Note: Descriptions are shown in the official language in which they were submitted.
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ACTIVATION OF NATURAL POZZOLAN AND USE THEREOF
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is generally in the field of supplementary cementitious
materials,
natural pozzolans, activation of natural pozzolans, and blends of natural
pozzolans and other
materials.
2. Relevant Technology
Supplementary Cementitious Materials (SCMs), such as coal ash, metallurgical
slags,
natural pozzolans, biomass ash, post-consumer glass, and limestone, can be
used to replace a
portion of Portland cement in concrete. SCMs can yield improved concrete with
increased
paste density, increased durability, lower heat of hydration, lower chloride
permeability,
reduced creep, increased resistance to chemical attack, lower cost, and
reduced environmental
impact.
Natural pozzolans such as volcanic ash, pumice, and other materials found in
the earth
can be calcined and/or ground to increase pozzolanic activity. Both processes
consume
substantially energy. Due to the hardness of volcanic glasses, grinding
natural pozzolans can
be difficult. Milling apparatus such as vertical roller mills and horizontal
roll presses may be
incapable of grinding natural pozzolans because of the difficulty of
maintaining a stable bed.
Natural pozzolans can also be interground with Portland cement clinker to form
Type
1P blended cement. Such interground blended cements can have low reactivity
unless ground
to much higher fineness than ordinary Portland cement (OPC). While
intergrinding naturally
pozzolans with cement clinker can be performed in a single step and is
therefore significantly
less expensive and more efficient than separately processing OPC and natural
pozzolan and
then blending them together, interground blends typically underperform non-
interground
blends with separately processed components.
Accordingly, there remains a long-felt need to find better and more cost-
effective
ways to activate natural pozzolans.
SUMMARY
Disclosed herein are activated natural pozzolans, pozzolan blends, cement-SCM
compositions, and methods and systems for activating natural pozzolans,
forming pozzolan
blends, and forming cement-SCM compositions. Natural pozzolans, such as
volcanic ash,
pumice, perlite, other materials of volcanic origin, and other pozzolans of
natural origin
found in the earth, can be activated by intergrinding with at least one
mineral material, such
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as at least one granular mineral material and/or limestone.
In some embodiments an initially coarse or granular material (e.g., 1-3 mm or
larger,
such as 2 mm or larger, in size) is interground with a natural pozzolan, such
as volcanic ash
(e.g., that contains a significant quantity of particles less than 1 mm, 500
p.m, or 200 p.m in
size), that might otherwise be difficult to grind in a vertical roller mill
(VRM) or horizontal
roll press (high pressure grinding roll) that require addition of an initially
coarse or granular
material to form a stable bed. For example, volcanic ash, tuff, pumice, or
other natural
pozzolan containing moisture, that has low surface area, or that is otherwise
insufficiently
reactive for use as a partial cement substitute in concrete, can be
interground with the
granular material to form an activated pozzolan or SCM blend having reduced
moisture
content, finer particle size, higher surface area, and higher pozzolanic
reactivity,
By way of example and not limitation, the coarse or granular SCM can be
granulated
blast furnace slag (GBFS), steel slag, other metallurgical slag, limestone,
fine or medium
aggregates, partially ground shale, geologic materials, waste glass, glass
shards, glass beads,
basalt, sinters, ceramics, recycled bricks, recycled concrete, porcelain, used
catalyst particles,
refractory materials, other waste industrial products, sand, gypsum, bauxite,
calcite, dolomite,
granite, volcanic rock, volcanic glass, quartz, fused quartz, natural
minerals. The natural
pozzolan can be volcanic ash, trass, pumice, perlite, other natural pozzolan.
The natural
pozzolan may initially have a moisture content (e.g., of at least 3% prior to
intergrinding) and
the interground particulate material may have a reduced moisture content
(e.g., less than
0.5%).
Intergrinding clinkers or granules with finer pozzolan materials can be
advantageous
when using a modern mill that requires some percentage of clinkers or granules
to be present
to form a stable grinding bed (e.g., vertical roller mills, horizontal roll
presses, and the like
used to process cement clinker). If included at all, cement clinker is
preferably less than 30%,
less than 25%, less than 20%, less than 15%, less than 10%, less than 5%, less
than 4%, less
than 3%, less than 2%, or less than 1% of the total interground material.
In some embodiments, a system of manufacturing an activated natural pozzolan
composition comprises one more milling apparatus configured to intergrind a
granular
material and/or limestone and one or more natural pozzolans to form an
activated interground
pozzolan composition. The milling apparatus may generate and/or involve the
input of heat,
which can advantageously reduce the moisture content of the natural pozzolan
during
grinding.
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In some embodiments, the interground particulate material can be used to
replace a
portion of cement and/or pozzolan normally used in concrete or other
cementitious
composition. The interground particulate material can be preblended with one
or more
additional SCMs and/or OPC prior to use. For example, the interground
particulate material
can be blended, without intergrinding, with an auxiliary particulate
component, such OPC,
magnesium cement, aluminate cement, bottom ash, fly ash, GGBFS, steel slag,
limestone,
and the like.
BRIEF DESCRIPTION OF DRAWINGS
FIGS. 1A and 1B are illustrative particle size distribution (PSD) charts of
exemplary
1() ordinary Portland cement (OPC) subdivided to show fine, medium, and
coarse fractions;
FIG. 2A is PSD chart of a finely ground cement clinker subdivided to show
fine,
medium, and coarse fractions;
FIG. 2B is a PSD chart comparing the PSD of the finely ground cement clinker
of
FIG. 2A with the PSD of a finely interground cement clinker and natural
pozzolan having an
approximate bimodal PSD, with estimated proportioning of the cement and
pozzolan
fractions within the fine, medium, and coarse fractions;
FIG. 3A is a PSD chart of another finely ground cement material made using
cement
clinker and subdivided to show fine, medium, and coarse fractions;
FIG. 3B is a PSD chart comparing the PSD of the finely ground cement material
of
FIG. 3A with the PSD of another finely interground cement clinker and natural
pozzolan
having an approximate bimodal PSD, with estimated proportioning of the cement
and
pozzolan fractions within the fine, medium, and coarse fractions;
FIG. 3C is a PSD chart of a fine interground cement clinker and natural
pozzolan,
with estimated proportioning of the cement and pozzolan fractions within the
fine, medium,
and coarse fractions;
FIG. 4A is graph illustrating the PSD of another finely interground cement
clinker and
natural pozzolan without an apparent bimodal PSD, with estimated proportioning
of the
cement and pozzolan fractions within the fine, medium, and coarse fractions;
FIG. 4B is graph illustrating the PSD of an interground limestone and natural
pozzolan having an approximate bimodal PSD, with estimated proportioning of
the limestone
and pozzolan fractions within the fine, medium, and coarse fractions;
FIG. 5A is a photograph made using a conventional microscope of sieved natural
pozzolan particles that are opaque and have a more rounded morphology;
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FIG. 5B is a photograph made using a conventional microscope of sieved natural
pozzolan particles that have a glassy appearance and a jagged and flat
morphology;
FIG. 6 is a flow diagrams illustrating an example method of manufacturing a
blended
composition, including a fine interground particulate component;
FIGS. 7-9 are flow diagrams illustrating example methods of manufacturing
Cement-
SCM compositions and/or components thereof;
FIGS. 10A and 10B schematically illustrate example milling apparatus for
manufacturing one or more components of compositions disclosed, including an
interground
particulate composition or component;
FIG. 11 is a flow diagram illustrating an example method of manufacturing a
coarse
supplementary cementitious material (SCM), including at least a portion of a
coarse
particulate component;
FIG. 12 schematically illustrates an example separation apparatus for use in
making
one or more components of a cement-SCM composition, including a coarse SCM;
and
FIGS. 13A-13C schematically illustrate exemplary manufacturing systems for
making
one or more cement-SCM compositions.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
I. INTRODUCTION
Disclosed herein are activated pozzolan compositions for use in making
concrete and
other cementitious compositions and methods and systems for manufacturing.
