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Comparison of ultra-fine fly ash and silica fume in concrete mixtures

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Title:
Comparison of ultra-fine fly ash and silica fume in concrete mixtures
Creator:
Ruybal, Stephanie Selina
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English
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xii, 92 leaves : illustrations ; 28 cm

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Subjects / Keywords:
High strength concrete -- Cracking ( lcsh )
Fly ash ( lcsh )
Silica fume ( lcsh )
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bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

Notes

Bibliography:
Includes bibliographical references (leaves 80-81).
General Note:
Department of Civil Engineering
Statement of Responsibility:
by Stephanie Selina Ruybal.

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|University of Colorado Denver
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|Auraria Library
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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
227996596 ( OCLC )
ocn227996596
Classification:
LD1193.LE53 2007m R88 ( lcc )

Full Text
COMPARISON OF ULTRA-FINE FLY ASH AND SILICA FUME IN
CONCRETE MIXTURES
by
Stephanie Selina Ruybal
B.S., University of Colorado, Boulder, 2004
A thesis submitted to the
University of Colorado at Denver and Health Sciences Center
in partial fulfillment
of the requirements for the degree of
Master of Science
Civil Engineering
2007


This thesis for the Master of Civil Engineering
degree by
Stephanie Selina Ruybal
has been approved
tloi/tmhu X?S,
Date


Ruybal, Stephanie Selina (M.S., Civil Engineering)
Comparison of Ultra-Fine Fly Ash and Silica Fume in Concrete Mixtures
Thesis directed by Assistant Professor Stephan Durham
ABSTRACT
Silica fume is often used as a supplementary cementitious material in concrete
mixtures to create high strength concrete; however, problems such as concrete
cracking can arise if not designed properly. Research has shown that silica fume
promotes cracking and increases the water demand of the concrete mixture. The
purpose of this thesis is to determine whether silica fume can be replaced by ultra-
fine fly ash (UFFA) in high strength concrete.
Research has shown that UFFA increases the strength of concrete. It has also
been proven that UFFA decreases the water demand and has not been shown to
promote cracking in previous studies.
This thesis focuses on two types of high strength concrete, Colorado Department
of Transportation (CDOT) Type H and Type HT. The mixtures used in this thesis
will follow CDOT standards for both Type H and Type HT concrete to determine
if UFFA can effectively replace silica fume in high strength concrete.


Only one of four concrete mixtures containing UFFA was able to produce similar
results to silica fume mixtures. UFFA improved some properties such as
workability of the mixture and water demand; however, mixtures containing silica
fume outperformed the UFFA when compared to 56-day compressive strength,
permeability, and durability. The UFFA exceeded the results of silica fume for
slump. An addition of 10% UFFA increased the slump value, regardless of the
w/cm. The silica fume exceeded the results of UFFA for compressive strength.
Although they performed similarly, silica fume increased the compressive
strength even at a higher w/cm. Silica fume was found to be more effective in
decreasing the permeability of the concrete mixture than UFFA.
This abstract accurately represents the content of the candidates thesis. I
recommend its publication.
Signed
Stephan A. Durham


DEDICATION
I dedicate this thesis to my mom and grandparents, who gave me an appreciation
of learning. I also dedicate this to Craig for his unfaltering support and
understanding while I was completing this thesis.


ACKNOWLEDGEMENT
My thanks to my advisor, Dr. Stephan Durham, for his contribution and support to
my research. I also wish to thank Dr. Rens and Dr. Chang for participating on my
masters committee and for their valuable participation and insights.


TABLE OF CONTENTS
Figures....................................................................x
Tables.....................................................................xi
Chapter
1. Introduction........................................................1
1.1 General.............................................................1
1.2 Objectives..........................................................2
1.3 Scope...............................................................2
2. Review of the Literature............................................4
2.1 Ultra-Fine Fly Ash (UFFA)...........................................4
2.1.1 Fresh Concrete Properties...........................................5
2.1.2 Hardened Concrete Properties........................................6
2.2 Silica Fume.........................................................6
2.2.1 Fresh Concrete Properties...........................................8
2.2.2 Hardened Concrete Properties........................................9
2.3 Conclusion.........................................................10
3. Experimental Procedures and Research Program.......................12
3.1 General............................................................12


12
3.2 Scope...............................................
3.3 Specifications for CDOT Type H and Type HT Concrete..............13
3.4 Materials........................................................14
3.4.1 Portland Cement..................................................14
3.4.2 Fine Aggregate...................................................15
3.4.3 Coarse Aggregate.................................................16
3.4.4 Fly Ash..........................................................17
3.4.5 Silica Fume......................................................17
3.4.6 Ultra-Fine Fly Ash...............................................18
3.5 Experimental Procedures..........................................18
3.5.1 Mixtures and Batching............................................18
3.5.2 Curing...........................................................25
3.5.3 Fresh and Hardened Concrete Tests................................26
4. Results and Discussion...........................................28
4.1 General..........................................................28
4.2 Fresh Concrete Tests.............................................28
4.2.1 Slump............................................................29
4.2.2 Air Content......................................................32


4.2.3 Unit Weight....................................................34
4.2.4 Concrete Temperature...........................................36
4.3 Hardened Concrete Tests........................................37
4.3.1 Compressive Strength...........................................37
4.3.2 Durability.....................................................48
4.3.3 Permeability...................................................63
4.4 Comparison of Study Findings with CDOT Specifications..........71
5. Conclusions and Recommendations................................73
5.1 Conclusions....................................................73
5.1.1 Fresh Concrete Properties......................................73
5.1.2 Hardened Concrete Properties...................................74
5.2 Recommendations................................................76
Bibliography...........................................................80
Appendix A.............................................................82
Appendix B.............................................................87


LIST OF FIGURES
Figure
1: Micrograph of Ultra-Fine Fly Ash....................................4
2: Micrograph of Silica Fume...........................................7
3: Effects of UFFA and Silica Fume on Slump............................30
4: Air Content.........................................................33
5: Photograph of Compressive Strength Test.............................40
6: Compressive Strength vs. Age........................................41
7: Rate of Strength Gain...............................................43
8: Reduced Compressive Strength........................................45
9: Difference from Required Compressive Strength.......................47
10: Photograph of Durability Test......................................49
11: Durability Results.................................................53
12: Rate of Frequency Loss.............................................56
13: Durability Factors.................................................58
14: Affects of Freezing and Thawing on Mass Loss.......................60
15: Photograph of Permeability Test....................................64
16: Permeability Results...............................................69


LIST OF TABLES
Table
1: Concrete Requirements.............................................13
2: Concrete Aggregate Gradation Table................................16
3: Mixture Design Table..............................................19
4: Modified UFFA-B Mixture Design Table..............................20
5: Specific Gravity..................................................22
6: Batch Volumes per Cubic Foot......................................23
7: Fresh and Hardened Concrete Tests.................................27
8: Fresh Concrete Properties.........................................28
9: Unit Weight Comparison............................................35
10: Corrected Unit Weights...........................................36
11: Maximum Load.....................................................38
12: Compressive Strength Values......................................39
13: Average Compressive Strengths....................................41
14: UFFA-A Freeze/Thaw Results.......................................51
15: UFFA-B Freeze/Thaw Results.......................................51
16: UFFA-C Freeze/Thaw Results.......................................51


17: UFFA-D Freeze/Thaw Results............................................51
18: SF-A Freeze/Thaw Results..............................................52
19: SF-B Freeze/Thaw Results..............................................52
20: Durability Factors....................................................57
21: Modulus of Elasticity.................................................62
22: Chloride Ion Penetrability Based on Charge Passed.....................65
23: 28-Day Permeability Results...........................................66
24: 56-Day Permeability Results...........................................68
25: Comparison to CDOT Requirements.......................................72


Chapter 1
Introduction
1.1 General
Silica fume has been used in concrete mixtures because of its ability to greatly
increase the strength of concrete. It has been instrumental in creating high
strength concrete mixtures and is widely used around the world. Silica fume
works excellent as a supplementary cementing material (SCM) by increasing
cohesiveness and reducing permeability, but it does have its disadvantages. Silica
fume increases both cracking and water demand for the mixture.
Researchers have found that silica fume alone can cause cracking, thus replacing
the silica fume with another additive could reduce or prevent concrete from
cracking as well as eliminate other problems silica fume presents in concrete
mixtures. Cracking is due to the molecular shape of the silica fume. The
increased water demand is due to its high surface area of approximately 20,000
m2/kg. Silica fume is limited in availability, making it an expensive SCM. The
focus of this research study is to evaluate another type of SCM that can replace
silica fume in high strength concrete while keeping its high strength properties.
- 1 -


Research has shown that ultra-fine fly ash (UFFA) can act similar to silica fume
in that it also increases concrete strength, increases cohesiveness, and decreases
permeability. It has not been found to contribute to concrete cracking. In
addition, the amount of water needed for lubrication of the concrete mixture
decreases. UFFA has a lower tendency to crack because it experiences
autogenous shrinkage, something that silica fume cannot experience due to its
molecular makeup.
1.2 Objectives
This study analyzed the use of both silica fume and UFFA to compare the fresh
and hardened properties of each. It was expected to find that UFFA exhibited
similar properties to silica fume with a reduction in the water content in high
strength concrete.
1.3 Scope
This study analyzed two types of high strength concrete, Colorado Department of
Transportation (CDOT) Type H and HT structural concrete. Both CDOT Type H
and HT structural concrete are used for bare concrete bridge decks that will not
receive a waterproofing membrane (CDOT, 2005). The difference between the
-2-


two is that CDOT Type HT concrete is used as the top layer of concrete but the
specifications for both types of concrete are identical.
-3-


Chapter 2
Review of the Literature
2.1 Ultra-Fine Fly Ash (UFFA)
The difference between fly ash and UFFA is particle size. Fly ash particles are
typically 20 microns in diameter while UFFA particles are about 3 microns in
diameter. Figure 1 shows a microscopic view of an UFFA particle.
Figure 1: Micrograph of Ultra-Fine Fly Ash (U.S. Department of Energy, 2007)
The ACI Manual states that the fineness of fly ash in concrete is a consistent
indicator of fly ash performance and that performance increases with fineness
-4-


(ACI 232.2R, 1996). The Federal Highway Administration (FHWA) found that
finer particles, such as UFFA, might more completely react than coarser particles
leading to higher durability and strength benefits at an earlier concrete age
(FHWA, 2003). UFFA is more efficient than fly ash and may offer a viable
alternative to silica fume in certain applications (Obla et.al. 2003). A study
comparing 8% and 12 % substitution of UFFA with baseline straight portland
cement concrete showed that UFFA decreases chloride permeability and diffusion
coefficient, and increases direct current resistivity of concrete (FHWA, 2003).
2.1.1 Fresh Concrete Properties
2.1.1.1 Slump
Slump is a measurement of workability. Studies have shown that since UFFA
reduces water content, workability is increased compared to concretes with the
same water content (Obla, et.al, 2003). The workability increases due to the
spherical shape of the UFFA.
-5-


