U.S. patent application number 13/329782 was filed with the patent office on 2012-04-12 for amine sacrificial agents and methods and products using same.
This patent application is currently assigned to Boral Material Technologies Inc. Invention is credited to Russell L. Hill, Brian Shaw, Zhaozhou Zhang.
Application Number | 20120085264 13/329782 |
Document ID | / |
Family ID | 43050854 |
Filed Date | 2012-04-12 |
United States Patent
Application |
20120085264 |
Kind Code |
A1 |
Zhang; Zhaozhou ; et
al. |
April 12, 2012 |
AMINE SACRIFICIAL AGENTS AND METHODS AND PRODUCTS USING SAME
Abstract
A method of producing cementitious mixtures containing fly ash
as one of the cementitious components, under air entrainment
conditions is described. The method involves forming a mixture
comprising water, cement, fly ash, optionally other cementitious
materials, aggregate, conventional chemical admixtures, and an air
entrainment agent and agitating the mixture to entrain air therein.
Additionally, at least one amine sacrificial agent is included in
the mixture. The cementitious mixtures and hardened concretes
resulting from the method and fly ash treated with sacrificial
agent, or air entrainment agent/sacrificial agent combinations, are
also described.
Inventors: |
Zhang; Zhaozhou; (San
Antonio, TX) ; Hill; Russell L.; (San Antonio,
TX) ; Shaw; Brian; (Elmendorf, TX) |
Assignee: |
Boral Material Technologies
Inc
|
Family ID: |
43050854 |
Appl. No.: |
13/329782 |
Filed: |
December 19, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12436648 |
May 6, 2009 |
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13329782 |
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Current U.S.
Class: |
106/661 ;
106/708 |
Current CPC
Class: |
Y02W 30/91 20150501;
Y02W 30/92 20150501; C04B 28/02 20130101; C04B 18/084 20130101;
C04B 16/00 20130101; C04B 2111/1087 20130101; C04B 28/02 20130101;
C04B 18/08 20130101; C04B 24/121 20130101; C04B 38/10 20130101;
C04B 40/0028 20130101; C04B 2103/304 20130101; C04B 28/02 20130101;
C04B 18/06 20130101; C04B 24/122 20130101; C04B 38/10 20130101;
C04B 40/0028 20130101; C04B 2103/304 20130101 |
Class at
Publication: |
106/661 ;
106/708 |
International
Class: |
C04B 24/08 20060101
C04B024/08; C04B 18/06 20060101 C04B018/06 |
Claims
1. A method of reducing or eliminating the effect of fly ash or
other combustion ashes on air entrainment in an air-entraining
cementitious mixture, comprising the steps of: forming a
cementitious mixture comprising water, cement, fly ash or another
combustion ash, and an air entrainment agent, and entraining air in
the mixture; wherein a sacrificial agent is also included in the
cementitious mixture in at least an amount necessary to neutralize
the detrimental effects of components of said fly ash or other
combustion ash on air entrainment activity, the sacrificial agent
comprising a material or mixture of materials that, when present in
the same cementitious mixture without fly ash or the other
combustion ash in said amount, causes less than 2 vol. % additional
air content in the cementitious mixture, wherein the sacrificial
agent comprises a compound selected from the group consisting of
the structure NR.sup.1R.sup.2R.sup.3, wherein: R.sup.1 is a
substituted or unsubstituted non-alkoxylated C.sub.5-22 alkyl,
substituted or unsubstituted non-alkoxylated C.sub.5-22 alkenyl,
substituted or unsubstituted non-alkoxylated C.sub.5-22 alkynyl,
substituted or unsubstituted C.sub.5-22 alkoxylated alkyl,
substituted or unsubstituted C.sub.5-22 alkoxylated alkenyl, or
substituted or unsubstituted C.sub.5-22 alkoxylated alkynyl; and
R.sup.2 and R.sup.3 are each independently selected from hydrogen,
substituted or unsubstituted C.sub.1-22 alkyl, substituted or
unsubstituted C.sub.2-22 alkenyl, or substituted or unsubstituted
C.sub.2-22 alkynyl; wherein R.sup.2 and R.sup.3 can be optionally
alkoxylated and are not both hydrogen.
2. The method of claim 1, wherein said amount of said sacrificial
agent exceeds an amount necessary to neutralize said detrimental
effects of said components of said fly ash or other combustion
ash.
3. The method of claim 1, wherein said fly ash or other combustion
ash can vary in content of said components from a minimum content
to a maximum content according to a source or batch of said fly ash
or other combustion ash, and wherein said amount of said at least
one sacrificial agent exceeds an amount necessary to neutralize
said detrimental effects of said components of said fly ash when
present in said maximum content.
4. The method of claim 1, wherein one or more of R.sup.1, R.sup.2,
and R.sup.3 is independently an alkoxylated or non-alkoxylated,
substituted or unsubstituted fatty acid residue.
5. The method of claim 4, wherein the fatty acid residue is
selected from the group consisting of saturated fatty acid
residues, monounsaturated fatty acid residues, polyunsaturated
fatty acid residues, and mixtures thereof.
6. The method of claim 4, wherein one or more of R.sup.1, R.sup.2,
and R.sup.3 is amino-substituted.
7. (canceled)
8. (canceled)
9. The method of claim 1, wherein said sacrificial agent comprises
a compound selected from the group consisting of tridodecylamine,
dodecyldimethylamine, octadecyldimethylamine,
cocoalkyldimethylamines, hydrogenated tallowalkyldimethylamines,
oleyldimethylamine, dicocoalkylmethylamine,
N-oleyl-1,1'-iminobis-2-propanol,
N-tallowalkyl-1,1'-iminobis-2-propanol, and mixtures thereof.
10. The method of claim 9, wherein said sacrificial agent comprises
dodecyldimethylamine.
11. The method of claim 9, wherein the sacrificial agent comprises
one or more compounds selected from the group consisting of
N-oleyl-1,1'-iminobis-2-propanol and
N-tallowalkyl-1,1'-iminobis-2-propanol.
12. (canceled)
13. The method of claim 1, wherein one of R.sup.2 and R.sup.3 is
hydrogen.
14. The method of claim 1, wherein R.sup.2 and R.sup.3 are other
than hydrogen.
15. The method of claim 1, wherein the amine is an
alcoholamine.
16. The method of claim 1, wherein the amine is a
polyetheramine.
17. The method of claim 1, wherein said sacrificial agent comprises
a compound having a hydrophobic lipophilic balance rating in the
range of 5 to 20.
18. The method of claim 1, wherein the sacrificial agent present is
a mixture of two or more compounds.
19. The method of claim 1, wherein the sacrificial agent includes a
first component having a compound A selected from the group
consisting of tridodecylamine, dodecyldimethylamine,
octadecyldimethylamine, cocoalkyldimethylamines, hydrogenated
tallowalkyldimethylamines, oleyldimethylamine,
dicocoalkylmethylamine, and mixtures thereof, and a second compound
B selected from the group consisting of polyetheramines, diamines,
alcoholamines, and mixtures thereof, wherein the weight ratio of
compound A to compound B is 1.25:1 to 1:25.
20. The method of claim 1, wherein said sacrificial agent is a
mixture of compounds of different HLB values that together provide
the sacrificial agent with an HLB value in said range of 5 to
20.
21. The method of claim 1, wherein said sacrificial agent comprises
a compound for which Log K.sub.ow is in the range of -3 to +2.
22. The method of claim 1, wherein said sacrificial agent comprises
a compound for which Log K.sub.ow is in the range of -2 to +2.
23. The method of claim 1, wherein said sacrificial agent further
comprises sodium naphthoate, sodium naphthalene sulfonate, sodium
diisopropyl naphthalene sulfonate, sodium cumene sulfonate, sodium
dibutyl naphthalene sulfonate, ethylene glycol phenyl ether,
ethylene glycol methyl ether, butoxyethanol, diethylene glycol
butyl ether, dipropylene glycol methyl ether, polyethylene glycol
and phenyl propylene glycol, or combinations thereof.
24. The method of claim 23, wherein said sacrificial agent further
comprises sodium diisopropyl naphthalene sulfonate.
25. The method of claim 1, wherein said cementitious composition
further comprises one or more water reducers selected from the
group consisting of lignosulfonates, polynaphthalene sulfonates,
and mixtures thereof.
26. The method of claim 1, wherein said sacrificial agent is mixed
with said air entrainment agent prior to mixing said sacrificial
agent and said air entrainment agent with the fly ash or other
combustion ash, cement and water.
27. The method of claim 1, wherein said sacrificial agent is mixed
with the fly ash or other combustion ash prior to mixing said
sacrificial agent and said fly ash or other combustion ash with
said cement, water and said air entrainment agent.
28. The method of claim 27, wherein said sacrificial agent is added
to said fly ash or other combustion ash by spraying a liquid
comprising said sacrificial agent onto said fly ash or other
combustion ash.
29. The method of claim 27, wherein said sacrificial agent is added
to said fly ash or other combustion ash by mixing a spray-dried
solid containing said sacrificial agent with said fly ash or other
combustion ash.
30. The method of claim 1, wherein said sacrificial agent is added
after the fly ash or other combustion ash, cement, water and air
entrainment agent have been mixed together.
31. The method of claim 1, wherein said amount of sacrificial agent
is at least 0.01% by weight of said fly ash or other combustion
ash.
32. The method of claim 1, wherein said amount of sacrificial agent
is in the range of 0.01 to 2.0% by weight of said fly ash or other
combustion ash.