Intergrinding processes can be used to manufacture a blended SCM material,
such as
an initially coarse granular SCM that is initially 1-3 mm in size with an
initially fine SCM
powder that might otherwise be difficult to grind in a vertical roller mill
(VRM) or horizontal
roll press. To form a stable bed, the initially coarse granular SCM is used to
form a stable bed
and interground with the finer SCM. For example, a volcanic ash or natural
pozzolan having
a moisture content or which is otherwise insufficiently reactive can be
interground with a
granular material to form an activated pozzolan or SCM blend having reduced
moisture and
finer particle size. The coarse granular SCM can be granulated blast furnace
slag, steel slag,
other metallurgical slags, pumice, limestone, dolomite, fine aggregates, glass
shards, recycled
bricks, ceramics, or concrete, basalt, shale, tuff, trass, or other geologic
material.
Activating natural pozzolans which contain substantial moisture (at least 3%,
5%,
7.5%, 10%, 15%, 20%, or 25%) by intergrinding with a coarse granular SCM
material
instead of cement clinker prevents the moisture from undesirably and
prematurely reacting
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with cement clinker, as can occur in typical interground cement-pozzolan
blends.
FIG. 1A is a PSD chart showing data measured by a laser diffraction technique
of a
commercially available Type I/II OPC having a Blaine fineness of 376 m2/kg.
The PSD chart
is further subdivided into three regions or fractions designated as "fine"
(e.g., <5 p.m),
"medium" (e.g., 5-30 p.m), and "coarse" (e.g., > 30 p.m). It will be
appreciated that these
particle size ranges and cutoffs are for illustration and comparison purposes
and should not be
taken as absolute or necessarily definitional.
FIG. 1B is a PSD chart showing data measured by a Malvern Mastersizer 2000 of
a
ground cement clinker material milled using a vertical roll mill (VRM) to a
d90 within a
typical range of about 40-45 pm. The PSD of the ground cement clinker in FIG.
1B is steeper
than the PSD of the OPC in FIG. 1A, with a d90 of about 43.4 p.m, a d50 of
about 18.8 p.m,
and a d10 of about 3.8 p.m. The ground cement clinker in FIG. 1B has fewer
"fine" particles
than the OPC of Fig. 1A, as illustrated by the smaller cross-hatched area
designed as "fine".
Nevertheless, both Portland cement materials have a typical d90 (e.g., about
40-45 p.m) and
typical d50 (e.g., about 18-20 p.m) and therefore contain a substantial
proportion of coarse
cement particles that may not fully hydrate, particularly at lower water-to-
cement ratios (w/c).
"Hydraulic cement" and "cement" include Portland cement and similar materials
that
contain one or more of the four clinker materials: C3S (tricalcium silicate),
C2S (dicalcium
silicate), C3A (tricalcium aluminate), and C4AF (tetracalcium aluminoferrite).
Hydraulic
cement can also include white cement, calcium aluminate cement, high-alumina
cement,
magnesium silicate cement, magnesium oxychloride cement, or oil well cement.
"Supplementary cementitious material" and "SCM" include any material commonly
understood in the industry to constitute materials that can replace a portion
of hydraulic
cement in concrete. Non-limiting examples include GGBFS, Class C fly ash,
steel slag, silica
fume, metakaolin, Class F fly ash, calcined shale, calcined clay, natural
pozzolans, ground
pumice, ground glass, ground limestone, ground quartz, and precipitated
CaCO3). Ground
quartz and other siliceous materials are understood to be pozzolanic when
ground to include a
substantial quantity of finer particles (e.g., 25 p.m and smaller).
In some embodiments, a fine interground material can include one or more types
of
clinkers or granules initially larger than about 1-3 mm (e.g., cement,
metallurgical slags,
limestone, pumice, coal ash, sinters, waste glass, natural pozzolans, bricks,
ceramics,
recycled concrete, refractory materials, other waste industrial products,
sand, natural minerals
interground with one or more finer SCMs having an initial particle size < 1 mm
(e.g.,
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volcanic ash, natural pozzolans, fly ash, waste fines from aggregate
processing, red mud).
In some embodiments, at least one of the SCM fraction of the fine interground
particulate component or the coarse SCM particles of the coarse particulate
component may
comprise one or more SCM materials selected from coal ashes, slags, natural
pozzolans,
ground glass, and non-pozzolanic materials. By way of example, coal ashes can
be selected
from fly ash and bottom ash, slags can be selected from ground granulated
blast furnace slag,
steel slag, and metallurgical slag containing amorphous silica, natural
pozzolans can be
selected from natural pozzolanic deposits, volcanic ash, metakaolin, calcined
clay, trass, and
pumice, ground glass can be selected from post-consumer glass and industrial
waste glass,
and non-pozzolanic materials can be selected from limestone, metastable
calcium carbonate
produced by reacting CO2 from an industrial source and calcium ions,
precipitated calcium
carbonate, crystalline minerals, hydrated cements, and waste concrete.
In some embodiments, an optional auxiliary particulate components can be
blended
with the interground particulate composition. The optional auxiliary
particulate component
can be virtually any hydraulic cement, SCM material, or blend thereof that has
not been
interground with the interground particulate composition.
ACTIVATION OF NATURAL POZZOLANS
A. Intergrinding to Activate Natural Pozzolan
FIGS. 2B, 3B, 4A, and 4B are PSD charts showing data measured by a Malvern
Mastersizer 2000 of example interground particulate compositions containing an
activated
natural pozzolan. The interground material of FIG. 4B can be used as a
component to make
cement-SCM compositions. It can be the end product as it is includes an
activated natural
pozzolan made without calcination and without intergrinding with cement
clinker.
For comparison purposes, FIG. 2A is a PSD chart, illustratively subdivided
with fine,
medium, and coarse fractions, showing data measured by a Malvern Mastersizer
2000, of a
finely ground cement material consisting of 100% Portland cement made from the
same
cement clinker used in FIG. 1B and milled using the same VRM. Interestingly,
the PSD chart
of FIG. 2A has a shape very similar to the PSD chart of FIG. 1B even though
the two
cements have very different d90s.
FIG. 2B graphically illustrates and compares the PSDs of the 100% ground
Portland
cement clinker of FIG. 2A (bold line curve) and a 50:50 (w/w) interground
blend (thin line
curve) of the same batch of cement clinker and a natural pozzolan. The PSD
chart in FIG. 2B
of the 50:50 blend is apparently bimodal and is further subdivided to
illustratively show fine,
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medium, and coarse fractions of each cement and pozzolan fraction. For
illustration purposes,
the PSD curve of FIG. 2A, which is overlaid over the PSD chart for the 50:50
blend, was
used to extrapolate and estimate the relative proportions of fine cement and
pozzolan within
the fine, medium, and coarse fractions. The PSD curve of the cement fraction
in FIG. 2B was
assumed to have similar shape as the PSD curves of FIGS. 1B and 2A, with the
apparent
bimodal feature being attributed to the different grinding characteristics of
the softer natural
pozzolan interground with the harder cement clinker.
For comparison, FIG. 3A is a PSD chart illustratively subdivided to show fine,
medium, and coarse fractions, showing data measured by a Malvern Mastersizer
2000 of
another finely ground cement material made from the cement clinker using a
VRM. The
finely ground cement material has a d90 of about 24.4 p.m, a d50 of about 10.2
p.m, and d10
of about 2.1 p.m. Compared to the PSDs of the conventional Portland cement
materials shown
in FIGS. 1A and 1B, the fine cement material of FIG. 3A has a substantially
lower d90,
higher reactivity, and substantially fewer particles that will not fully
hydrate at 28 days.
