rmy

Conducted by

U. S. Army Engineer Waterways Experiment Station CORPS OF ENGINEERS

Vicksburg, Mississippi

THIS DOCUMENT HAS BEEN APPROVED FOR PUBLIC RELEASE AND SALE; ITS DISTRIBUTION IS UNLIMITED

RESEMCli crnm1 UBf?/\P.Y US ARMY ft~GINF.ER W1;T'cf\'.//4.YS EY.PEPiMENT STATION

.YICK'JBUfiG. M1:.,si:s1PPI

MISCELLANEOUS PAPER C-70-1

THE EFFECT OF TEMPERATURE ON CREEP OF CONCRETE; A LITERATURE REVIEW

•

by

1-1. G. Geymayer

January 1970

Sponsored by

Office, Chief of Engineers U. S. Army

Conducl:ed by

U. S. Army Engineer Waterways Experiment Station CORPS OF ENGINEERS

Vicksburg, Mississippi

AftMY·MRC VICKaBURQ, Ml89,

THIS DOCUMENT HAS BEEN APPROVED FOR PUBLIC RELEASE AND SALE; ITS DISTRIBUTION IS UNLIMITED

I.,{~ I

I I J _ \.._, -

Foreword

The literature review reported herein was part of the U. S. Army

Corps of Engineers Civil Works Investigations--Engineering Studies Item

ES 626 "Investigation of Time Dependent Volume Changes in Concrete," Sub­

item 626.7 "Effect of Temperature Upon Creep," and was authorized at the

Consultants Conference on Engineering Studies, 30 October-1 November 1968.

The work was performed at the U. S. Army Engineer Waterways Experi­

ment Station's (WES) Concrete Division during the period July 1968-

January 1969 under the general supervision of Messrs. Bryant Mather and

James M. Polatty. This report was prepared by Dr. Helmut G. Geymayer.

Director of the WES during the preparation and publication of this

report was COL Levi A. Brown, CE. Technical Directors were Mr. J. B.

Tiffany and Mr. F. R. Brown.

iii

69301

Contents

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . Conversion Factors, British to Metric Units of Measurement

Summary ..

Introduction

Review of Published Work •

Discussion . . . . . . .

Temperature Influence in the Light of Creep Theories .

Conclusions ...•...

. . . . .

Recommendations for Future U. S. Army Corps of Engineers Sponsored Research

Literature Cited

Tables 1 and 2

Plates 1-4

v

Page

iii

vii

ix

1

1

7

10

12

13

14

Conversion Factors, British to Metric Units of Measurement

British units of measurement used in this report can be converted to metric

units as follows:

Multi Ell By To Obtain

inches 2.54 centimeters

cubic yards 0.764555 cubic meters

pounds o.45359237 kilograms

pounds per square inch 0.070307 kilograms per square centimeter

Fahrenheit degrees 5/9 Celsius or Kelvin degrees*

* To obtain Celsius (C) temperature readings from Fahrenheit (F) readings, use the following formula: C = (5/9)(F - 32). To obtain Kelvin (K) readings, use: K = (5/9)(F - 32) + 273.15.

vii

Summary

A review of the literature on the effect of elevated temperatures on the time-dependent volume change due to load (creep) of concrete reveals incomplete and conflicting evidence. Some workers have found a "creep maxi­mum" at a particular temperature range; others have not encountered this phenomenon. Among those who have found it, there is lack of agreement as to what the range is. All available data have been collected, reduced to com­parable form, and analyzed. The analysis has been reviewed in the light of the several theories of the mechanism of concrete creep. It is concluded that the new results on temperature effects on creep do not resolve the con­flicts among the various creep theories, but they tend to support the seepage theory more than any other. Many factors affecting creep are found to be influential at elevated temperatures in analogous fashion to their influence at room temperature. These factors include time under load, applied stress, maturity of concrete, and moisture content of concrete. The effect of tem­perature, at least up to 50 C, is to increase creep by a factor of two or three at 50 C. Creep may or may not increase from 50 to 100 c, or it may increase sometimes and not increase other times. The limited data on tests at temperatures above 100 C are not in agreement. A program of testing in the range -35 to 149 C using stress/strength ratios of 0.20, o.40, and o.60, including periods of sustained load of up to 2 to 3 years, is proposed.

ix

THE EFFECT OF TEMPERATURE ON CREEP OF

CONCRETE; A LITERATURE REVIEW

Introduction

1. Since interest in the development of prestressed concrete nuclear

reactor containment vessels arose 'in the late 1950's, interest in the ef­

fects of temperature on the time-dependent deformation (creep) of concrete

has rapidly increased. The subject had received little attention before

the late 1950's, perhaps due in part to the fact that Davis, et a1., 1 had

reported in 1934 that the creep of concrete stored in water at 33 C differed

little from that of concrete stored in water at 21 C. Also, before 1960

concrete in service was rarely subjected to a continuous elevated tempera­

ture ahd high stress; consequently, deformation of concrete under such con­

ditions was not of practical concern.

2. The use of prestressed concrete nuclear reactor containment ves­

sels created a need for detailed knowledge of the strain behavior of con­

crete subjected to temperatures above those normally experienced in service,

thus giving impulse to new research. The unexpected results of early in­

vestigations, in turn, focused attention on the creep problem and promoted

the beginning of a continuing reevaluation of existing creep theories.

Review of Published Work

3. Perhaps the first indication that creep in concrete can drasti-"-cally be affected by temperature was given by Theuer in 1937.c Performing

short-term creep tests on two different concretes in the temperature range

from -3 to +50 c, Theuer found the 3-day creep values of moist-cured and

"half-dry" sealed concrete cylinders to be fairly linear functions of the

temperature, the creep at 50 C being about two to four times that at room

temperature. Predried cylinders, however, showed very little creep, and

the creep values were almost identical for the temperatures investigated.

4. Additional evidence of a strong temperature dependency of creep

was presented by Ruetz3 in 1958. Describing tests on hermetically sealed,

pure, cement-paste specimens, he reported that "the modulus of elasticity

1

decreased as the moisture content decreased" and "the n.lli1il.y 01· Ll1c .Pa:~Ll~

to creep and itr, inelastic deformations increased with increasing Lcrnpcra­

ture. " Within <, temperature range of 50 C, the creep of tl: e pas tc was

found to increa:;e as nruch as 10 to 20 times its value at tle lowest test

temperature. l+

5. Serafim and Guerreiro conducted tests on "mass concrete" speci-

mens at room temperature and at 45 C. They found that the creep of mass

cured (i.e. sealed) specimens at 45 C, which were loaded at 3 and 8 days

age, increased .·mly moderately (about 10 percent after 100 days under load)

compared with that of the specimens tested at "room temperature." Practi­

cally all of th: s increase occurred within the first few d&ys under load;

after 4 to 7 da:-s under load, the creep rate became the sarre for both

temperatures .

6 ~ 5 . In 19:i0, Hansen reported the results of flexural tests on con-

crete beams at temperatures between -15 and +60 C. All specimens were

cured under wat~r at 35 C for 6 months before being loaded in a scaled con­

dition. The re.mlts indicated that creep of specimens tested at li.O and

60 C was approx:.mately double and almost triple, respectively, the creep of

specimens teste<.". at 20 C. The reduction in modulus of ela2ticity with an

increase in temperature was also reported.

7. .Two YE"ars later, England and Ross6

presented results of tests on

:::;ealed and unsealed concrete cylinders at temperatures up to llio C for

loading periods up to 80 days. Results of tests on the sealed cylinders

Tor the 80- day 1-oadtng period showed that the creep at 80 arid 140 C was

about 3.5 and 4.2 times, respectively, as great as that at 20 C. Varia­

bility in the n~sults of the tests on the unsealed specimens made _i_11terpre­

tation difficult; however, it appears that England and Ross's data indicate

a creep maximum a.t approximately 100 C for both sealed and unsealed speci­

mens (see plater: 1 and 3 and tables 1 and 2).

8. A novt;l, and rather startling, observation was first reported by

Nasser and Neville7 in 1965. Studying the creep behavior of mass and water­

cured 6000-psi-ll- concrete that was cured at test temperature 24 hr after

-x- A table of f11,ctors for converting British units of measurement to metric units is presented on page vii.