33. The method of claim 1, wherein said amount of sacrificial agent
is in the range of 0.1 to 1.0% by weight of said fly ash or other
combustion ash.
34. The method of claim 1, wherein said amount of said sacrificial
agent is in the range of 0.001% to 0.25% by weight of the total
amount of cementitious material including said fly ash or other
combustion ash.
35. The method of claim 1, wherein said amount of said sacrificial
agents is in the range of 0.001% to 0.10% by weight of the total
amount of cementitious material including fly ash or other
combustion ash.
36. The method of claim 1, wherein an additional material selected
from the group consisting of sand, aggregate, concrete modifier,
and combinations thereof, is incorporated into said mixture.
37. The method of claim 1, wherein said cementitious mixture is
formed by mixing an amount of said sacrificial agent with said fly
ash or other combustion ash to form a pre-treated fly ash or other
combustion ash, and then mixing said pre-treated fly ash or other
combustion ash with said water, said air entrainment agent and said
cement.
38. The method of claim 1, wherein said cementitious mixture is
formed by mixing said air entrainment agent and said sacrificial
agent to form a component mixture, and then mixing said component
mixture with said water, fly ash or other combustion ash and
cement, and entraining said air in said mixture.
39. The method of claim 1, wherein water, cement, fly ash or other
combustion ash, air entrainment agent and sacrificial agent are
mixed together simultaneously while entraining said air in the
mixture.
40. The method of claim 1, wherein said sacrificial agent is mixed
with said water, cement and fly ash or other combustion ash before
said air entrainment agent is added.
41. The method of claim 1, wherein said sacrificial agent is mixed
with said water, cement and fly ash or other combustion ash at the
same time as said air entrainment agent.
42. The method of claim 1, wherein said fly ash or other combustion
ash consists essentially of fly ash.
43. The method of claim 1, wherein said fly ash or other combustion
ash comprises a blend of fly and another combustion ash.
44. The method of claim 1, wherein the sacrificial agent, when
present in the same cementitious mixture without fly ash or the
other combustion ash in said amount causes less than 1 vol. %
additional air content in the cementitious mixture.
45. The method of claim 1, further comprising the step of selecting
a sacrificial agent comprising a material or mixture of materials
to reduce or eliminate the effect of fly ash or another combustion
ash on air entrainment in a cementitious mixture and selecting an
amount of the sacrificial agent such that the amount is at least an
amount necessary to neutralize the detrimental effects of
components of said fly ash on air entrainment activity and the
amount of sacrificial agent causes less than 2 vol. % additional
air content in the same cementitious mixture without fly ash or the
other combustion ash.
46. The method of claim 45, wherein said fly ash or other
combustion ash has a predetermined maximum carbon content and the
amount of sacrificial agent exceeds the amount necessary to
neutralize the maximum carbon content in the fly ash or other
combustion ash.
47. The method of claim 2, wherein the sacrificial agent amount
used does not result in a substantial increase in air entrainment
compared to providing the sacrificial agent in an amount necessary
to neutralize the detrimental effects of components of said fly ash
on air entrainment activity.
48. The method of claim 47, wherein the sacrificial agent causes
less than 2 vol. % additional air content in the cementitious
mixture without fly ash.
49. The method of claim 1, wherein said components are carbon
content.
50. A method of reducing or eliminating the effect of fly ash on
air entrainment in an air-entraining cementitious mixture,
comprising the steps of: forming a cementitious mixture comprising
water, cement, fly ash, and an air entrainment agent, and
entraining air in the mixture; wherein a sacrificial agent is also
included in the cementitious mixture in at least the amount
necessary to neutralize the detrimental effects of the carbon
content of said fly ash on air entrainment activity, the
sacrificial agent comprising a material or mixture of materials
that, when present in the same cementitious mixture without fly ash
in said amount causes less than 2 vol. % additional air content in
the cementitious mixture, wherein the sacrificial agent comprises a
compound selected from the group consisting of the structure
NR.sup.1R.sup.2R.sup.3, wherein: R.sup.1 is a substituted or
unsubstituted non-alkoxylated C.sub.5-22 alkyl, substituted or
unsubstituted non-alkoxylated C.sub.5-22 alkenyl, substituted or
unsubstituted non-alkoxylated C.sub.5-22 alkynyl, substituted or
unsubstituted C.sub.5-22 alkoxylated alkyl, substituted or
unsubstituted C.sub.5-22 alkoxylated alkenyl, or substituted or
unsubstituted C.sub.5-22 alkoxylated alkynyl; and R.sup.2 and
R.sup.3 are each independently selected from hydrogen, substituted
or unsubstituted C.sub.1-22 alkyl, substituted or unsubstituted
C.sub.2-22 alkenyl, or substituted or unsubstituted C.sub.2-22
alkynyl; wherein R.sup.2 and R.sup.3 can be optionally alkoxylated
and are not both hydrogen.
51. A method of addressing the variance of carbon content in fly
ash used in cementitious compositions to provide a cementitious
composition with a substantially constant level of air entrainment,
comprising: forming a cementitious mixture comprising water,
cement, fly ash, an air entrainment agent, and a sacrificial agent
and entraining air in the mixture, wherein the fly ash has a
maximum carbon content; and selecting a sacrificial agent for the
cementitious mixture and an amount of the sacrificial agent such
that the amount of the sacrificial agent exceeds the amount
necessary to neutralize the maximum carbon content in the fly ash,
wherein the sacrificial agent comprises a material or mixture of
materials that, when present in the same cementitious mixture
without fly ash in said amount causes less than 2 vol. % additional
air content in the cementitious mixture, and wherein the
sacrificial agent comprises a compound selected from the group
consisting of the structure NR.sup.1R.sup.2R.sup.3, wherein:
R.sup.1 is a substituted or unsubstituted non-alkoxylated
C.sub.5-22 alkyl, substituted or unsubstituted non-alkoxylated
C.sub.5-22 alkenyl, substituted or unsubstituted non-alkoxylated
C.sub.5-22 alkynyl, substituted or unsubstituted C.sub.5-22
alkoxylated alkyl, substituted or unsubstituted C.sub.5-22
alkoxylated alkenyl, or substituted or unsubstituted C.sub.5-22
alkoxylated alkynyl; and R.sup.2 and R.sup.3 are each independently
selected from hydrogen, substituted or unsubstituted C.sub.1-22
alkyl, substituted or unsubstituted C.sub.2-22 alkenyl, or
substituted or unsubstituted C.sub.2-22 alkynyl; wherein R.sup.2
and R.sup.3 can be optionally alkoxylated and are not both
hydrogen.
52-58. (canceled)
59. The method according to claim 1, wherein only one of R.sup.2
and R.sup.3 is alkoxylated.
60. The method according to claim 1, wherein R.sup.2 and R.sup.3
are non-alkoxylated.
Description
BACKGROUND AND FIELD
[0001] This application relates to the use of sacrificial agents in
cementitious mixtures containing ash including fly ash concrete,
and to the resulting mixtures and compositions. More particularly,
this application relates to sacrificial agents that reduce or
eliminate the detrimental effects of ash such as fly ash on the air
entrainment properties of cementitious mixtures.
[0002] The partial replacement of portland cement by fly ash is
growing rapidly, driven simultaneously by more demanding
performance specifications on the properties of concrete and by
increasing environmental pressures to reduce portland cement
consumption. Fly ash can impart many beneficial properties to
concrete such as improved rheology, reduced permeability and
increased later-age strength; however, it also may have a negative
influence on bleed characteristics, setting time and early strength
development. Many of these issues can be managed by adjusting
mixture proportions and materials, and by altering concrete
placement and finishing practices. However, other challenging
problems encountered when using certain fly ash are not always
easily resolved. The most important difficulties experienced when
using fly ash are most often related to air entrainment in
concrete.
[0003] Air entrained concrete has been utilized in the United
States since the 1930's. Air is purposely entrained in concrete,
mortars and grouts as a protective measure against expansive forces
that can develop in the cement paste associated with an increase in
volume resulting from water freezing and converting to ice.
Adequately distributed microscopic air voids provide a means for
relieving internal pressures and ensuring concrete durability and
long term performance in freezing and thawing environments. Air
volumes (volume fraction) sufficient to provide protective air void
systems are commonly specified by Building Codes and Standard
Design Practices for concrete which may be exposed to freezing and
thawing environments. Entrained air is to be distinguished from
entrapped air (air that may develop in concrete systems as a result
of mixing or the additions of certain chemicals). Entrained air
provides an air void system capable of protecting against
freeze/thaw cycles, while entrapped air provide no protection
against such phenomena.
[0004] Air is also often purposely entrained in concrete and other
cementitious systems because of the properties it can impart to the
fresh mixtures. These can include: improved fluidity, cohesiveness,
improved workability and reduce bleeding.
[0005] The air void systems are generated in concrete, mortar, or
paste mixtures by introducing air entrainment admixtures (referred
to as air entrainment agents or air-entraining agents) which are a
class of specialty surfactants. When using fly ash, the
difficulties in producing air-entrained concrete are related to the
disruptive influence that some fly ashes have on the generation of
sufficient air volumes and adequate air void systems. The primary
influencing factor is the occurrence of residual carbon, or
carbonaceous materials (hereafter designated as fly ash-carbon),
which can be detected as a discrete phase in the fly ash, or can be
intimately bound to the fly ash particles. Detrimental effects on
air entrainment by other fly ash components may also occur, and
indeed air entrainment problems are sometimes encountered with fly
ash containing very low amounts of residual carbon.