2.1.2 Hardened Concrete Properties
2.1.2.1 Compressive Strength
Many studies have found that UFFA produces concrete strength comparable to
silica fume (Obla, et.al. 2003). To reach the performance levels of silica fume
concrete at an early age, the concentration of UFFA must be slightly greater than
that of the silica fume content. This study also found that the total water content
can be reduced by as much as 10%.
2.1.2.2 Permeability
Studies have shown that in the chloride ion penetration test, the addition of UFFA
reduced the permeability category compared to 100% portland cement control
mixtures (Obla, et.al., 2003). However, compared to silica fume concretes, the
UFFA mixtures had slightly higher permeability values.
2.2 Silica Fume
Silica fume is created from the smoke that results from heating quartz, coal, and
woodchips. It consists primarily of amorphous silicon dioxide, making it a very
reactive pozzolan. Silica fume particles are spherical in shape with an average
-6-


diameter of about 0.1 microns. See Figure 2. This is approximately 1/100 of the
size of an average cement particle.
Figure 2: Micrograph of Silica Fume (www.silicafume.org. 2007)
'y
The surface area of silica fume is approximately 20,000 m /kg. Finer particles
will react more quickly or to a greater extent than coarser ones; however, the
increased water demand of finer silica fumes may offset, to some degree, the
beneficial effects of the increased reactivity of the particles, unless a water-
reducing admixture or high-range water-reducing admixture is used (ACI 234R,
1996). The quality of the silica fume is specified by ASTM C 1240 and
AASHTO M 307.
-7-


2.2.1 Fresh Concrete Properties
Fresh concrete containing silica fume is more cohesive and less prone to
segregation than concrete without silica fume. Because of the very high surface
area of silica fume of about 20,000 m2/kg, the water demand becomes quite high.
When combined with very low water contents there is little, if any, bleed water.
This results in the concrete being finished and completed sooner. However, the
lack of bleeding also means that under the appropriate environmental conditions,
the concrete will dry from the surface downward, making it more susceptible to
plastic shrinkage cracking (Jaber, 2007).
2.2.1.1 Slump
The Colorado Department of Transportation (CDOT) study found that the
fineness of silica fume requires the use of high range water reducers, which may
result in rapid slump loss. The CDOT study also found that silica fume has a high
heat of hydration and tends to be sticky and difficult to finish (CDOT, 2001).
Concrete mixtures with over 5% silica fume exhibit increased water demand and
less workability when compared to concrete with UFFA.
-8-


2.2.2 Hardened Concrete Properties
In hardened concrete, silica fume particles increase the packing of the solid
materials by filling the spaces between the cement grains (ACI 234R, 1996). The
minute silica fume particles can improve packing in the interfacial transition zone,
which is frequently the weakest area of the concrete.
2.2.2.1 Compressive Strength
Silica fume increases the strength of concrete largely because it increases the
strength of the bond between the cement paste and aggregate particles (Mindess
et. al., 2003). It has been found that silica fume improves compressive strength,
bond strength, and abrasion resistance. The improvements in concrete properties
from the addition of silica fume stem from both the mechanical improvements
resulting from the addition of a very fine powder to the cement paste matrix as
well as from pozzolanic reactions between the silica fume and free calcium
hydroxide in the paste (Detwiler, et.al., 1989).
2.2.2.2 Permeability
According to the Silica Fume Association, silica fume concrete with a low water
content is highly resistant to penetration by chloride ions. Freeze-thaw testing
-9-


(ASTM C 666) on silica fume concrete demonstrated acceptable results with the
average durability factor greater than 99% (Luther and Hansen. 1989; Ozyildirim,
1986).
2.3 Conclusion
Past research on silica fume and ultra-fine fly ash have shown:
Fresh Concrete Properties
o Slump
UFFA increases the workability due to its spherical
molecular shape
Silica fume decreases the workability due to its increased
the water demand in concrete
Hardened Concrete Properties
o Compressive Strength
Both UFFA and silica fume increase the compressive
strength of concrete when compared to 100% portland
cement mixtures.
o Permeability
- 10-


Compared to silica fume concretes, UFFA mixtures have
slightly higher permeability values
- 11 -


Chapter 3
Experimental Procedures and Research Program
3.1 General
This study sought to determine if UFFA was a viable replacement for silica fume
in high strength concrete. The fresh and hardened concrete properties were
compared between UFFA and silica fume to determine if UFFA could replace
silica fume in the CDOT Type H and HT concretes.
3.2 Scope
This research focused on the effect of water to cementitious materials ratio (w/cm)
as well as the effect that differing amounts of UFFA has on CDOT Type H and
HT concretes. To examine these effects, the concrete mixtures contained a w/cm
of either 0.38 or 0.42. In addition, the concrete mixtures contained UFFA values
of 0%, 5%, and 10%. If no UFFA was used in the mixture, 4% of silica fume was
used and tested to determine the effects of UFFA and w/cm on concrete properties.
The two mixtures with silica fume acted as the control mixtures for this research.
- 12-


3.3 Specifications for CDOT Type H and Type HT Concrete
According to the CDOT Standard Specifications for Road and Bridge
Construction, Class H concrete is used for bare concrete bridge decks that do not
receive a waterproofing membrane (CDOT, 2005). Class HT concrete is used as
the top layer for bare concrete bridge decks. Table 1 shows the CDOT
requirements for each mixture:
Table 1: Concrete Requirements (CDOT Standard Specifications Table 601-1,2005)
Concrete Class Required Field Compressive Strength Cement Content Air Content Water Cement Ratio
H 4500 psi at 56 days 580 to 640 pcy 5 8% 0.38-0.42
HT 4500 psi at 56 days 580 to 640 pcy 5 8% 0.38 0.42
1 psi = 6.89 kPa
1 pcy = 0.59 kg/m3
This table shows that both Class H and Class HT concrete must meet the same
requirements. Additional requirements for these two classes are:
1. Concrete shall contain a minimum of 55 percent AASHTO M 43 size No.
67 coarse aggregate
2. Concrete shall contain cementitious materials in the following ranges:
- 13-


a. 450 to 500 pounds per cubic yard (267 to 296 kg/m3) Type II
Portland cement
b. 90 to 125 pounds per cubic yard (53 to 74 kg/m3) fly ash
c. 20 to 30 pounds per cubic yard (12 to 18 kg/m3) silica fume
3. Laboratory trial mix for Class H concrete must not exceed permeability
of 2000 coulombs at 56 days (ASTM C 1202)
4. Laboratory trial mix for Class H concrete must not exhibit a crack at or
before 14 days in the cracking tendency test (AASHTO PP 34)
3.4 Materials
The materials used in the concrete included ASTM Type I/II portland cement,
fine aggregate, coarse aggregate, fly ash, silica fume, and UFFA. The material
specifications are shown in detail in Appendix A.
3.4.1 Portland Cement
CDOT specifies that portland cement must follow ASTM C 150 requirements. In
addition, the maximum percent of equivalent alkalis (Na20 + 0.658 K2O) shall
not exceed 0.90 percent. Specifications for the type of cement used in this
experiment were not available, however, Holcim Type I/II portland cement was
- 14-


used for this research. It is assumed that the cement used met the ASTM C 150
requirements.
3.4.2 Fine Aggregate
According to the CDOT specifications, the fine aggregate should meet the
requirements specified in section 703.01. This section states the following
criteria:
The amount of material finer than 75 pm (No. 200) sieve shall not exceed
three percent by dry weight of fine aggregate, when tested in accordance
with AASHTO T 11 or Colorado Procedure 31, Method D, unless
otherwise specified
The minimum sand equivalent, as tested in accordance with AASHTO T
176 shall be 80 unless otherwise specified
The fineness modulus, as determined by AASHTO T 27, shall not be less
than 2.50 or greater than 3.50 unless otherwise approved
The sieve analysis of fine aggregate used in this study, shown in Appendix A,
shows that the amount of material finer than the No. 100 sieve is 1.6%, thus the
amount finer than the No. 200 sieve is less than the maximum 3%. The fineness
- 15-


modulus is 2.63, which is between the required 2.50 and 3.50 values. The fine
aggregate meets the CDOT requirements.
3.4.3 Coarse Aggregate
The CDOT specification for Type H and HT concretes calls for the use of No. 67
coarse aggregate, following section 703.02. This section states that coarse
aggregate shall conform to the grading in Table 703-2 (CDOT, 2005). The No.
67 coarse aggregate was not available for use in this experiment, thus a size No. 8
aggregate was used. The following table is a summary of the CDOT Standard
Specifications Table 703-2 that compares No. 67 aggregate to No. 8 aggregate.
Table 2: Concrete Aggregate Gradation Table
Percentage Passing Designated Sieves and Nominal Size Designation
Sieve Size Coarse Aggregates (from AASHTO M 43)
No. 67 No. 8
1 in. 100
3/4 in. 90-100
1/2 in. 100
3/8 in. 20-55 85-100
#4 0-10 10-30
#8 0-5 0-10
#16 0-5
- 16-


This table shows that the No. 67 aggregate is larger than the No. 8 aggregate used
in this study. Generally, an increase in aggregate size will improve concrete
durability because there will be less paste subject to chemical or physical attack.
However, if an aggregate is susceptible to freeze-thaw damage, a reduction in
aggregate size will improve durability.
3.4.4 Fly Ash
According to the CDOT specifications, the fly ash should meet the requirements
specified in section 703.02. This section states fly ash for concrete shall
conform to the requirements of ASTM C 618, Class C or Class F (CDOT 2005).
The Class C fly ash used in this study meets the requirements of ASTM C 618, as
shown in Appendix A.
3.4.5 Silica Fume
The silica fume admixture shall conform to the requirements of subsection 701.03
of the CDOT specifications, which states that silica fume shall conform to the
requirements of ASTM C 1240 (CDOT, 2005). Specifications for the silica fume
used in this study are not available. It is assumed that the silica fume meets the
CDOT requirements.
- 17-


3.4.6 Ultra-Fine Fly Ash
The UFFA is manufactured at one power station in Texas, Boral Mineral
Technologies, under the trademark Micron This UFFA is generally an
amorphous alumina silica and silicate with iron and calcium as the other major
constituents. This UFFA is spherical in shape and has a mean particle diameter
ranging from only 2.6 to 3.4 microns with over 90% of the material having a
particle diameter less than 7 microns. Conventional fly ash contains particle sizes
ranging from 5 to 100 microns with the mean diameter of about 20 microns. As
shown in Appendix A, the Class F UFFA used in this research meets the
requirements of ASTM C618.
3.5 Experimental Procedures
3.5.1 Mixtures and Batching
For this research, six mixture designs were batched following ASTM C 192
Standard Practice for Making and Curing Concrete Test Specimens in the
Laboratory (AASHTO T 126-97 Making and Curing Concrete Test Specimens in
the Laboratory). Each design met the CDOT Class H and Class HT material
- 18-


requirements with the exception of the coarse aggregate not meeting the size No.
67 requirement. Table 3 lists the six mixture designs used in this study.
Table 3: Mixture Design Table
MIX ID UFFA-A UFFA-B UFFA-C UFFA-D SF-A SF-B
Cement (lbs/yd3) 450 420 450 420 480 480
Fly Ash (lbs/yd3) 120 120 120 120 120 120
Micron 3 (lbs/yd3) 30 60 30 60 0 0
Silica Fume (lbs/yd3) 0 0 0 0 24 24
Coarse Aggregate (lbs/yd3) 1883 1883 1883 1878 1883 1883
Fine Aggregate (lbs/yd3) 1149 1143 1086 1079 1092 1155
Water (lbs/yd3) 259 259 283 288 283 260
Water to Cement Ratio 0.38 0.38 0.42 0.42 0.42 0.38
1 pcy = 0.59 kg/m3
When batching mixture UFFA-B (w/cm=0.38, UFFA=10%), an error in measuring
occurred. This error was discovered after this material was added to the concrete
mixer so the mixture was modified in an effort to maintain the w/cm and the
percentage of UFFA. The modified batch mix is shown in Table 4.
- 19-