2

casting within a tem;perature range from 21.l to 96.1 C at stress/strength

ratios from 0.35 to 0.70, they found a pronounced maximum for the creep

rate at a tem;perature of about 71 C (plate 3). This creep rate was based

on creep measurements made during a period from 21 to 91 days after load­

ing, but it appeared to remain essentially constant up to the 15-month

loading period for which measurements were reported.

9. However, the creep rate of several specimens for up to 21 days of

loading was substantially different from the creep rate after 21 days of

loading; hence, the creep values after 90 days of loading did not consis­

tently show a maxirrrum in the vicinity of 71 C (plate 1). In fact, one test

series indicated a steady increase of 90-day creep with increasing tem;pera­

ture, in spite of a maximum creep rate at about 71 C for the 21- to 91-day

loading period (plates 1 and 2).

10. Nasser and Neville found the other aspects of the patterns of

creep behavior, specifically the creep-time curve and creep recovery, to be

the same at elevated tem;perature as at normal temperatures. They also

found creep to be proportional to the stress/strength ratio at any tempera­

ture within the range tested. A later extension of the program to old con­

cretes (1 and 50 years old), reported by the same investigators in 1967, 8

gave essentially identical results.

11. The occurrence of the "creep maximum" in the range of 50 to 70 c has attracted nruch attention, and some additional evidence pointing to the

9 occurrence of such a maximum has been reported. Peschel has reported re-

cent experiments in which the viscosity of thin water films (about 80 A)

between quartz glass plates was measured as a function of temperature. A

number of pronounced maxima were recorded--among them, one at 62.5 C with a

corresponding minirrrum around 50 C. It can be speculated that there is a

relation between these extremes and the phenomenon of a creep maximum ob­

served between 50 and 70 C. An explanation based on the influence of tem­

perature upon the properties of load-bearing water, which is similar to the . . . 7 h 1 10,11 hypothesis outlined by Nasser and Neville and Maree a , has been sug-

gested by Powers. Marechal has also observeQ a profiounced creep rate maxi­

mum (and a corresponding maximum for total creep) at a tem;perature substan­

tially below 80 C. Performing creep tests at temperatures up to 1~00 c on

3

unsealed specimens of siliceous and siliceous-calcareous aggregate con­

cretes loaded after 1 year of moist-curing at 20 C and 15 days of air­

curing at the respective test temperature, he found, at the end of a 100-

day loading period, a definite maximwn for both creep rate (1 to 100 days)

and creep magnitude at 50 C (plates 2 and 3). Predrying thf; specimen for

30 days at 105 C before application of the load reduced crel?p at tempera­

tures below 105 C drastically and eliminated the creep maxirrrum (plates 2 f)

and 3), a result consistent with Theuer's earlier findings.'-

12. Several other investigators who have conducted creep tests at

elevated temperatures in recent years have not observed a mn.ximum for total

creep, at least not at comparably low temperatures. Howeve·:, most results

indicate a maxiwwn for the rate of creep in the temperature range of 50 to

100 C (i.e., if the creep rate is computed for some period iJetween 1 and

100 days under J.oad).

13. Hannant,12

for instance, conducted creep tests on sealed 4-1/8-

by 12-in. cylinders of an approximately 9000-psi limestone n.ggregate con­

crete after curjng them 5 months in water and an additional month in a

sealed, saturated condition. The results showed a nearly linear increase

of specific creep with temperature within a range of 27 to 77 C for all

loading periods up to 2 years, the creep at 77 C being approximately 4 to

4.8 times .that a.t 27 C. A still higher rate of increase was observed in

the 77 to 93 C temperature range (plate 1). Up to stresses of 2000 psi,

creep remained proportional to stress. The values of creep strains for con­

crete that had been dried before lua-d±n~ -were -again only small fractions of

the values for ''wet" concrete. In triaxial tests, stresses at right angles

to the principal stress were found to reduce creep in the direction of the

principal stress; however, considerable creep remained even under a hyclro­

static state of stress. Poisson's ratios for creep determined on sealed

specimens were similar in magnitude to the elastic value. ~emperatures

also had a considerable influence on the modulus of elasticity, as reported

by other investigators,5,l3-l5 with Young's modulus decreasing almost

linearly with increasing temperature for short heating periods; however, if

the specimens were heated for an extended period (such as 2 years), the

modulus recovered to values approaching those at normal temperatures.

4

14. Hickey15

recently performed tests on unsealed G- by lG-in. cyl­

inders of a 7000-psi, amphibole-schist aggregate concrete loaded to 800-psi

uniaxial compression after 1 month of moist-curing and an additional month

of curing at 50 percent relative humidity (RH). Subsequent to the appli­

cation of loads, the specimens were heated to 54.4, 82.2, llG, and 143.3 c. A~er 6 months under load, creep* appeared to be a fairly linear function

of temperature up to 82.2 c, but increased nonlinearly with temperature

between 82.2 and 143.3 C, indicating a maximum around 143 C. At 143 c, creep was five times as great as the creep measured on companion speci­

mens kept at room temperature. Six-month creep values at 54.4, 82.2,

and 110 C were, respectively, 2-2/3, 4, and 4-2/3 times the creep values at

22.8 C. Initial creep rates (up to 1 or 2 days) of the unsealed specimen

increased dramatically with temperature; however, after the first few days,

the creep rates at the two highest temperatures (110 and 143.3 c) decreased

substantially. At these temperatures, about 90 percent of the 6-month

creep occurred in the first month, apparently due to the accelerated loss

of water. When creep rates were computed for a period between 1 and 107

(or 1 and 180) days after loading, they showed a distinct maximum at ap­

proximately 90 C (plate 3).

15. An almost linear increase of creep with temperature in the 20 to

75 C range was also observed by Arthanari and Yu16

on sealed and unsealed

12- by 12- by 4-in. slabs of a 6000-psi, Thames River gravel aggregate con­

crete loaded to 1000 psi, both uniaxially and biaxially, at an age of 10 to

100 days. At the end of a 40;..day load.ing period, for which resurts were

given, creep at 80 C was approximately twice the creep at 20 C in sealed

specimens and three times the creep at 20 C in unsealed specimens. The in­

fluence of age at loading upon the rate and magnitude of creep appeared to

be less at higher temperatures than at room temperature, and an incremental

increase of temperature to a maximum tended to result in higher creep val­

ues than a continuous exposure to the same maximum temperature. As in Nas­

ser and Neville's earlier investigations, 7 '8

creep recovery and Poisson's

* Creep values were, as usual, computed as the differences between loaded and unloaded specimens exposed to the same environment, minus the initial deformations upon loading.

5

ratio in creep were found to be essentially the same at elevated tempera­

tures as at room temperature.

16. Recently, however, Da Silveira and Florentino17 have challenged

the hypothesis that creep recovery is independent of temperature. Report­

ing on an extension of earlier work4

on creep of mass concrete between 20

and 45 C, they concluded that creep recovery as well as creep itself was

higher at 45 C than at 20 C, and they also confirmed that the Poisson's ra­

tio in creep (in sealed or water-cured specimens) was approximately equal to

the elastic val11e. McHenry' s18 expression, rather than a logarithmic rep­

resentation, apJleared most suitable to fit Da Silveira and Florentino's

experimental daca.

17. Browne and Blundel119 have described recent resv.lts on limestone

and dolerite aggregate concretes loaded to 2110 psi at tem1•eratures between

20 and 95 C and ages between 7 and 400 days. Although initial data indi­

cated that creep could be regarded as linear with respect to logarithmic

time from loading, a definite upward deviation from the straight line was

consistently observed at longer periods under load. Plotting the results

on a log/log ba;3is showed that for the sealed specimen, the experimental

creep curves rertained linear up to 6 years. Browne and Bhndell demon­

strated the improved linearity of creep curves in a log E versus log t or

log E versus log (t + 1) presentation on the basis of the work of England 6 12 . 7 10 and Ross, Hannant, Nasser and Neville, and Marechal. The creep curves

were finally expressed by E = a(t)n or log E = log a + n log (t) where

E specific creep strain

a a factor decreasing with age at loading, k , and increasing with absolute temperature, e

t time under load in days

n a factor decreasing with age at loading, k , and varying wi.th absolute temperature, e

Concerning the slope of the straight lines in a log/log presentation,

Browne and Blundell suggested hypothetically that n can be expressed in

terms of a modified Arrhenius activation energy equation, i.e.