[0006] Fly ash-carbon, a residue of incomplete coal or other
hydrocarbon combustion, is in many ways similar to an "activated
carbon." For example, like activated carbon, fly ash-carbon can
adsorb organic molecules in aqueous environments. In cement paste
containing organic chemical admixtures, the fly ash-carbon can thus
adsorb part of the admixture, interfering with the function and
performance of the admixture. The consequences of this adsorption
process are found to be particularly troublesome with air
entrainment admixtures (air entrainment agents) which are commonly
used in only very low dosages. In the presence of significant
carbon contents (e.g. >2 wt %), or in the presence of low
contents of highly reactive carbon or other detrimental fly ash
components, the air entrainment agents may be adsorbed, interfering
with the air void formation and stability; this leads to tremendous
complications in consistently obtaining and maintaining specified
concrete air contents.
[0007] To minimize concrete air entrainment problems, ASTM
guidelines have limited the fly ash carbon content to less than 6
wt %. Other institutions such as AASHTO and state departments of
transportation have more stringent limitations. Industry experience
indicates that, in the case of highly active carbon (for example,
high specific surface area), major interferences and problems can
still be encountered, even with carbon contents lower than 1 wt
%.
[0008] Furthermore, recent studies indicate that, while fly ash
carbon content, as measured by loss on ignition (LOI) values,
provides a primary indicator of fly ash behavior with respect to
air entrainment, it does not reliably predict the impact that a fly
ash will have on air entrainment in concrete. Therefore, there
currently exist no means, suitable for field quality control,
capable of reliably predicting the influence that a particular fly
ash sample will have on air entrainment, relative to another fly
ash sample with differing LOI's, sources, or chemistries. In
practice, the inability to predict fly ash behavior translates into
erratic concrete air contents, which is currently the most
important problem in fly ash-containing concrete.
[0009] Variations in fly ash performance are important, not only
because of their potential impact on air entrainment and resistance
to freeze thaw conditions, but also because of their effects
related to concrete strength. Just as concrete is designed
according to building standards for a particular environment,
specifications are also provided for physical performance
requirements. A common performance requirement is compressive
strength. An increase in entrained air content can result in a
reduction in compressive strength of 3-6% for each additional
percentage of entrained air. Obviously, variations in fly
ash-carbon, which would lead to erratic variations in air contents,
can have serious negative consequences on the concrete
strength.
[0010] The fly ash-carbon air entrainment problem is an on-going
issue that has been of concern since fly ash was first used nearly
75 years ago. Over the past ten years, these issues have been
further exacerbated by regulations on environmental emissions which
impose combustion conditions yielding fly ash with higher carbon
contents. This situation threatens to make an increasingly larger
portion of the available fly ash materials unsuitable for use in
concrete. Considering the economic impact of such a trend, it is
imperative to develop practical corrective schemes that will allow
the use, with minimal inconvenience, of fly ash with high carbon
contents (e.g., up to 10 wt %) in air-entrained concrete.
[0011] Air entrainment in fly ash-concrete may become yet more
complicated by pending regulations that will require utilities to
reduce current mercury (Hg) emissions by 70-90%. One of the
demonstrated technologies for achieving the Hg reduction is the
injection of activated carbon into the flue gas stream after
combustion so that volatile Hg is condensed on the high surface
area carbon particles and discarded with the fly ash. Current
practices are designed such that the added activated carbon is
generally less than 1% by mass of the fly ash, but preliminary
testing indicates this is disastrous when using the modified fly
ash in air-entrained concrete.
[0012] The origin of air entrainment problems in fly ash concrete,
and potential approaches to their solution, have been the subject
of numerous investigations. Most of these investigations focused on
the "physical" elimination of the carbon by either combustion
processes, froth floatation, or electrostatic separation. To date,
the proposed fly ash treatment approaches have found limited
application due to their inherent limitations (e.g., separation
techniques have limited efficiency in low carbon fly ash; secondary
combustion processes are most suitable for very high carbon
contents), or due to their associated costs.
[0013] "Chemical" approaches have also been proposed to alleviate
carbon-related problems in concrete air entrainment, for example
through the development of alternative specialty surfactants for
air entrainment agents such as polyoxyethylene-sorbitan oleate as
an air entrainment agent (U.S. Pat. No. 4,453,978). Various other
chemical additives or fly ash chemical treatments have been
proposed, namely: [0014] the addition of inorganic additives such
as calcium oxide or magnesium oxide (U.S. Pat. No. 4,257,815); this
patent prescribes the use of inorganic additives which may
influence other properties of fresh mortars or concrete, for
example, rate of slump loss and setting time; [0015] the addition
of C8 fatty acid salts (U.S. Pat. No. 5,110,362); the octanoate
salt is itself a surfactant, and it is said to "stabilize the
entrained air and lower the rate of air loss" (claim 1 of U.S. Pat.
No. 5,110,362); [0016] the use of a mixture of high-polymer
protein, polyvinyl alcohol and soap gel (U.S. Pat. No. 5,654,352);
this discloses the use of protein and polyvinyl alcohol, and
optionally a colloid (for example, bentonite) to formulate air
entrainment admixtures; [0017] treatment with ozone (U.S. Pat. No.
6,136,089); the ozone oxidizes fly ash-carbon, reducing its
absorption capacity for surfactants and thus making the fly ash
more suitable for use in air entrained systems.
[0018] None of these proposed solutions have found significant
acceptance in the industry, either because of their complexity and
cost, or because of their limited performance in actual use. For
example, a clear limitation to the addition of a second surfactant
(e.g., C8 fatty acid salt), to compensate for the adsorption of the
air entrainment agents surfactant, simply shifts the problem to
controlling air content with a combination of surfactants instead
of a single one. The problem of under- or over-dosage of a
surfactant mixture is then the same as the problem discussed above
with conventional air entrainment agents.
[0019] Hence, a practical solution is needed for efficiently
relieving air entrainment problems for a wide variety of fly ash
materials and for other ashes, in ready mix facilities or in the
field.
SUMMARY
[0020] The methods and compositions described herein facilitate the
formation of cementitious mixtures containing fly ash and other
combustion ashes, and solid products derived therefrom. Further,
these methods and compositions facilitate air entrainment into such
mixtures in a reliable and predictable fashion.
[0021] According to some embodiments, there is provided a method of
reducing or eliminating the effect of fly ash or other combustion
ashes on air-entrainment in an air-entraining cementitious mixture
containing fly ash or another combustion ash, comprising the steps
of: forming a cementitious mixture comprising water, cement, fly
ash or another combustion ash, (and optionally other cementitious
components, sand, aggregate, etc.) and an air entrainment agent
(and optionally other concrete chemical admixtures); and entraining
air in the mixture; wherein an amount of at least one sacrificial
agent is also included in the cementitious mixture in at least an
amount necessary to neutralize the detrimental effects of
components of said fly ash or other combustion ash on air
entrainment activity, the sacrificial agent comprising a material
or mixture of materials that, when present in the same cementitious
mixture without fly ash or the other combustion ash in said amount,
causes less than 2 vol. % additional air content in the
cementitious mixture.
[0022] The amount of the sacrificial agent used in the cementitious
mixture can, in some embodiments, exceed the amount necessary to
neutralize the detrimental effects of the components of the fly ash
or other combustion ash. Thus, if the fly ash varies in content of
the detrimental components from a minimum content to a maximum
content according to the source or batch of the fly ash or other
combustion ash, the amount of the at least one sacrificial agent
can exceed the amount necessary to neutralize the detrimental
effects of the components of the fly ash when present at their
maximum content.
[0023] The sacrificial agent is a primary amine, secondary amine,
or tertiary amine compound, or any combination thereof. The
sacrificial agent can be a compound selected from the group
consisting of the structure NR.sup.1R.sup.2R.sup.3. R.sup.1 is
substituted or unsubstituted non-alkoxylated C.sub.5-22 alkyl,
substituted or unsubstituted non-alkoxylated C.sub.5-22 alkenyl,
substituted or unsubstituted non-alkoxylated C.sub.5-22 alkynyl,
substituted or unsubstituted C.sub.2-22 alkoxylated alkyl,
substituted or unsubstituted C.sub.2-22 alkoxylated alkenyl, or
substituted or unsubstituted C.sub.2-22 alkoxylated alkynyl.
R.sup.2 and R.sup.3 are each independently selected from hydrogen,
substituted or unsubstituted C.sub.1-22 alkyl, substituted or
unsubstituted C.sub.2-22 alkenyl, or substituted or unsubstituted
C.sub.2-22 alkynyl. R.sup.2 and R.sup.3 can be optionally
alkoxylated. One or more of R.sup.1, R.sup.2, or R.sup.3 can be an
alkoxylated or non-alkoxylated, substituted or unsubstituted, fatty
acid residue. The fatty acid residues can be saturated fatty acid
residues, monounsaturated fatty acid residues, polyunsaturated
fatty acid residues, or mixtures thereof. In some embodiments, one
or more of R.sup.1, R.sup.2, and R.sup.3 can be amino-substituted
including NR.sub.4R.sub.5 as a substituent. For example, the
sacrificial agent can be polyoxypropylenediamine or
triethyleneglycol diamine. In some embodiments, the sacrificial
agent is an alcoholamine. In some embodiments, the sacrificial
agent is a mixture of two or more compounds. In some embodiments,
the HLB value of the sacrificial agent or the mixture of
sacrificial agents is in the range of 5 to 20 (e.g., 4 to 18). In
some embodiments, the Log K.sub.ow for the sacrificial agent can be
in the range of -3 to +2 (e.g. -2 to +2).
