mp c-70-1 'the effect of temperature on the creep of concrete …short-term creep tests on two...
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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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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
4
Remarks
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3
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Automatic: Engineering Societies Library
l, l l l l
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Library, Div of Public Doc (NO CLASSIFIED REPORTS TO THIS AGENCY), U. S. Govt Printing Office, Washington, D. C.
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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)
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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