6

where

C = a constant

a = stress

E = activation energy

R = Boltzman constant

-E RS e

18. A similar approach has been described by Marecha1. 10 Although

many of the data obtained or reviewed by Browne and Blundell19 indicated a

decrease of n with a decrease in i , or an increase of the creep rate

with increasing temperature, the inconsistency of the results did not allow

a conclusive answer as to how temperature in general affects the creep

rate. Browne and Blundell's own results, however, did consistently show

an increase of total creep with temperature up to 95 C.

Discussion

19. To facilitate comparison,- the results described by various in­

vestigators were "normalized" (i.e., expressed in terms of "specific creep"

and "specific creep rate") and subsequently compiled in tables 1 and 2, and

plotted in plates 1-3·

20. It should be noted that the term "f" (specific creep rate) as

used here is not equivalent to the term "F" in the creep equation:

E - _! + E 1-og (t + 1) E

As used here, f represents the average slope of the creep curve in a semi­

logarithmic presentation within the time period specified (plate 4). Conse­

quently, the specific deformation at the end of this time period is given

by the equation:

where is the specific defonnation at the beginning of the period, t0

•

Plate 4 shows a schematic creep curve in semilogarithmic

7

presentation, exhibiting the double inflection between about 3 and 10,000

days after loading that is typical of many of the creep curves c;iven ln

Wagner 1 s20 extensive literature review on creep or shown in Wallo and 21 Kesler's recent report. The origin of the time scale at 0.001 day (i.e.

approximately 1.5 min after application of the load) was chosen arbitrar­

ily, as was the shape of the creep curve in the 0.001- to 1-day range.

Plate 4 is intended to demonstrate the limited significance of a creep rate

computed, for instance, for a period of 1 to 100 days after loading, and to

clarify why it is possible to observe maximum creep rates for a time period

t0

.to t 1 without observing correspondent maximum total creep values at

the end of the period.

22. Plate 1 and table 1 summarize results of tests to determine spe­

cific creep of sealed or water-stored specimens at the end of a 60- to 100-

day loading period, as influenced by environmental temperature. In general,

the data show a fairly linear increase of creep with temperature up to

about 60 or 70 C. At higher temperatures, however, there is considerable

disagreement. Some results indicate a diminishing temperature effect and

a maximum for the 60- to 100-day creep values somewhere in the 70 to 115 C

range, while other data imply an increasing temperature effect as tempera­

tures exceed about 70 C.

23 .. For an explanation of these differences, it may be significant

that the specimen that showed a definite creep maximum around 70 C after 90

days of loading had been exposed to the respective test temperature some

13 days before loading, while in all series that failed to indicate a creep

maximum below about 100 C, the specimens were loaded within about 24 hr

after heating.

24. Two of Nasser and Neville's test series exhibited an apparent

first creep maximum at a temperature of about 33 C; although this is most

likely an experimental variation, it seems noteworthy that the apparent

maximum occurred very close to the temperature at which Peschel found the

most pronounced viscosity maximum in thin water films (33 C).

25. In plate 2 and table 2, a similar comparison is made for un-

al d · d th t · Whereas MarechallO,ll se e specimens, an e agreemen is even worse.

found a pronounced maximum for the 60- or 100-day creep values at a

8

1 d d R 6 . 15 . temperature of 50 C, Eng an an oss and Hickey did not observe a maxi-

mum until the temperatures exceeded 100 C. Again, it appears more than a

coincidence that Marechal's specimen had been heated 14 days before load­

ing, while in the other two series, the specimens were not exposed to the

test temperature until about 2lr hr before loading6 or even after loading, 15 10 11 2 12 26. Marechal 's, ' as well as Theuer' s and Hannant 's, results

on predried specimens (bottom curve, plate 2) also provide further convinc­

ing evidence of the important role of water in the creep mechanism.

27. Plate 3 shows the relation between temperature and the specific

creep rate determined for some arbitrary period between 1 and 107 days af­

ter application of the loads. All data except those obtained on predried

specimens indicate a creep rate maximum occurring at a temperature below

100 C, but there is considerable difference in the temperatures at which

this maximum occurs. Again, it appears significant that the most pro­

nou11ced creep rate maxima and those found at the lowest temperatures were

observed on specimens that had been heated for about two weeks or more be­

fore the application of the loads. In view of the fact that most investi­

gators have not found a corresponding maximum for total creep at the end of

a 60- to 100-day loading period, this creep rate maximum is a somewhat puz­

zling result. The initial creep rates, i.e. those obtained shortly after

the application of the loads and, therefore, not included in the rates dis­

cussed above, rrrust be substantially different from the average creep rates

computed for a period of 1 to 60, l to 107, or 21 to 91 days under load, as

the case may be in each particular series. This sugg_ests that the_ eSJ'-ect

of elevated temperature$ is to magnify and accelerate the creep phenomenon,

causing more of it to occur during the first few hours (or days) after ap-plication of the load. The appearance of a creep rate maximum at some tern-perature, T ' computed for a period to to tl after loading, without the

concurrent appearance of a total creep maximum at the time t1

, merely in­

dicates that above the temperature T a relatively larger portion of the

creep deformation occurs prior to the time t 0 .

28. Hickey'sl5 and England and Ross 1 s6 results on unsealed specimens

(loaded before15 and shortly after6

heating) strongly support this simple

concept, as might be expected for their particular tests due to the

9

influence of "drying creep." Serafim and Guerreiro 1 s4

and some of Nasser

and Neville 1 s8 data on sealed or submersed specimens also support the con­

cept, but other results obtained by Nasser and Neville do not, and neither 10

do the results of Marechal.

Temperature Influence in the Light of Creep Theories

29. Of the various creep theories that have been proposed, it ap­

pears that those which attribute concrete creep principally to the movement

of water, or to the viscous flow of cement gel, or both, can most readily

account for the increase of creep at elevated temperatures. The best known

and most promising among these theories is the seepage theory as originally

conceived by Lynam22 and later expanded and modified by Powers23 , 24 and

others. 25 - 27 In Powers' version of the seepage theory, the effect of

elevated temperatures can be visualized as increasing the mobility of the

"load-bearing water" (i.e., the strongly adsorbed water in narrow, inter­

stitial spaces of hindered adsorption) by reducing its viscosity or in­

creasing the diffusion rate of water molecules. If it is assumed that

Peschel's viscosity measurements on Bo-A-thick water films are relevant for

the much thinner layers of load-bearing water, even the controversial creep

maximum occurring somewhere between 50 and 70 C can be conveniently ex­

plained. Expressing the same concept differently, it can be hypothesized

that within a certain temperature range, the thermodynamic equilibrium of

the load-bearing water is -iess stable than at rdg:her or l-0wer temperatures;

thus, the addition of an external load causes more water to move more

rapidly.

30. Essentially the same explanation seems applicable also to

-Gllicklich and Ishai' s26 or Feldman and Sereda' s28

modifications of the seep­

age concept, which consider creep to be at least partly due to movement of

intercrystalline (zeolitic) water or interlayer water from the layered

structure of tobermorite and other hydration products, rather than to move­

ment of strongly adsorbed water from narrow, interstitial spaces in the gel.

31. In yet another modifica.tion of the seepage concept, Ali and

Kesler25 differentiate between basic creep and drying creep, the former

10

being a manifestation of the viscoelastic behavior of the paste without any

moisture exchange with the environment, and the latter occurring as a re­

sult of simultaneous moisture losses. Both components of creep are af­

fected by temperature, basic creep through the temperature influence on

"paste viscosity," and drying creep through the effect of temperature on

the moisture exchange with the environment.

32. The phenomenon of decreasing viscosity with increasing tempera­

ture can, of course, be used to explain the temperature effect in all vis­

cous creep theories29, 3o regardless of whether the theories expressively

attribute paste viscosity to the presence of water or not. However, the

shortcomings of purely viscous theories (e.g., their inability to account

for creep recovery and volume changes with time under load) and the results

on predried specimens strongly point to the important role of water

movement.