Table 4: Modified UFFA-B Mixture Design Table
MIX ID UFFA-B
Cement (lbs/yd3) 597
Fly Ash (lbs/yd3) 170
Micron 3 (lbs/yd3) 85
Silica Fume (lbs/yd3) 0
Coarse Aggregate (lbs/yd3) 1883
Fine Aggregate (lbs/yd3) 1143
Water (lbs/yd3) 365
Water to Cement Ratio 0.38
1 pcy = 0.59 kg/m3
From Table 1, the cementitious content is required to be between 580 and 640 pcy
5
(344 and 380 kg/m ). This includes the portland cement, fly ash, UFFA, and
silica fume. As shown in Table 3, the sum of the cementitious content of the
-3
mixtures used ranged from 600 to 624 pcy (356 to 370 kg/m ), within the required
range. As shown in Table 4, the total cementitious material for UFFA-B is 852
pcy (505 kg/m ), which is greater than the maximum of 640 pcy (380 kg/m ).
-20-


Also from Table 1, the w/cm must be maintained between 0.38 and 0.42. The
w/cm of the mixtures is either 0.38 or 0.42, meeting these criteria. The
requirements of air content and compressive strength are discussed in sections
4.2.2 and 4.3.1, respectively.
Listed are the additional CDOT requirements for Type H and HT concrete:
1. Concrete shall contain a minimum of 55 percent AASHTO M 43 size No. 67
coarse aggregate
CDOT requires that each mixture should be 55% No. 67 coarse aggregate by
volume. Equation 1 was used to determine the volume of coarse aggregate.
W
V =----------- Equation 1
SG x 62.4
where:
V = volume of material
W = weight of material in lbs
SG = specific gravity of material from Appendix A
The absolute volume method was used to design all of the mixtures used in this
research study. Thus, Equation 1 was used for each material in order to determine
-21 -


the volume that each material represented within the mixture. The specific
gravity of each material is shown in Table 5.
Table 5: Specific Gravity
Specific Gravity
Cement 3.15
Fly Ash 2.36
Micron3 2.57
Silica Fume 2.20
Coarse Aggregate 2.62
Fine Aggregate 2.67
Water 1
The complete batch mixture calculations are shown in Appendix B and Table 6
lists a summary of the volumes of the materials used in each mixture.
-22-


Table 6: Batch Volumes per Cubic Foot
UFFA- A UFFA- B UFFA- C UFFA- D SF-A SF-B
Cement 2.29 2.14 2.29 2.14 2.44 2.44
Fly Ash 0.72 0.72 0.72 0.72 0.72 0.72
Micron3 0.19 0.38 0.19 0.38 0 0
Silica Fume 0 0 0 0 0.17 0.17
Coarse Aggregate 11.71 11.71 11.71 11.71 11.71 11.71
Fine Aggregate 7.09 6.86 6.70 6.66 6.74 7.12
Water 3.65 4.32 4.04 4.04 4.04 3.65
Air 1.35 1.35 1.35 1.35 1.35 1.35
Total 27.00 27.00 27.00 27.00 27.00 27.00
% Coarse Aggregate 43% 43% 43% 43% 43% 43%
1 cf = 0.03 cubic meters
This table shows that none of the mixtures contained the required 55% of coarse
aggregate because during the initial batch design, this criteria was overlooked.
This could affect the results for both the fresh and hardened properties of the
concrete. For the fresh properties, the amount of aggregate affects the slump. For
a constant w/cm, an increase in the aggregate/cement ratio will decrease the
workability; also, more cement is needed when finer aggregate gradings are used
(Mindess et. al., 2003). For this experiment, the slump, which measures
-23-


workability, will be higher than expected for mixtures containing a higher volume
of aggregate.
2. Concrete shall contain cementitious materials in the following ranges:
a. 450 to 500 pounds per cubic yard (267 to 297 kg/m3) Type II portland
cement
All of the mixtures meet this criterion except for mixtures UFFA-B (w/cm=0.38,
UFFA=10%) and UFFA-D (w/cm=0.42, UFFA=10%). UFFA-B (w/cm=0.38,
UFFA=10%) contains 597 pcy (354 kg/m3) of portland cement. UFFA-D
(w/cm=0.42, UFFA=10%) only contains 420 pcy (249 kg/m3) of portland cement
because the increased amounts of UFFA replaced cement.
3
b. 90 to 125 pounds per cubic yard (53 to 74 kg/m ) fly ash
-3
120 pcy (71 kg/m ) of fly ash is used in all mixtures except mixture UFFA-B
(w/cm=0.38, UFFA=10%) contains 170 pcy (101 kg/m3) of fly ash, greater than
-3
the maximum of 125 pcy (74 kg/m ) allowed.
c. 20 to 30 pounds per cubic yard (12 to 18 kg/m ) silica fume
Only mixtures SF-A and SF-B meet this criterion while the other mixtures used
UFFA to replace the silica fume.
-24-


3. Laboratory trial mixture for Class H concrete must not exceed permeability of
2000 coulombs at 56 days (ASTM C 1202).
The permeability results are discussed in section 4.3.3.
4. Laboratory trial mixture for Class H concrete must not exhibit a crack at or
before 14 days in the cracking tendency test (AASHTO PP 34).
The cracking tendency test was not performed in this research study.
Each mixture was batched such that the volume was 1.68 cubic feet (0.05 cubic
meters), allowing for 18 cylinders and 2 freeze-thaw beams per mixture to test for
compression, durability, and permeability. For mixture UFFA-B (w/cm=0.38,
UFFA=10%), the trial batch volume was 2.00 cubic feet (0.06 cubic meters) to
correct for the error in measuring the water.
3.5.2 Curing
Once the mixtures were batched and molded, they were moist cured until time for
testing. For moist curing, the samples were placed in water tanks in a room with a
-25-


constant temperature of 73 + 3F (23C). The samples remained completely
submerged in water until testing was performed.
3.5.3 Fresh and Hardened Concrete Tests
For each mixture batched, both the fresh and hardened concrete properties were
tested. The fresh concrete properties include slump, unit weight, air content, and
concrete temperature. The hardened properties include compressive strength,
freeze-thaw durability, and permeability. Both the fresh and hardened concrete
tests are shown in Table 7.
-26-


Table 7: Fresh and Hardened Concrete Tests
Fresh Concrete Tests Standard Time of Test
Slump ASTM C 143, AASHTOT 119 At Batching
Unit Weight ASTM C 138, AASHTOT 121 At Batching
Air Content ASTM C 231, AASHTOT 152 At Batching
Temperature ASTM C 1064, AASHTO T 309 At Batching
Hardened Concrete Tests Standard Time of Test
Compressive Strength ASTM C 39, AASHTO T 22 1, 7, 28, 56 Days
Durability ASTM C 666, Procedure A AASHTO T 161 14 and Subsequent Days
Permeability ASTM C 1202 28 and 56 Days
At the time of batching, 18 cylinders and 2 freeze-thaw beams were cast for each
mixture. The cylinders were 4 inches (101.6 mm) in diameter and 8 inches (203.2
mm) in length and the freeze-thaw beams measured 3 inches (76.2 mm) in width,
4 inches (101.6 mm) in depth, and 16 inches (406.4 mm) in length.
-27-


Chapter 4
Results and Discussion
4.1 General
4.2 Fresh Concrete Tests
As previously mentioned, the fresh concrete tests included slump, unit weight, air
content, and concrete temperature. The fresh concrete properties were determined
at batching and recorded. See Table 8.
Table 8: Fresh Concrete Properties
UFFA- A UFFA- B UFFA- C UFFA- D SF-A SF-B
w/cm 0.38 0.38 0.42 0.42 0.42 0.38
Slump (in.) 0.50 5.25 0.25 7.50 0.50 0.25
Air Content (%) 2.6 2.2 2.1 1.7 2.9 6.8
Concrete TemperatureF 74 75 74 74 76 76
Weight of Bucket (lbs) 7.90 7.90 7.90 7.90 7.90 7.90
Volume of Bucket (cf) 0.25 0.25 0.25 0.25 0.25 0.25
Weight of Bucket + Concrete (lbs) 44.40 43.75 44.85 43.85 43.90 43.40
Unit Weight (pcf) 146.0 143.4 147.8 143.8 144.0 142.0
-28-


4.2.1 Slump
The mixtures with the highest w/cm were expected to measure the highest slump.
These mixtures were UFFA-C (w/cm=0.42, UFFA=5%), UFFA-D (w/cm=0.42,
UFFA=10%), and SF-A (w/cm=0.42, SF=4%). Although mixture UFFA-D
(w/cm=0.42, UFFA=10%) measured the highest slump of 7.50 inches (190.5 mm),
the other mixtures with a w/cm of 0.42 only measured 0.25 and 0.50 inches (6.35
and 12.7 mm). The mixtures with the lowest w/cm were expected to measure the
lowest slump values. These mixtures were UFFA-A (w/cm=0.38, UFFA=5%),
UFFA-B (w/cm=0.38, UFFA=10%), and SF-A (w/cm=0.38, SF=4%). Mixtures
UFFA-A (w/cm=0.38, UFFA=5%) and SF-A (w/cm=0.38, SF=4%) both measured
slumps of only 0.50 inches (12.7 mm). Mixture UFFA-B (w/cm=0.38,
UFFA=10%), however, measured a slump of 5.25 inches (133.35 mm), the
second highest slump measured. These results imply that more than just the w/cm
affects the slump. Figure 3 illustrates the effects of UFFA and silica fume on
slump.
-29-


12
_ 10
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61
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CM
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1 inch = 25.4 mm
Mixture
Slump
% Ultra-fine Fly Ash
% Silica Fume
Figure 3: Effects of UFFA and Silica Fume on Slump
This figure illustrates that an increase in the UFFA content of the mixture results
in a higher slump value, even at a low w/cm as was the case for mixture UFFA-B
(w/cm=0.38, UFFA=10%). Because slump is a measure of workability, it is
possible to have greater workability with a low w/cm by increasing the UFFA
replacement to 10%. UFFA is able to increase the workability due to its spherical
particles having a low surface-to-volume ratio, requiring less mortar to coat the
particles and leaving more to provide for workability (Mindess, 2003).
-30-


The mixtures other than UFFA-B and UFFA-D, measured comparable slumps of
either 0.25 or 0.50 inches (6.35 or 12.70 mm). The common thread these
mixtures share is that neither of them contain more than 5% UFFA. Mixtures
UFFA-A and SF-A both measured slumps equal to 0.5 inches (12.70 mm).
Mixtures UFFA-C and SF-B measured slumps equal to 0.25 inches (6.35 mm).
These results indicate that an addition of more than 5% of UFFA is needed to
result in higher slump values.
Comparing mixtures UFFA-A and SF-B shows that the slump increases by 0.25
inches (6.35 mm) when adding 5% UFFA replacement at a w/cm of 0.38.
Comparing mixtures UFFA-C and SF-A indicates that the slump decreases by
0.25 inches (6.35 mm) when adding 5% UFFA replacement at a w/cm of 0.42.
Since this change in measured slump is small, only 0.25 inches (6.35 mm), the
conclusion drawn for this result is that UFFA does not affect the measured slump
when only 5% is added; however, a significant increase in slump is observed
when the UFFA increases to a 10% replacement.
-31 -