FIG. 3B graphically illustrates and compares the PSDs of the finely ground
cement
material of FIG. 3A (thin line curve) and another 50:50 (w/w) interground
blend (bold line
curve) of cement clinker and natural pozzolan. The clinker and pozzolan were
initially pre-
blended and then milled using the VRM. The interground blend has a d90 of
about 24.6 p.m,
a d50 of about 9.2 pm, and a d10 of about 1.8 p.m. Similar to FIG. 2B, the PSD
of the 50:50
(w/w) interground blend in FIG. 3B appears to have an approximate bimodal
shape, although
not as distinctive as in FIG. 2B, which again suggests a non-uniform
distribution of cement
and pozzolan particles within the interground blend. For illustration
purposes, the PSD curve
of FIG. 3A, which is overlaid over the PSD chart for the 50:50 blend, was used
to extrapolate
and estimate the relative proportions of cement and pozzolan within the fine,
medium, and
coarse fractions. The PSD curve of the cement fraction in FIG. 3B was assumed
to have
similar shape as the PSD curves of FIG. 3A, with the apparent bimodal feature
being
attributed to the different grinding characteristics of the softer natural
pozzolan and harder
cement clinker.
Figure 3C is a PSD chart of an interground blend of cement clinker and natural
pozzolan that does not have an apparent bimodal shape. Nevertheless, the shape
of the PSD
curve of the cement fraction was assumed to have the same shape as the PSD
curves in FIGS.
1B and 2A for the same cement material. On this assumption, FIG. 3C is
subdivided between
cement and pozzolan materials throughout the PSD curve and still shows a
higher
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preponderance of fine pozzolan particles in the fine particle region and a
higher
preponderance of cement particles in the medium and coarse particle regions
even without an
apparent bimodal distribution within the overall interground blend.
FIG. 4A is a chart PSD of a 50:50 (w/w) interground blend of cement clinker
and a
volcanic ash from Utah. The PSD of this interground blend does not appear to
have a bimodal
shape, which might suggest a fairly uniform distribution of cement and natural
pozzolan
particles throughout the interground blend. For illustrative purposes, the PSD
chart is
subdivided to show the relative preponderance cement and pozzolan particles
within fine,
medium, and coarse regions of the PSD curve.
FIG. 4B is a PSD chart of a 50:50 (w/w) interground blend of limestone and the
Utah
volcanic ash. The limestone and natural pozzolan were initially pre-blended
and then milled
using a VRM. The interground blend of limestone and natural pozzolan has a d90
of about
24.2 i.tm, a d50 of about 6.3 i.tm, and a d10 of about 1.4 i.tm. The PSD of
this interground
blend has an approximate bimodal shape, which suggests a non-uniform
distribution of
limestone and pozzolan particles within the interground blend. Because
limestone is generally
softer than cement clinker, because this natural pozzolan appears to be as
hard or harder than
cement clinker, and because the PSD is broadened compared to the other
illustrated PSDs, it
is hypothesized that the finer particles in this 50:50 interground blend
(e.g., below the d50)
are predominately composed of limestone particles and the coarser particles
(e.g., above the
d50) are predominately composed of natural pozzolan particles. The PSD chart
was
subdivided for illustrative purposes based on an extrapolation of the PSD
curves shown in
FIGS. 2A-4B. The inclusion of finely ground limestone particles can
beneficially offset the
retardation effect of many pozzolans in cement-SCM blends.
FIG. 5A is a photograph made using a conventional microscope of sieved coarse
natural pozzolan particles provided by Drake cement, which is the pozzolan
used to make the
fine interground blended materials described with reference to FIGS. 2B, 3B,
and 3C. The
coarse particles appear to be substantially opaque with a generally rounded
and somewhat
globular morphology. Coarse SCM particles having a generally rounded
morphology should
provide higher fluidity and lower water demand compared to jagged particles.
Nevertheless,
because the pozzolan particles are not perfect spheres, they have some uneven
surface that
might provide for improved pozzolanic reactivity. Intergrinding with granules
or clinker to
make a fine interground particulate material as disclosed herein would likely
significantly
increase their pozzolanic reactivity.
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FIG. 5B is a photograph made using a conventional microscope of sieved coarse
natural pozzolan particles provided by Jack B. Parsons Ready Mix, which is the
pozzolan
used to make the fine interground blended materials described with reference
to FIGS. 4A
and 4B. The coarse particles have a glassy, more transparent appearance,
suggesting an
amorphous rather than crystalline structure and a jagged and more flat
morphology. The
glassy and jagged nature of these particles might increase their pozzolanic
reactivity
compared to spherical pozzolanic particles, such as fly ash, of similar size.
However, their
flat, plate-like morphology may reduce fluidity and increase water demand
compared to
similarly sized particles having a rounded morphology. Intergrinding with a
granular material
to make a fine interground particulate material should increase pozzolanic
reactivity and
reduce water demand.
In some embodiments, the fine interground particulate blend can have a d90
equal to
or less than about 45 p.m, 42.5 p.m, 40 p.m, 37.5 p.m, 35 pm, 32.5 p.m, 30 pm,
27.5 p.m, 25
p.m, 23 p.m, 21 p.m, or 20 p.m. In such cases, the d90 can be selected to be
greater than about
10 p.m, 11 pm, 12 p.m, 13 p.m, 14 p.m, 15 p.m, 17 p.m, or 19 p.m. In other
embodiments, the
fine interground particulate blend has a d90 equal to or less than about 25
p.m, 23 p.m, 21 p.m,
19 p.m, 17.5 p.m, 16 p.m, 15 p.m, 14 p.m, 13 p.m, 12 p.m, or 11 p.m. In such
cases, the d90 can
be selected so as to be equal to or greater than 5 p.m, 6 p.m, 7 p.m, 8 p.m, 9
p.m, or 10 p.m.
In some embodiments, the fine interground particulate blend can have a d10
equal to
or less than about 5 p.m, 4.5 p.m, 4 p.m, 3.5 p.m, 3 p.m, 2.75 p.m, 2.5 p.m,
2.25 p.m, 2 p.m, 1.75
p.m, 1.5 p.m, 1.35 p.m, 1.25 pm, 1.15 p.m, 1.07 pm, or 1 p.m. In some
embodiments, the d10
of the fine interground particulate blend can be equal to or greater than
about 0.2 p.m, 0.25
p.m, 0.3 p.m, 0.35 p.m, 0.4 p.m, 0.5 p.m, 0.6 p.m, 0.7 p.m, 0.8 p.m, 0.9 p.m,
or 1.0 p.m.
In some embodiments, the fine interground particulate blend can have a d50
equal to
or less than about 18 p.m, 16 p.m, 14.5 p.m, 13 p.m, 12 p.m, 11 p.m, 10 p.m, 9
p.m, 8 p.m, or 7
p.m and/or equal to or greater than 4 pm, 5 p.m, 6 p.m, 7 p.m, 8 p.m, 9 p.m,
10 p.m, 11 p.m, or
12 p.m.
In some embodiments, the natural pozzolan fraction of the fine interground
particulate
blend comprises at least about 5%, 10%, 15%, 20%, 25%, 35%, 40%, or 45% and
less than
about 90%, 80%, 70%, 60%, or 50% by weight of the fine interground particulate
blend
and/or the initial clinker or granular material fraction of the fine
interground particulate blend
comprises at least about 10%, 20%, 30%, 40%, or 50% and less than about 95%,
90%, 85%,
80%, 75%, 70%, 65%, or 55% by weight of the fine interground particulate
blend.