33. It appears somewhat more difficult to reconcile some other creep

theories with observed temperature effects. Freyssinet•s31 well known cap­

illary condensation theory, for instance, which has been questioned for

various reasons, 20 , 25,32 seems unsuitable for explaining the phenomenon of

higher creep rates and magnitudes at elevated temperatures in saturated and

sealed or water-stored specimens in which capillary forces should not play

a major role. But even if high capillary forces do exist, as in partly dry

specimens, the changes caused by a given load-induced deformation of the

capillaries will be smaller at elevated temperatures than at room tempera­

ture since the surface tension decreases filth increasing temperature. It

can be argued, on the other hand, that there is ample evidence of a consid­

erable reduction of the elastic modulus at elevated temperatures and that '

consequently, the dimension changes in the capillaries for a given load

should be substantially larger at higher temperatures, an effect that pos­

sibly outweighs the effect of reduced surface tension. This may be plau­

sible for partly dry specimens, but the inability to account for creep in

saturated specimens remains. Even less suitable for explaining the ob­

served creep behavior of concrete at elevated temperatures are plastic the­

ories, 33 which cannot be used to explain creep recovery, low Poisson's ra­

tio in creep, linear increase of creep with stress, etc., and differential

11

shrinkage theories, 34 which fail to give an explanation for the results on

water-stored or sealed specimens.

34. In summary, it can be said that the new experimental results on

temperature effects have as yet done little to resolve the controversy

about different creep hypotheses, although they certainly appear to lend

further support to the seepage concept.

Conclusions

35. Based on the results of this literature review, the following

conclusions are believed warranted:

a. Creep at elevated temperatures follows the same general pat­tern as creep at room temperatures, i.e., it is approxi­mately an exponential function of the time under load and a fairly linear function of the stress applied at least up to a stress/strength ratio of about 0.50. Sealed or water­stored specimens generally exhibit less creep than unsealed specimens, and creep decreases with increasing maturity and increases with increasing moisture content of the specimen at loading. Poisson's ratio in creep appears unaffected by elevated temperatures.

b. The effect of elevated temperatures (at least up to 50 C) is to increase creep, creep at 50 C being approximately two to three times as great as, creep at room temperature.

c. For temperatures of 50 to about 100 C, some controversy ex­ists about whether or not there is a further increase of to­tal creep with increasing temperature. Some investigators have found a definite maximum of total creep in the range of 50 to 80 C, but most have not and have concluded that creep of' concrete increases with temperature up to around 100 C, the creep at 100 C being on the order of four to six times as great as the creep at room temperature (at the end of a 60- to 100-day loading period).

d. On the other hand, in an apparent contradiction, most inves­tigators have also found a definite maximum for the creep rate between 50 and 80 C, if the creep rate is computed for some period between 1 and 107 days under load (plate 2). This seems to indicate that as the temperature increases, a larger portion of the (larger) total creep deformation oc­curs during the first few hours under load with the effect that the creep values at the end of a 100-day loading period, for instance, increase steadily with temperature, in spite of a creep rate maximum at about 50 to 80 C for the 1- to 100-day loading period.

12

e. Only few data are available concerning the creep at tempera­tures exceeding 100 C. Tests on unsealed specimens showed no appreciable change in total creep within the temperature range of about 100 to 140 C; the creep rate for a 1- to 100-day loading period appeared to decline. Beyond ll+o c, according to Marechal,10,11 both creep rate and creep magni­tude increase with temperature (unsealed specimens).

f. Some controversy apparently exists concerning creep recovery. Although Theuer2 and Nasser and Neville7,8 found creep re­covery to be essentially independent of temperature and stress, Da Silveira and Florentinol7 recently reported a significantly higher creep recovery at 45 C than at room temperature.

_g_. The described experimental results concerning the effect of temperatures appear to lend further support to the "seepage theory," while casting some further doubt upon the validity of other concepts.

Recommendations for Future U. S. Army Corps of Engineers Sponsored Research

36. To avoid the influence of specimen size and variations in the

relative humidity of the environment, it is suggested that research be con­

centrated, for the time being, on hermetically sealed (mass cured) speci­

mens, which from the standpoint of massive structures are the most inter­

esting and realistic. It is believed that systematic tests should be con­

ducted over a temperature range of about -35 to 149 C, with the temperature

intervals being small enough to ensure that local maxima, if any, are not

being overlooked fe-.g., intervals_ Qf' 10 or 15 degrees). This tem:R_erature

range would cover structures exposed to environmental temperatures as well

as structures such as prestressed concrete nuclear reactor containment ves­

sels, radiation shields, or flash chambers in desalination plants, which

are exposed to moderately high temperatures. As a starting point, it would

further seem appropriate to restrict tests to a typical, good-quality struc­

tural concrete and to stress/strength ratios of 0.20, 0.40, and 0.60. Em­

phasis should be placed on the measurement of very early creep, on creep

after up to 2 or 3 years under load, and on creep recovery in order to help

resolve some of the existing controversies. Another question that seems in

need of systematic investigation is the effect of the length of exposure to

13

the pertinent test temperature prior to loading.

37. Obviously, there are many other factors that should be investi­

gated. Literally thousands of creep specimens have been tested at room

temperature during the last 60 years or so, and there are still many unan­

swered questions. A few parameters, however, appear particularly important,

especially for prestressed reactor vessels, namely the influence of multi­

axial stress conditions, of stress gradients, and of temperature variations.

The first is currently under study in a major Atomic Energy Commission spon­

sored program; however, research concerning the last two has not yet been

initiated.

Literature Cited

1. Davis, R. E., Davis, H. E., and Hamilton, J. S., "Plastic Flow of Concrete Under Sustained Stress," Proceedings, American Society for Testing Materials, Vol 34, Part 2, 1934, pp 354-386.

2. Theuer, A. E., "Effect of Temperature on the Stress-Deformation of Concrete," Journal of Research, National Bureau of Standards, Vol l·S, No. 2, Feb 1937, pp 195-204.

3. Ruetz, W. , "On the Deformation Behavior of Hardened Cement Pastes," RILEM Colloquium on the Influence of Time Upon Strength and Deforma­tion of Concrete, Munich, Nov 1958.

4. Serafim~ J, L. and Guerreiro, M. Q., "Influence of Temperature on the Creep of Mass Concrete," RILEM Colloquium on the Influence of Time Upon Strength and Deformation of Concrete, Munich, Nov 1958; also RILEM Bulletin No. 6 (Reunion Internationale des Iaboratoires d'essais et de Recherches sur les Materiaux et les Constructions), Mar 1960, pp 23-32.

5. Hansen, T. C., "Creep and Stress Relaxation of Concrete, A Theoretical and Experimental Investigation," Proceedings NR 31, Swedish Cement and Concrete Research Institute, Royal Institute of Technology, Stockholm, 1960.

6. England, G. L. and Ross, A. D., "Reinforced Concrete Under Thermal Gradients," 1•\agazine of Concrete Research, Cement and Concrete Associa­tion, Vol 14, No. 4o, Mar 1962, pp 5-12.

7, Nasser, K. W. and Neville, A. M., "Creep of Concrete at Elevated Tem­peratures," Proceedings, Americ'ln Concrete Ir:stitute, Vol 62, 1965, pp 1567-1579.

8. , "Creep of Old Concrete at Normal and Elevated Tempera-tures," Proceedings, Americe.n C'Jncrete Institute, Vol 61+, 1967, PP 97-103.

14

9. Peschel, G., "The Viscosity of Thin Water Films Between Two Q.uartz Glass Plates," RILEM Colloquium on the Physical and Chemical Causes of Creep and Shrinkage of Concrete, Munich, Apr 1968; also Materials and Structures (RILEM), Vol 1, No. 6, Dec 1968, pp 529-534.

10. Marechal, J.C., "Causes physiques et chimiques du fluage et du retrait du beton," RILEM Colloquium on the Physical and Chemical Causes of Creep and Shrinkage of Concrete, Munich, Apr 1968; also Materials and Structures (RILEM), Vol 2, No. 8, Mar 1969, pp 111-116.

11. , "Evolution des proprietes thermiques et mechaniques des betons et autres materiaux en fonction de la temperature," Annales Travaux Publics, Vol 21, No. 246, June 1968, pp 852-855,

12. Hannant, D. J., "The Strain Behavior of Concrete Under Compressive Stress at Elevated Temperatures, 11 Laboratory Note No. RD/L7N 67/66, June 1966, Central Electricity Research Laboratories, United Kingdom.

13. Philleo, R., "Some Physical Properties of Concrete at High Tempera­tures," Proceedings, American Concrete Institute, Vol 54, 1958, pp 857-864.

