flexural fatigue behaviour of concrete containing varoius sources
TRANSCRIPT
Center for By-Products Utilization
FLEXURAL FATIGUE BEHAVIOR OF CONCRETE
CONTAINING VARIOUS SOURCES OF FLY ASH
By Tarun R. Naik, V.M. Malhotra, Shiw S. Singh, and
Bruce W. Ramme
Report No. CBU-1997-25
November 1997
To be submitted for publication in the ACI Materials Journal
Department of Civil Engineering and Mechanics College of Engineering and Applied Science THE UNIVERSITY OF WISCONSIN - MILWAUKEE
1
FLEXURAL FATIGUE STRENGTH OF HVFA CONCRETE SYSTEMS
By
Tarun R. Naik, V.M. Malhotra, Shiw S. Singh, and Bruce W. Ramme
ABSTRACT
There is a lack of information on fatigue behavior of fly ash concrete, especially concrete
incorporating large amounts of fly ash. The major focus of this investigation was to
establish fatigue properties of high-volume fly ash concrete systems. In this work, a total
of eight concrete mixtures were proportioned using four sources of fly ash and two Type
I portland cements (low-alkali and high-alkali). The levels of fly ash content (58% of total
cementitious materials) and water to cementitious materials ratio (0.33) were maintained
constant for all test mixtures. Each mixture was tested under both static as well as cyclic
flexural loadings. These loads were applied using third-point loading in accordance with
ASTM C 78. The resulting data were analyzed to establish stress versus number of
cycles to failure curve (S-N curve). Experiments were also carried out to determine the
modified cube compressive strength (ASTM C 116) of each mixture using portions of the
beam, which were previously tested for static flexural strength. Fatigue or endurance
limit was defined as fatigue stress at 2 million of loading cycles. This limit was found to
vary significant from mixture to mixture. The ratio of fatigue limit to static flexural strength
varied in the range of 0.45-0.60. Based on pooled data, a fatigue limit for HVFA concrete
system was found to be 0.51, which is in the range of values observed for non-fly ash
concrete systems.
Keywords: Fly ash; concrete; endurance ratio; fatigue limit; fatigue strength
2
INTRODUCTION
Rational design of concrete structures requires an accurate knowledge of concrete
properties under anticipated loading conditions. A large body of information is available
on behavior of concrete under static loading conditions. However, relatively limited
information is available on behavior of concrete subjected to dynamic loadings.
Structures that are subjected to repeated loads are susceptible to failure due to fatigue.
Fatigue is a process of progressive permanent internal changes in the materials that
occur under the actions of cyclic loadings. These changes can cause progressive growth
of cracks present in the concrete system and eventual failure of structures when high
levels of cyclic loads applied for short times or low levels of loads are applied for long
times.
Many concrete structures such as highway pavements, highway bridges, railroad bridges,
airport pavements and bridges, marine structure, etc. are subjected to dynamic loads.
Fatigue strength data of concrete and other materials that are used in these structures
are needed for obtaining their safe, effective, and economical design. A low cycle fatigue
is important for structures subjected to earthquake loads.
Numerous investigations [1-64] have been directed toward evaluation of fatigue behavior
of materials, including concrete. Although fatigue research began almost one hundred
years ago, there is still a lack of understanding concerning the nature of fracture
mechanism in cementitious composite materials due to fatigue. This is partly due to the
3
complex nature of structure of such materials and their properties are influenced greatly
by a large number of parameters. Fatigue behavior of concrete is also influenced by
several parameters such as type of loading, range of loading, rest period, material
properties, environmental conditions, etc. Moreover, concrete properties are known to
depend upon the variables such as water-to-cement ratio, cement content, air content,
curing technique, age, admixture content, etc. Consequently, it is quite complex to
develop theoretical models to evaluate fatigue behavior of concrete and to determine
flexural fatigue behavior of fly ash concrete systems.
The specific objectives of this investigation was to present state-of-the-art information on
fatigue behavior of concrete made with and without mineral admixtures and therefore,
this investigation was directed toward determining fatigue behavior of fly ash concrete
systems. Additionally, to establish fatigue behavior of HVFA concrete systems through
laboratory investigation.
BEHAVIOR OF MATERIALS UNDER CYCLIC LOADINGS
The mechanical response of a material is substantially altered by cyclic loadings. In the
case of metals, it depends greatly upon hardness of materials and experimental
conditions. Under cyclic loading conditions, a metal may either harden, soften, remain
stable, or have mix behavior (soften or harden depending upon strain level) [8]. During
constant strain cycling of a material, an increase in stress with time is called strain
hardening and a decrease in stress is called a strain softening. These are related to the
4
nature and stability of the dislocation substructure of a given metallic material [8].
In general, the dislocation density is low for soft materials. For such a material, the
increase in density of material resulting from cyclic plastic straining causes strain
hardening. Whereas for a hard metal, the cyclic strain causes a rearrangement of
dislocations. The resulting structure for the metal becomes soft as it offers low resistance
to deformation [8].
A kinematically irreversible microscopic deformation is the precursor to fatigue in both
ductile and brittle solids [1]. It is now well established that the cyclic slip is not only cause
of fatigue damage but it can occur due to microcracking, interfacial sliding or creep, etc.
The irreversible deformation in brittle solids can occur due to various processes. These
include [1]: (1) frictional sliding of the microcracks that are nucleated at grain boundaries,
and along the interfaces between the matrix and the filler, (2) the release of residual
stresses may cause microcracking at the grain boundaries and the interfaces resulting in
plastic deformation strain, etc.
Concrete is a complex hybrid composite material. During cyclic loading fracture to
concrete can occur by fracture of the cement paste, fracture of aggregate, failure of bond
between the cement paste aggregate or any combination of these mechanisms.
Compared to metals, concrete is prone to have a large number of flaws resulting from
hydration, shrinkage and other causes. Mechanism of fatigue in concrete is not well
5
established and numerous hypothesis related to crack initiation and propagation have
been proposed by Neal and Kesler [16], Kesler [3], Raithby and Whiffin [25], and several
others [75,76].