The CDOT specifications for Type H and HT concrete do not stipulate required
slump values. To be workable in the field, slump values should range between 3
and 6 inches (76.2 and 152.4 mm), which only mixture UFFA-B meets. This
study found that a 10% replacement of UFFA could replace silica fume to
produce better slump results at a lower w/cm. The measured slump of mixture
UFFA-D of 7.5 inches (190.5 mm) is higher than typically used in the field.
4.2.2 Air Content
No air entraining agents were used in any of the six mixtures because this
research focused on comparing how the addition of UFFA and silica fume affect
the strength, permeability, and durability of concrete mixtures. The addition of
air would increase the durability of the concrete mixtures and might not allow this
research to compare the sole affects of UFFA and silica fume alone on durability.
In addition, air content has a contributing factor on compressive strength and
permeability.
The pressure method (ASTM C 231) was used to measure the total air content of
the concrete. This method measures the change in volume of the concrete when
-32-


subjected to a given pressure. Since no air entraining admixtures were used, the
measured air content is only entrapped air, not entrained air.
Because no air entraining agents were used, the air content was expected to be
approximately 2%. Figure 4 shows the actual air content of each mixture.
Air Content
UFFA-A UFFA-B UFFA-C UFFA-D SF-A SF-B
Mixture
Figure 4: Air Content
As expected, all of the air contents except for SF-B measured around 2%.
Mixture SF-B measured an air content of 6.8%, much higher than the expected
2%. Reasons for this mixture to contain such a high air content could be due to an
error in conducting the air content test.
-33-


The required air content for Type H and HT concretes is 5-8%. To achieve this
air content amount, air entraining admixtures would need to be used. By adding
an air-entraining admixture, the compressive strengths would be reduced by
approximately 5% for each 1% increase in air content. By adding 5% of air, the
compressive strength would decrease by 25%. This is further discussed in section
4.3.1.
4.2.3 Unit Weight
The unit weight was determined by first weighing a known volume of concrete
immediately before conducting the air content test. Then, the weight of the
bucket was subtracted from the weight of the concrete plus bucket and then
divided by the volume of the bucket. Table 9 compares the measured unit weight
to the predicted unit weight of each mixture.
-34-


Table 9: Unit Weight Comparison
UFFA- A UFFA- B UFFA- C UFFA- D SF-A SF-B
Predicted Unit Weight (pcf) 144.1 141.5 142.7 142.4 143.8 145.2
Measured Unit Weight (pcf) 146.0 143.4 147.8 143.8 144.0 142.0
1 pcf = 16.02 kg/m3
This table shows that the measured unit weight values were higher than the
predicted unit weights in all mixtures except SF-B. This difference can be due to
the estimate of air content because air contributes to the volume of the concrete
but not to its weight.
To further investigate this, the unit weight including the actual air content was
calculated to compare to the measured unit weight. The volume of the air was
estimated to be 5% to obtain the predicted unit weights. For the estimation of 5%
air, the volume was 0.05 cy (0.04 cubic meters) multiplied by 27, which equals
1.35 cf (0.04 cubic meters). Since this estimation was much higher than the
measured air contents, except mixture SF-B, the predicted volume is lower than
the measured volume, resulting in a lower predicted unit weight. For SF-B, the
estimated air content is less than the actual air content, resulting in a higher
-35-


predicted unit weight. The corrected unit weight based on the measured air
content is shown in Table 10.
Table 10: Corrected Unit Weights
UFFA- A UFFA- B UFFA- C UFFA- D SF-A SF-B
Predicted Unit Weight (pcf) 144.1 141.5 142.7 142.4 142.9 144.3
Corrected Unit Weight (pcf) 147.6 145.2 147.0 147.3 145.9 141.8
Measured Unit Weight (pcf) 146.0 143.4 147.8 143.8 144.0 142.0
1 pcf = 16.02 kg/mJ
This table shows that the corrected unit weights are higher than the predicted unit
weights except for the SF-B (w/cm=0.38, SF=4%) mixture. This is a result of the
predicted air content being higher than the actual air content. Comparing the
corrected unit weight to the measured unit weight shows that the corrected unit
weights are somewhat higher than the measured unit weights except in mixtures
UFFA-C and SF-B. The corrected unit weights are much closer to the actual unit
weights than the predicted unit weights.
4.2.4 Concrete Temperature
The temperature of the concrete ranged from 74 to 76 degrees Fahrenheit (23 to
24 degrees Celsius). According to Mindess et al., the optimum concrete
-36-


temperature should be in the range of 50 to 60 degrees Fahrenheit (10 to 16
degrees Celsius) (Mindess et. al., 2003). A major problem associated with high
concrete temperatures is moisture loss due to evaporation. Water was not added
to compensate for high temperatures because although the temperature of the
concrete was above the optimum temperature, it remained below 85 degrees
Fahrenheit (29 degrees Celsius), which according to Mindess et al., is the
maximum temperature concrete should not exceed. The small variation in
temperature was assumed not enough to affect the concrete properties for
comparison purposes.
4.3 Hardened Concrete Tests
The hardened concrete tests performed during the study were compressive
strength, permeability, and freeze-thaw durability.
4.3.1 Compressive Strength
The compressive strength of concrete is perhaps the most important design factor
in concrete. Compressive strengths were measured at 1, 7, 28, and 56 days of age.
-37-


Three cylinders were tested in compression for each mixture and the maximum
loads in units of pounds were recorded. See Table 11.
Table 11: Maximum Load (lbs)
UFFA-A UFFA-B UFFA-C UFFA-D SF-A SF-B
Day 1 11,845 27,575 7085 9195 24,555 24,775
11,515 26,305 4945 9670 22,435 25,020
12,130 27,805 8675 9125 25,270 24,210
Day 7 63,595 69,915 50,465 42,675 62,290 68,230
65,830 68,425 24,910 42,740 54,250 42,465
68,580 72,705 53,435 44,570 64,795 29,205
Day 28 30,670 100,985 61,970 57,925 82,065 85,545
26,710 101,905 63,585 57,680 81,780 83,065
79,535 99,905 23,875 54,570 83,575 82,495
Day 56 93,070 108,835 39,040 71,485 100,925 96,865
83,075 107,400 57,940 75,435 97,125 91,550
99,130 106,335 70,240 70,550 93,145 97,095
1 lb = 0.45 kg
The compressive strength of each mixture was then determined by dividing the
maximum load (lbs) by the cross-sectional area of the test cylinder (in ). These
values are recorded in Table 12.
Radius of cylinder = 2 in.
Cross-sectional area = m1 = n{2")2 = 12.57m2
^ , load
Compressive Strength = ---- Equation 2
area
-38-


Table 12: Compressive Strength Values (psi)
UFFA-A UFFA-B UFFA-C UFFA-D SF-A SF-B
Day 1 942 2194 564 732 1954 1971
916 2093 393 769 1785 1991
965 2212 691 730 2010 1926
Day 7 5059 5562 4015 3395 4955 5428
5237 5444 1982 3400 4315 3378
5456 5784 4241 3546 5155 2323
Day 28 2440 8034 4930 4608 6529 6805
2125 8107 5058 4589 6506 6608
6327 7884 1899 4341 6649 6563
Day 56 7404 8658 3106 5687 8029 7706
6609 8554 4609 6001 7723 7283
7886 8459 5588 5613 7410 7724
1 psi = 6.895 kPa
Figure 5 shows a cylinder loaded to failure.
-39-


Figure 5: Photograph of Compressive Strength Test
The average compressive strength values were then determined and recorded in
Table 13. If any of the compressive strengths differed by more than 8%, it was
not included in the average. Reasons for this variation include errors in
consolidating the concrete in the cylinder mold or an error in testing the concrete
in compression.
-40-


Table 13: Average Compressive Strengths (psi)
UFFA-A UFFA-B UFFA-C UFFA-D SF-A SF-B
Day 1 941 2166 549 744 1982 1963
Day 7 5251 5597 4128 3447 5055 5428
Day 28 6327 8009 4994 4513 6561 6659
Day 56 7645 8557 5588 5767 7876 7571
1 psi = 6.895 kPa
The average compressive strength values versus time were then plotted and are
shown in Figure 6.
Compressive Strength vs. Age
0 4
8
12 16 20 24 28 32 36 40 44 48 52 56
Age(Days)
Figure 6: Compressive Strength vs. Age
1 psi = 6.895 kPa
-41 -


This figure shows that by 7 days of age, the concrete reaches the majority of its
56-day compressive strength. This figure also indicates that mixture UFFA-B
(w/cm=0.38, UFFA=10%) exhibited the highest compressive strength for all test
days. This is most likely due to the increased amount of cementitious material in
the mixture. At 7 days, all mixtures except UFFA-C (w/cm=0.42, UFFA=5%) and
UFFA-D (w/cm=0.42, UFFA=10%) displayed similar compressive strength
values. This is presumably a result of the high w/cm of 0.42 for both mixtures.
Comparing these two mixtures to SF-A (w/cm=0.42, SF=4%), the addition of
silica fume was found to increase the compressive strength, even at a high w/cm.
Comparing the 56-day compressive strengths to the required CDOT Type H and
HT strengths showed that all six mixtures performed well above the required 4500
psi (31 MPa) compressive strength.
The following figure presents the percentage of each mixtures 56-day
compressive strength at 1, 7, and 28 days for each mixture.
-42-


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1 Day
7 Days
28 Days
56 Days
Figure 7: Rate of Strength Gain
Figure 7 shows that the mixtures containing UFFA, except UFFA-B (w/cm=0.38,
UFFA=10%), exhibited lower early strengths when compared to the silica fume
mixtures. This result proves that UFFA reduces the early age compressive
strength in concrete. At 7 days, UFFA-C (w/cm=0.42, UFFA=5%) and SF-B
(w/cm=0.38, SF=4%) reached the highest percentages of ultimate strength of 74%
and 72%, respectively. This result may imply that mixtures with low UFFA
replacements at a high w/cm act similarly to the silica fume mixtures with a low
-43-


w/cm at 7 days for compressive strength. The other mixtures at 7 days reached
comparable percentages of ultimate strength, ranging from 60-69%.
At 28 days, 94% of the ultimate compressive strength for UFFA-B (w/cm=0.38,
UFFA=10%) is reached. This is presumably due to the increased amount of
cementitious material in the mixture. Mixtures UFFA-C (w/cm=0.42, UFFA=5%)
and SF- B (w/cm=0.38, SF=4%) reached comparable percentages of ultimate
strength at 28 days of 89% and 88%, respectively. Mixtures UFFA-A
(w/cm=0.38, UFFA=5%) and SF-A (w/cm=0.42, SF=4%) both reached 83% of
ultimate strength at 28 days.
As mentioned earlier in section 4.2.2, the air content should be increased by
approximately 5% in all mixtures, except SF-B (w/cm=0.38, SF=4%), to meet the
CDOT specification for air content. Mixture SF-B (w/cm=0.38, SF=4%)
contained 6.8% of air, which falls in the required range of 5-8%. It is unknown
how this mixture contained such a large amount of air since no air entraining
admixtures were used and is assumed as an error in measuring the air content.
The addition of 5% of an air entraining admixture would decrease the
-44 -


compressive strength by 25% because for every 1% increase in air, the
compressive strength decreases by 5%. The following figure shows the
compressive strength values of all mixtures decreased by 25%:
Compressive Strength vs. Age
Age (Days)
Figure 8: Reduced Compressive Strength
This figure illustrates that neither mixture UFFA-C (w/cm=0.42, UFFA=5%) nor
UFFA-D (w/cm=0.42, UFFA=10%) met the CDOT required 4500 psi (31 MPa)
-45-


compressive strength when the compressive strength was decreased by 25% to
account for the air content. These two mixtures have the highest w/cm ratio of
0.42 for the UFFA mixtures. The other mixture with a w/cm ratio of 0.42, SF-A,
met the 4500 psi (31 MPa) compressive strength requirement, showing that silica
fume is more effective in increasing the compressive strength of concrete than
UFFA. Figure 9 illustrates the difference between the required compressive
strength and the actual compressive strength for each mixture with the 25%
reduction:
-46-