[0024] In some embodiments, the sacrificial agent is a compound
selected from tridodecylamine, dodecyldimethylamine,
octadecyldimethylamine, cocoalkyldimethylamine, hydrogenated
tallowalkyldimethylamines, oleyldimethylamine,
dicocoalkylmethylamine, N-oleyl-1,1'-iminobis-2-propanol,
N-tallowalkyl-1,1'-iminobis-2-propanol, polyoxypropylenediamine,
triethyleneglycol diamine, and mixtures thereof. In some
embodiments, the sacrificial agent includes dodecyldimethylamine.
In some embodiments, the sacrificial agent includes one or more
compounds selected from N-oleyl-1,1'-iminobis-2-propanol and
N-tallowalkyl-1,1'-iminobis-2-propanol. In some embodiments, the
sacrificial agent includes a polyethcramine.
[0025] The dosage, or amount, of the sacrificial agent can vary
from 0.005% to 5% by weight based on the weight of the fly ash or
other combustion ash. In some embodiments, the amount is from 0.01
to 2%, 0.02-1% and 0.05-0.5% (e.g. 0.1-0.3%) by weight based on the
weight of the fly ash or other combustion ash. The sacrificial
agent can be added directly to the fly ash by pre-treating the fly
ash or can be added to the cementitious composition or with other
components of the cementitious composition.
[0026] Typically, the fly ash or other combustion ash is provided
in the cementitious composition in an amount of from 5% to 55% by
weight of the total amount of cementitious materials in the
cementitious composition (cement and fly ash or other combustion
ash), depending on the type and composition of the fly ash or other
combustion ash. In some embodiments, the amount of fly ash or other
combustion ash is from 10% to 50% or 15% to 30% by weight (e.g. 25%
by weight) of the total amount of cementitious materials in the
cementitious composition.
[0027] The sacrificial agent can be mixed with the air entrainment
agent prior to mixing the sacrificial agent and air entrainment
agent with the fly ash or other combustion ash, cement, and water.
Alternatively, the sacrificial agent can be mixed with the fly ash
or other combustion ash prior to mixing the sacrificial agent and
the fly ash or other combustion ash with the cement, water, and the
air entrainment agent. In the latter case, the sacrificial agent
can be added to the fly ash or other combustion ash by spraying a
liquid containing the sacrificial agent onto the fly ash or other
combustion ash, or by mixing a spray-dried solid sacrificial agent
formulation with the fly ash or other combustion ash. Suitable
methods are described in published U.S. Patent Application No. US
2004/0144287, which is hereby incorporated by reference in its
entirety. Alternatively, the sacrificial agent can be added after
the fly ash or other combustion ash, cement, water, and air
entrainment agent have been mixed together. In some embodiments, an
additional material selected from sand, aggregate, concrete
modifier, and combinations thereof, can be incorporated into the
mixture.
[0028] In some embodiment's, the cementitious mixture can be formed
by mixing an amount of the sacrificial agent with the fly ash or
other combustion ash to form a pre-treated fly ash or other
combustion ash, and then mixing the pre-treated fly ash or other
combustion ash with the water, air entrainment agent and cement. In
some embodiments, the cementitious mixture is formed by mixing the
air entrainment agent and the sacrificial agent to form a component
mixture, and then mixing the component mixture with the water, fly
ash or other combustion ash and cement, and entraining the air in
the mixture. In some embodiments, water, cement, fly ash or other
combustion ash, air entrainment agent and sacrificial agent are
mixed together simultaneously while entraining the air in the
mixture. In some embodiments, the sacrificial agent is mixed with
the water, cement and fly ash or other combustion ash before the
air entrainment agent is added. In some embodiments, the
sacrificial agent is mixed with the water, cement, and fly ash or
other combustion ash at the same time as the air entrainment
agent.
[0029] In some embodiments, the fly ash or other combustion ash
consists essentially of fly ash. In some embodiments, the fly ash
or other combustion ash comprises a blend of fly and another
combustion ash. In some embodiments, the sacrificial agent, when
present in the same cementitious mixture without fly ash or the
other combustion ash in the appropriate amount causes less than 1
vol. % additional air content in the cementitious mixture.
[0030] In some embodiments, the method further includes the step of
selecting a sacrificial agent including a material or mixture of
materials to reduce or eliminate the effect of fly ash or another
combustion ash on air entrainment in a cementitious mixture and
selecting an amount of the sacrificial agent such that the amount
is at least an amount necessary to neutralize the detrimental
effects of components of the fly ash on air entrainment activity
and the amount of sacrificial agent causes less than 2 vol. %
additional air content in the same cementitious mixture without fly
ash or the other combustion ash. In some embodiments, the fly ash
or other combustion ash has a predetermined maximum carbon content
and the amount of sacrificial agent exceeds the amount necessary,
to neutralize the maximum carbon content in the fly ash or other
combustion ash. In some embodiments, the sacrificial agent amount
used does not result in a substantial increase in air entrainment
compared to providing the sacrificial agent in an amount necessary
to neutralize the detrimental effects of components of the fly ash
on air entrainment activity. In some embodiments, the sacrificial
agent causes less than 2 vol. % additional air content in the
cementitious mixture without fly ash. In some embodiments, the
components to be neutralized are carbon content.
[0031] There is also provided a method of reducing or eliminating
the effect of fly ash on air entrainment in an air-entraining
cementitious mixture, comprising the steps of: forming a
cementitious mixture comprising water, cement, fly ash, and an air
entrainment agent, and entraining air in the mixture; wherein a
sacrificial agent is also included in the cementitious mixture in
at least the amount necessary to neutralize the detrimental effects
of the carbon content of said fly ash on air entrainment activity,
the sacrificial agent comprising a material or mixture of materials
that, when present in the same cementitious mixture without fly ash
in said amount causes less than 2 vol. % additional air content in
the cementitious mixture.
[0032] There is further provided a method of addressing the
variance of carbon content in fly ash used in cementitious
compositions to provide a cementitious composition with a
substantially constant level of air entrainment, comprising:
forming a cementitious mixture comprising water, cement, fly ash,
an air entrainment agent, and a sacrificial agent and entraining
air in the mixture, wherein the fly ash has a maximum carbon
content; and selecting a sacrificial agent for the cementitious
mixture and an amount of the sacrificial agent such that the amount
of the sacrificial agent exceeds the amount necessary to neutralize
the maximum carbon content in the fly ash, wherein the sacrificial
agent comprises a material or mixture of materials that, when
present in the same cementitious mixture without fly ash in said
amount causes less than 2 vol. % additional air content in the
cementitious mixture.
[0033] Furthermore, a method of pre-treating fly ash or another
combustion ash to reduce or eliminate the effect the fly ash or the
other combustion ash has on air entrainment in an air-entraining
cementitious mixture comprising the fly ash or other combustible
fly ash and an air-entraining agent is provided, the method
comprising: mixing a sacrificial agent with fly ash or another
combustion ash to form a pre-treated ash, wherein the sacrificial
agent is combined with the fly ash or the other combustion ash in
at least an amount necessary to neutralize the detrimental effects
of components of the fly ash or the other combustion ash on air
entrainment activity in the air-entraining cementitious mixture,
the sacrificial agent comprising a material or mixture of materials
that, when present in a cementitious mixture without fly ash or
another combustion ash in said amount causes less than 2 vol. %
additional air content in the cementitious mixture.
[0034] There is also provided a method of addressing the variance
of carbon content in fly ash used in cementitious compositions to
provide a cementitious composition with a substantially constant
level of air entrainment, comprising: selecting a sacrificial agent
and an amount of the sacrificial agent such that the amount of the
sacrificial agent exceeds the amount necessary to neutralize the
maximum carbon content in the fly ash, mixing the sacrificial agent
with fly ash or another combustion ash to form a pre-treated ash,
wherein the sacrificial agent is combined with the fly ash or the
other combustion ash in at least an amount necessary to neutralize
the detrimental effects of components of the fly ash or the other
combustion ash on air entrainment activity in the air-entraining
cementitious mixture, the sacrificial agent comprising a material
or mixture of materials that, when present in a cementitious
mixture without fly ash or another combustion ash in said amount
causes less than 2 vol. % additional air content in the
cementitious mixture
[0035] Also provided herein is a composition comprising fly ash or
another combustion ash that reduces or eliminates the effect the
fly ash or the other combustion ash has on air entrainment in an
air-entraining cementitious mixture comprising the fly ash or the
other combustion ash and an air-entraining agent, the composition
comprising fly ash or another combustion ash and a sacrificial
agent, the sacrificial agent present in at least an amount
necessary to neutralize the detrimental effects of components of
the fly ash or the other combustion ash on air entrainment activity
in the air-entraining cementitious mixture, the sacrificial agent
comprising a material or mixture of materials that, when present in
a cementitious mixture without fly ash or another combustion ash in
said amount causes less than 2 vol. % additional air content in the
cementitious mixture.
[0036] Also provided herein is a composition that addresses the
variance of carbon content in fly ash or another combustion ash
used in cementitious compositions to provide a cementitious
composition with a substantially constant level of air entrainment,
comprising fly ash or another combustion ash and a sacrificial
agent, the sacrificial agent present in at least an amount
necessary to neutralize the detrimental effects of components of
the fly ash or the other combustion ash on air entrainment activity
in the air-entraining cementitious mixture, the sacrificial agent
comprising a material or mixture of materials that, when present in
a cementitious mixture without fly ash or another combustion ash in
said amount causes less than 2 vol. % additional air content in the
cementitious mixture.