Mudock and Kesler [6] proposed that initiation of fatigue failure in concrete is due to
progressive deterioration of the bond between the coarse aggregate and the matrix. This
results in reduction in section of the specimen leading to its failure due to fracture of
matrix. However, most researchers support that during cyclic loading, fatigue of concrete
occurs because of the propagation of the micro cracks and macro cracks present in the
material, especially in the interface region as well as in the matrix. Since the interface
region is the weakest region, there is a very high probability that initiation of fatigue cracks
occurs in this region. However, initiation of fatigue cracks that can occur either in matrix
or at the interfacial region would greatly depend on the size of dominant flaws present in
these regions.
Addition of fiber to concrete restrict crack formation and delays crack growth. Therefore,
unstable cracks produced during loading is transformed into a slow and controlled growth.
Also, crack path length is increased in presence of fibers. The overall tensile rupture
strain of concrete is increased due to the introduction of fiber. This depends greatly upon
the elasto-plastic properties of the fiber and the effectiveness of the bond between the
fibers and the concrete matrix. Due to improved ductibilty of the fiber reinforced concrete,
their dynamic properties including fracture toughness and fatigue life are greatly
improved. To some extent, the presence of fine and coarse aggregates in cement paste
improves its toughness due to increased crack propagation path length.
6
PREVIOUS INVESTIGATIONS
A detailed review of fatigue behavior of concrete has been reported to EPRI in a previous
report published by the UWM Center for By-Products Utilization [20]. However, a brief
review is presented here for the sake of completeness of information on the subject.
Fatigue testing of cement-based materials began more than 10 decades ago. Early
studies have been reviewed by a number of investigators including Nordby [16], Murdock
[17], Lloyd et al. [18], Raithby and Whiffin [19], and Naik et al. [20]. Although, the earliest
work on fatigue of mortar specimen in compression was conducted by Considere in 1898,
and concrete specimen by Van Ornum in 1903 as reported by Nordby [16],
comprehensive studies on fatigue behavior of concrete began after 1930.
Several parameters such as stress range, load history, rate of loading, rest periods,
stress gradients, material properties, etc can affect fatigue characteristics of concrete
substantially. More recently, the effects of these parameters on fatigue strength was
extensively reviewed by Naik et al. [20]. However, this paper includes a brief description
of the results reported by previous investigators.
Several studies have shown that the range of stress can influence the fatigue strength of
concrete considerably [21,22,23,24]. A decrease in the stress range seems to increase
7
fatigue strength during fatigue testing. Rate of loading is an important variable that
affects fatigue strength of concrete significantly. Several studies [23,25,26,27,28,29,30]
have presented the effect of rate of loading on fatigue behavior of plain concrete. The
frequency of loading in the range of 1-30 CPS does not have an appreciable affect on
concrete fatigue behavior if the maximum stress level remains less than about 75% of the
static strength [23,31]. Applications of stress levels above 75% can cause decrease in
fatigue strength when the frequency of loading is decreased [23,27,29]. This may be
attributed to a significant increase in creep effects, resulting in a reduction in fatigue
strength with decreasing rate of loading.
Under most practical conditions, concrete structures experience cyclic loadings that vary
greatly in magnitude, number, and order [31]. The resulting fatigue damage due to such
loadings is often determined by the Miner hypothesis. This hypothesis assumes that
damage accumulates linearly with the number of cycles applied at a particular load level.
Experimental investigations [22,31] have indicated conservative as well as unsafe
prediction of the Miner hypothesis. Holmen [32] reported that random loadings caused
more cumulative damage compared to the predictions made by the Miner hypothesis.
This occurred primarily due to the loading sequence effect that is ignored in the Miner
hypothesis. As a result, he established a modified version of the Miner hypothesis
involving a loading function to handle variable amplitude loadings. However, some other
investigators found that the Miner hypothesis is appropriate to predict fatigue life of
concrete subjected to variable amplitude loadings [35,36].
8
The stress reversal causes reduction in fatigue life of concrete when compared to
concrete loading with stress cycles having positive stress ratio [35,36].
A number of researchers [5,38,14] have shown beneficial effects of previous cyclic
loadings on concrete static strength provided the loadings remain at below endurance
limits. Bennett and Raju [5] found 11% increase in static strength of high strength
concrete specimens which were previously subjected to several million applications of
cyclic loads between 0.5 and 0.7 of the static ultimate strength. Other investigators as
cited by Ramakrishnan et al. [38] indicated increase in the static strength in the range of
5 to 15 percent for specimens loaded below their endurance limits relative to control
specimens. An investigation [14] reported that beams subjected to a similar stress history
endured increased number of load applications when tested later at a higher stress level
compared to control specimens. The above results may be attributed to the release of
residual stresses and strain hardening effects [5].
Rest periods and sustained loading between the repeated load cycles produced a
beneficial effect on the fatigue strength of concrete [22,30,38]. This occurs in absence
of stress reversals and when the sustained stress level is below 75 percent of the static
strength. Hilsdorf and Kesler [22] reported that rest periods of up to 5 minutes increased
the fatigue strength. However, beyond 5 minutes the periods did not exhibit any
appreciable effect.
Ople and Hulsbos [40] investigated the effect of stress gradient on the fatigue strength of
9
concrete in compression. In order to simulate the compression zone of a beam, concrete
prisms were eccentrically loaded in the fatigue tests. The results showed increase in the
fatigue strength of eccentric specimens of the order of 15 to 18 percent higher relative to
uniformly stressed specimens for a fatigue life of 40,000 to 1,000,000 cycles. The
authors recommended that the fatigue strength of uniformly stressed specimens be used
as a lower limit of fatigue life of flexural members in compression.