Difference from Required Compressive Strength
Figure 9: Difference from Required Compressive Strength
Figure 9 illustrates that both UFFA-C (w/cm=0.42, UFFA=5%) and UFFA-D
(w/cm=0.42, UFFA=10%) failed to meet the specified requirement of 4500 psi (31
MPa) by 7% and 4%, respectively.
The mixtures should be designed for more than the minimum specified
requirement for compressive strength of 4500 psi (31 MPa). From Table 9-11 of
-47-


the PCA Manual, the required average compressive strength can be found by
using the following equation:
fc+ 1200 Equation 3
The design compressive strength is now 4500 psi + 1200 psi = 5700 psi (39.3
MPa). All of the mixtures except for UFFA-C (w/cm=0.42, UFFA=5%) and
UFFA-D (w/cm=0.42, UFFA=10%) met this compressive strength requirement.
4.3.2 Durability
The deterioration of concrete exposed to freezing and thawing is caused by the
expansion of freezing water in the void system of the cement paste of the concrete
aggregates (Cordon, 1966). To test for durability, the method of ASTM C 666,
Procedure A AASHTO T 161 was utilized in this study. Using this method, two
beams from each mixture were subjected to freezing and thawing at a rate of 4
cycles per day. For this process, the molded beam specimens were moist cured
for 14 days. At 14 days, the beams were weighed and tested for fundamental
frequency. These values were recorded and the beams were then placed in the
freeze/thaw chamber.
-48-


In the chamber, each specimen is placed in a metal container. Each metal
container is then filled with water and the chamber lid is closed. Once the lid is
closed, the freeze/thaw cycle begins. The cycle alternates from 0 to 40F (-17 to
4C) four times a day. Every seven days, the beam specimens were removed
from the chamber to be weighed and tested for frequency. A beam specimen is
being tested for fundamental frequency in Figure 10.
Figure 10: Photograph of Durability Test
-49-


As shown in Figure 10, the device located on top of the middle portion of the
beam sends a frequency through the beam. The sensor on the left side of the
beam measures the frequency that travels through the deteriorated beam. As the
beam deterioration increases, the measured frequency will decrease due to the
formation of small micro-cracks within the concrete. A higher frequency implies
that less cracks occur inside the concrete beam. Beams with a high amount of
cracks or voids exhibit low frequencies since the frequency wave is terminated at
these voids. The frequency and weight of each beam specimen were recorded in
Tables 14 through 19.
-50-


Table 14: UFFA-A Freeze/Thaw Results
DAY UFFA-A-1 UFFA-A-2
FREQUENCY (HZ) MASS (G) FREQUENCY (HZ) MASS (G)
14 2134 7245.5 2144 7368.7
21 996 7287.2 1009 7408.8
28 - 7279.2 322 7353.9
Table 15: UFFA-B Freeze/Thaw Results
DAY UFFA-B-1 UFFA-B-2
FREQUENCY (HZ) MASS (G) FREQUENCY (HZ) MASS (G)
14 2118 7500.2 2123 7390.4
21 1250 7515.7 1238 7403.5
28 890 7490.9 984 7380.7
35 573 7410.2 597 7316.6
42 - 7259.2 452 7317.8
Table 16: UFFA-C Freeze/Thaw Results
DAY UFFA-C-1 UFFA-C-2
FREQUENCY (HZ) MASS (G) FREQUENCY (HZ) MASS (G)
14 1994 6854.3 1894 6743.0
21 511 6732.2 686 6828.0
28 805 6091.4 6587.6
Table 17: UFFA-D Freeze/Thaw Results
DAY UFFA-D-1
FREQUENCY (HZ) MASS (G)
14 2026 6805.3
21 776 6795.5
28 590 6669.2
35 545 6543.9
-51 -


Table 18: SF-A Freeze/Thaw Results
DAY SF-A-1 SF-A-2
FREQUENCY (HZ) MASS (G) FREQUENCY (HZ) MASS (G)
14 2042 7057.1 1951 7073.0
21 1454 7108.5 1255 7091.4
28 693 6976.7 613 6952.5
35 918 7226.1 1116 7126.5
42 - 6806.8 - 6879.7
Table 19: SF-B Freeze/Thaw Results
DAY SF-1 B-l SF-1 B-2
FREQUENCY (HZ) MASS (G) FREQUENCY (HZ) MASS (G)
14 1755 6549.7 1651
21 950 6531.4 256 6614.4
28 738 6462.5 671 6046.2
35 723 6499.3 584 5928.5
42 - 6323.1 - 5366.8
49 - - - -
56 - - - -
The second beam for mixture UFFA-D broke before testing, thus was unable to
be subjected to the durability test. Figure 11 illustrates the relationship between
durability and freeze/thaw cycles.
-52-


Durablity Results
Figure 11: Durability Results
ASTM C 666 requires freezing and thawing cycles be continued for 300 cycles or
until the concrete has reached 60% of its initial value, whichever occurs first.
None of the six mixtures lasted more than 112 cycles of freezing and thawing.
This was expected since air entrainment was not used in the mixtures. Also
expected was that the higher the air content in a mixture, the higher the durability
of that mixture. In non-entrained paste, frost forms on the outer surface of the
specimen since air voids are not present. The capillaries then serve as the main
-53-


freezing site, resulting in cement paste that is severely damaged upon freezing
(Mindess et. al., 2003).
Figure 11 shows that both UFFA-A (w/cm=0.38, UFFA=5%) and UFFA-B
(w/cm=0.38, UFFA=10%) exhibit the highest initial frequency while SF-B
(w/cm=0.38, SF=4%) and UFFA-C (w/cm-0.42, UFFA=5%) exhibit the lowest
initial frequency. This result demonstrates that UFFA compared to silica fume
may increase the initial frequency.
Figure 11 also shows that the frequency decreases with time. Two of the
mixtures, UFFA-C and SF-A, measured an increase in frequency. This result is
most likely due to an error in measuring the frequency or the presence of ice
filling the concrete voids. When ice fills the voids, the frequency is allowed to
travel through the ice, measuring a higher frequency than if the beam was
completely thawed.
-54-


The durability factor is a value calculated to gage the performance of a concrete
mixture. From the frequencies obtained for each sample, the durability factor can
be calculated using Equation 4.
PN
DF =----- Equation 4
M
where:
DF = durability factor of the test specimen
P = relative dynamic modulus of elasticity at N cycles, %
N = number of cycles at which P reaches the specified minimum value for
discontinuing the test or the specified number of cycles at which the
exposure is to be terminated, whichever is less
M = specified number of cycles at which the exposure is to be terminated
The relative dynamic modulus of elasticity, P, is calculated by dividing the
measured frequency closest to 60% squared by the initial frequency squared and
then multiplying by 100. The number of cycles, N, at which P reaches 60% is
illustrated in Figure 12.
-55-


100
90
59 80
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c 70
3
O
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u_
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S 50
0)
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ra
c
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o
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0.
40
30
20
10
0
0 Cycles
28 Cycles
56 Cycles j
T CM T CM t CM T T CM T- CM
< < CD CQ 6 6 Q < < < < < < < LL LL LL LL
LL U_ LL LL LL LL LL O) CO CO CO
U_ LL LL LL LL LL LL
D D D D D D D
Figure 12: Rate of Frequency Loss
From Figure 12, the values closest to 60% were determined. For mixtures UFFA-
A (w/cm=0.38, UFFA=5%) and UFFA-B (w/cm=0.38, UFFA=10%), the 60%
value is closest to the frequency measured at 28 cycles. For samples UFFA-C-1
(w/cm=0.42, UFFA=5%) and SF-B-2 (w/cm=0.38, SF=4%), the measurement
closest to the 60% value appears to be at 56 cycles, but this is most likely an error
-56-


since the measured frequency at 28 cycles is lower than that at 56 cycles. The
value closest to 60% is assumed to be at 28 cycles for all mixtures except UFFA-
C-2 and SF-B-2, which use 56 cycles. As specified by ASTM C 666, the
specimen should be tested for 300 cycles, making this the M value. The
following table shows the initial frequency, the frequency closest to 60% of the
initial frequency, the relative dynamic modulus of elasticity, the number of cycles
at 60% frequency, and the durability factor, DF, for all samples.
Table 20: Durability Factors
Initial Frequency Frequency Closest to 60% of Initial Frequency Relative Dynamic Modulus of Elasticity Cycles Durability Factor
UFFA-A-1 2134 996 21.8 28 2.04
UFFA-A-2 2144 1009 22.1 28 2.07
UFFA-B-1 2118 1250 34.8 28 3.25
UFFA-B-2 2123 1238 34.0 28 3.18
UFFA-C-1 1994 805 16.3 56 3.04
UFFA-C-2 1894 686 13.1 28 1.23
UFFA-D-1 2026 776 14.7 28 1.37
SF-A-1 2042 1454 50.7 28 4.73
SF-A-2 1951 1255 41.4 28 3.86
SF-B-1 1755 950 29.3 28 2.74
SF-B-2 1651 671 16.5 56 3.08
-57-


Figure 13 presents the difference in durability factors for each mixture.
Durability Factor
SF-B-2
SF-B-1
H
iUr,;.'-.-u


SF-A-2
SF-A-1
UFFA-D-1
UFFA-C-2
UFFA-C-1
UFFA-B-2
UFFA-B-1
UFFA-A-2
UFFA-A-1

!>;-< lit-.'-
ftsswife-T.-1 'r m
0 1 2 3 4 5
Figure 13: Durability Factors
Figure 13 indicates that silica fume is more effective at increasing the durability
factor when compared to UFFA. When comparing the samples of silica fume
mixtures SF-A and SF-B to the other mixtures, the mixtures containing silica
fume have durability factors much higher than the UFFA mixtures except for
UFFA-B. This UFFA mixture exhibited a durability factor slightly greater than
-58-


mixture SF-B. This apparent similarity may not imply that at a low w/cm and high
UFFA use that the durability factor is greater than concrete mixtures containing
silica fume because the UFFA-B mixture has a higher cementitious content,
which increases durability. This figure also shows that the durability factor
increases as the air content increases.
Mass readings of each specimen were recorded at the time of frequency testing.
As deterioration of the concrete specimen occurs, the mass of that specimen
decreases. Figure 14 demonstrates the mass lost due to deterioration of the
samples until termination.
-59-