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B. Blending Interground Material With Auxiliary Particles
The interground particulate blend can be blended with a separately processed
auxiliary particulate material to form a blended particle composition. The
auxiliary
particulate material can be one or more of commercially available hydraulic
cements, such as
OPC, or commercially available SCMs, such as fly ash (Class C and/or Class F),
GGBFS,
metakaolin, silica fume, rapid hardening cement, supersulfated cement,
magnesium cement,
aluminate cement, low CO2 cement, low C3S and high C2S cement, calcium salt,
magnesium
salt, alkali salt, or geopolymer cement. A blended particle composition having
a broader PSD
can be provided by blending a fine interground particulate blend with an
auxiliary particulate
material that contributes a higher quantity of coarser particles.
In some cases, an activated natural pozzolan having certain chemical
attributes can be
blended with a pozzolan having other chemical attributes to yield a pozzolan
blend having
desired chemical attributes. Such blending of two or more pozzolans can be
carried out to
yield a blended pozzolan material having desired chemical and/or physical
properties.
Examples of desirable chemical modifications that can be achieved by blending
two or more
different pozzolans include adjustments to one or more of silica content,
aluminum oxide
content, iron oxide content, alkaline earth metal content, alkali metal
content, sulfate content.
An example is where a natural pozzolan having high silica and/or
aluminosilicate
content and low in carbon is blended with a pozzolan, such as fly ash, that is
deficient in
silica and/or aluminosilicate and/or high in carbon to yield a blended
pozzolan having a
desired silica and/or aluminosilicate and/or carbon content. To qualify as
Class C fly ash
under ASTM C-618, fly ash must contain at least 50% by combined weight of
silica,
aluminum oxide, and iron oxide ("SAF") and have a maximum loss on ignition
(LOT) of 6%.
To qualify as Class F fly ash under ASTM C-618, fly ash must have an SAF
contain of at
least 70% and a maximum LOT of 6%. Non-conforming fly ash that is deficient in
SAF can
be blended with a natural pozzolan (e.g. activated by intergrinding with
another mineral
material) to yield a pozzolan blend having an SAF that conforms to the SAF
requirements for
Class C or Class F fly ash. In this way, non-confirming fly ash can be
remediated to yield a
blended pozzolan having an SAF that conforms to SAF requirements for
conforming Class C
or Class F fly ash under ASTM standards, even if the blend does not
technically qualify as fly
ash per se (i.e., because it's a blended material with non-fly ash
components).
Another problem is the diminishing supply of fly ash in certain regions as
coal power
plants are decommissioned or converted to other fuels. Activated natural
pozzolans can
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augment the supply of fly ash in such regions, either by being pre-blended
with fly ash or
added to concrete directly to replace some or all of the fly ash.
In rare cases, there may be a supply of already activated natural pozzolan
that requires
no grinding and/or additional heating or processing to be suitable as a
blending material
and/or partial replacement for fly ash. For example, in Utah there is a supply
of calcined shale
dust that is coarser than OPC and coarser than commercially sold fly ash but
is nonetheless
pozzolanic with high SAF. Such calcined shale dust is a biproduct of the
manufacture of
light-weight aggregate by Utelight in Coalville, Utah. Raw shale is mined,
calcined at around
1500 F (815 C) in a rotary kiln, and then graded into coarse, medium and fine
aggregates.
The waste shale fines, including baghouse dust, are collected and typically
discarded or used
as cheap filler in asphalt or earth grading. The inventor, for the first time,
used the discarded
shale fines in several concrete compositions and had great success in
producing high quality
concrete mixes. In some cases, unmodified waste shale dust received from
Utelight has been
used to substitute for at least some of the fly ash when making concrete. The
waste shale dust
.. has also been blended with natural pozzolan that has been activated by
intergrinding with
granular limestone to form a blended pozzolan having higher SAF and lower LOT
than the
interground pozzolan-limestone material. The shale dust was also blended with
another
biproduct of aggregate manufacture rich in calcium carbonate (i.e., quarry
fines from the
Keigley aggregate facility in Genoa, Utah, which had been process in a Raymond
mill to 200
mesh and used as mine rock dust). The calcium carbonate accelerated strength
development
in a ternary blend containing Portland cement, shale dust, and the mine rock
dust. The blends
were used to make concrete having 28-day strengths ranging from 3800 psi to
6500 psi at 28
days with reduced Portland cement content. Sometimes these mixes were further
augmented
with supplement lime (e.g., Type S lime or quicklime) and/or supplemental
sulfate (e.g.,
plaster of Paris or gypsum).
In some embodiments, the auxiliary particulate material can provide very fine
SCM
particles by having a d90 less than the d90, d50, or d10 of the fine
interground blend.
Examples include any of the various micro silica materials known in the art,
such as silica
fume, which is an industrial byproduct formed during the manufacture of
silicon and
ferrosilicon materials, and metakaolin. Another example is ultrafine fly ash
produced by air-
classifying fly ash, sometimes otherwise non-conforming fly ash (e.g., from
the Huntington
and Hunter power plants in central Utah). Air-classification to produce
ultrafine fly ash may
only partially remediate non-conforming fly ash, while blending with activated
natural
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pozzolan can further remediate the fly ash. A very fine auxiliary material may
be desirable
when the fine interground particulate material is deficient in the quantity of
very fine
particles, particularly very fine SCM particles (e.g., below 2 p.m, which are
generally more
desirable than cement particles below 2 p.m; very fine cement particles
increase water
demand and cement paste porosity while very fine SCM particles can reduce
water demand
and reduce paste porosity).
In some embodiments, the auxiliary particulate material can provide coarse SCM
particles having a d90, d50, or d10 greater than the d90 of the fine
interground particulate
material. The auxiliary particulate component may comprise ultra-coarse
particles, such as
ground limestone, ground recycled concrete, quartz, minerals, bottom ash, the
coarse fraction
of air-classified fly ash, shale dust, crystalline metallurgical slags, or
industrial waste
materials that have low reactivity. If the fine interground particulate
material is itself deficient
or excessive in a material, the coarse SCM can help balance that out. For
example, if the
amount of limestone used to activate the natural pozzolan yields a fine
particulate blend
having an LOT higher than 10% (the maximum for natural pozzolan), a coarse SCM
having
lower LOT can be used to yield a blend having a maximum LOT of 10%.
Activated natural pozzolan compositions can be made using commercially
available
milling, separating and blending apparatus known in the art, sometimes with
modification in
order to obtain blends and compositions having a desired PSD. Non-limiting
examples of
milling apparatus include vertical roller mills, high pressure grinding rolls,
horizontal roll
presses, ball mills, rod mills, hammer mills, jaw mills, Raymond mills, jet
mills, dry bead
mills, ultrasonic fracturing mills, and the like. Non-limiting examples of
separating apparatus
include stand-alone classifiers, classifiers integrated with a vertical roller
mill, and sieving
apparatus. Non-limiting examples of blending apparatus include planetary
mixers, dry
rotating mixers, dry stirring apparatus, dry shakers, and concrete mixing
apparatus, such as
concrete mixing trucks and batch plant mixers.
In order to ensure that the interground particulate composition and auxiliary
particulate component have respective PSDs within desired parameters, it is
typically
advantageous to periodically sample and accurately determine particle size and
PSD, such as
by using particle size analyzers and techniques known in the art. For example,
PSD can be
determined using laser diffraction techniques. An example of a particle size
analyzer that is
commonly used to determine the PSD of cements and SCMs is a Malvern
Mastersizer 2000.