[0037] Also provided herein is an air-entraining cementitious
mixture comprising fly ash or another combustion ash that reduces
or eliminates the effect the fly ash or other combustion ash has on
air entrainment in the air-entraining cementitious mixture; the
air-entraining cementitious mixture comprising air, water, cement,
fly ash, an air entrainment agent and a sacrificial agent, wherein
the sacrificial agent is present in at least an amount necessary to
neutralize the detrimental effects of components of the fly ash or
the other combustion ash on air entrainment activity in the
air-entraining cementitious mixture, the sacrificial agent
comprising a material or mixture of materials that, when present in
a cementitious mixture without fly ash or another combustion ash in
said amount causes less than 2 vol. % additional air content in the
cementitious mixture.
[0038] Further provided herein is an air-entraining cementitious
mixture comprising fly ash or another combustion ash that addresses
the variance of carbon content in fly ash used in cementitious
compositions to provide a cementitious composition with a
substantially constant level of air entrainment, the air-entraining
cementitious mixture comprising air, water, cement, fly ash, an air
entrainment agent and a sacrificial agent, wherein the sacrificial
agent is present in at least an amount necessary to neutralize the
detrimental effects of components of the fly ash or the other
combustion ash on air entrainment activity in the air-entraining
cementitious mixture, the sacrificial agent comprising a material
or mixture of materials that, when present in a cementitious
mixture without fly ash or another combustion ash in said amount
causes less than 2 vol. % additional air content in the
cementitious mixture, wherein the sacrificial agent is present in
at least an amount necessary to neutralize the detrimental effects
of components of the fly ash or the other combustion ash on air
entrainment activity in the air-entraining cementitious mixture,
the sacrificial agent comprising a material or mixture of materials
that, when present in a cementitious mixture without fly ash or
another combustion ash in said amount causes less than 2 vol. %
additional air content in the cementitious mixture.
[0039] Also provided herein is an air-entrained hardened
cementitious mass comprising fly ash or another combustion ash that
reduces or eliminates the effect the fly ash or other combustion
ash has on air entrainment in the air-entrained hardened
cementitious mass, the air-entrained hardened cementitious mass
comprising air, cement, fly ash, an air entrainment agent and an
amount of a sacrificial agent, wherein the sacrificial agent is
present in at least an amount necessary to neutralize the
detrimental effects of components of the fly ash or the other
combustion ash on air entrainment activity in the air-entraining
cementitious mixture, the sacrificial agent comprising a material
or mixture of materials that, when present in a cementitious
mixture without fly ash or another combustion ash in said amount
causes less than 2 vol. % additional air content in the
cementitious mixture.
[0040] As described herein, the sacrificial agents can be used to
eliminate or drastically reduce air entrainment problems
encountered in concrete containing fly ash. Such additives, or
combinations of such additives, can be added before (e.g. in the
fly ash material), during, or after the concrete mixing operation.
The use of these materials can have the following advantages. They:
[0041] enable adequate levels (typically 5-8 vol %) of gas,
normally air, to be entrained in concrete or other cementitious
products, with dosages of conventional air entrainment agents that
are more typical of those required when no fly ash, or fly ash with
low carbon content, is used; [0042] confer predictable air
entrainment behavior onto fly ash-concrete regardless of the
variability in the fly ash material, such as the source, carbon
content, chemical composition; [0043] do not interfere with cement
hydration and concrete set time; [0044] do not alter other physical
and durability properties of concrete; [0045] do not significantly
alter their action in the presence of other concrete chemical
admixtures, for example, water reducers, superplasticizers and set
accelerators; and [0046] do not cause detrimental effects when
added in excessive dosages, such as excessive air contents,
extended set times; or strength reduction.
[0047] The acceptability of "overdosage" of these sacrificial
agents is advantageous in some embodiments, since large
fluctuations in fly ash properties (carbon content, reactivity,
etc.) can be accommodated by introducing a moderate excess of these
sacrificial agents without causing other problems. This provides
operators with a substantial trouble-free range or comfort
zone.
[0048] The cementitious mixtures can contain conventional
ingredients such as sand and aggregate, as well as specific known
additives.
DEFINITIONS
[0049] The term "fly ash", as defined by ASTM C 618 (Coal Fly Ash
or Calcined Natural Pozzolan For Use in Concrete) refers to a by
product of coal combustion. However, other combustion ashes can be
employed which are fine ashes or flue dusts resulting from
co-firing various fuels with coal, or resulting from the combustion
of other fuels that produce an ash having pozzolanic qualities (the
ability to form a solid when mixed with water and an activator such
ash lime or alkalis) or hydraulic qualities (the ability to form a
solid when mixed with water and set). The ash itself has
pozzolanic/hydraulic activity and can be used as a cementitious
material to replace a portion of portland cement in the preparation
of concrete, mortars, and the like. The term "fly ash and other
combustion ash" as used herein includes: [0050] 1) Ash produced by
co-firing fuels including industrial gases, petroleum coke,
petroleum products, municipal solid waste, paper sludge, wood,
sawdust, refuse derived fuels, switchgrass or other biomass
material, either alone or in combination with coal. [0051] 2) Coal
ash and/or alternative fuel ash plus inorganic process additions
such as soda ash or trona (native sodium carbonate/bicarbonate used
by utilities). [0052] 3) Coal ash and/or alternative fuel ash plus
organic process additives such as activated carbon, or other
carbonaceous materials, for mercury emission control. [0053] 4)
Coal ash and/or alternative fuel ash plus combustion additives such
as borax. [0054] 5) Coal ash and/or alternative fuel gases plus
flue gas or fly ash conditioning agents such as ammonia, sulfur
trioxide, phosphoric acid, etc.
[0055] The term "fly ash concrete" means concrete containing fly
ash and portland cement in any proportions, but optionally
additionally containing other cementitious materials such as blast
furnace slag, silica fume, or tillers such as limestone, etc.
[0056] The term "surfactants" is also well understood in the art to
mean surface active agents. These are compounds that have an
affinity for both fats (hydrophobic) and water (hydrophilic) and so
act as foaming agents (although some surfactants are non-foaming,
e.g. phosphates), dispersants, emulsifiers, and the like, e.g.
soaps.
[0057] The term "air entrainment agent" (AEA) means a material that
results in a satisfactory amount of air being entrained into a
cementitious mixture, e.g. 5-9 vol % air, when added to a
cementitious formulation. Generally, air entrainment agents are
surfactants (i.e. they reduce the surface tension when added to
aqueous mixtures), and are often materials considered to be
soaps.
[0058] The mode of action of air entrainment agents, and the
mechanism of air void formation in cementitious mixtures are only
poorly understood. Because of their influence on the surface
tension of the solution phase, the surfactant molecules are
believed to facilitate the formation of small air cavities or voids
in the cementitious paste, by analogy to formation of air
`bubbles`. It is also believed that the wall of these voids are
further stabilized through various effects, such as incorporation
into the interfacial paste/air layer of insoluble calcium salts of
the surfactants, or of colloidal particles.
[0059] The performance of surfactants as concrete air entrainment
admixture depends on the composition of the surfactant: the type of
hydrophilic group (cationic, anionic, zwitterionic, or non-ionic),
the importance of its hydrophobic residue (number of carbon groups,
molecular weight), the chemical nature of this residue (aliphatic,
aromatic) and the structure of the residue (linear, branched,
cyclic), and on the balance between the hydrophilic and lipophilic
portions of the surfactant molecule (HLB). Cationic and non-ionic
surfactants are reported to entrain more air than anionic
surfactants because the latter are often precipitated as insoluble
calcium salts in the paste solution; however, the stability of the
air void has also been reported to be greater with anionic
surfactant than with cationic or non-ionic surfactants. Typical
examples of compounds used as surface active agents are sodium
salts of naturally occurring fatty acid such as tall oil fatty
acid, and sodium salts of synthetic n-alkylbenzene sulfonic acid.
Common concrete air entrainment (or air-entraining) agents include
those derived from the following anionic surfactants: neutralized
wood resins, fatty acids salts, alkyl-aryl sulfonates, and alkyl
sulfate's.
[0060] The term "sacrificial agent" (SA) means a material, or a
mixture of materials, that interacts with (and/or neutralizes the
detrimental effects of) components of fly ash that would otherwise
interact with an air entrainment agent and reduce the effectiveness
of the air entrainment agent to incorporate air (or other gas) into
the cementitious mixture. The sacrificial agents are not "air
entrainment agents" as they are understood in the art and, in the
amounts used in the cementitious mixture, do not cause more than 2
vol % additional air content (or even less than 1 vol % additional
air content) into the same mixture containing no fly ash. In some
embodiments, the sacrificial agent, in the amounts employed in fly
ash-containing mixtures, is responsible for introducing less than
0.5 vol % or even substantially no additional air content into the
same mixture containing no fly ash. In some embodiments, the
sacrificial agent neither promotes nor inhibits the functioning of
the air entrainment agent compared with its functioning in a
similar mixture containing no fly ash.
[0061] The term "cementitious mixture" means a mixture such as
concrete mix, mortar, paste, grout, etc., that is still in castable
form and that, upon setting, develops into a hardened mass suitable
for building and construction purposes. Likewise, the term "cement"
means a product (other than fly ash) that is capable of acting as
the principal hardenable ingredient in a cementitious mixture. In
some embodiments, the cement is portland cement, but at least a
portion can include blast furnace slag, gypsum, and the like.
[0062] The term "percent" or "%" as used herein in connection with
a component of a composition means percent by weight based on the
cementitious components (cement and fly ash) of a cementitious
mixture (unless otherwise stated). When referring to air content,
the term % means percent by volume or vol %.