14. Thorne, C. P., "Concrete Properties Relevant to Reactor Shield Be­havior," Proceedings, American Concrete Institute, Vol 57, 1961, pp 1491-1508.

15. Hickey, K. B., "Creep, Strength, and Elasticity of Concrete at Ele­vated Temperatures' II Report No. c-1257' Dec 1967' Bureau of Reclar.:a­tion, Washington, D. C.

16. Arthanari, S. and Yu, C. W., "Creep of Concrete Under Uniaxial and Biaxial Stresses at Elevated Temperatures," Magazine of Concrete Re­search, Cement and Concrete Association, Vol 19, No. 60, Sept 1967, pp 149-156.

17. Da Silveira, A. F. and Florentino, C. A., "Influence of Temperature on the Creep of Mass Concrete," American Concrete Institute Symposium on the Effect of Temperatirre on Concrete, Memphis, Nov 1968.

18. McHenry, D., "A New Aspect of Creep in Concrete and Its Application to Design' M Proceedings' American so-ciety- for- Testing-- Materia-ls' Vol 43, 1943, pp 1069-lo8l+.

19. Browne, R. D. and Blundell, R., "The Influence of Loading Age and Temperature on the Long Term Creep Behavior of Concrete in a Sealed, Moisture Stable, State," RILEM Colloquium on Physical and Chemical Causes of Creep and Shrinkage of Concrete, Munich, Apr 1968; also Materials and Structures (RILEM), Vol 2, No. 8, Mar 1969, pp 133-144.

20. Wagner, o., 11Das Kriechen unbewehrten Betons," Deutschev Ausschuss fur Stahlbeton, Heft 131, 1958.

21. Wallo, E. M. and Kesler, C. E., "Prediction of Creep in Structural Con­crete," Bulletin 498, 1968, Engineering Experiment Station, University of Illinois, Urbana, Ill.

15

22.

23.

24.

25.

26.

zr.

28.

Lynam, c. G., Growth and Movements in Portland Cement Concrete, Oxford Press, London, 1934. Powers, T. C., "Mechanism of Shrinkage and Reversible Creep of Hardened Cement Paste," International Conference on the Structure of Concrete, London, 1965.

, "Some Observations on the Interpretation of Creep Data," -----RILEM Bulletin No. 33 (Reunion Internationale des Laboratoires d'essais et de Recherches sur les Materiaux et les Constructions), Dec 1966, pp 381-391. Ali, L. and Kesler, C. E., "Mechanism of Creep in Concrete," S~osium on Creep of Concrete, Houston, Special Publication No. 9, pp 3§:63, 1964, American Concrete Institute.

GlUcklich, J. and Ishai, O., "Creep Mechanism in Cement Mortar," Pro­ceedings, American Concrete Institute, Vol 59, 1962, pp 923-948.

Lorman, W.R., "Theory of Concrete Creep," Proceedings, American Soci­ety for Testing Materials, Vol 4o, 1940, pp 1082-1102. Feldman, R. F. and Sereda, P. J., "A Model for Hydrated Portland Cement Paste as Deduced from Sorption-Length Change and Mechanical Proper-ties," RILEM Colloquium on the Physical and Chemical Causes of Creep and Shrinkage of Concrete, Munich, Apr 1968; also Materials and Structures (RILEM), Vol 1, No. 6, Nov 1968, pp 509-520.

29. Glanville, W. H. and Thomas, F. G., "Further Investigations on·the Creep or Flow of Concrete Under Load," Building Research Technical Paper No. 21, 1939, Department of Scientific and Industrial Research, London.

30. Freudenthal, A. M., The Inelastic Behavior of Engineering Materials and Structures, Wiley, New York, 1950.

31. Freyssinet, E., "The Deformation of Concrete," Magazine of Concrete Re­search, Vol 3, No. 8, Dec 1951, pp 49-56.

32. Neville, A. M., "Theories of Cr~ep in_ Cor;crete," Proceedings, American Concrete Institute, Vol 52, 1950, pp 47-bO.

33. Bingham, E. c. and Reiner, M., "Rheological Properties of Cement and Cement-Mortar-Stone," Physics, Vol 4, Mar 1933, pp 88-96.

34. Maney, G. A. , "Concrete Under Sustained Working Loads ; Evidence That Shrinkage Dominates Time Yield," Proceedings, American Society for Testing Materials, Vol 41, 1941, pp 1021-1030.

16

':':.;.C:ic: l

I::fluer:ce uf ':\~r.:r~eratur~ .'n Cree12 and CreeE Fate

Setlt:d or "l'iater-f~ored Specimens

Arbi-trar;r

Lva.d.ine Period for De-

Specific termi-

Specific nation Creep

..t.:::c...rcsa.te Cement Loa." Test Creepi.-* 0f" Creep Rate**

f' Tel'!T1er~ture - 9in./in. lo--:\n. 1in. c Cize A,;e Type 7ypc Specimen Content and __:_!!;___

l'uratior: JO Rate Investi~ator ~ ~ ~ at Loa.din;: "'.'f Gase of S..;al ~ r:/c.,, CuriI'-~ ~ d~s __L _2_ n::i ~ T"si x lo< t Remarks

Nasser and 19G5 -<iOOO 3/~-ir.. 14 da.ys Med:e.nical Polyprov....-- 3- by 25~ volume Test temper:iture 1950 0.3) 21.1 70 255 21-91 Sc r~eville7 do lo- exter- lene 9-1;\+- paste; from 21.- !-.r 33.G 92.5 280 80

r.d.te mil jackets in. wlc o o.6 age. Sen.led 46.1 ll5 310 121 horn- and water cyl- after 1 d.ey, 58.b 137 .5 355 189 l:lende bat!:i inders then ;.·::i.ter- 71.l 160 390 2!..f2

store<.', 83.6 132.5 450 225 9'~•.l 205 550 :_G9

3400 0.60 90 21.l 70 300 21-s-1 102 33.C 92.5 1.10 l~I 46.1 115 275 132 5S.6 137 .5 L20 236 71.1 160 550 35L 23.C- 162.5 11.0 291 :c.1 205 520 '),

3900 0.70 21.1 70 310 21.-91 89 33.6 92.5 1.50 103 46.1 ll5 270 lll 58.G 137-5 ?50 242 71.1 l.GO 700 3~0 83.6 182.5 '125 2)0 s.c.1 205 510 1'17

1950 0.35 21.1 70 318 71.l lcO 543 9(.1 205 c51

3400 0.60 360 21.1 70 359 71.l 160 818 ~_;.]. 205 ~15

3900 0.10 21.l 70 379 71.1 lC.O y20 g;.1 205 )00

u. J. 12 lS(f -3ooo 3/4-in. G months Vibrating Copper 4-1/2- w/c = o.47 5 months in 700 to About 100 days; 'Z1 tv 95 c See Plate l !:arJ1ar:.t lime- wire and by water, then 2000 o.o8 to da.ta for (Bo.(, to

stone Demcc 12-in. l month 0.25 0 to 733 203 F) cyl- zealed at days were indet·s 20 c; heated reported

for 24 h:- be-for·~ loading

Englanc} and 1902 -5000 Unknown 10 do;'s Mechanical Polyester 4-1/2 w/c = o.45 Stripped at 1 1000 -0.20 80 20 08 170 1-~o 59 2cal sorr".:"\\·~:at

Ros st' to (Whi tte- fiber- by day, 3 days 53 127.4 390 102 que;:; tional::le 5500 more, glass 12-in. underwater, 6 7b 168.6 clO iG7 on Demec} cyl.- day.;; at 17 c 5)1, 201.2 700 18C 4-in. inders and 9(1'; RH ll4 237.2 730 180 cubes 125 257 t-90 173 at 14 days

(Contimed)

* ;de denotes water/cement T3.tio by wei:;ht. Approximate values; most were read from small-scale charts given in pertinent reference.