Another example is an online laser diffraction particle size analyzer, such as
the Malvern
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Insitec Fineness Analyzer, available from Malvern Instruments (Worcestershire,
UK), which
can automatically take a series of PSD measurements of the product in real
time and, through
a feedback loop, such information can be used to modify the grinding and/or
classification
process to maintain the PSD within a desired range. Other methods for
determining or
estimating particle size include, but are not limited to, sieving, optical or
electron microscope
analysis, x-ray diffraction, sedimentation, elutriation, microscope counting,
Coulter counter,
and Dynamic Light Scattering.
FIGS. 6-9 are flow charts that illustrate exemplary methods for activating
natural
pozzolans and manufacturing cement-SCM and other mixed pozzolan compositions
and/or
1() components thereof. While the descriptions often mention intergrinding
clinker with a
pozzolan, it is understood that "clinker" can mean granular materials other
than cement
clinker used to make ordinary Portland cement (OPC).
FIG. 6 illustrates a basic method of manufacturing a blended composition
(e.g.,
activated pozzolan composition or interground cement and SCM) 600 comprising:
step 602 -
intergrinding clinker (e.g., cement clinker) or granules (e.g., metallurgical
slag, aggregate or
ground mineral) and one or more SCMs (e.g., natural pozzolan) to form a fine
interground
particulate component; step 604 ¨ forming or providing a coarse particulate
component that is
not interground with the fine interground particulate component; and step 606
¨ blending the
fine interground particulate component with the coarse particulate component
without
intergrinding to form a blended composition (e.g., cement-SCM composition). To
this
blended composition may optionally be added one or more other additional
components as
disclosed herein, such as hydraulic cement, SCM or other component, to yield a
modified
cement-SCM composition.
FIG. 7 illustrates a method of manufacturing a cement-SCM composition 700
comprising: step 702 ¨ intergrinding clinker (e.g., cement clinker or
granules) and one or
more SCMs (e.g., natural pozzolan) to form a fine interground particulate
component; step
704 ¨ forming or providing a coarse particulate component that is not
interground with the
fine interground particulate component; step 706 ¨ dry blending the fine
interground
particulate component with the coarse particulate component without
intergrinding to form a
dry blend; and step 708, optionally blending the dry blend with one or more of
aggregate,
water, or admixture. To the cement-SCM composition following either of steps
706 or 708
can optionally be added one or more other additional components as disclosed
herein to yield
a modified cement-SCM composition.
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FIG. 8 illustrates another method of manufacturing a cement-SCM composition
800
comprising: step 802 ¨ intergrinding clinker (e.g., cement clinker or
granules) and one or
more SCMs (e.g., natural pozzolan) to form a fine interground particulate
component; step
804 ¨ forming or providing a coarse particulate component that is not
interground with the
fine interground particulate component; and step 806 ¨ blending the fine
interground
particulate component, the coarse particulate component, and one or more of
aggregate,
water, or admixture. To the cement-SCM composition, as part of or following
step 806, can
be added one or more other additional components as disclosed herein to yield
a modified
cement-SCM composition.
1()
FIG. 9 illustrates another method of manufacturing a cement-SCM composition
900
comprising: step 902 ¨ intergrinding clinker or granules, such as cement or
SCM, and one or
more SCMs (e.g., natural pozzolan) to form a fine interground particulate
component; step
904 ¨ forming or providing a coarse particulate component that is not
interground with the
clinker or granules of used to make the fine interground particulate
component; step 906 -
forming or providing an auxiliary particulate component, such as hydraulic
cement or SCM;
and step 908 ¨ blending the fine interground particulate component, the coarse
particulate
component, and the auxiliary particulate component without intergrinding to
form the
cement-SCM composition. To the cement-SCM composition can be added one or more
other
additional components as disclosed herein to yield a modified cement-SCM
composition.
Although some of the foregoing methods identify "cement clinker" is being
interground with one or more SCMs to yield the fine particulate component, it
is understood
that other granules or clinkers other than cement clinker can be used to form
the fine
particulate component, such as one that includes a plurality of SCMs. In such
case, the source
of hydraulic cement (e.g., OPC) can be blended with the fine particulate
component to yield a
ternary blend of two separate feed streams. This blend can be blended with a
coarse SCM
without intergrinding to yield a quaternary blend of three different feed
streams.
In some embodiments, a system of manufacturing a cement-SCM composition
comprises: (A) one more milling apparatus configured to intergrind hydraulic
cement (e.g.,
cement clinker) or other granular material with one or more SCMs (e.g.,
natural pozzolan) to
form a fine interground particulate component; (B) one or more blending
apparatus
configured to blend, without intergrinding, the fine interground particulate
component with a
coarse particulate component comprised of coarse SCM particles; and optionally
(C) one or
more apparatus for combining, without intergrinding, an auxiliary particulate
component with
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the fine interground particulate component and the coarse particulate
component.
In some embodiments, a system of manufacturing a cement-SCM composition
comprises: (A) one more milling apparatus configured to intergrind one or more
clinkers or
granules initially larger than about 1-3 mm with one or more finer particles
or powders
having an initial particle size less than about 1 mm to form a fine
interground particulate
component; (B) one or more blending apparatus configured to blend, without
intergrinding,
the fine interground particulate component with a coarse particulate component
comprised of
coarse SCM particles; and optionally (C) one or more apparatus for combining,
without
intergrinding, an auxiliary particulate component with the fine interground
particulate
.. component and the coarse particulate component. Where fine interground
component (A) is
insufficiently hydraulically reactive, the auxiliary particulate component may
advantageously
include hydraulically reactive particles.
In some embodiments, a system of manufacturing a cement-SCM composition
comprises: (A) one more milling apparatus configured to intergrind (1) a first
SCM
component and (2) a second SCM component to form a fine interground
particulate
component; (B) one or more blending apparatus configured to blend, without
intergrinding,
the fine interground particulate component with a hydraulic cement component;
and (C) one
or more blending apparatus configured to blend, without intergrinding, the
fine interground
particulate component and the hydraulic cement component with a coarse
particulate
.. component; and optionally (D) one or more apparatus for combining, without
intergrinding,
an auxiliary particulate component (e.g., OPC, SCM, or other material) with
components (A),
(B) and (C).
FIGS. 10A and 10B schematically illustrate exemplary milling apparatus that
can be
used to manufacture the fine interground particulate component and,
optionally, in the
manufacture at least part of the coarse particulate component and/or the
optional auxiliary
particulate component.
FIG. 10A more particularly discloses a milling circuit 1000 that includes a
transport
conduit, conveyor, or apparatus 1002 configured to deliver a stream or mixture
of particles,
clinker and/or other material to a mill 1004 that comminutes or otherwise
reduces the particle
size of the material to form a comminuted stream 1005. A separator 1006
integrated with or
separate from mill 1004 further processes comminuted stream 1005 and separates
it into a
coarse fraction 1008, which can be collected as product and/or recycled back
to mill 1004 for
further comminution, and a fine fraction 1010, which can be collected as
product and/or
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intermediate material that is subjected to further processing using known
processing
equipment, including, for example, processing equipment disclosed herein. Mill
1004 and/or
separator 1006 can be adjusted or modified to produce a fine fraction 1010
having a desired
d90, d50, d10 and/or fineness.
Mill 1004 can be any mill used in the art of grinding or comminuting. In the
case
where mill 1004 and separator 1006 are independent rather than integrated
apparatus, mill
1004 can be any known mill that does not include an integrated or internal
separator. Non-
limiting examples include a ball mill, rod mill, horizontal roll press, high
pressure grinding
roll, hammer mill, jaw mill, Raymond mill, jet mill, bead mill, high velocity
impact mill,
acoustic fracturing mill, and the like. Independent separator 1006 can be any
known
separator, such as a high efficiency air classifier, cyclonic separator, or
sieving apparatus.