[0063] The terms "alkyl", "alkenyl", and "alkynyl" as used herein
can include straight-chain and branched monovalent substituents.
Examples include methyl, ethyl, isobutyl, 2-propenyl, 3-butynyl,
and the like.
[0064] The term "substituted" as used herein indicates the main
substituent has attached to it one or more additional components,
such as, for example, amino, hydroxyl, carbonyl, or halogen groups.
The term "unsubstituted" indicates that the main substituent has a
full compliment of hydrogens, i.e., commensurate with its
saturation level, with no substitutions, e.g., linear decane
(--(CH.sub.2).sub.9--CH.sub.3).
[0065] The term "alkoxylated" as used herein is an adjective
referring to a compound having an "alkoxyl" linkage having the
formula --(OR).sub.n-- wherein R can be an alkyl, alkenyl, or
alkynyl group. Examples of suitable "R" groups include ethyl
(ethoxylate), propyl (propoxylate), or butyl (butoxylate)groups.
The value for n is an average value and can vary for the
sacrificial agent (where alkoxylation is present) from 1 to 10, 1.5
to 9 or 2 to 8.
TABLE-US-00001 ABBREVIATIONS Fly Ash FA Portland cement A PCA
Portland cement C PCC Sacrificial agent SA Air entrainment agents
or AEA admixtures Relative to cementitious wt % materials (CM)
Amount of air entrained vol % Average of Air Entrained Aver (%)
Relative Standard Deviation RSD (%) HLB Hydrophilic Lipophilic
Balance K.sub.ow Ratio of solubility in oil (octanol) and in water
LogK.sub.ow Logarithm of K.sub.ow LOI Loss on ignition
BRIEF DESCRIPTION OF THE DRAWINGS
[0066] FIG. 1 is a graph illustrating the competitive absorption by
activated carbon with various sacrificial agents at saturated
concentrations.
[0067] FIG. 2 is a graph illustrating the percentage of air in
concrete with increasing concentrations of an air entrainment agent
with various activated carbon samples at varying amounts.
[0068] FIG. 3 is a graph illustrating the dosage of an air
entrainment agent at 6% air in concrete with increasing amounts of
carbon contents.
[0069] FIG. 4 is a graph illustrating the percentage of air in
concrete with increasing concentrations of an air entrainment agent
with various amounts of activated carbon.
[0070] FIG. 5 is a graph illustrating the percentage of air in
concrete with increasing concentrations of an air entrainment agent
with sacrificial agents and activated carbon.
[0071] FIG. 6 is a graph illustrating the percentage of air in
concrete with increasing concentrations of an air entrainment agent
with sacrificial agent-treated fly ash combined with activated
carbon.
[0072] FIG. 7 is a graph illustrating the percentage of air in
concrete with increasing concentrations of an air entrainment agent
with sacrificial agent-treated fly ash with and without activated
carbon.
[0073] FIG. 8 is a graph illustrating the percentage of air in
concrete with increasing percentages of activated carbon in the
presence of an air entrainment agent and with and without
sacrificial agents.
[0074] FIG. 9 is a graph illustrating the percentage of air in
concrete with increasing concentrations of an air entrainment agent
with and without sacrificial agents.
[0075] FIG. 10 is a graph illustrating the percentage of air in
concrete with increasing concentrations of an air entrainment agent
with concrete friendly activated carbon and varying quality fly ash
samples.
[0076] FIG. 11 is a graph illustrating the percentage of air in
concrete with increasing concentrations of an air entrainment agent
with high and poor quality fly ash, concrete friendly activated
carbon, and sacrificial agents.
DETAILED DESCRIPTION
[0077] In the following description, reference is made to air
entrainment in concrete and cementitious mixtures. It will be
realized by persons skilled in the art that other inert gases, such
as nitrogen, that act in the same way as air, can be entrained in
concrete and cementitious mixtures. The use of air rather than
other gases is naturally most frequently carried out for reasons of
simplicity and economy. Techniques for entraining air in
cementitious mixtures using air-entraining agents are well known to
persons skilled in the art. Generally, when an air entrainment
agent is used, sufficient air is entrained when the ingredients of
the mixture are simply mixed together and agitated in conventional
ways, such as stirring or tumbling sufficient to cause thorough
mixing of the ingredients.
[0078] As noted earlier, air entrainment problems in fly ash
concrete have been traced to undesirable components contained in
the fly ash materials, particularly residual carbon. These fly ash
components can adsorb and/or react or interact with the air
entrainment agent (surface active compounds, e.g. soaps) used for
entrainment air in concrete, thereby neutralizing or diminishing
the functionality of such agents and consequently reducing the
uptake of air. Up to the present, the industrial approach to
dealing with these air entrainment problems consisted in adding
higher dosages of the air entrainment agents in order to overwhelm
the deleterious processes. Because the quantities of detrimental
components in fly ash can vary greatly among fly ashes from
different sources, or for a fly ash from any particular source at
different times, the current practices lead to other complications,
namely in assessing the adequate dosage of air entrainment agents
to achieve a specified air content, in maintaining the specified
air content over adequate time periods, in guarding against
excessive entrained air contents that would detrimentally impact
concrete strength and durability, in obtaining specified air void
parameters, etc. In particular, the fact that excessive dosages of
the air entrainment agent can result in excess air entrainment and
subsequent reduction in concrete compressive strength, is
particularly serious and a major disadvantage of the prior
approach.
[0079] The issues with the components of fly ash and other
combustion ash and the effects of these components on air
entrainment are further complicated by the addition of activated
carbon to fly ash and other combustion ashes. Specifically, mercury
(Hg) is present as a trace element in coal that becomes a
contaminant in fly ash from coal-fired power plants and other coal
fired furnaces. As a result, processes have been developed to
capture Hg contained in fly ash. For example, one process that has
been developed injects activated carbon in fly ash to absorb Hg.
Unfortunately, activated carbon is expensive and thus its use for
Hg removal adds significantly to overall costs. Fly ash without
activated carbon may be used as a partial replacement for portland
cement in concrete if it meets certain specifications (such as
those found in ASTM C618-05 "Standard Specification for Coal Fly
Ash and Raw or Calcined Natural Pozzolan for Use in Concrete"). The
most common reason fly ash without activated carbon cannot be used
in concrete is excess unburned carbon content in the ash. Excess
unburned carbon is not allowed because it absorbs additives used in
concrete making and makes them ineffective. However, after addition
of activated carbon for Hg capture, ash is generally unusable even
if it meets the unburned carbon specifications. This is because the
activated carbon absorbs the concrete additives to a much large
degree than the unburned carbon normally found in fly ash.
Therefore, adding activated carbon to fly ash to capture Hg
requires additional thermal beneficiation to make the resulting fly
ash usable. The inventors have found that adding an amine
sacrificial agent can make fly ash concrete including activated
carbon useful without employing the expensive treatment methods
associated with activated carbon.
[0080] To address the above problems, an amine sacrificial agent is
used to neutralize or eliminate the effect of the harmful
components of fly ash on the air entrainment agent. Typically, the
sacrificial agent acts preferentially (i.e. when present at the
same time as the air entrainment agent, or even after the contact
of the air entrainment agent with the fly ash, the sacrificial
agent interacts with the fly ash), does not itself entrain air in
significant amounts, and does not harm the setting action or
properties of the cementitious material in the amounts employed.
The inventors have now found certain amines capable of
"neutralizing" the detrimental fly ash components, while having
little or no influence on the air entrainment process provided by
conventional air entrainment agents and having no adverse effects
on the properties of the concrete mix and hardened concrete
product. These amine sacrificial agents, introduced into the
mixture at an appropriate time, render fly ash concrete comparable
to normal concrete with respect to air entrainment. The finding of
economically viable chemical additives of this type, as well as
practical processes for their introduction into concrete systems,
constitutes a major advantage for fly ash concrete
technologies.
[0081] It has been found that primary, secondary, and tertiary
non-aromatic amines are the most suitable as sacrificial agents,
namely compounds selected from the group consisting of the
structure NR.sup.1R.sup.2R.sup.3, wherein R.sup.1 is substituted or
unsubstituted non-alkoxylated C.sub.5-22 alkyl, substituted or
unsubstituted non-alkoxylated C.sub.5-22 alkenyl, substituted or
unsubstituted non-alkoxylated C.sub.5-22 alkynyl, substituted or
unsubstituted C.sub.2-22, alkoxylated alkyl, substituted or
unsubstituted C.sub.2-22 alkoxylated alkenyl, or substituted or
unsubstituted C.sub.2-22 alkoxylated alkynyl. R.sup.2 and R.sup.3
are each independently selected from hydrogen, substituted or
unsubstituted C.sub.1-22 alkyl, substituted or unsubstituted
C.sub.2-22 alkenyl, or substituted or unsubstituted C.sub.2-22
alkynyl. In some embodiments, the Log K.sub.ow is in the range of
-3 to +2 (e.g., -2 to +2) and/or the HLB value is in the range of 5
to 20 (e.g., 4 to 18). The alkyl, alkenyl or alkynyl chains can be
branched or straight chains. R.sup.2 and R.sup.3 can be optionally
alkoxylated. The R.sup.1, R.sup.2 and R.sup.3 can be substituted
with groups such as halogen, carbonyl, hydroxyl, amine, and the
like. In some embodiments, these compounds are used in pure or
substantially pure form.
[0082] In some embodiments, one or more of R.sup.1, R.sup.2, and
R.sup.3 is independently an alkoxylated or non-alkoxylated,
substituted or unsubstituted fatty acid residue. In some
embodiments, R.sup.1, R.sup.2, and R.sup.3 can be selected from the
group consisting of saturated fatty acids, monounsaturated fatty
acids, polyunsaturated fatty acids, and mixtures thereof.