Parameters such as water-to-cementitious materials ratio, curing, cement content, age,
aggregate properties, admixture content, etc. are known to affect fatigue strength of
concrete. The effects of these parameters exhibit the same trend as observed in the
case of static strength. Studies have been carried out to evaluate the effects of age
[23,30,41,42,43], moisture conditions [30,31,42], curing conditions [42,43], air
entrainment [44,45,46], water-to-cement ratio [16,45], type and quality of aggregate, and
concrete strength [30,39,46,47,48], and superplasticizer [51,52] on fatigue strength
behavior of concrete. Previous studies have substantiated that endurance limit is
relatively independent of material properties when expressed as a percentage of static
strength. According to ACI Committee 215 report [24], the fatigue strength for a life of 10
million cycles of load at a 50% probability of failure, is approximately 55% of static
strength, regardless of types of cyclic loading. Test results from some past investigations
showed that endurance limit does not exist for plain concrete [53]. More recently, studies
[38] have proved that endurance limit at 2 million cycles of loading does exist for plain as
well as reinforced concretes. Some studies [24,38] reported a flexural fatigue limit in the
range of 50 - 60 percent of the static strength for loading cycles varying between 106 to
10
107 cycles.
Fatigue behavior of fly ash concretes have been reported by a few researchers [54-57].
Ghosh et al. [54] determined the flexural fatigue strength of plain low cement content
concrete and low cement-fly-ash concrete (lean mixtures). The mixture proportions were
1 cement : 4 sand : 8 coarse aggregate for plain concrete, and 1 cement : 3.5 sand : 3.5
n fly ash : 14 coarse aggregate for lean cement-fly-ash concrete (n is ratio of specific
gravity of fly ash and sand). The flexural stress was applied through third-point loading at
74 CPM using test specimens of 75 x 100 x 500 mm. Test results indicated that at 75%
of the maximum flexural stress level, the number of repetitions to failure was 2,000 and
20,000 cycles for the lean mixtures of cement and cement-fly ash concretes,
respectively.
Tse et al. [56] evaluated compressive fatigue strength of cylindrical concrete specimens
(15() x 300 mm) made with both Class C and Class F fly ashes. The study developed
concrete mixture proportions to have four levels of cement replacements (0, 25, 50, and
75%) by these fly ashes. The cyclic stress range was varied from a minimum level of
about zero to a predetermined maximum stress as a percentage of the compressive
strength (between 55% to 95%) at 4 CPS. The authors reported that concrete with
equivalent or higher compressive and fatigue strength could be obtained with cement
replacement of 25% by weight of low-calcium fly ash or 50% by weight of high-calcium fly
ash.
11
Ramakrishnan et al. [57] investigated flexural fatigue strength behavior of high-volume fly
ash concrete systems. Superplasticized concrete mixtures were proportioned to have
zero and 58% cement replacements with a low-calcium fly ash at a water to cementitious
materials ratio of 0.32. From these mixtures, beam specimens of 75 x 100 x 400 mm
were subjected to non-reversed fluctuating flexural loads using a third-point loading
system at a frequency of 20 CPS. A constant lower limit of 10% of the flexural static
strength was used, and the upper limit was varied from about 90% of the static strength
down to the fatigue limit. The fatigue limit values, expressed as proportions of the static
flexural strength, were 0.65 for the non-fly ash concrete and 0.70 for the high-volume
Class F fly ash concrete. However, the values of static flexural strength and fatigue
strength were slightly higher for the reference concrete. They further reported a 15 to
30% increase in the static flexural strength for both the high-volume fly ash concrete and
the non-fly ash concrete specimens which were previously loaded to four million cycles
of fatigue stresses at their respective fatigue limit loads compared to the specimens not
loaded before.
Generally, a plot of the ratio of fatigue stress to static strength (S) versus logarithm of
number of cycles (N), becomes independent of the specimen shape, strength properties,
curing condition age, moisture condition at loading, etc. This curve is adequately
represented by several empirical models [38,39,53,59,60,61]. Aas-Jakobsen [59]
established an empirical relation to express the ratio S as a function of the ratio of
minimum stress to maximum stress (R) and number of load cycles. This model was
found to be adequate to describe fatigue strength of plain normal weight and lightweight
12
concretes in both compression [60] and tension [61]. Oh [62] developed a linear relation
between the ratio S and N.
Hsu [53] proposed a more general model to take into accounts of the four parameters
S-N-T-R which includes an additional variable T (time). The product of T and N denotes
duration of loading; and, therefore, the model presents the joint effects of time and
loading rate on fatigue behavior of concrete. The author established empirical models for
both high-cycle and low-cycle fatigue failures.
EXPERIMENTAL PROGRAM
An experimental program was designed to establish fatigue behavior of high-volume fly
ash concrete systems. The work related to material selection and characterization,
mixture proportioning, and specimen preparation was performed at the CANMET, Ottawa,
Canada. The work concerning the fatigue testing was performed at the UWM Center for
By-Products Utilization, University of Wisconsin-Milwaukee.
MATERIALS
Cement
Two different cements designated as S and G were used. Cement S was a low-alkali
(about 0.2% Na2O) ASTM Type I cement, whereas cement G was a high-alkali (about
1.1% Na2O) ASTM Type I cement. The physical and chemical properties of these
cements are presented in Table 1.
13
Fly Ash
Four fly ashes obtained from four different sources in the USA were used in this
investigation. Their physical and chemical properties are given in Table 2.
MIXTURE PROPORTIONS
The concrete mixture proportions are summarized in Table 3. The parameters such as
water to cementitious materials ratio, and water, cement, and fly ash contents were
maintained approximately constant for all mixtures. All mixtures were air entrained and
a HRWR was used. Appropriate amounts of air entraining admixtures were added to
entrain air content of 5 ± 0.5%. A napthalene-based HRWR (superplasticizer) was used
to obtain the desired level of slump.
SPECIMEN PREPARATION
Cylindrical specimens (152 x 305 mm) were cast for compressive strength determination.