FIG. 10B more particularly discloses a vertical roller mill system 1020 that
includes a
feed silo 1021 for storing and delivering a feed material to be processed,
metering equipment
1022, such as an auger, for delivering feed material at a predetermined rate,
and a vertical
roller mill 1023, which receives feed material and mills it using a rotating
table (not shown)
and rotating stationary rollers (not shown) positioned above the rotating
table. A high
efficiency classifier 1024 is integrated with and positioned above vertical
roller mill 1023. A
hot gas generator 1025, which can be powered by natural gas, other fuel, or
waste heat from a
cement kiln, produces hot gas, which is introduced into vertical roller mill
1023 at a desired
temperature, pressure and velocity. The hot gases move upwardly around the
outer perimeter
of the rotating table within vertical roller mill 1023, where they contact
ground particles
expelled from the rotating table by centrifugal force and carry at least a
portion of the milled
particles upward to high efficiency classifier 1024. The hot gases also dry
the milled
particles. Coarse particles (not shown) that are not carried by the upwardly
moving gases to
high efficiency classifier 1024 instead drop down below the rotating table,
where they are
carried by a bucket elevator 1030, passed through a magnetic separator 1031,
which separates
a waste iron containing stream from a remaining portion of the coarse
particles, and the
remaining portion is returned to vertical roller mill 1023 (e.g., together
with the feed material
from feed silo 1021).
High efficiency classifier 1024 separates the milled particles received from
vertical
roller mill 1023 into a finer fraction, which is carried by the upwardly
moving gases to
cyclone collector 1026, and a coarser fraction (not shown), which is dropped
back onto the
rotating table of vertical roller mill 1023 for further milling. The d90 of
the finer fraction can
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be controlled by modifying various parameters of the vertical roller mill
system 1020, such as
the rate at which the feed material is introduced into vertical roller mill
1023, the pressure
exerted on the rotating stationary rollers and transferred to the grinding bed
of particles, the
speed and/or pressure of the hot gases, and the speed of a rotor containing
fins or blades
within high efficiency classifier 1024. The d90 can be periodically measured
using known
PSD-measuring equipment known in the art, such as a laser-diffraction
measuring device. A
mill fan 1027 assists in causing upward flow of hot gases through vertical
roller mill 1023
and high efficiency classifier 1024 and separating milled product 1032 from
ultrafine
particles, which are collected by a filter 1028 and then combined with milled
product 1032
from cyclone collector 1026. A filter fan 1029 assists in moving the ultrafine
particles from
cyclone collector 1026 toward filter 1028 and expels waste gases into the air.
FIG. 11 is a flow diagram that illustrates an exemplary method 1100 of
manufacturing
a coarse supplementary cementitious material comprising: step 1102 ¨
optionally grinding
and/or classifying an initial SCM; step 1104 ¨ dedusting the SCM to form a
coarse SCM
product; and step 1106, optionally collecting the dedusted fine fraction and
using it as
desired. For example, the dedusted fine fraction can be used as a micro silica
component of
concrete and/or blended cement and/or as an SCM feed component for
manufacturing the
fine interground particulate component. The dedusting process can be performed
using
known apparatus, such as a high efficiency air classifier that is capable of
making sharp cuts
or separations, a sieve apparatus, or combination thereof.
FIG. 12 schematically illustrates an exemplary separation apparatus 1200,
which can
be used to manufacture one or more particulate components, such as the coarse
particulate
component and, optionally, in the manufacture of the fine interground
particulate component
and/or the auxiliary particulate component. The separation apparatus 1200
further includes
one or more separation mechanisms 1204 known in the art of particle
separation, which
receives a stream of particles 1202 and separates the particles into at least
a finer particle
fraction 1206 and a coarser particle fraction 1208. The one or more separation
mechanisms
1204 may also be configured to produce other particle fractions, such as an
intermediate
particle fraction (not shown) that is less fine than finer particle fraction
1206 and/or less
coarse than coarser particle fraction 1208. Examples of one or more separation
mechanisms
1204 include apparatus associated with a high efficiency classifier, a
cyclonic separator,
sieving apparatus, or filter.
FIG. 13A schematically illustrates an exemplary system 1300 for manufacturing
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cement-SCM compositions as disclosed herein. System 1300 more particularly
includes at
least a first storage silo or other container 1302 for a pozzolan or other SCM
and a second
silo or other storage container 1304 for clinker (e.g., cement clinker or
granules), which can
be raw or partially milled clinker, other hydraulic cement material, or other
large particulate,
clinker, or nodule material. Clinker(s) and SCM(s) from storage containers
1302, 1304 are
processed according to methods disclosed herein and/or other methods known to
those of
ordinary skill in the art, such as by means of one or more grinders 1306 or
other milling
apparatus and one or more classifiers 1308 or other separation apparatus to
yield desired
materials for making cement-SCM compositions. These include at least (1) a
fine interground
particulate component comprising a hydraulic cement fraction and an SCM
fraction (or first
and second SCM fractions), which can be stored within a fine interground
particulate silo
1310, and (2) a coarse particulate component comprising coarse SCM particles,
which can be
stored within a coarse particulate silo 1312. In addition, an optional
auxiliary particulate
material can be stored within an auxiliary particulate silo 1314.
In some embodiments, as indicated by the dotted arrow leading to coarse
particulate
silo 1312, the coarse particulate component may be used as received without
milling,
dedusting or further processing (e.g., fly ash, GGBFS, or other SCMs having a
sufficient
proportion of coarse particles that complement the fine particulate
component). While this
may sometimes yield cement-SCM compositions that are less optimal than cement-
SCM
compositions made using milled, dedusted or other further processed SCMs,
simplification of
the manufacturing process may justify this outcome (e.g., by reducing capital
and/or
operating costs of the manufacturing facility). In some embodiments, as
indicated by the
dotted arrow leading to auxiliary particulate silo 1314, the optional
auxiliary particulate
component may come pre-processed and need not be further processed by
apparatus used to
process the fine interground particulate component and/or the coarse
particulate component.
A blender 1316 can be used to blend the fine interground particulate material,
coarse
particulate material, and optional auxiliary particulate material to form a
finished product,
which, in the case of a dry blended composition, can be stored within finished
product silo
1318. In other cases, blender 1316 can be a concrete mixer, such as a
stationary mixer used
for mixing and batching concrete, or a concrete mixing truck used to mix and
transport
concrete.
For example, FIG. 13B illustrates a modified system 1300 that includes a
blender
1316 that is a stationary mixer used to make a dry blend or fresh concrete
mixture that is then
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fed to a concrete delivery truck or vehicle 1320. If blender 1316 produces a
dry blend, water
and admixtures can be added directly to concrete delivery vehicle 1320 to form
freshly mixed
concrete, either at the concrete batch plant, during transport, or at the job
site.
FIG. 13C illustrates yet another modified system 1300 in which the blending
apparatus is a concrete delivery truck or vehicle 1320. For example, fine
interground
particulate silo 1310, coarse particulate silo 1312, and optional auxiliary
particulate silo 1314
can be located at a concrete manufacturing plant for dispensing and mixing
these material
directly within concrete delivery vehicle 1320. As in FIG. 13B, water and
admixtures can be
added directly to concrete delivery vehicle 1320 to form freshly mixed
concrete, either at the
1() concrete batch plant, during transport, or at the job site.
A. Additional Aspects of Natural Pozzolan Activation
The ratio of clinker or granules to natural pozzolan can be 5:95, 10:90,
15:85, 20:80,
25:75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45, 60:40, 65:35, 70:30, 75:25,
80:20, 85:15,
90:10, 95:5, or any range between any of the foregoing values.