[0083] In some embodiments, R.sup.1 is a higher alkyl, alkenyl or
alkynyl group having 7 or more carbon atoms (e.g, C8-C25 or
C10-C20) and is generally an alkyl or alkenyl group. The R.sup.2
and R.sup.3 groups can also be a higher alkyl, alkenyl or alkynyl,
group although, in some embodiments, are lower alkyl, alkenyl or
alkenyl groups (e.g. C1-C5) such as C1-C3 alkyl or hydrogen.
Exemplary compounds include tridodecylamine, dodecyldimethylamine,
octadecyldimethylamine, cocoalkyldimethylamines, hydrogenated
tallowalkyldimethylamines, oleyldimethylamine,
dicocoalkylmethylamine, and mixtures thereof. The compounds can
also be polyetheramines including the groups for R.sup.1, R.sup.2
and R.sup.3 described above and further being alkoxylated to the
levels described herein.
[0084] In some embodiments, one or more of R.sup.1, R.sup.2, and
R.sup.3 is independently amino-substituted (e.g. with a
NR.sup.4R.sup.5 group where R.sup.4 and R.sup.5 are H or
substituted or unsubstituted, alkoxylated or non-alkoxylated,
alkyl, alkenyl or alkynyl groups). For example, the amine
sacrificial agent can be a diamine compound wherein R.sup.1 is
amino-substituted. Exemplary diamines include polyetherdiamines
(such as polyoxypropylenediamines and polyoxyethylene diamines)
wherein the average level of alkoxylation is from 1 to 10, from 1.5
to 9 or from 2 to 8. Suitable alkoxylated diamines can have the
formula NH.sub.2--R--(R.sup.1O).sub.x--NH.sub.2 wherein R is C1-C5
alkyl, R.sup.1 is C2-C4 alkyl, and x is the level of alkoxylation.
For example, polyoxypropylenediamines are commercially available as
Jeffamine D 400 and Jeffamine D 230; and triethyleneglycol diamine
is commercially available as Jeffamine EDR 148, all from Huntsman
International LLC. In some embodiments, the diamines are
non-alkoxylated wherein x is 0 and R can be C5 or greater (e.g.
C8-C25 or C10-C20). In some embodiments, the diamines are
alkoxylated and have the formula
R.sup.3((R.sup.4O).sub.wH)N--R.sup.2--N((R.sup.5O).sub.yH)((R.sup.6O).sub-
.zH) wherein R.sup.2 is C1-C5 alkyl, R.sup.3 is C1-C25 alkyl,
alkenyl or alkynyl, R.sup.4, R.sup.5 and R.sup.6 are independently
C2-C4 alkyl, one or more of x, y and z is greater than 0, and the
total level of alkoxylation (w+y+z) is 1 to 10, 1.5 to 9 or 2 to 8.
In some embodiments, R.sup.3 is C5-C25 alkyl, alkenyl, or alkynyl
(e.g. C8-C25 or C10-C20 alkyl). Exemplary alkoxylated'diamines
include N-oleyl-1,1'-iminobis-2-propanol and
N-tallowalkyl-1,1'-iminobis-2-propanol. One commercially available
example is N-tallowalkyl-1,1'-iminobis-2-propanol available from
Akzo Nobel as Ethoduomeen T/13N. In some embodiments, the diamines
can be non-alkoxylated (w+y+z)=0 and R.sup.2 can be C5 or greater
(e.g. C8-C25 or C10-C20).
[0085] In some embodiments, the amine is hydroxyl substituted (e.g.
at one, two or three of R.sup.1, R.sup.2 and R.sup.3) and is an
alcoholamine. In some embodiments, R.sup.1 is higher alkyl as
described above and can be optionally substituted with a carbonyl
group and one or more of R.sup.2 and R.sup.3 are hydroxyl
substituted. For example, Amadol 1017 commercially available from
Akzo Nobel and having the formula
CH.sub.3(CH.sub.2).sub.10C(.dbd.O)N(CH.sub.2CH.sub.2OH).sub.2 can
be used. Alternatively, R.sup.1 and one or more of R.sup.2 and
R.sup.3 can be hydroxyl substituted.
[0086] In some embodiments, the amine sacrificial agent has a
particular "Hydrophilic Lipophilic Balance" (HLB) rating, or
oil/water (or octanol/water) partition coefficients (K.sub.OW).
These terms are understood in the art and are described, for
example, in U.S. Pat. No. 7,485,184, which is hereby incorporated
by reference in its entirety. In some embodiments, the HLB value of
the sacrificial agent or the mixture of sacrificial agents is in
the range of 5 to 20 (e.g., 4 to 18). In some embodiments, the Log
Kow for the sacrificial agent can be in the range of -3 to +2 (e.g.
-2 to +2).
[0087] Combinations of these amine sacrificial agents can be used
as the sacrificial agent composition. For example, in some
embodiments, dodecyldimethylamine, polyoxypropylenediamine,
triethyleneglycol diamine, and mixtures thereof are used as the
sacrificial agent. In some embodiments, the sacrificial agent can
two or more amine sacrificial agents in weight a ratio of 1:1-1:50
wherein the total sacrificial agent is as described herein. For
example, the sacrificial agent can include a first component having
a compound A from the group of tridodecylamine,
dodecyldimethylamine, octadecyldimethylamine,
cocoalkyldimethylamines, hydrogenated tallowalkyldimethylamines,
oleyldimethylamine, dicocoalkylmethylamine, and mixtures thereof
(e.g. dodecyldimethylamine), and a second compound B from the group
of polyetheramines, diamines, alcoholamines, all as described
above, and mixtures thereof (e.g. polyoxypropylenediamine), wherein
the weight ratio of compound A to compound B is 2:1 to 1:50, 1.25:1
to 1:25, or 1:1 to 1:5. In some cases, it can be advantageous to
mix a sacrificial agent having different HLB values (e.g. high and
low values) to produce a combined sacrificial agent mixture that is
approximately neutral in its effect on the entrainment of air in
the mixture. In this way, it is possible to use highly active
sacrificial agents that would otherwise interfere too much with the
entrainment of air.
[0088] In some embodiments, the amounts of such sacrificial agents
are sufficient to neutralize the harmful components of the fly ash
that adsorb or react with the air entrainment agents. The required
minimum dosage can be determined experimentally through air
entrainment protocols since, as discussed earlier and shown below,
the deleterious effects of fly ash components are not necessarily
directly related to their carbon content or LOI. In some
embodiments, the sacrificial agents can be used in reasonable
excess over the neutralizing amounts without entrainment of excess
air (or reduction of such entrainment) or harming the concrete
mixture or the subsequent setting action or properties of the
hardened concrete. This means that an amount can be determined
which exceeds the neutralizing amount required for a fly ash
containing the highest amount of the harmful components likely to
be encountered, and this amount can then be safely used with any
fly ash cement mixture.
[0089] The amine sacrificial agents can be used in combination with
one or more sacrificial agents described in U.S. Pat. No.
7,485,184, which is incorporated by reference herein in its
entirety. For example, additional sacrificial agents can include
sodium naphthoate, sodium naphthalene sulfonate, sodium diisopropyl
naphthalene sulfonate, sodium cumene sulfonate, sodium dibutyl
naphthalene sulfonate, ethylene glycol phenyl ether, ethylene
glycol methyl ether, butoxyethanol, diethylene glycol butyl ether,
dipropylene glycol methyl ether, polyethylene glycol and phenyl
propylene glycol and combinations thereof. In addition, In some
embodiments, sodium diisopropyl naphthalene sulfonate is included
with the amine sacrificial agent in the sacrificial agent
composition. The additional sacrificial agent can be included at a
weight ratio of non-amine sacrificial agent to amine sacrificial
agent of 1:2 to 1:150, or 1:5 to 1:100, or 1:10 to 1:75.
[0090] In some embodiments, the amine sacrificial agents can be
used in combination with a water reducer. For example,
lignosulfonates and polynaphthalene sulfonates have been found to
particularly enhance the properties of the amine sacrificial
agents. The water reducer can be included in a weight ratio of
water reducer to amine sacrificial agent of 40:1 to 1:1.25 or 15:1
to 2:1.
[0091] The sacrificial agents can be added at any time during the
preparation of the concrete mix. In some embodiments, they are
added before or at the same time as the air entrainment agents so
that they can interact with the fly ash before the air entrainment
agents have an opportunity to do so. The mixing in this way can be
carried out at ambient temperature, or at elevated or reduced
temperatures if such temperatures are otherwise required for
particular concrete mixes. The sacrificial agents can also be
premixed with the fly ash or with the air entrainment agent.
[0092] It is particularly convenient to premix the sacrificial
agent with the fly ash because the sacrificial agent can commence
the interaction with the harmful components of the fly ash even
before the cementitious mixture is formed. The sacrificial agent
can simply be sprayed or otherwise added in liquid form onto a
conventional fly ash and left to be absorbed by the fly ash and
thus to dry. If necessary, the sacrificial agent can be dissolved
in a volatile solvent to facilitate the spraying procedure. Fly ash
treated in this way can be prepared and sold as an ingredient for
forming fly ash cement and fly ash concrete.