Table 1 (Concluded)

Arbi-trary

Loading Period for De- Specific term!-

Specific nation Creep

Aggregate Cement Load Test Creep ot Creep Rate f' Temperature 10-91n./in. 10-91n./1n. c Size Age fype fype Specimen Content and _!!!£__ Duration Rate

Investigator ~ J!.!_ ~ at Loading ~ ot Seal ~ wf.c Curi!!E!j .!......E!!. dats l _'.'.r_ l!Si ~ :Esi x ios t Remarks

Arthanari 1967 -5000 3/8-in. 15 days Mechanical. Epoxy resi[~l 12- by w/c = 0.564 Moist-cured 7 1000 -0.20 60 20 68 260 1-60 124 Slab tests, and Yu.16 to Thames and pain{. 12- by days, then 40 lo4 360 152 seal

6000 River 4-in. sealed 60 140 510 197 questionable on gravel slabs 80 176 560 2o8 10-in. cubes at 28 days

Nasser and 1967 7250 3/4-in. 1 year Mechanical Stored 3- by 25~ by vol- Water storage at 3260 o.45 90 21.l 70 90 21-91 21 Neville8 do lo- (water underwat~r 9-1/4- \lll1e 70Fuptol 46.1 115 300 84

mite storage in. paste week before 71.1 160 430 113 horn- at 70 F) cyl· (type III loading; sub• 96.1 205 500 50 blende inders cement); sequently 1810 0.25 21.l 70 22 w/c = o.6 stored at 46.1 115 65 test tempera- 71.l 160 139 ture

96.1 205 43

Stored at test 3260 o.45 90 21.1 70 21-91 19 temperature 46.1 115 130 t'rom 24 hr age 71.1 160 219

,96.1 205 183 1810 0.25 21.1 70 17

46.1 115 130 71.l 160 143 96.1 205 lo4

Nasser and 1967 5370 Similar 50 years Mechanical. Stored 3- by About l~ 50 years out- 2400 o.45 90 21.1 70 120 21-91 10 Neville8 to (out- underwat.er 9-1/4- by vol- doors; 14 46.1 115 215 78

&bow doors) in. \lll10 days at test 71.1 160 370 188 cyl- paste temperature 96.1 205 280 162 inders before load-

ing

Table 2

Innuence of Te!SEerature on Cre~ and Cre~ Rate

Unsealed Specimens

Arbi-trary

Loa.ding Period 1'or De-termi- Specific

Specific nation Creep

Cement Load Test Creep** of Creep Rate**

f' Temperature l0-9in.Lin. l0-9in.Lin. c Aggregate f\<5e Type Type Specimen Content and

3--Duration Rate

Investigator ~ ~ Size and Type at Loa.ding of Gase __E!.,~ ~ w/c• Curing -1..i....llL days ~ _l_ si ~ :psi x log t ~

K. ~~keyl5 1967 -7500 Gooi-quall ty 60 days Mechanical No mqisture 6- by 560 lb/cu 30 deys in fog 8oo .....().10 107 143.3 290 806 (881)! 1-107 157 1174 l Heated amphibole- Whitte- sea,l; 16-in. yd room; 30 days (18o) 110 230 812 (825) (1-180) 209 194 after schist river fiq,er- cyl- Wce =V; at 73 F and 82.2 180 681 (694) 219 (202) loading aggregate gl9rSS for inders 5<J1 RH 54.4 130 419 (450) 148 (147)

terr/Pera- o.468 23 73 150 (175) 65 (69) tm:e

E~~~~ and 1962 -5000 Unknown 10 days Whittemore None 4-1/2- w/c o 0.1,5 3 days water 1000 --0.20 60 20 68 195 1-60 91

to by 12- storage; 45 113 510 181 5500 in. 6 days at 64 147.2 510 164 on cyl- 17 C and 80 176 550 175 4- inders %RH 100 212 810 182 in. 116 240.8 655 144 cubes 140 284 745 133 at 14 days

J. c. 10 1968 Unlmown Quartzite About Mechanical None Unknown 6-1/2 About 1 year at 1400 ..... 100 (ex- 20 68 170 (155) 4-60 73 (70) Marechal l year sacks/cu 20 c and l~ (700) trapo- 50 122 400 (420) 195 (198)

yd RH; then 14 lated 70 158 300 (240) 138 (--) days at test frcm 60- 105 221 125 (130) 52 (70) temperature day test) 150 302 150 (130) 66 (68)

250 482 350 (460) 166 (205) 400 752 (950) (450)

J. c. 10 1968 Unknown Quartzite About Mechanical None Unlmown 6-1/2 About l year at 1400 -100 (ex- 20 68 4-60 14 Ma.rechal 1 year sacks/cu 20 c and lo% trapo- 50 122 38 19

yd RH; then dried lated 70 158 44 26 l month at from 6o-105 C ; then 14 day test) days at test temperature

* w/c denotes water/cement ratio by weight. Approximate values; most were read from small-scale charts given in pertinent reference.

t Values in parentheses are ad.di tional results taken under somewhat different test conditions or for different loading periods.

800

i .... z

"' "' Cl. 1100 I

0

a "' "' a: 0

~ 400 ... 0 "' Cl.

"' 200

0 0 20 40

32 es 104

60 80 100 120 140 TEMPER~fTURE, DEG c

140 176 212 248 284 TEMPER~TURE, DEG F

0

0

v

•

~ NASSER ANO NEVILLE;

8 5370-PSI, 50-YEAR•OLO

CONCRETE LOADED TO 1/1~ OF 0.45; CREEP MEASURED ON 3- x 9-1/4-IN. CYLINDERS AFTER 90 DAYS OF LOADING STORED IN WATER

NASSER AND NEVILLE ; 7 -6000-PSI DOLOMITE HORNBLENDE CONCRETE LOADED AT 14 DAYS TO 1/1~ OF 0.35; CREEP DETERMINED ON 3- x 9-1/4-IN. SEALED CYLINDERS AFTER 90 DAYS OF LOADING

SAME AS ABOVE:_ BUT 1/1~ : 0.60

SAME AS ABOVE ,7 BUT 1/1~: 0.70

ENGLAND ANO ROSS;6 -5000-PSI CONCRETE LOADED AT 10 DAYS TO f/f~ OF -0.20; CREEP DETERMINED ON 4-1/2- x 12-IN. SEALED CYLIN­DERS AFTER 80 DAYS OF LOADING

HANNANT:12

8000-PSI LIMESTONE CONCRETE LOADED AT 6 MONTHS TO I/I~ OF -0.0B TO 0.25; CREEP DETERMINED ON 4-1/2- x 12-IN. SEALED CYLINDERS AFTER 100 DAYS OF LOADING

• ARTHANARI AND YU;16

-sooo-PSI GRAVEL CON­CRETE LOAOED AT 1S DAYS TO 1/1~ OF -0.20; CREEP DETERMINED ON 12- x 12- x 4-IN. SLABS AFTER 60 DAYS OF LOADING

NASSER AND NEVILLE ;8

7250-PSI DOLOMITE HORNBLENDE CONCRETE LOADED AFTER 1 YEAR WATER STORAGE TO 1/1~ OF 0.45; CREEP DE­TERMINED ON 3- x 9-1/4-IN. CYLINDERS AFTER 90 DAYS OF LOADING UNDERWATER

INFLUENCE OF TEMPERATURE ON CREEP

SEALED OR WATER-STORED SPECIMENS AFTER 60, 80, 90, OR

100 DAYS OF LOADING

"'U r ~ fTl I\)

00 20

32 68

---v----40 II()

104 140

-----v--- -----

80 100 120 TEMPERATURE, DEG C

176 212 2.48 TEMPERATURE, DEG F

140 160

284 320

LEGEND

• ENGLAND AND ROSS:6

- 5000-PSI CONCRETE LOADED AT 10 DAYS TO f/f~ OF - 0.20; CREEP WAS DETERMINED ON 4-1/2- x 12-IN. CYLINDERS AFTER 60 DAYS OF LOADING

.t. HICKEY; 15 - 7500-PSI CONCRETE LOADED AT 60 DAYS TO f/f~ OF - 0.10; CREEP WAS DETER­MINED ON & x 16-IN. CYLINDERS AFTER 107 DAYS OF LOADING

0 MA RECH AL; tO CONCRETE cf~ UNKNOWN) LOADED TO 1400 PSI AT - 1-YEAR AGE; SUBJECTED TO TEST TEMPERATURE FOR 14 DAYS PRIOR TO LOADING; CREEP VALUES PLOTTED ARE THOSE FOR - 100 DAYS OF LOADING {EXTRAPOLATED FROM 60-DAY TEST RESULTS)

V MARECHAL; to SAME AS ABOVE, BUT SPECIMENS WERE OVEN-DRIED FOR 1 MONTH BEFORE LOADING

180 200

356 392

INFLUENCE OF TEMPERATURE ON CREEP UNSEALED SPECIMENS AFTER

60, 100, OR 107 DAYS OF LOADING

zoo z +' ..... " i 0

..J

x ... I

"' 0 n. 150

"' .... < II:

n.