In general, the clinker or granular material is a grindable grinding medium
that
transfers grinding forces to small pozzolan particles. The preponderance of
fine or coarse
interground particles from either the initially clinker or granular material
or the natural
pozzolan often depends on their grindability or hardness. The following are
hardness values
of various materials, which can be used to determine or estimate the
effectiveness of a
particular clinker or granular material in transferring grinding forces down
to the natural
pozzolan being activated:
Material Moh Hardness
talc 1
gypsum 2-3
anhydrite 3-3.5
bauxite 1-3
calcite/limestone/chalk 3
dolomite 3.5-4
synthetic alumina 3.4
granite 4
obsidian (volcanic glass) 5
volcanic ash 5-6
pumice 6,
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GBF S 5-6
glass bead 5.5
steel slag 6
feldspar 6
copper slag 7
fused quartz 6-7
quartz 7
porcelain 6-7
bricks 5-7
ceramic (e.g., used catalyst) 7
concrete 5-7
silica sand 6-7
basalt 7
In general, using a harder material like steel slag will tend to result in
more finely
ground natural pozzolan particles with a higher surface area than when a
softer material is
used (e.g., the particles smaller than the d50 in the interground blend can
have a higher
percentage of natural pozzolan particles by number, volume, or weight than the
particles
larger than the d50). Conversely, using a softer material like limestone will
tend to result in
more coarsely ground natural pozzolan particles with a lower surface area than
when a harder
material is used (e.g., the particles smaller than the d50 in the interground
blend can have a
lower percentage of natural pozzolan particles by number, volume, or weight
than the
particles larger than the d50).
In some embodiments, the activated natural pozzolan can be blended with a
pozzolan,
such as fly ash that is otherwise out of specification, in order to
beneficiate such material
(e.g., in order to satisfy the minimum silicon dioxide, plus aluminum oxide,
plus iron oxide
(SAF) requirements of ASTM C-618 for class C or F fly ash). Granules that
contain a high
silica content (e.g., granite, basalt, quartz) can be especially beneficial
when beneficiating out
of specification fly ash. Examples of blending methods for modifying one or
more chemical
attributes of a blended pozzolan, such as silica content, alumina content,
iron oxide content,
calcium oxide, or sulfate content, are disclosed in U.S. Patent No. 9,067,824
to Hansen et al.,
which is incorporate by reference.
In some embodiments, it may be desirable to intergrind the natural pozzolan
with
bauxite to increase aluminate content and early strength.
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In some embodiments, it may be desirable to mix in one or more additives
during or
after intergrinding, such as amines, accelerators, alkali salts, calcium
salts, lime, gypsum,
salts of weak acids, citric acid, and tartaric acid.
The natural pozzolan can be blended or interground with silica rock dust to
make an
interground material that has a higher silica content, which may made the
blend more
pozzolanic. Alternatively, the natural pozzolan can be blended or interground
with limestone
rock dust to make an interground material that is less pozzolanic and more
accelerating.
In some embodiments, steel slag can be a useful grindable grinding media. It
is
extremely inexpensive, hard, expensive to grind, and on its own it yields a
poor quality SCM.
1() However, because it is hard, it can effectively transfer grinding
forces down to minute
pozzolan (volcanic ash) particles to further reduce size.
CEMENTITIOUS COMPOSITIONS
In some embodiments, activated pozzolan and cement-SCM compositions disclosed
herein can be used as general purpose or specialty cements in place of OPC and
other
hydraulic cements known in the art. They can be used as sole or supplemental
binder to make
concrete, ready mix concrete, bagged concrete, bagged cement, mortar, bagged
mortar, grout,
bagged grout, oil well cement, molding compositions, or other fresh or dry
cementitious
compositions known in the art. The cement-SCM compositions can be used to
manufacture
concrete and other cementitious compositions that include a hydraulic cement
binder, water
and aggregate, such as fine and coarse aggregates. Mortar typically includes
cement, water,
sand, and lime and is sufficiently stiff to support the weight of a brick or
concrete block. Oil
well cement refers to a cementitious composition continuously blended and
pumped into a
well bore. Grout is used to fill in spaces, such as cracks or crevices in
concrete structures,
spaces between structural objects, and spaces between tiles. Molding
compositions are used
to manufacture molded or cast objects, such as pots, troughs, posts, walls,
floors, fountains,
ornamental stone, and the like.
Activated natural pozzolans may include one or more of the following auxiliary
components: a calcium-based set accelerator, such as calcium oxide (CaO),
calcium chloride
(CaCl2), calcium nitrite (Ca(NO2)2, or calcium nitrate (Ca(NO3)2 and/or an
alkali metal salt
capable of increasing the pH of the mix water, such as sodium hydroxide
(NaOH), sodium
citrate, or other alkali metal salt of a weak acid. The calcium ions provided
by the calcium-
based set accelerator will not only accelerate hydration of hydraulic cement
(e.g., in cold
weather or other situations where it is desired to increase early strength),
they can
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beneficially react with silicate ions from the pozzolan to form additional
cement binder
products. Alternatively, or in addition, the increased pH provided by the
alkali metal salt can
accelerate the pozzolanic reaction by accelerating dissolution of silicate
ions and/or aluminate
ions from the pozzolan and making them more readily available for reaction
with calcium
and/or magnesium ions provided by the hydraulic cement fraction.
IV. EXAMPLES
The following examples are provided to illustrate example cementitious
compositions
that were made using interground limestone and natural pozzolan particulate
blends. In
addition, examples of cementitious compositions that utilize(d) an interground
blend of
limestone and natural pozzolan are set forth in U.S. Provisional Patent
Application No.
62/337,424, filed May 17, 2016; U.S. Provisional Patent Application No.
62/451,533, filed
January 27, 2017; U.S. Patent No. 9,957,196; U.S. Provisional Patent
Application No.
62/444,736, filed January 10, 2017; U.S. Provisional Patent Application No.
62/451,484,
filed January 27, 2017; U.S. Provisional Patent Application No. 62/522,274,
filed June 20,
2017; U.S. Patent No. 10,131,575; U.S. Patent Application No. 16/028,398,
filed July 5,
2018; and U.S. Patent Application No. 16/180,323, filed November 5, 2018. The
foregoing
patents and patent applications are incorporated herein by reference.
Example 1
A concrete composition was made using the following components, expressed in
quantity per cubic yard of concrete.
Portland Cement 282 lb
GGBFS (Grade 120) 141 lb
Interground Limestone-Volcanic Ash 141 lb
Water 266.6 lb
Coarse Aggregate (1 inch minus) 1750 lb
Fine Aggregate (ASTM C33 sand) 1321 lb
The concrete composition was cast into 4 x 8 inch cylinders, which were tested
and
had a compressive strength of 5200 psi at 28 days, similar to a control
concrete containing
564 lb of OPC per cubic yard.
Example 2
A concrete composition was made using the following components, expressed in
quantity per cubic yard of concrete.
Portland Cement 169.2 lb
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GGBFS (Grade 120) 253.8 lb
Interground Limestone-Volcanic Ash 141 lb
Water 266.6 lb
Coarse Aggregate (1 inch minus) 1750 lb
Fine Aggregate (ASTM C33 sand) 1320 lb
The concrete composition was cast into 4 x 8 inch cylinders, which were tested
and
had a compressive strength of 4450 psi at 28 days.
Example 3
A concrete composition was made using the following components, expressed in
quantity per cubic yard of concrete.
Portland Cement 387.2 lb
Interground Limestone-Volcanic Ash 211.2 lb
Finely Ground Volcanic Ash 105.6 lb
Water 245.7 lb
Pea Gravel 1408 lb
Fine Aggregate (ASTM C33 sand) 1408 lb
The concrete composition was mixed together with a superplasticizer, air
entraining
agent, and viscosity modifying agent to form concrete, cast into 4 x 8 inch
cylinders, and
found to have a compressive strength of 7940 psi at 28 days.