[0093] Surprisingly, it has also been found that the sacrificial
agent is even effective when added after the mixing of the other
components of the cementitious mixture (including the air
entrainment agent). Although not wishing to be bound by a
particular theory, it appears that the sacrificial agent can
reverse any preliminary deactivation of the air entrainment agent
caused by contact with the fly, ash, and thus reactivate the air
entrainment agent for further air entrainment. It is observed,
however, that the beneficial effect of the sacrificial agents is
somewhat lower when added at this stage rather than when added
before or during the mixing of the other components.
[0094] As noted above, in some embodiments, the chemical additives
used as sacrificial agents are not effective air entrainment agents
in the amounts employed, so that they do not contribute directly to
air entrainment and can thus also be used in normal concrete
containing no fly ash. This confers on the sacrificial agents the
particularly important feature that these sacrificial agents can be
introduced at dosages higher than the minimum dosage required to
restore normal air entrainment without leading to erratic air
entrainment and excessive air entrained levels. If one of the
sacrificial agents used in a combination of sacrificial agents
exhibits some surfactant (air entrainment) properties, it can be
proportioned in such a way that the combination of sacrificial
agents will entrain less than 2% air (or less than 1% air, or
substantially no air), above the control values, in normal concrete
without any fly ash. That is to say, when a concrete formulation is
produced without fly ash, but with an air entrainment agent, the
extra amount of air entrained when a sacrificial agent is added
represents the extra air entrained by the sacrificial agent. The
amount of air entrained in a cementitious mixture can be measured
by determination of specific gravity of the mixture, or other
methods prescribed in ASTM procedures (ASTM C231, C173, and
C138--the most recent disclosures of which are incorporated herein
by reference in their entirety).
[0095] Typical concrete air entrainment agents are n-dodecylbenzene
sulfonate salts (referred to as Air 30) and tall oil fatty acid
salts (referred to as Air 40). The typical dosage range of these
ingredients in portland cement concrete mixes is 0.002 to 0.008 wt
% of the cementitious components. The targeted air entrainment for
the cementitious composition is typically 6-8 vol % air.
[0096] Other components of the cementitious mixtures are water,
cement and fly ash. These can be used in proportions that depend on
the type of material desired (e.g., pastes, grouts, mortars,
concrete) and on the required fresh and hardened properties of the
finished material. Such systems and their composition, as well as
equipment and protocols for their preparation, are well known in
the art; for mortars and concrete, these are adequately described
in standard reference texts, such as ASTM Cement and Concrete
(e.g., 4.01, 4.02); Design and Control of Concrete
Mixtures--Portland Cement Association; and American Concrete
Institute--Manual of Concrete Practice (the disclosures of which
are incorporated herein by reference). For pastes, the composition
and preparation equipment and protocols will be described in detail
in following sections. In practice, the content of various
ingredients in a cementitious mixture are often reported as weight
ratios with respect to the cement or to the total cementitious
materials when other cementitious materials such as fly ash, slag,
etc., are present. These ratios are well known to persons skilled
in the art.
[0097] Once formed, the cementitious mixture can be used in any
conventional way, e.g. poured into a form and allowed to harden and
set. The hardened product will contain fly ash and entrained air,
but no excess of air entrainment agent that could adversely affect
the air content and properties of the hardened product.
[0098] The cementitious mixtures can include other standard or
specialized concrete ingredients known to persons skilled in the
art.
[0099] The following examples are provided to more fully illustrate
some of the embodiments of the present invention. It should be
appreciated by those of skill in the art that the techniques
disclosed in the examples which follow represent techniques
discovered by the inventors to function well in the practice of the
invention, and thus can be considered to constitute exemplary modes
for its practice. However, those of skill in the art should, in
light of the present disclosure, appreciate that many changes can
be made in the specific embodiments that are disclosed and still
obtain a like or similar result without departing from the spirit
and scope of the invention. Parts and percentages are provided on a
per weight basis except as otherwise indicated.
EXAMPLES
Example 1
PACT Formulation
[0100] A sacrificial agent formulation (PACT) is prepared by mixing
polyoxypropylenediamine, dodecyldimethylamine, and optionally
sodium diisopropylnapthalenesulfonate. For the following examples,
PACT was formulated as follows: 0.05% dodecyldimethylamine and
0.15% polyoxypropylenediamine, by weight of fly ash.
Composition Preparation:
[0101] To prepare the composition, the aggregate is mixed with
partial water followed by the portland cement. Fly ash combined
with activated carbon is then added followed by the PACT
formulation and the air entrainment agent. Alternatively, the PACT
formulation can be added directly to the fly ash. Additional water
is added to obtain a 4-6 inch slump. The composition is then mixed
using a rotary mixer, and tested for volume percentage of air using
a pressure meter according to the ASTM C 231 method.
[0102] Activated carbon for the following examples was obtained
from three sources:
PAC-A: Norit HgLH (Norit Americas Inc., Marshall, Tex.)
PAC-B: ADA-ES (ADA Environmental Solutions, Littleton, Colo.)
PAC-C: Calgon MC Plus (Calgon Carbon, Pittsburgh, Pa.)
[0103] The air entrainment agent used in the following examples was
MB-AE 90 (BASF Construction Chemicals, Shakopee, Minn.) and is
labeled as AEA-1.
Example 2
[0104] The competitive absorption by PAC-C with various sacrificial
agents at saturated concentrations was determined (FIG. 1). The
trace labeled Model AEA (DDBS) displays the absorption of an air
entrainment agent (dodecylbenzenesulfonate (DDBS)) by MC activated
carbon without the presence of a sacrificial agent. The trace
labeled DDBS (with SA-A2) displays the absorption of DDBS by PAC-C
and Jeffamine EDR-148. The trace labeled DDBS (with SA-C) displays
the absorption of DDBS by MC activated carbon and Jeffamine 230.
The trace labeled DDBS (with SA-J4) displays the absorption of DDBS
by MC activated carbon and Jeffamine 400.
Example 3
[0105] The percentage of air in concrete with increasing
concentrations of air entraining agent AEA-1 with varying amounts
of activated carbon samples PAC-A, PAC-B, and PAC-C was determined.
The amounts tested for each activated carbon sample include 0.75%
and 1.5% (FIG. 2). Cement and fly ash cement independently served
as controls. All activated carbon samples increased the air
entraining agent demand.
Example 4
[0106] The dosage of an air entrainment agent for 6% air in
concrete with increasing amounts of carbon content with activated
carbon samples PAC-A, PAC-B, and PAC-C was determined (FIG. 3). Fly
ash served as the control.
Example 5
[0107] The percentage of air in concrete with increasing
concentrations of an air entrainment agent (AEA-1) with varying
amounts of activated carbon (PAC-A) was determined (FIG. 4). Fly
ash served as the control. The presence of activated carbon caused
the air entraining admixture demand to reach unacceptable
levels.
Example 6
[0108] The percentage of air in concrete with increasing
concentrations of an air entrainment agent (AEA-1) with varying
amounts of activated carbon (PAC-A) with and without PACT (as
formed in Example 1) was determined (FIG. 5). The amounts tested
include 0.75% PAC, 2% PAC, 3% PAC, 0.75% PAC with PACT, 2% PAC with
PACT, and 3% PAC with PACT. Fly ash served as the control. The
inclusion of PACT in the activated carbon formulations reduced the
air entraining admixture demand to acceptable levels.
Example 7
[0109] The percentage of air in concrete with increasing
concentrations of an air entrainment agent (AEA-1) with fly ash
treated with activated carbon (PAC-A) in the presence of PACT was
determined (FIG. 6). The amounts tested included fly ash treated
with 1.5% activated carbon and fly ash treated with 3% activated
carbon. The PACT was present in constant, high dosage. Untreated
fly ash served as the control. Increasing the dosage of PACT
resulted in a performance comparable to that of untreated fly
ash.
Example 8
[0110] The percentage of air in concrete with increasing
concentrations of an air entrainment agent (AEA-1) with PACT
treated fly ash in the presence and absence of 3% activated carbon
(PAC-A) was determined (FIG. 7). Both the PACT treated fly ash that
contained activated carbon and the PACT treated fly ash that did
not contain activated carbon displayed similar entraining
properties.
Example 9
[0111] The percentage of air in concrete with varying amounts of
activated carbon (PAC-A) with a constant concentration (1 oz/cwt)
of an air entrainment agent (AEA-1) was determined (FIG. 8). The
air entrainment agent was treated with PACT. Untreated AEA-1 served
as the control. PACT treatment was shown to minimize air
fluctuations over a broad range of PAC contamination levels.
Example 10
[0112] The percentage of air in concrete with increasing
concentrations of air entrainment agent (AEA-1) was determined for
untreated activated carbon and activated carbon treated with PACT
(FIG. 9). The activated carbon samples were obtained from three
different sources (PAC-A, PAC-B, and PAC-C). PACT was effective for
all of the PAC samples tested; however, in some cases, it may be
better to adjust the formulation depending upon the PAC source.
Example 11
[0113] The percentage of air in concrete with increasing
concentrations of air entrainment agent (AEA-1) was determined for
high quality fly ash having a LOI of about 1% and a low quality fly
ash having a LOI of about 2.5% with or without the addition of CF
PAC-C activated carbon, a concrete friendly activated carbon
available from Calgon Corp. and present in an amount of 3% (FIG.
10). The concrete friendly activated carbon influenced air
entrainment, but did not compensate for underlying ash quality
issues related to high or varying native carbon content.
Example 12
[0114] The percentage of air in concrete with increasing
concentrations of air entrainment agent (AEA-1) was determined for
the same high quality and low quality fly ashes from Example 11
with or without the addition of CF PAC-C activated carbon and/or
PACT (FIG. 11). PACT effectively decreased the negative influence
of carbon.
* * * * *