Cycles
Figure 14: Affects of Freezing and Thawing on Mass Loss
UFFA-B (w/cm=0.38, UFFA=10%) was found to have the highest mass and
experienced the least amount of mass lost during the test. Mixture SF-A
(w/cm=0.42, SF=4%) shows a mass gain for both samples at 140 cycles; however,
this is most likely due to the mass of ice that formed in and around the sample.
-60-


Mixture UFFA-C (w/cm=0.42, UFFA=5%) experienced the largest mass lost
during the cycle.
The modulus of elasticity of each concrete mixture was determined by the
fundamental frequency. The modulus of elasticity, Ed, was calculated by using
the following equation:
Ed = CWn2 Equation 5
where:
W = weight of the specimen, lbs
n = fundamental flexural frequency, Hz
C _ 0.00245Z3T bt3
L = length of specimen, in.
t, b = dimensions of cross-section of prism (in.), t being in the
direction in which it is driven
T = correction factor
For each specimen, L = 16 in. (406 mm), t = 4 in. (102 mm), b = 3 in. (76 mm), T
= 1.40, and C = 0.073 sec2/in2. The following table shows the modulus of
-61 -


elasticity for each mixture as well as the values used to find the modulus of
elasticity, Ed-
Table 21: Modulus of Elasticity
W (lbs) n (Hz) Ed (ksi)
UFFA-A-1 16.0 2134 5332
UFFA-A-2 16.2 2144 5449
UFFA-B-1 16.5 2118 5416
UFFA-B-2 16.3 2123 5376
UFFA-C-1 15.1 1994 4393
UFFA-C-2 14.9 1894 3911
UFFA-D-1 15.0 2026 4505
SF-A-1 15.6 2042 4760
SF-A-2 15.6 1951 4345
SF-B-1 14.4 1755 3245
SF-B-2 14.6 1651 2912
1 ksi = 6.89 M Pa
Table 21 shows that mixture UFFA-A had the highest modulus of elasticity and
mixture SF-B had the lowest modulus of elasticity. All mixtures exhibited a
modulus of elasticity around the typical concrete modulus of elasticity of 3000 to
5000 ksi (20,684 to 34,474 MPa).
-62-


4.3.3 Permeability
The permeability of concrete controls the rate of entry of moisture that may
contain aggressive chemicals. The test used in this research measures the
concretes ability to resist chloride ion penetration in accordance with the
standards ASTM C 1202-97 or AASHTO T 277-831. Electrical current passes
through a concrete specimen for 6 hours at a standard voltage of 60V and the
resulting coulombs, according to ASTM C 1202-97, are an indication of the
concretes ability to resist chloride ion penetration. For this test, 2 specimens
from 2 separate test cylinders were saw cut 2 inches (50.8 mm) thick from the
finished top section of the cylinder with a water-cooled concrete saw. These
samples were then placed in a vacuum desiccator bowl. The vacuum was then
allowed to run until the pressure in the desiccator bowl equaled approximately 25
inches of mercury. The samples remained in the vacuum for approximately 3
hours after which water was introduced until it completely covered the specimens.
At this time, vacuuming resumed and remained constant for a period of one hour.
At the end of the one hour, the vacuum was released. The specimens soaked for a
period of at least 24 hours, after which they were removed and blotted dry. The
specimens were then placed inside the testing cells as shown in Figure 15.
-63-


Figure 15: Photograph of Permeability Test
As Figure 15 illustrates, for each test cell, the 2 inch (50.8 mm) thick concrete
cylinder sample is placed between two chambers. The right cell is filled with a
sodium hydroxide (NaOH) solution and connected to the positive charge. The left
cell is filled with a sodium chloride (NaCl) solution and connected to the negative
charge. The cells are then charged at 60 volts for 6 hours. At the end of the 6
hours, the sample is removed from the cell and amount of coulombs that passed
through the specimen is recorded. For this research, the cells were charged for 2
-64-


hours instead of 6 hours because experience has shown that after about 2 hours,
the current steadies. The measured coulombs that passed through the specimen
after 2 hours were then multiplied by 3 to mimic a 6-hour test. These recorded
coulombs were compared to Table 22 to determine the concrete permeability:
Table 22: Chloride Ion Penetrability Based on Charge Passed
COULOMBS CHLORIDE ION PERMEABILITY
>4000 High
4000-2000 Moderate
2000-1000 Low
1000-100 Very Low
<100 Negligible
Table 23 lists the results from the two samples for each mixture at 28 days of age.
-65-


Table 23: 28-Day Permeability Results
UFFA-A UFFA-B UFFA-C UFFA-D
1 2 1 2 1 2 1 2
Voltage 60 V 60 V 60 V 60 V 60 V 60 V 60 V 60 V
Current 110.4 88.5 107.2 130.0 122.9 139.6 188.9 209
Elapsed Time 2 hrs 2 hrs 2 hrs 2 hrs 2 hrs 2 hrs 2 hrs 2 hrs
Predicted Coulombs 2371 1894 2264 2713 2624 2963 3977 4431
Testing Time 6 hrs 6 hrs 6 hrs 6 hrs 6 hrs 6 hrs 6 hrs 6 hrs
Coulombs 2328 1872 2163 2535 2532 2814 3784 4194
Permeability Mod. Low Mod. Mod. Mod. Mod. Mod. High
SF-A SF-B
1 2 1 2
Voltage 60 V 60 V 60 V 60 V
Current 141 116.5 147.8 162.0
Elapsed Time 2 hrs 2 hrs 2 hrs 2 hrs
Testing Time 6 hrs 6 hrs 6 hrs 6 hrs
Coulombs 2868 2328 2889 3144
Permeability Mod. Mod. Mod. Mod.
From the 28-day permeability results, UFFA-D (w/cm=0.42, UFFA=5%) shows
the highest permeability when compared to the other mixtures while both UFFA-
A (w/cm=0.38, UFFA=5%) and UFFA-B (w/cm=0.38, UFFA=10%) experienced
the lowest permeability values.
-66-


Comparing this mixture to UFFA-C (w/cm=0.42, UFFA=5%), which also contains
a w/cm of 0.42 but has a UFFA replacement of only 5% indicates that increased
amounts of UFFA decrease the permeability of the concrete mixture. Comparing
UFFA-C (w/cm=0.42, UFFA=5%) and UFFA-D (w/cm=0.42, UFFA=10%) to SF-
A (w/cm=0.42, SF=4%), shows that UFFA-C and SF-A exhibit similar
permeability results.
UFFA-A and UFFA-B have a w/cm equal to 0.38 showing that the w/cm may
contribute to permeability. This is because as the w/cm decreases, the porosity of
the paste decreases and the concrete becomes more impermeable (Mindess et. al.,
2003). The SF-B mixture also has a w/cm equal to 0.38 but exhibited one of the
highest permeability values. The difference between these three mixtures is
UFFA. SF-B contains only silica fume and fly ash, not UFFA. The results from
Table 23 indicate that at low w/cm, concrete mixtures with UFFA experience
lower permeability readings than mixtures containing silica fume. In addition, the
increased amount of UFFA does not appear to significantly change the
permeability results.
-67-


The 56-day permeability results are presented in Table 24.
Table 24: 56-Day Permeability Results
UFFA-A UFFA-B UFFA-C UFFA-D
1 2 1 2 1 2 1 2
Voltage 60 V 60 V 60 V 60 V 60 V 60 V 60 V 60 V
Current 96.9 99.6 104.1 104.1 94.7 83.2 134.8 123.1
Elapsed Time 2 hrs 2 hrs 2 hrs 2 hrs 2 hrs 2 hrs 2 hrs 2 hrs
Predicted Coulombs 2070 2109 2200 2206 2019 1782 2848 2607
Testing Time 6 hrs 6 hrs 6 hrs 6 hrs 6 hrs 6 hrs 6 hrs 6 hrs
Coulombs 2037 2064 2099 2133 1976 1742 2678 2473
Permeability Mod. Mod. Mod. Mod. Low Low Mod. Mod.
SF-A SF-B
1 2 1 2
Voltage 60 V 60 V 60 V 60 V
Current 82.8 74.1 103.3 103.9
Elapsed Time 2 hrs 2 hrs 2 hrs 2 hrs
Predicted Coulombs 1740 1575 2197 2181
Testing Time 6 hrs 6 hrs 6 hrs 6 hrs
Coulombs 1542 1476 2016 1962
Permeability Low Low Mod. Low
This table shows that mixture SF-A has the lowest permeability while UFFA-D
resulted in the highest permeability reading. SF-A contains 4% cement
replacement with silica fume and a w/cm ratio of 0.42. The UFFA-D mixture
-68-


contains 10% UFFA replacement and a w/cm ratio of 0.42. Figure 16 illustrates
the differences in permeability between the mixtures in this study at 28 and 56
days of age.
Permeability
28 Days
56 Days
Figure 16: Permeability Results
Figure 16 demonstrates that for each mixture, the permeability decreased from 28
to 56 days except for the UFFA-A-2 sample. CDOT specifies that Type H and
HT concrete cannot exceed 2000 coulombs at 56 days. Although all of the
mixtures except UFFA-D had a permeability reading close to 2000 coulombs,
only mixtures UFFA-C, SF-A, and SF-B actually had recorded lower than 2000
-69-


coulombs. This small difference from the maximum coulombs could be adjusted
for by using more coarse aggregate. As mentioned, none of the mixtures
contained the required 55% amount of coarse aggregate. Adding more coarse
aggregate would decrease the permeability because coarse aggregate is an
impermeable material.
Mixtures UFFA-A and UFFA-B experienced the least amount of decrease in
permeability over time. These two mixtures have a w/cm ratio of 0.38.
Comparing these mixtures to SF-B that also had a w/cm ratio of 0.38 indicates that
SF-B has a significantly larger decrease in permeability over time, measuring an
average permeability at 56 days of less than 2000 coulombs. To further
investigate, the mixtures with a w/cm ratio of 0.42, UFFA-C, UFFA-D, and SF-A,
are compared. At 28 days of age, UFFA-C and SF-A exhibit similar permeability
values while UFFA-D exhibits an extremely high permeability value. At 56 days,
both UFFA-C and SF-A measured permeability values less than 2000 coulombs.
All mixtures except UFFA-D experienced permeability readings close to or below
the CDOT specified 2000 Coulombs. The permeability investigation revealed
-70-


that the silica fume was more effective in decreasing the permeability of the
concrete than UFFA. Also noted was that an increase in coarse aggregate would
decrease the permeability, possibly reducing the measured permeability below the
maximum of 2000 coulombs.
4.4 Comparison of Study Findings with CDOT Specifications
With the exception of the air content and amount of aggregate, the silica fume
mixtures met the CDOT requirements. See Table 24. Both UFFA-A and UFFA-
C met the same requirements as the silica fume mixtures except for one
requirement. The UFFA-A mixture failed to meet the permeability requirement
while the UFFA-C mixture failed to meet the compressive strength requirement.
The maximum permeability allowed by CDOT is 2000 coulombs at 56 days and
UFFA-A experienced 2070 and 2109 coulombs at 56 days. These values exceed
the allowed coulombs by 3.5% and 5.5%, respectively.
The minimum compressive strength requirement is 4500 psi (31.0 MPa) at 56
days. Per PCA, this minimum was increased by 1200 psi (8.3 MPa) to be 5700
psi (39.3 MPa). UFFA-C exhibited an average compressive strength of only 5588
-71 -


psi (38.5 MPa), only 2.0% less than the required minimum compressive strength.
Both UFFA-A and UFFA-C contained a 5% UFFA replacement. It is
recommended that further study be done on w/cm in between 0.38 and 0.42 with a
5% UFFA replacement.
Table 25: Comparison to CDOT Requirements
UFFA-A (w/cm=0.38, UFFA=5%) UFFA-B (w/cm=0.38, UFFA=10%) UFFA-C (w/cm=0.42, UFFA=5%) UFFA-D (w/cra=0.42, UFFA=10%) Co 0s Ti- ll b 00 rf Tf II <^l fee c O'' Ti- ll u. 00 oe o II J fcu ^ 00 vS
56-day compressive strength > 4500 psi X X X X
Cement content 580-640 pcy X X X X X
Air content 5-8% X
w/cm 0.38-0.42 X X X X X X
55% coarse aggregate
Portland cement 450-500 pcy X X X X X
Fly Ash 90-125 pcy X X X X X
Silica fume 20-30 pcy X X X X X
56-day permeability coulombs < 2000 X X X
-72-