Prism specimens (75 x l00 x 400 mm) were cast for flexural static and fatigue strength
measurements of concrete. These specimens were cast in two layers using an internal
vibrator. All test specimens were subjected to moist curing in accordance with ASTM C
192. After one year of moist curing at CANMET, all the specimens were shipped to the
UWM Center for By-Products Utilization, University of Wisconsin- Milwaukee, where they
were stored in lime-saturated water until the time of the test.
TESTING OF SPECIMENS
Compressive Strength
14
Concrete compressive strength was determined in accordance with ASTM C 39. The
modified cube compressive strengths of concrete mixture using portions of beam
specimens which were previously broken in flexure, were determined in accordance with
the ASTM C 116 at the time of fatigue testing.
Fatigue Strength
Static and fatigue flexural strength of concrete were determined using third-point loading.
In this work, endurance limit was defined as the flexural stress level at which the beam
specimen could withstand two million cycles of nonreversed cyclic loading. The static
flexural strengths of beam specimens (75 x 100 x 400 mm) were determined using a
third-point loading in accordance with ASTM C 78 with a span of 300 mm. Three
specimens were used to determine the average static flexural strength of concrete. All
specimens were tested with respect to their stronger axis.
The upper and lower limits for the cyclic loading were determined from the average static
flexural strength of the mixture. The lower limit was taken as 10% of the static flexural
strength of each mixture. In this investigation, the lower limit was kept constant for all
specimens and upper limit was varied from about 90% of the static flexural strength down
to endurance limit (fatigue limit) of the mixture.
The flexural fatigue test was carried out between the upper and lower limits of the loading
using the third-point loading system. Three specimens were tested for each load
condition. If three specimens failed before two million cycles, the upper limit was reduced
15
by 10% or more depending upon the number of upper load levels needed to establish
endurance limit for a given mixture. Two additional specimens were tested at the load
level at which three beams survived two million cycles. The endurance limit was taken
as an average flexural strength based on the results of the five specimens which survived
two millions cycles of loading. The beams which survived two million loading cycles were
also tested in static loading using the third-point loading.
Since fatigue testing of concrete is very time consuming, it was not possible to test all the
mixtures at a constant age. Each test specimen took up to about 28 hours to test.
Therefore, after completion of testing of one mixture, the next mixture was tested. This
resulted in differences in age among test specimens mixtures tested. However, at about
one year age, at which the fatigue testing was started, the age effect on strength gain was
already negligible. In
order to further eliminate the effect of age to a considerable extent, fatigue strength data
were expressed as a ratio of fatigue flexural strength to static flexural strength for each
mixture.
RESULTS AND DISCUSSION
COMPRESSIVE STRENGTH
The compressive strength at the 28-day age of all concrete mixtures are shown in Table
3. The strength of the mixtures at one year of age was found to be in the range of 30 - 40
MPa, depending upon type of cement and source and type of fly ash used.
16
FATIGUE BEHAVIOR
The flexural fatigue strength test data were plotted as a ratio of flexural stress to static
flexural strength (S) versus number of cycles (N) for each mixture. As expected, this type
of plot showed a non-linear trend for all the mixtures (Fig. 1). A plot of S-N curve for each
mixture could be approximated by a linear model when the ratio of flexural fatigue stress
to static flexural strength versus log number of cycles is plotted (Fig. 2). The linear model
was used to represent fatigue for cycles less than 2 million.
The fatigue limit data for each mixture derived from the S-N curves are given in Table 4.
The analysis of test data showed that both static flexural strength and fatigue flexural
strength were heavily dependent upon source of fly ash used. The effect of type of
cement was relatively small compared to fly ashes' effects.
The results revealed that the concrete mixture having the highest flexural strength did not
exhibit the maximum fatigue limit (fatigue stress at two million cycles of loading). This
occurred primarily due to differences in crack propagation patterns during cyclic loadings.
The crack pattern is primarily influenced by size and location of flaws/cracks present in
the test specimens, etc.
A plot of fatigue limit or endurance limit, of test mixture are mixtures (EP9F through
EP16F) are shown in Figure 3. A plot of endurance ratio and fatigue limit of the mixtures
expressed as a proportion of their respective static flexural strengths, is also shown in
17
Figure 4.
The results showed that the fatigue limit varied from 2.6 MPa to 3.3 MPa for the mixtures
tested. Whereas, the endurance ratio, defined as the ratio of flexural fatigue limit to static
flexural strength, varied between 0.5-0.6 for the concrete specimens tested. The results
further indicated that endurance ratio when expressed as proportion of static strength,
was relatively unaffected by the type of cement and source and type of fly ash used. This
is in agreement with results reported by a majority of researchers on concrete fatigue [20].
Based on pooled data, the endurance ratio for the test mixtures was found to be
approximately 0.51.
CHANGE IN STATIC FLEXURAL STRENGTH AFTER TWO MILLION CYCLES
In general, the reduction was found to vary between 0% and 32.2% compared to the
reference specimens. all test specimens which had undergone 2 million cycles of fatigue
loading showed reduced static flexure strength compared to the respective reference
specimen not loaded previously (Table 4). This indicates that high-volume fly ash
concrete specimens tested in this work displayed a strain softening behavior, in contrast
to a strain hardening trend reported by some researchers [38,20]. The strain softening
behavior may be a the results of slippage caused between the unreacted fly ash particles
and the paste during the cyclic loading, internal structure of concrete, presence of flaws,
etc. during the cyclic loading used. Probably the increased slippage caused considerable
18
cracks which resulted in reduced strength after the fatigue loading.
MODIFIED CUBE COMPRESSIVE STRENGTH
The modified cube compressive strength data were determined in accordance with
ASTM C 116. Average modified cube strengths were 46.3 MPa for EP9F, 45.2 MPa for
EPl0F, 40.5 MPa for EP11F, 43.2 MPa for EP12F, 36.4 MPa for EP13F, 35.6 MPa for
EP14F, 36.1 MPa for EP15F, and 45.3 MPa for EP16F. The corresponding compressive
strength values for these mixtures measured according to ASTM C 39 were at one year
age were 63.1 MPa, 61.2 MPa, 54.7 MPa, 58.7 MPa, 49.2 MPa, 51.4 MPa, 58.2 MPa,
and 57.5 MPa, respectively.