"' "' 100 II: <.)

<.)

0 "' n.

"' 50

40 80 IZO 160 zoo TEUPERATURE, DEG C

32 104 176 Z48 320 39Z TEMPERATURE, DEG F

Z40 Z80

484 538

3ZO

808

LEGEND

0 MARECHAL; 10LQA[JE0 TO 1400 PSI AFTER

1 YEAR OF MOIST-CURING; 14 DAYS OF PREHEAT­

ING; LOADING PERIOD, 4-60 DAYS; UNSEALED

6. SAME AS ABOVE, 1° BUT SPECIMEN WAS OVEN­

ORIEO BEFORE LOADING

0 NASSER ANO NEVILLE;8

7250-PSI DOLOMITE

HORNBLENDE CONCRETE LOADED AFTER 1 YEAR

WATER STORAGE AT 70 F TO f/f~ OF 0.45; 3· x 9-1/4-IN. CYLINDERS; UNDERWATER; LOADING

PERIOD, 21-91 DAYS

'<l

0

D

• ,.

SAME AS ABOVE, 8 BUT f 'f~ .:::: 0.25

SAME AS ABOVE, 8 BUT STORED UNDERWATER AT

TEST TEMPERATURE ANO f/f~ ~ 0.45

::::E:s AAN:0

~=~8

1~~; ;! ·:~7:_0

~:~. 50-YEAR-OLO CONCRETE LOADED TO f/f~ OF 0.45; 3- x 9-1/4-IN. CYLINDERS; STORED UNDERWATER; LOADING

PERIOD, 21-91 DAYS

NASSER ANO NEVILLE ;7

-6000-PSI DOLOMITE

HORNBLENDE CONCRETE LOADED AT 14 DAYS

TO f/f~ OF -0.35; 3- x 9-1 1 4-IN. CYLINDERS; SEALED; UNDERWATER; LOADING PERl00,21-

91 DAYS

• ARTHANARI ANO YU; 16 -SOOO-PSI GRAVEL CON­CRETE LOADED AT 15 DAYS TO f!f~ OF -0.20; 12- x 12- x 4-IN. SLABS; SEALED; LOADING PERIOD, h

60 DAYS

• ENGLAND ANO ROSS ; 6-5000-PSI CONCRETE

LOADED AT 10 DAYS TO frf~ OF-0.20; 4-1/2- x 12-IN. CYLINDERS; UNSEALED; LOADING PERIOD, 1-

60 DAYS

• •

SAME AS ABOVE, 6 BUT SEALED

HICKEY; 15-7500-PSI AMPHIBOLE SCHIST CON­

CRETE LOADED AT 60 DAYS TO f!f~ OF -0.10; 6- x 16-IN. CYLINDERS; UNSEALED; LOADING PERIOD,

1-107 DAYS

INFLUENCE OF TEMPERATURE ON CREEP RA TE

f'/f'c I~ 0.50

c = l<log t·- log 0.001)

ASSUMED ACTUAL CREEP

0.001 0.01 0.1 10 1,000 10,000 100,000

------ LOG t, DAYS

SCHEMATIC CREEP CURVE

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ATTN: ATTN: ATTN:

2

Library Mr. D. J. Deeds Mr. L. R. Clayton, Jr. Mr. G. Robinette Mr. V. L. Odale Mr. H. K. Crisp Mr. J. M. Foster Mr. W. F. McCraw, Jr. Mr. W. A. King, Jr. Mr. J. R. Turner Ill

Chief, Construction Division Mr. C. V. Edwards Mr. A. Harrison

Office

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No. of Copies

1 1 1 1 1 1

1 1

1 1 1 1

1 1 1 l 1 1 1 1 1

1 1 1 1 r

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2

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Remarks

ATTN: Chief, Design Branch, Engrg Div ATTN: Chief, Construction Division ATTN: Chief, Foundations & Matls Branch Res Engr, J, P. Priest Res Office (Mr. J. P. Dealy) Res Engr, Cordell Hull Proj (Mr. L. Marcum) Res Engr, Laurel River Reservoir Proj

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ATTN: Engineering Div Tech Library ATTN: Chief, Design Branch ATTN: Chief, Construction Division ATTN: Chief, District Laboratory Abstract: Mr. J, C. Staples, Mr. J, B. Lloyd, Mr. E.

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ATTN: District Librarian

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Engineering Division Librarian

3

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ATTN: Librarian

ATTN: Librarian ATTN: Mr. E. 0. McGehee (l abstract) ~bstract: Mr. J. L. Ransom, Mr. E. W. Schuldt,

Mr. C. Ramsbacher

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DDC

Chief, R&D, Hqs, DA

Consultants: Mr. Byram W. Steele Mr. R. L. Blaine Professor Raymond E. Davis Dr. Roy W. Carlson Dr. Bruce E. Foster

Automatic: Engineering Societies Library

l, l l l l

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20

DE ATTN: Mr. J. W. Story ~TTN: Mr. C. D. Boyd ATTN: Mr. F. D. Welshans ATTN: Mr. R. S. Durham ATTN: Mr. C. E. Mayo ATTN: Mr. H. A. Rabjohn ATTN: Mr. L. D. Carter ATTN: Mr. W. 0. Gray ATTN: Mr. J. K. Cowger ATTN: Mr. H. L. Dobbins

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Director

ATTN: Library

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ATTN: Dir of Army Tech Info 3 copies of Form 1473

Library, Div of Public Doc (NO CLASSIFIED REPORTS TO THIS AGENCY), U. S. Govt Printing Office, Washington, D. C.

Library of Congress, --Ooc -Exp-0 ·Proj, -Washington, -D. -C. Bureau of Reclamation, ATTN: Code 294, Denver, Colo. COL C. T. Newton Mr. Ralph Lane, TV A, Materials Engrg Lab, Knoxville, Tenn.

Exchange Basis, Foreign: Dept of Civil Engineering, McGill University, Canada (ENG-271) Swedish Cement & Cone Res Inst, Stockholm, Sweden (ENG-121) National Research Council, Ottawa, Canada (ENG-17) Inst of Civil Engineers, London, England (ENG-47) Institution of Engineers, Sydney, Australia (ENG-162) Cement and Concrete Assoc, London, England (thru ENGME-AS) P. Dutron, Centre National de Recherches Scientifiques and Techniques pour l'Industrie Cimentiere,

Bruxelles 5, Belgium (ENG-304) Director, Public Works Research Inst, Ministry of Constr, Bunkyo-ku, Tokyo, Japan (ENG-324) Instituto Mexicana de! Cemento y de! Concreto, A.C., Mexico 20, D.F. (ENG-329) Centre d'Etudes et de Recherches de l'Industrie du Beton Manufacture, Epernon, France (ENG-336) Chief Librarian, CSIRO, Victoria, Australia (ENG-291) Cembureau, Sweden (ENG-268) Statens Byggeforskningsinstitut, Kobenhavn, Denmark (ENG-36) Library, Royal Institute of Technology, Stockholm, Sweden (ENG-122) Institute Eduardo Tarroja de la Construccion y del Cemento, Madrid, Spain (ENG-263)

4

and

l l l l l

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Exchange Basis, Foreign (Continued): Librarian, Bldg Research Sta, Ministry of Public Building and Works, Herta, England (ENG-335) Commission on Irrigation and Drainage, New Delhi-21, India (ENG-337) Cement Research Institute of India, New Delhi 16, India (ENG-340)