Chapter 5
Conclusions and Recommendations
5.1.1 Conclusions
This thesis evaluated the fresh and hardened concrete properties of six different
concrete mixtures containing either UFFA or silica fume. This thesis consists of a
comparison of UFFA to silica fume in the use of two types of high strength
concrete, CDOT Type H and HT structural concrete.
5.1.1 Fresh Concrete Properties
The slump values for mixtures containing UFFA measured higher than the
mixtures containing silica fume. At a 10% UFFA replacement of cement, the
slump values greatly increased even at a low w/cm. The mixtures containing only
a 5% replacement of UFFA performed almost identical to the mixtures containing
silica fume. This research confirmed that when compared to silica fume, the
addition of 10% UFFA increases the measured slump.
The mixture with the lowest air content was the mixture with both the highest
w/cm and highest amount of UFFA. The mixtures containing silica fume
-73-


contained the highest air content. This research established that UFFA decreases
the air content when compared to silica fume.
The unit weight of concrete for each mixture differed, ranging from 142.0 to
147.8 pcf (2274.6 to 2367.5 kg/m3). This difference is due to the air content of
the mixtures because typically, higher air contents produce a lower concrete unit
weight.
The temperature of the concrete mixtures ranged from 74 to 76F (23 to 24C). It
was assumed that this small range of temperature did not influence the concrete
properties for comparison purposes.
5.1.2 Hardened Concrete Properties
The mixtures containing UFFA exhibited lower early age compressive strengths
than the mixtures containing silica fume. In addition, the UFFA mixtures gained
strength at a slower rate than the silica fume mixtures. The 56-day compressive
strengths of the mixtures with 10% UFFA exhibited similar compressive strengths
as the silica fume mixtures, indicating that at high amounts, UFFA can produce
-74-


similar compressive strength values to silica fume. The compressive strengths of
the mixtures containing only 5% UFFA only exhibited strengths of approximately
75% of the mixtures containing 10% UFFA, proving that an increase of UFFA
increases the compressive strength. All mixtures met the CDOT required
compressive strength of 4500 psi (31.0 MPa) at 56 days. This minimum was
increased per PCA to 5700 psi (39.3 MPa), which all mixtures except UFFA-C
and UFFA-D met. Both of these mixtures contained a w/cm of 0.42. The
mixtures containing silica fume were more effective at increasing the 56-day
compressive strength than the mixtures containing UFFA.
The durability test proved that when compared to UFFA, silica fume is more
effective at resisting freeze-thaw conditions. The mixture with the highest
durability factor of 4.73 was SF-A with a w/cm of 0.42 and 4% silica fume. The
lowest durability factor of 1.23 was exhibited by UFFA-C with a w/cm of 0.42 and
5% UFFA. Since air entrained admixtures were not used in this research, the
measured durability factors were expected to be low.
-75-


The permeability investigation revealed that silica fume was more effective in
decreasing the permeability of the concrete than UFFA. Mixture SF-A measured
the lowest permeability while UFFA-D measured the greatest permeability. Only
mixtures UFFA-C, SF-A, and SF-B met the maximum measured coulombs of
2000 in 56 days. UFFA-C contained a w/cm of 0.42 and 5% UFFA. Mixture
UFFA-A measured coulombs within 3.2% of the maximum and contained a w/cm
of 0.42 and 5% UFFA. By adding the required amount of coarse aggregate, the
permeability of all mixtures could possibly be lowered below the maximum of
2000 coulombs at 56 days.
5.2 Recommendations
The scope of this research was to compare both the fresh and hardened properties
of UFFA to silica fume for high strength concrete. The concrete mixtures
compared contained 0, 5, or 10% UFFA as well as a w/cm of either 0.38 or 0.42.
Based on this research, recommendations to improve this research are to compare
mixtures containing UFFA ranging between 5 and 10% to determine the
minimum amount of UFFA that can be used in order to perform similar to silica
fume. This research found that at 10%, UFFA performed similar to silica fume in
-76-


compressive strength. This recommendation would also help to determine if a
linear correlation exists between amounts of UFFA and compressive strength.
This thesis recommends further study of the hardened concrete properties at later
ages. The compressive strengths tested in this research focused on the
compressive strengths at 1, 7, 28, and 56 days. By performing additional tests at
later ages, results that are more conducive can be drawn about the increase in
compressive strength with age. These additional tests could be performed at 90
days and even later to provide results that are more conducive. The permeability
testing could start at 28 days instead of 14 days as was tested for this research.
Waiting until 28 days would allow the calcium hydroxide to fully react, providing
more accurate permeability results.
Another recommendation is to produce concretes containing both silica fume and
UFFA to determine how these two react with one another and compare their
concrete properties. This research separated silica fume and UFFA to determine
how each affected concrete properties.
-77-


The major findings in this research are:
Slump
o When compared to silica fume, UFFA increased the slump
regardless of the w/cm when 10% UFFA replacement of cement is
used.
Compressive Strength
o Silica fume was more effective in increasing compressive strength
than UFFA.
o All of the UFFA mixtures met the required CDOT minimum
compressive strength except for UFFA-C with a w/cm of 0.42 and
5% UFFA
Durability
o When compared to silica fume, UFFA was not as effective in
increasing the durability factor, thus increasing freeze thaw
resistance. Air entraining admixture was not used in any of the
mixtures.
-78-


Permeability
o When compared to UFFA, silica fume was not as effective in
reducing permeability at 28 days of age; however, mixtures
containing silica fume produced the most impermeable mixtures at
56 days of age
o Only mixtures SF-A and SF-B met the CDOT requirements for 56
day compressive strength and permeability
-79-


BIBLIOGRAPHY
ACI 234R-96 (1996). Guide for the Use of Silica Fume in Concrete
ACI 363R-92 (1992). State-of-the-Art Report on High-Strength Concrete
Colorado Department of Transportation (2005). Evaluation of Products that
Protect Concrete and Reinforcing Steel of Bridge Decks from Winter
Maintenance Products.. Report No. CDOT Study 80.15. Denver, CO:
2005
Colorado Department of Transportation (2005), Standard Specifications for Road
and Bridge Construction., Denver, CO: 2005
Colorado Department of Transportation (2001), Evaluation of Cracking Problem..
Denver, CO: 2001
Detwiler, R.J. and Mehta, P.K. (1989), Chemical and Physical Effects of Silica
Fume on the Mechanical Behavior of Concrete. Materials Journal
(November 1989)
FHWA-IF-03-019 (2003)., Fly Ash Facts for Highway Engineers., Aurora, CO:
2003
Hooton, R.D., Pun, Kojundic, and Fidjestol (1997). Influence of Silica Fume on
Chloride Resistance of Concrete. Presented at PCI/FHWA International
Symposium on HPC, October, 1997.
Internet (2007): www.silicafume.org, July 17, 2007
Jaber, Tarif (2007). Silica Fume for Concrete Bridge Decks. Concrete
Construction February 2007.
-80-


Luther, M. D., and W. Hansen (1989). Comparison of Creep and Shrinkage of
High-Strength Silica Fume Concretes with Fly Ash Concretes of Similar
Strengths. In ACI special publication SP-114. Vol. 1, Fly ash, silica fume,
slag and natural pozzolans in concrete, ed. V. M. Malhotra. 573-91.
Detroit: American Concrete Institute, 1989.
Malhotra, V.M. and Carette, G.G (2000). Department of Energy, Mines and
Resources Canada. Silica Fume: A Pozzolan of New Interest for Use in
Some Concretes
Mindess, S., Young, and Darwin (2003). Concrete Second Edition. Upper Saddle
River, NJ Prentice Hall 2003.
Obla, K.H., R.L. Hill, M.D.A. Thomas, S.G. Shashiprakash, and O. Perebatova
(2003). Properties of Concrete Containing Ultra-Fine Fly Ash. ACI
Materials Journal Vol. 100. No. 5 (2003): 426-433.
Ozyildirim, C (1986). Investigation of Concrete Containing Condensed Silica
Fume: Final report. Report no. 86-R25 (January). Charlottesville: Virginia
Highway & Transportation Research Council, 1986.
Portland Cement Association (2005), Design and Control of Concrete Mixtures.,
Skokie, IL: 2005.
Peterman, M.B., and R.L. Carrasquillo (1986). Production of High Strength
Concrete. Park Ridge, N.J. Noyes Publications, cl986.
Torrey, S (1978). Coal Ash Utilization: Fly Ash. Bottom Ash, and Slag. Park
Ridge, N.J.: Noyes Data Corp., 1978.
U. S. Department of Energy (2007), Advanced Multi-Product Coal Utilization
By-Product Processing Plant., Lexington, KY: April 2007
-81 -


APPENDIX A
ASTM SPECIFICATION C33, C136: Sieve Analysis of Coarse Aggregate
(mm) (grams) (grams) (grams) (grams) (%) (%) (%)
1" 26 566.00 666.00 0.00 0.00 0.00 0.00 100.00
1/2 12.6 554.00 554.00 0.00 0.00 0.00 0.00 100.00
3/8 9.5 836.00 917.91 81.91 81.91 452 4.52 95.48
No. 4 4.75 736.95 2338.27 1601.32 1683.23 92.90 92.90 7.10
No. 8 2.36 732.78 855.27 122.49 1805.72 99.67 99.67 0.33
No. 16 1.18 669.26 674.64 5.38 1811.10 99.96 99.96 0.04
Pan 502.10 502.78 0.68 1811.78 100.00 100.00 0.00
DATA RESULTS
Original Wl. Wo = 1820 grams
Final Wt. Wf = 1811.78 grams
Percent Loss % Loss = 0.45 %
Maximum Ago. Size MAS = 1/2 in.
Norn. Max. Agg. Size NMAS = 3/8 In.
ASTM C33 Grading Limits for Coarse Aggregates
Size # 8
% Passing
Sieve Size Size (mm) Upper Limit Lower Limit
1/2 12.5 100 100
3/8 9.5 100 85
4 4.75 30 10
8 2.36 10 0
16 1.18 6 0
e Upper Limit Lower Limit -Ar- Exp. Data
-82-