The results revealed some difference between the strength values determined by ASTM
C 39 and ASTM C 116. The major reason for the difference is due to variation in
geometry of test specimens. Other factors such as difference in age and previous strain
history might have slightly affected the compressive strength results. The specimens
used for the modified cube compressive tests might have experienced some previous
strain because they were already obtained from specimens which were subjected static
to flexural strength tests.
CONCLUSIONS
The major conclusions based on experimental data collected in this work are as follows.
(1) Static flexural strength of concrete was significantly influenced by the
source of fly ash used. The effect of cement type had a little influence on
19
the flexural fatigue strength of high-volume fly ash concrete systems.
(2) The effect of fly ash source was significant on the flexural fatigue stress of concrete.
(3) The concrete mixture having the highest static flexural strength did not attain the
highest fatigue limit. This revealed that fatigue flexural strength was more sensitive
to internal structure of concrete structure and flaws than of static flexural strength.
(4) As anticipated, the S-N curve exhibited a non linear trend.
(5) The relation between the ratio of flexural fatigue stress to static flexural
strength and logarithmic of number of cycles can be modelled by a linear
model. This is consistent with results obtained from previous investigations,
as the relationship between the strength ratio and number of cycles
becomes relatively independent of age, strength, and material properties to
a marked extent. Based on the pooled data, the value of endurance ratio
was approximately 0.51, in the same range as observed for fly-ash free
concrete.
REFERENCES
1. Suresh, S., Fatigue of Materials, Cambridge University, England, 1991, 586 pages.
2. Murdock, J., Kesler, C.E., "The Mechanism of Fatigue in Concrete," Report No.
587, University of Illinois, August 1960. 3. Antrim, J.C., "A Study of the Mechanism of Fatigue in Cement Paste and Plain
Concrete," Ph.D. Thesis, Purdue University, 1967. 4. Boswell, L.F., and Chen, Z., "General Criterion for Fatigue Failure of Plain
Concrete," International Journal of Solids and Structures, Vol. 23, 1987, pp. 621-630.
20
5. Bennett, E.W ., and Raju, N.K., "Cumulative Fatigue Damage of Plain Concrete in Compression," Proceedings of the International Conference on Structure,Solid Mechanics and Engineering Design in Civil Engineering Materials, Southampton, Wiley-Interscience, London, 1971, pp. 1089-1102.
6. Anderson, T.L., "Fracture Mechanics: Fundamentals and Applications," CRC
Press, Inc., 1991, 793 pages. 7. Batson, G., Ball, C., Bailey, L., Landers, E., and Hooks, J., "Flexural Fatigue
Strength of Steel Fiber Reinforced Concrete Beams," ACI Journal, Proc. Vol. 69, No. 11, November 1972, pp. 673-677.
8. Bannantine, J.A., Comer, J.J., and Handrock, J.L., Fundamentals of Metal Fatigue
Analysis, Prentice Hall, Englewood Cliffs, New Jersey, 1990, 273 pages. 9. Paris, P.C., and Erdugan, F., "A Critical Analysis of Crack Propagation Laws,"
Journal of Basic Engineering, Vol. 85, 1960, pp. 528-534. l0. Paris, P.C., Gomez, M.P., and Anderson, W.P., "A Rational Analytic Theory of
Fatigue," Trend in Engineering, Vol. 13, No. 1, 1961, pp. 9- 14. 11. Foreman, R.G., Peary, V.E., and Engle, R.M., "Numerical Analysis of Crack
Propagation in Cyclic–Loaded Structures," Journal of Basic Engineering, Vol. 89,
1967, pp. 459-464. 12. Kocand, S., "Fatigue Failure of Metals," Wydawnicta Naukowo-Techiczno.
Warsaw, Poland, 1978, 368 pages. 13. Dowling, N.E., and Begley, J.A., "Fatigue Crack Growth During Plasticity and the
J Integral," ASTM STP 590, American Society for Testing and Materials, Philadelphia, 1976, pp. 82-103.
14. Zhang, B.S., Zhu, Z.H., and Wu, K.R., "Fracture Rupture of Plain Concrete
Analyzed by Fracture Mechanics," Proceedings of the SEM-RILEM International Conference on Fracture of Concrete and Rock, Houston, Texas, S.P. Shah and S.E. Swartz, Eds., June 1987, pp. 58-63.
15. Baluch, M.H., Qureshy, A.B., and Azad, A.K., "Fracture Crack Propagation in Plain
Concrete," Proceedings of the SEM-RILEM International Conference on Fracture of Concrete and Rock, Houston, Texas, S.P. Shah and S.E. Swartz, Eds., June 1987, pp. 80-87.
16. Nordby, G.M., "Fatigue of Concrete - A Review of Research," ACI Journal,
Proceedings, Vol. 55, No. 2, Aug. 1958, pp. 191-220.
21
17. Murdock, J.W., "A Critical Review of Research on Fatigue of Plain Concrete,"
Engineering Experiment Station, Bulletin No. 475, University of Illinois, Urbana, Feb. 1965, 25 pages.
l8. Lloyd, J.P., Lott, J.L., and Kesler, C.E., "Fatigue of Concrete," Engineering
Experiment Station, Bulletin No. 499, University of Illinois, Urbana, 1968, 25 pages.
19. Raithby, K.D., and Whiffin, A.C., "Failure of Plain Concrete Under Fatigue
Loading - A Review of Current Knowledge," Ministry of Transportation, RRL Report LR 231, Research Laboratory, Crowthorne, 1968.