Exchange Basis, Domestic: APPLIED MECHANICS REVIEWS, San Antonio, Tex. Dept of Civil Engineering, The University of Arizona, Tucson, Ariz. Civil Engr Dept, Auburn Univ, Auburn, Ala. Library, Bureau of Reclamation, Denver, Colo. Engineering Library, Univ of Calif., Berkeley, Calif. Central Records Lib, Dept of Water Resources, Sacramento, Calif. Prof. H. R. Nara, Engrg Div, Case Inst of Tech, Cleveland, Ohio Central Serial Record Dept, Cornell Univ Lib, Ithaca, N. Y. Engrg & Industrial Experi Sta, Univ of Florida, Gainesville, Fla. Price Gilbert Memorial Lib, Georgia Inst of Tech, Atlanta, Ga. Gordon McKay Library, Harvard Univ, Cambridge, Mass. Gifts & Exchange Div, Univ of Ill. Library, Urbana, Ill. Library, Iowa State Univ of Science & Tech, Ames, Iowa Engrg Experi Sta, Kansas State Univ of Agric & Applied Science, Manhattan, Kans. University Library, Univ of Kansas, Lawrence, Kans. Librarian, Fritz Engineering Lab, Lehigh Univ, Bethlehem, Pa. Hydrodynamics Lab, 48-209, MIT, Cambridge, Mass. Mr. Robert T. Freese, Engineering Librarian, Univ of Michigan, Ann Arbor, Mich. Engrg & Industrial Research Station, State College, Miss. College of Engrg, Univ of Missouri, Columbia, Mo. Librarian, Univ of Mo., School of Mines & Metallurgy, Rolla, Mo. National Sand & Gravel Assoc, Silver Spring, Md. Dept of Engrg Research, N. C. State College, Raleigh, N. C. New York University, ATTN: Engrg Lib, University Heights, Bronx, N. Y. Dept of Civil Engrg, Technological Inst, Northwestern Univ, Evanston, Ill. Gifts & Exchange, Main Library, Ohio State Univ, Columbus, Ohio College of Engrg, Univ of Arkansas, Fayetteville, Ark. Engrg Experi Station, Oregon State Univ, Corvallis, Oreg. Engrg Lib, Pennsylvania State Univ, University Park, Pa. Periodicals Checking Files, Purdue Univ Lib, Lafayette, Ind. Engrg Library, Stanford Univ, Stanford, Calif. Chief Engineer, Tennessee Valiey Authority, Knoxville, Tenn. Research Editor, Texas Transportation Inst, Texas A&M Univ, College Station, Tex. Trend in Engineering, Univ of Washington, Seattle, Wash. Allbrook Hydraulic Lab, Washington State Univ, Pullman, Wash. Engineering Library, Univ of Wisconsin, Madison, Wis. Research Librarian, Portland Cement Assoc, Skokie, Ill. Serials Acquisitions, Univ of Iowa Libraries, Iowa City, Iowa Prof. S. P. Shah, Dept of Mtls Engrg, Univ of Illinois, Chicago, DI. Mr. H. H. Newlon, Asst State Highway Res Eng, Virginia Highway Research Council,

Charlottesville, Va. Prof. Sandor Popovics, Northern Arizona University, Box 5753, Flagstaff, Arizona 86001 Prof. Dean C. McKee, Department of Civil Engineering, Loul.:siana State University,

Baton Rouge, Louisiana 70803

Abstract of report: Commandant, USAREUR Engineer-Ordnance School, APO New York 09172 U. S. Naval Civil Engineering Laboratory, ATTN: Mr. Lorman Mr. William A. Maples, American Concrete Institute Bureau of Public Roads, ATTN: Harold Allen Highway Research Board, National Research Council National Crushed Stone Assoc, Washington, D. C. CG, Fourth U. S. Army, Fort Sam Houston, Tex., ATTN: AKAEN-01 Princeton University River & Harbor Library, Princeton, N. J. Duke University Library, Durham, N. C. Princeton University Library, Princeton, N. J. Serials Record, Pennsylvania State University, University Park, Pa. Louisiana State University Library, Baton Rouge, La. The Johns Hopkins University Library, Baltimore, Md. Laboratorio Nacional de Engenharia Civil, Lisboa, Portugal University of Tokyo, Bunkyo-ku, Tokyo, Japan University of California Library, Berkeley, Calif. Mr. C. H. Willetts, Alabama Power Co., Box 2641, Birmingham, Ala. Commanding Officer & Director, U. S. Naval Civil Engineering Laboratory,

Port Hueneme, C tlif. 93041, ATTN: Code L31

5

1 1 1

2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

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Abstract of report (Continued): Mr. David A. King, Manager, Quality Control Dept., Maule Industries, Inc., 2801 N. W. 38th Ave.,

Miami, Fla. Amman and Whitney, Consulting Engineers, 76 Ninth Ave., New York, N. Y. Engineering Library, University of Virginia, Charlottesville, Va. Northeastern Forest Experiment Station, Forestry Sciences Lab, Morgantown, W. Va.

Announcement of Availability by Public Affairs Office: CIVIL ENGINEERING; THE MILITARY ENGINEER; ENGINEERING NEWS-RECORD; PIT AND QUARRY Magazine; and ROCK PRODUCTS Magazine

6

Unclassified Security Classification

DOCUMENT CONTROL DAT A • R & D ($•cutlt1' t:l••dflc•tlon ol tlrl•. body ol •b•tract and Ind••'"' •nnotatlon mu•t b• •nt•r•d wh•n th• over•U report h cl•••lll•dl

'· 0"1GINATING ACTIVITY (Corporan •utllor) la. AEPO"T Sl:CULIUTV CL.Alll~ICATION

u. S. A~y Enc;in~e!' \1'.l.ter.·re.ys Experiment Station Unchssified Vicksburg, Mississippi all, Cl"OUI"

I ... EPO"T TITL.IE

THE EFFECT OF TEMPERATURE ON CREEP OF CONCRETE; A LITERATURE REVIEW

•· Ol:SC,.IPTIVI: NOTEI (Type ol t•JHWI _,d lncluel•e dateaJ

Final report a. AU THOfltl•t (Flrat na111•. 11tlddl• Initial, laat name)

Helmut G. Geymayer

I• "l:l"O"T OATI: 7a. TOTAL NO. OP' PACll:I 17"' 34· OP' "l:l'S January 1970 28

... CONTRACT 0" G .. ANT NO. ... O"ICllNATO"'S "l:l"O"T NUMlll:"ISI

.. ""OJSCT NO. Miscellaneous Paper C-70-1

.. It. ~T.H!.::..~1'"0"T NOCll (AnJI' ol/tnn_,..,. ,,,.,_,, ,.. ... , .. ..,

~

10. OllT .. IOUTION ITATSMSNT

This document has been approved for public release and sale; its distribution is unlimited.

II• SUl"l"Ll:MSNTA"Y NOTl:I la. l .. ONIO .. INCI MILi TA"Y AC Tl YI TY

Office, Chief of Engineers, u. s. Army Washington, D. C.

II. AOIT"ACT

A review of the literature on the effect of elevated temperatures on the time-dependent volume change due to loacl. (creep) of concrete reveals incomplete and con-flicting evidence. Some workers have found a "creep maxim.um" at a particular tem-perature range; others have not encountexed- this phenomenon. Among -tho s-e-wl-.LO- l:1ave-found it, there is lack of agreement as to what the range is. All available data have been collected, reduced to co.niparable form, and analyzed. The analysis has been reviewed in the light of the several theories of the mechanism of concrete creep. It is concluded that the new res~lts on temperature effects on creep do not resolve the conflicts among the various creep theories, but they tend to support the seepage theory more than any other. Many factors affecting creep are found to be influential at elevated temperatures in analogous fashion to their influence at room temperature. These factors include time under load, applied stress, maturity of concrete, and moisture content of concrete. The effect of temperature, at least up to 50 c, is to increase creep by a factor of two or three at 50 C. Creep may or may not increase from 50 to 100 c, or it may increase sometimes and not increase other times. The limited data on tests at temperatures above 100 C are not in agreement. A program testing in the range -35 to 149 C using stress/strength ratios of 0.20, o.4o, and o.€io, including periods of sustained load of up to 2 to 3 years, is proposed.

DD ,'!~ .. 1473 111a~LACCe DD "01'11M t•fl. I JAN ••• W .. ICH 18 O•IOL•TK "0• A"MY u••• Und:::.cci:!'lcd

security Cl1Hlflc1Uon

of.

Unclassified seeurtt'I clHSlricetlon ...

K&Y WOR08 I.INK A I.INK a LINK C

ROI.II WT "01.& WT "01.& WT

Creep properties

Concrete creep

Concretes

Temperature effects

Unclassified lacwlty Cl•Hlflcatlon