ASTM SPECIFICATION C33, C136: Sieve Analysis of Fine Aggregate
(mm) (Arams) (Arams) (grams) (grams) (%) (%) . (%)
3/8" 9.5 836.0 836 0.0 0.0 0.0 0.0 100.0
4 4.75 814.8 814.82 0.0 0.0 0.0 0.0 100.0
8 2.38 456.6 463.6 7.0 7.0 0.5 0.5 99.5
16 1.18 648.2 850.2 202.0 209.0 13.5 14.0 86.0
30 0.6 599.6 1270.33 670.7 879.8 44.9 58.9 41.1
50 0.3 376.2 857.61 481.4 1361.2 32.3 91.2 8.8
100 0.15 355.6 463.27 107.7 1468.8 7.2 98.4 1.6
Pan 493.8 517.47 23.7 1492.5 1.6 100.0 0.0
DATA RESULTS
Original Wt. Wo = 1492.68 grams
Final Wt. Wf = 1492.5 grams
Percent Loss % Loss = 0.03 %
Fineness Modulus FM = £53

ASTMC33 - Grading Limits for Fine Aaareaates
% Passing
Sieve Size Size (mm) Upper Llmi Lower Limit
3/8" 9.5 o 100
4 4.75 100 95
8 2.36 100 80
16 1.18 85 50
30 0.6 60 25
50 0.3 30 10
100 0.15 10 2
i
-83-


Boral
Material
tedinologlBB
[boral
Hi
ASTM C 618 TEST REPORT
Sampla Numbar: ,S-0706130t l
Sample Dates. May 7007
Report Dale: 7/27/1007
Semple Source Powr i*
Tested By: Kl*
i
I
i
TESTS_________
C6I8QC
CHEMICAL TESTS
RESULTS
ASTM C 618
CLASS F/C
A*SHTO
JcL£SS
i
Silicon Dioxide ($K>2). %
Aluminum Oxide (AI203), %
Iron Oxide (Fe203). %
Sum of SI02. AI203, Fe2Q3, %
Calcium Oxide (CeO), %
Magnesium Oxide (MgO). %
Sulfur Trioxide (S03), %
Sodium Qxtde (Na20), %
Potassium (K20). %
Total Alkanes (a* Na20). %
Available Alkalies (as Na20), %
30.14
18.73
5.70
54.63
2854
7 fitS
2.74
2.07
0.33
2.29
70.0/50.0 min
70
0/50 Omir
I
5 0 max
1.1) max.
PHYSICAL TESTS
Moisture Content, % 0.03 3.0 max 3 0 mux.
Loss on Ignition % 0.26 6.0 max. Omnx.
Amount Retained on No. 32$ Sieve, % 1455 34 mux. 5 0 mux
Specific Gravity 2 79
Autoclave Soundness, 'A 0.0} 0.6 max. 0 8 max,
SAI, with Portland Cement at 7 days, % of Control 908 75 min*. 7 mm.*
SAI, with Portland Cement at 28 days. % of Control 918 75 min.*. 7 min.*
Water Required, % of Control 93.4 105 max. 1' 3 mox.
Sulk Density
Meet* ASTM C $11 end AA&HTO M 285, C|m C
* Mt(ng tM 7 d*y or 3i day S(rangIk Activity index we indlcele tpecflceSon compliance
The CUte (C) Fty Ash from this plant meets the reqi
of ihe MOOT and SCOHPT BpBOfieslIon*.
Approved By:
is Nd i.oopno. suite 7cc
Hi
Diana Bnlild \
OO 5f*CsMlst
Approval! By:
Brian Shew
Materials Testing Manager
Mremento
fo,..
SAN ANTONIO. TEXAS
-84-


Bora]
Material
Technologies
Semple Number:
Sample Dales:
BORAl
ASTM C 618 TEST REPORT
S-07062501I
.Tune 2007
\
TESTS \
C618QC \
CHEMICAL TESTS
Silicon Dioxide (S102), ft
Aluminum Oxide (AI203), ft
Iron Oxide (Fe203), %
Sum o( SI02, AI203. Fe203. %
Calcium Oxide (CeO), %
Magnesium Oxide (MgO), Vo
SullUrT'ioxide (S03), %
Sodium Oxide (Na20), %
Potassium (K20), ft
Totel Alkalies (as Na20), %
Available Alkalies (as Ne20). ft
PHYSICAL TESTS
Moisture Content, ft
loss on ignition ft
Amount Retained on No. 325 Sim
Specific Gravity
Autoclave Soundness, ft
SAI, with Portland Cement at /days, ft of Control
SAI, with Portland Cement wh& days, ft of Control
Water Required. % of Control
Bulk Density /
Approved By:/
S NS LOOP <10. SUITE 700
Maeta ASTM C S1I and AASHTO M2S5, FOOT Section til. 3CDHPT and MOOT apaclfleatlon* for Claes F Fly Ash
* Maeilnp mo 7 Oiy or 28 day saangtti Activity Indax will indicate epeotllcatlon eomplianca.
Diana Senfbeid |
Approved By:
C:C 3pec*dls<
Brian Shew
Materials Testing I
SAN ANTONIO. TEXAS
-85-


ASTM C 618 TEST REPORT
Sample Number: S-070613019
Sample Dales: May 2007
TESTS
C618QC
CHEMICAL TESTS
Report Oats:
Sample Source:
Tested By:
I/8/2H07
Craig Station
rm
RESULTS
ASTM C 618
CLASS F/C
AASHTO
IcLASS
I
'l
298
IC
Silicon Dioxide (SI02), 54
Aluminum Oxide (AI203), %
Iron Oxide (Fe203), 54
Sum of SI02. AI203, Fe203. 54
Calcium Oxide (CaO), 54
Magnesium Oxide (MgO), /*
Sulfur Trioxide (S03). 54
Sodium Oxide (Na20), %
Potassium (K20), 54
Total Alkalies (as Na20), 54
Available Alkalies (as Na20), 54
52.30
23.91
4.4k
82.22
9.52
2.01
0.44
0.72
0.94
1.34
0.44
70.0/50.0 min. 70 0/50.0 min
5.0 max. 5 0 max.
PHYSICAL TESTS
Moisture Content, 54
Loss on Ignition %
Amount Retained on No. 32S Sieve. 54
Specific Gravity
Autoclave Soundness, 54
SAI, with Portland Cement at 7 days, 54 of Control
SAI, with Portland Cement at 28 days. 54 of Control
Water Required, 54 of Control
Bulk Density
0.02 3.0 max.
0.70 6.0 max.
24.44 34 max.
2.36
0.01 0.8 max.
15.6 73 min.*.
97.9 75 min.*.
959 105 max.
3.) max.
J.) J11SX.
3< .0 max.
T.
t max.
min.*,
min,*.
l( S mox.
Matte ASTM C eta and AASHTO M 296, FOOT Section 929, SCOHPT and MOOT epecWIcatlona tor Chat F Fly Ash
Mattino lha 7 Sty or 21 day Strength Activity Index wNt Indicate cpteUicanon conyilonce.
v\.
Approved By;
49 NE LOOP 470. SUITE 700
N \ * *
Diana BanlMCf |
OC Specialist
App oved
SAN ANTONIO. TEXAS
By: ft)-*'*-*-#'....
Grlan shew
Materials Testlno Mtaaoer
-86-


APPENDIX B
Concrete Mixture Design Spreadsheet: UFFA-A
Mix Proportion (SSD)
Material Weiaht Volume (cf) Volume Check Unit Cost ($/ton) Amount ($)
Cement 450.00 2.29 0.085 120 27.00
Fly Ash 120 0.72 0.027 100 6.00
BFS 0 0.00 0.000 85 0.00
Micron 3 30 0.19 0.007 500 7.50
Silica Fume 0 0.00 0.000 500 0.00
Rock 1900.00 11.71 0.434 18 17.10
Sand 1162.81 7.09 0.262 18 10.47
Water 228.00 3.65 0.135 0.6 0.07
Air 0.050 1.35 0.050 -
27.00 1.00 - -
Total Cost = 68.13
Mix Characteristics
w/c 038
Unit Weiaht (Dcf) 144.1
Cementitious material (lb) 600
Suool Cementitious Mat. Percent (%) Weiaht (lb)
Fly Ash reolacement (%) 20 120
BFS reolacement (%) 0 0
Micron 3 (%) I 5 30
Silica Fume (%) 0 0
Material Properties
Material S.G. A.C
Cement 3.15 -
Fly Ash 2.67 -
Micron 3 2.53
BFS 2.90 -
Silica Fume 2.20 -
Rock 2.60 1.15
Sand 2.63 1.3
Moisture Content
sand pan 395.5 sand +oan wt. 967.7
rock pan 295.7 rock pan wt. 1017.4
dry wt. sand 967.2
dry wt. rock 1015.7
sand me (%) 0.09 mc-ssd -0.012125415
rock me (%) 0.24 mc-ssd -0.009138889
Batch Weights (yd3)
Cement 450 lb Testing Specimens Required
Fly Ash 120 lb Compressive cylinders 18 1.05
BFS 0 lb RCIP cylinders 4 0.23
Micron 3 30 lb MOR 0 0.00
Silica Fume 0 lb Unit weight 1 0.25
Rock 1883 lb Permeameter slabs 0 0.00
Sand 1149 lb Salt Ponding 0 0.00
Water 259 lb MOE 0 0.00
HRWR/AEA 0.0 ft oz./ewt FAT Beams 0 0.00
HRWR/AEA 0 ml Split Cylinder 0 0.00
Total 1.53
Batch Weights (ft3) Amount ($) x 1.1 1.68
Batch size 1.68 cf
Cement 28.0 lb 1.68
Fly Ash 7.5 lb 0.37
BFS 0.0 lb 0.00
Micron 3 1.9 lb 0.47
Silica Fume 0.0 0.00
Rock 117.3 lb 0.64
Sand 71.6 lb 0.64
Water 16.2 lb 0.005
HRWR/AEA 0.0 ml -
3.82
-87


Concrete Mixture Design Spreadsheet: UFFA-B
Min Proportion (SSD)
Material Weight Volume (cf) Volume Check Unit Cost ($/ton) Amount ($)
Cement 420.00 2.14 0.079 120 25.20
Flv Ash 120 0.72 0.027 100 6.00
BFS 0 0.00 0.000 85 0.00
Micron 3 60 0.38 0.014 500 15.00
Silica Fume 0 0.00 0.000 500 0.00
Rock 1900.00 11.71 0.434 18 17.10
Sand 1156.67 7.05 0.261 18 10.41
Water 228.00 3.65 0.135 0.6 0.07
Air 0.050 1.35 0.050 -
27.00 1.00 - -
Total Cost - 73.78
Material Properties
Material S.G. AC
Cement 3.15 -
Flv Ash 2.67 -
Micron 3 2.53
BFS 2.90 -
Silica Fume 2.20 -
Rock 2.60 1.15
Sand 2.63 1.3
Mix Characteristics
w/c 0.38
Unit Weight (pcf) 143.9
Cementitious material (lb) 600
SuddI. Cementitious Mat. Percent (%) Weight (lb)
Flv Ash replacement (%) 20 120
BFS replacement (%) 0 0
Micron 3 (%) I 10 60
Silica Fume (%) 0 0
Moisture Content
sand pan 395.5 sand +pan wt. 967.7
rock pan 295.7 rock + pan wt. 1017.4
dry wt. sand 967.2
drv wt. rock 1015.7
88