20. Naik, T.R., Singh, S.S., and Ye, C., "Fatigue Behavior of Plain Concrete Made
With or Without Fly Ash," A Progress Report Submitted to EPRI, March, 1993. 21. Murdock, J.W., and Kesler, C.E., "Effect of Range of Stress on Fatigue Strength
of Plain Concrete Beams," ACI Journal, Proceedings Vol. 55, No. 2, Aug. 1958, pp. 221-231.
22. Hilsdorf, H.K., and Kesler, C.E., "Fatigue Strength of Concrete Under Varying
Flexural Stresses," ACI Journal, Proceedings Vol. 63, No. 10, Oct. 1966, pp. 1059-1076.
23. Awad, M.E., "Strength and Deformation Characteristics of Plain Concrete
Subjected to High Repeated and Sustained Loads," Ph.D. Thesis, University of Illinois at Urbana - Champaign, Illinois. 1971.
24. ACI Committee 215, "Consideration for Design of Concrete Structures Subjected to Fatigue Loading," ACI Manual of Concrete Practice, 1990, Part 1, pp. 215R-1 to 215R-25.
25. Kesler, C.E., "Effect of Speed of Testing on Flexural Fatigue Strength of Plain
Concrete," Highway Research Board, Vol. 32, 1953, pp. 251-258. 26. Assimacopoulos, B.A., Warner, R.F., and Ekberg, C.E., "High Speed Fatigue
Tests on Small Specimens of Plain Concrete, "Journal of Prestressed Concrete Institute, Vol. 4, No. 2, Sept. 1959, pp. 53-70.
27. Sparks, P.R., and Menzies, J.B., "The Effect of the Rate of Loading upon the
Static and Fatigue Strengths of Plain Concrete in Compression," Magazine of Concrete Research, Vol. 75, No. 83, June 1973, pp. 73-80.
28. Galloway, J.W., and Raithby, K.D., "Effects of Rate of Loading on Flexural
Strength and Fatigue Performance of Concrete," Department of the Environment, TRRL Report LR 547, Crowthorne, Transport and Road Research Laboratory,
22
1973. 29. Awad, M.E., and Hilsdorf, H.K., "Strength and Deformation Characteristics of Plain
Concrete Subjected to High Repeated and Sustained Loads," Fatigue of Concrete, ACI Special Publication, SP-41, 1974, pp. 1-13.
30. Raithby, K.D., and Galloway, J.W., "Effects of Moisture Condition, Age, and Rate
of Loading on Fatigue of Plain Concrete," Fatigue of Concrete, ACI Special Publication, SP-41,1974, pp.15-34.
31. RILEM Committee 36-RDL, "Long Term Random Dynamic Loading of Concrete
Structures," Materials and Structures, Research and Testing (RILEM, Paris), Vol. 17, No. 97, Jan. 1984, pp. 1-28.
32. Holmen, J.O., "Fatigue of Concrete by Constant and Variable Amplitude Loading,"
ACI Special Publication, SP-75, S.P. Shah, Ed., Detroit, 1982, pp. 47-69. 33. Siemes, A.J.M., "Miner's Rule with Respect to Plain Concrete Variable Amplitude
Tests," ACI Special Publication, SP-75, S.P. Shah, Ed., Detroit, 1982, pp. 343-372.
34. Sakata, K., Yamura, K.. and Nishibayashi, S., "Study on Fatigue Properties of
Concrete Under Variable Repetitive Compressive Loading," Transactions of the Japan Concrete Institute, Vol. 7, Published by Japan Concrete Institute, Tokyo, 1985, pp. 257-262.
35. Tepfers, R., "Fatigue of Plain Concrete Subjected to Stress Reversals,"
Proceedings of the Abeles Symposium on Fatigue of Concrete Structures, ACI Special Publication, SP-75, S.P. Shah, Ed., Detroit, 1982, pp. 195-215.
36. Zhang, B.S., and Phillips, D.V., "Fatigue Life of Plain Concrete Under Stress
Reversal," Proceedings of the International Conference on Fracture of Concrete and Rock: Recent Developments, University of Wales, College of Cardiff, School of Engineering, S.P. Shah, S.E. Swartz, and B. Barr, Ed., Sept. 20-22, 1989,
pp. 183-192.
37. Cornelissen, H.A.W., and Siemes, A.J.M., "Plain Concrete Under Sustained
Tensile or Tensile and Compressive Fatigue Loadings," Proceedings of the 4th International Conference on Behavior of Offshore Structures, 1985, pp. 487-498.
38. Ramakrishnan, V., and Lokvik, B.J., "Fatigue Strength and Endurance Limit of
23
Plain and Fiber Reinforced Concretes–A Critical Review," Proceedings of the
International Symposium on Fatigue and Fracture in Steel and Concrete Structures, Madras, India, 1991, pp. 381-407.
39. Ramakrishnan, V., Bremmer, T.W., and Malhotra, V.M., "Fatigue Strength and
Endurance Limit of Lightweight Concrete," Presented at the ACI Meeting in Dallas, TX, November 1991.
40. Ople, F. S., and Hulsbos, C.L., "Probable Fatigue Life of Plain Concrete with
Stress Gradient." ACI Journal, Proceedings Vol. 63, No. 1, January 1966, pp. 59-82.
41. Galloway, J.W., Harding, H.M., and Raithby, K.D., "Effects of Age on Flexural
Fatigue and Compressive Strength of Concrete," TRRL Report No. 865, Crowthorne, Transport and Road Research Laboratory, 1979, 20 pages.
42. Galloway, J.W., Harding, H.M., and Raithby, K.D., "Effects of Moisture Changes
on Flexural and Fatigue Strength of Concrete," TRRL Report No. 864, Crowthorne, Transport and Road Research Laboratory, 1979, 30 pages.
43. Raithby, K.D., "Some Flexural Fatigue Properties of Concrete-Effects of Age and
Methods of Curing," First Australian Conference on Engineering Materials, University of New South Wales, 1974, pp. 211-229.
44. Antrim, J.C., and McLaughlin, J.F., "Fatigue Study of Air-Entrained Concrete," ACI
Journal, Proceedings Vol. 55, No. 11, May 1959, pp. 1173- 11 82. 45. Lee, D.Y., Klaiber, F.W., and Coleman, J.W., "Fatigue Behavior of Air-Entrained
Concrete," Engineering Research Institute, Iowa State University, Ames, Iowa Department of Transportation, Final Report, July 1977; also, Transportation Research Record No. 671, 1978. pp. 20-23.
46. Klaiber, F.W., Thomas, T.L., and Lee, D.Y., "Fatigue Behavior of Air-Entrained
Concrete: Phase II," Report, Ames, Iowa, Engineering Research Institute, Iowa State University, Feb. 1979.
47. Gary, W.H., McLaughlin, J.F., and Antrim, J.C., "Fatigue Properties of Lightweight
Aggregate Concrete," ACI Journal, Proceedings Vol. 58, No. 2, Aug. 1961, pp. 149- 161.
48. Bennett, E.W., and Muir, S.E.St.J., "Some Fatigue Tests of High-Strength
24
Concrete in Axial Compression," Magazine of Concrete Research, London, Vol. 19, No. 59, June 1967, pp. 113-117.
49. Sparks, P.R., "The Influence of Rate of Loading and Material Variability on the
Fatigue Characteristics of Concrete," Proceedings of the Abeles Symposium on Fatigue of Concrete Structures, ACI Special Publication SP-75, S.P. Shah, Ed., Detroit, 1982, pp. 331-341.
50. Tepfers, R., and Kutti, T., "Fatigue Strength of Plain, Ordinary, and Lightweight
Concrete," ACI Journal, Proceedings, Vol. 76, No. 5, May 1979, pp. 635-652. 51. Whiting, D., "Evaluation of Super-Water Reducers for Highway Applications,"
Report No. FHWA/RD-80/132, Federal Highway Administration, Washington, D.C., 1981.
52. Lee, D.Y., Yang, J.J.F., and Klaiber, F.W., "Fatigue Behavior of Superplasticized
Concrete," ASTM Cement, Concrete, and Aggregates, CCAGDP, Vol. 7, No. 1, Summer 1985, pp. 1924.
53. Hsu, T.T.C., "Fatigue of Plain Concrete," ACI Journal, Proceeding Vol. 78, No. 4,
July-August 1981, pp. 292-305. 54. Ghosh, R.K., Sethi, K.L., and Arora, V.P., "Laboratory Studies on Lean
Cement-Fly Ash Concrete as Construction Material," IRC Highway Research Board, No. 19, 1982, pp. 13-26.
55. Burcharth, H.F., "Fatigue in Breakwater Concrete Armour Units," Proceedings of
the Nineteenth Coastal Engineering International Conference, Vol. 3, No. 19, pp. 2692-2607.
56. Tse, E.W., Lee, D.Y., and Klaiber, F.W., "Fatigue Behavior of Concrete Containing
Fly Ash," Proceedings of the Second International Conference on the Use of Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete, Madrid, Spain, V.M. Malhotra, Ed., Vol. 1, ACI Special Publication, SP-91, 1986, pp. 273-289.
57. Ramakrishnan, V., Malhotra, V.M., and Longley, W.S., "Comparative Evaluation
of Flexural Fatigue Behavior of High Volume Fly Ash and Plain Concrete," Presented at the 70th Annual Meeting of the Transportation Research Board, Washington, D.C., Jan. 1991.
58. Ozaki, S., and Sugata, N., "Fatigue of Concrete Composed of Blast Furnace Slag
or Silica Fume Under Submerged Conditions," Proceedings of the Fourth International Conference, Istanbul, Turkey, May 1992, pp. 1509- 1524.
25
59. Aas-Jakobsen, K., "Fatigue of Concrete Beams and Columns," Bulletin No. 70-1, NTH Institute for Betonkonstruksjoner, Trondheim, Norway, Sept. 1970, 148 pages.
60. Tepfers, R., and Kutti, T., "Fatigue Strength of Plain, Ordinary, and Lightweight
Concrete," ACI Journal, Proceeding Vol. 76, No. 5, May 1979, pp. 635-652. 61. Tepfers, R., "Tensile Fatigue Strength of Plain Concrete," ACI Journal,
Proceeding, Vol. 76, No. 8, August 1979, pp. 919-933.
62. Oh, B.H., "Fatigue Analysis of Plain Concrete in Flexure," Journal of Structural
Engineering, ASCE, Vol. 112, No. 2, Feb. 1986, pp. 273-288. 63. Oh, B.H., "Fatigue-Life Distribution of Concrete for Various Stress Levels," ACI
Materials Journal, Vol. 88, No. 2, March-April 1991, pp. 122-128. 64. Ye, C., "Shrinkage and Fatigue Properties of Concrete Containing High Volumes
of Fly Ash," M.S. Thesis, May 1993. REP-337 SSS/llm
26
Table 1: Physical and Chemical Characteristics of Portland Cements
Property
Cement S
Type 1
(low alkali)
Cement G
Type 1
(high alkali) Physical Properties:
Fineness: Passing 45 μm, %
Blaine, m2/kg
Specific Gravity
Compressive Strength (ASTM C 109)
of 51-mm Mortar Cubes, MPa
3 days
7 days
28 days
93.6
371
3.14
21.2
31.5
45.0
94.9
376
3.14
31.5
34.5
41.9 Chemical Composition (Mass %)
SiO2
Al2O3
Fe2O3
CaO
MgO
Na2O
K2O
TiO2
MnO
P2O5
SO3
LOI
21.16
4.75
3.65
64.99
1.24
0.07
0.18
0.31
0.02
0.10
2.27
1.11
19.20
5.79
2.03
63.48
2.52
0.33
1.16
0.28
0.06
0.10
3.50
2.61 Compound (Bogue) composition:
C3S
C2S
C3A
C4AF
CaCO3 (TGA)
CSH2 (QXRD)
65.37
11.35
6.41
11.11
0.52
4.4
63.65
7.03
11.91
6.18
3.02
4.0
27
Table 2: Physical and Chemical Characteristics of Fly Ashes
Property
Fly Ash Source
Coal Creek (CC)
Belews Creek
(BC) Gorgas (GO)
Navajo (N)
Physical Properties:
Fineness (% -45 μm)
Blaine (m2/kg)
Density (g/cm3)
Pozz. activity with PC:
PC G 7d
28d
PC S 7d
28d
80.2
256
2.50
95.9
101.7
89.0
93.4
72.1
211
2.30
81.1
88.5
83.7
87.6
85.4
289
2.43
88.2
92.3
87.8
93.6
82.7
320
2.39
89.2
95.8
90.4
93.8 Chemical Composition
(%):
SiO2
Al2O3
Fe2O3
CaO
MgO
Na2O
K2O
SO3
Carbon
46.38
15.32
7.38
19.34
5.48
0.83
1.82
1.45
0.04
54.54
31.53
6.28
1.17
0.85
0.22
2.00
0.40
0.95
47.33
25.44
13.82
1.81
1.52
1.18
2.80
0.90
1.38
55.39
18.54
6.38
9.51
2.16
3.08
1.22
0.92
0.31
Mineralogical*
Composition (%):
Glass
Quartz (Qz)
Mullite (Mu)
Ferrite/Spinels (Sp)
Hematite (Hm)
Other
89 (GII)
8
0
3
0
Pc,Mw,Lm
61 (GI)
4
31
2
2
--
68 (GI)
5
21
2
3
--
73 (GII)
15
10
1
1
Lm
28
* GI/GII = aluminaocilicate glass (glass I or glass II); Pc = periclase: Mw = merwinite;
Lm = lime.
29
Table 3: Mixture Proportions and Properties of Freshly-Mixed Concrete for Mix No. 1 (EP1F) through Mix No. 16 (EP16F)
Mix
No.
W/(C+FA)
Water
(kg/m3)
Cement
Type
Cement
(kg/m3)
Fly Ash
Source
Fly
Ash
(kg/m3)
Coarse
Agg.
(kg/m3)
Fine
Agg.
(kg/m3)
AEA*
(mL/m3)
SP**
(L/m3)
Slump
(mm)
Unit
Weight
(Kg/m3)
Entraine
d Air
(%)
28-Day
Strength
Entrained
f'c
(MPa)
9
0.33
119
S
153
CC
212
1205
648
175
1.9
160
2345
5.3
34.5
10
0.33
120
G
153
CC
212
1205
648
75
2.1
140
2345
5.7
39.1
11
0.33
120
S
154
BC
214
1211
651
325
3.2
95
2360
4.8
28.7
12
0.33
120
G
153
BC
213
1203
647
335
4.2
135
2345
5.3
34.6
13
0.33
120
S
153
GO
212
1205
647
290
2.4
120
2360
5.7
33.5
14
0.33
119
G
152
GO
211
1202
645
200
3.7
100
2330
5.8
33.7
15
0.33
119
S
151
N
210
1195
642
280
3.0
100
2320
6.1
30.2
30
16 0.33 119 G 152 N 211 1199 644 210 3.4 125 2330 5.9 38.1
* Air-Entraining Admixture
** Superplasticizer
Table 4: Change in static Flexural strength Test After Fatigue testing for Mixture No. 9 to No. 12 (EP9F to EP12F)
Mix No.
(1)
Specimen No.
(2)
Maximum
Stress in
Fatigue (psi)
(3)
f
f
r
max
(4)
Static Flexure
Stress After
Fatigue (psi)
(5)
Static Flexure
Stress Before
Fatigue (psi)
(6)
Change in
Stress,
Percent
(5) - (6)
EP9F
12
443
0.45
704
977
-27.9
13
499
0.51
746
977
-23.6
14
440
0.45
814
977
-16.7
16
439
0.45
778
977
-20.4
17
447
0.45
867
977
-11.3
EP10F
14
459
0.56
792
827
-4.3
31
16
458
0.55
731
827
-11.6
17
420
0.51
775
827
-6.3
18
419
0.51
652
827
-21.2
EP11F
13
423
0.50
815
844
-3.4
14
440
0.52
647
844
-23.3
15
440
0.52
715
844
-15.3
17
437
0.52
684
844
-19.0
EP12F
13
435
0.51
771
870
-11.4
14
433
0.50
750
870
-13.8
15
431
0.50
781
870
-10.2
16
429
0.50
710
870
-18.4
18
436
0.51
692
870
-20.5
32
Table 4 (cont'd): Change in Static Flexural strength After Fatigue Testing for Mixture No. 13 to No. 16 (EP13F to EP16F)
Mix No.
(1)
Specimen
No.
(2)
Maximum
Stress in
Fatigue (psi)
(3)
f
f
r
max
(4)
Static
Flexure
Stress
After
Fatigue
(psi)
(5)
Static Flexure
Stress Before
Fatigue (psi)
(6)
Change in
Stress,
Percent
(5) - (6)
EP13F
7
369
0.45
672
817
-17.7
8
372
0.46
496
817
-39.3
9
371
0.45
613
817
-25.0
10
373
0.46
554
817
-32.2
EP14F
5
361
0.45
650
801
-18.9
6
356
0.44
688
801
-14.1
7
355
0.44
721
801
-10.0
8
360
0.45
676
801
-15.6
9
357
0.45
703
801
-12.2
EP15F
5
419
0.56
742
754
-1.6
11
420
0.56
722
754
-4.2
13
460
0.61
756
754
0.3
15
454
0.60
653
754
-13.4
17
446
0.59
662
754
-12.2
EP16F
13
460
0.59
694
774
-10.3
14
468
0.60
847
774
9.4
15
461
0.61
773
774
-0.1
16
468
0.60
719
774
-7.1
17
389
0.50
772
774
-0.2
33
f max. = maximum flexural fatigue stress at two million cycles of loading