Example 4
A concrete composition was made using the following components, expressed in
quantity per cubic yard of concrete.
Portland Cement 387.2 lb
Interground Limestone-Volcanic Ash 211.2 lb
Fine Classified Fly Ash 105.6 lb
Water 245.7 lb
Pea Gravel 1408 lb
Fine Aggregate (ASTM C33 sand) 1408 lb
The concrete composition was mixed together with a superplasticizer, air
entraining
agent, and viscosity modifying agent to form concrete, cast into 4 x 8 inch
cylinders, and
found to have a compressive strength of 7950 psi at 28 days.
Example 5
A concrete composition was made using the following components, expressed in
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quantity per cubic yard of concrete.
Portland Cement 366.6 lb
Interground Limestone-Volcanic Ash 56.4 lb
Coarse Dedusted Fly Ash 141 lb
Water 264.9 lb
Coarse Aggregate (1 inch minus) 1750 lb
Fine Aggregate (ASTM C33 sand) 1316 lb
The concrete composition was cast into 4 x 8 inch cylinders, which were tested
and
had a compressive strength of 4440 psi at 28 days.
Example 6
A mortar cube composition was made using the following components.
Portland Cement 752 g
Interground Limestone-Volcanic Ash 188 g
Water 450 g
Sand (ASTM C109 sand) 2550g
The mortar cube composition was cast into 2 x 2 inch cubes, which were tested
and
had a compressive strength of 6470 psi at 28 days.
Example 7
A mortar cube composition was made using the following components.
Portland Cement 752 g
Interground Limestone-Volcanic Ash 141 g
Finely Ground Volcanic Ash 47 g
Water 450 g
Sand (ASTM C109 sand) 2550 g
The mortar cube composition was cast into 2 x 2 inch cubes, which were tested
and
had a compressive strength of 6950 psi at 28 days.
Example 8
A mortar cube composition was made using the following components.
Portland Cement 752 g
Interground Limestone-Volcanic Ash 141 g
Fine Classified Fly Ash 47 g
Water 450 g
Sand (ASTM C109 sand) 2550 g
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The mortar cube composition was cast into 2 x 2 inch cubes, which were tested
and
had a compressive strength of 6780 psi at 28 days.
Example 9
A mortar cube composition was made using the following components.
Portland Cement 752 g
Interground Limestone-Volcanic Ash 282 g
Finely Ground Steel Slag 47 g
Water 450 g
Sand (ASTM C109 sand) 2550 g
The mortar cube composition was cast into 2 x 2 inch cubes, which were tested
and
had a compressive strength of 7250 psi at 28 days.
Example 10
A mortar cube composition was made using the following components.
Portland Cement 658 g
Interground Limestone-Volcanic Ash 211.5 g
Finely Ground Volcanic Ash 70.5 g
Water 450 g
Sand (ASTM C109 sand) 2550 g
The mortar cube composition was cast into 2 x 2 inch cubes, which were tested
and
had a compressive strength of 5795 psi at 28 days.
Example 11
A mortar cube composition was made using the following components.
Portland Cement 490 g
GGBFS (Grade 120) 245 g
Interground Limestone-Volcanic Ash 245 g
Water 474 g
Sand (ASTM C109 sand) 2550 g
The mortar cube composition was cast into 2 x 2 inch cubes, which were tested
and
had a compressive strength of 6705 psi at 28 days.
Example 12
A mortar cube composition was made using the following components.
Portland Cement 490 g
GGBFS (Grade 120) 245 g
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Interground Limestone-Volcanic Ash 122.5 g
Coarse Dedusted Fly Ash 122.5 g
Water 476 g
Sand (ASTM C109 sand) 2550 g
The mortar cube composition was cast into 2 x 2 inch cubes, which were tested
and
had a compressive strength of 6550 psi at 28 days.
Example 13
A mortar cube composition was made using the following components.
Portland Cement 282 g
GGBFS (Grade 120) 470 g
Interground Limestone-Volcanic Ash 188 g
Water 456 g
Sand (ASTM C109 sand) 2580 g
The mortar cube composition was cast into 2 x 2 inch cubes, which were tested
and
had a compressive strength of 6705 psi at 28 days.
Example 14
A mortar cube composition was made using the following components.
Portland Cement 294 g
GGBFS (Grade 120) 490 g
Coarse Dedusted Fly Ash 147 g
Interground Limestone-Volcanic Ash 49 g
Water 476 g
Sand (ASTM C109 sand) 2550 g
The mortar cube composition was cast into 2 x 2 inch cubes, which were tested
and
had a compressive strength of 6710 psi at 28 days.
Example 15
A mortar cube composition was made using the following components.
Portland Cement 245 g
GGBFS (Grade 120) 245 g
Ultrafine Fly Ash 146 g
Interground Limestone-Volcanic Ash 292 g
Lime (Calcium Hydroxide) 49 g
Water 254 g
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Sand (ASTM C109 sand) 1900 g
The mortar cube composition was mixed with a superplastizer and cast into 2 x
2 inch
cubes, which were tested and had a compressive strength of 9155 psi at 28
days.
Example 16
A mortar cube composition was made using the following components.
Portland Cement 283.5 g
GGBFS (Grade 120) 283.5 g
Interground Limestone-Volcanic Ash 243 g
Water 324 g
Sand (ASTM C109 sand) 1903.5g
The mortar cube composition was mixed with a low range water reducer and cast
into
2 x 2 inch cubes, which were tested and had a compressive strength of 8040 psi
at 28 days.
Example 17
A mortar cube composition was made using the following components.
Portland Cement 283.5g
GGBFS (Grade 120) 283.5 g
Ultrafine Fly Ash 77 g
Interground Limestone-Volcanic Ash 162 g
Lime (Calcium Hydroxide) 4.05 g
Water 324 g
Sand (ASTM C109 sand) 1896 g
The mortar cube composition was mixed with a low range water reducer and cast
into
2 x 2 inch cubes, which were tested and had a compressive strength of 7915 psi
at 28 days.
Example 18
A mortar cube composition was made using the following components.
Portland Cement 400 g
GGBFS (Grade 120) 400 g
Ultrafine Fly Ash 77 g
Interground Limestone-Volcanic Ash 294 g
Lime (Calcium Hydroxide) 8.10 g
Water 243 g
Citric Acid 0.33 g
Sand (ASTM C109 sand) 1850 g
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The mortar cube composition was mixed with a superplasticizer and cast into 2
x 2
inch cubes, which were tested and had a compressive strength of 12,315 psi at
28 days.
Example 19
A mortar cube composition was made using the following components.
White Cement 472 g
GGBFS (Grade 120) 472 g
Interground Limestone-Volcanic Ash 212.4 g
Lime (Calcium Hydroxide) 23.6 g
Water 424.06g
Silica Sand 1320 g
The mortar cube composition was mixed with a superplasticizer and cast into 2
x 2
inch cubes, which were tested and had a compressive strength of 9735 psi at 28
days.
Example 20
A mortar cube composition was made using the following components.
White Cement 413 g
GGBFS (Grade 120) 472 g
Interground Limestone-Volcanic Ash 283.2 g
Lime (Calcium Hydroxide) 11.8 g
Water 424.06g
Silica Sand 1304 g
The mortar cube composition was mixed with a superplasticizer and cast into 2
x 2
inch cubes, which were tested and had a compressive strength of 7520 psi at 28
days.
Example 21
A mortar cube composition was made using the following components.
White Cement 354 g
GGBFS (Grade 120) 531 g
Interground Limestone-Volcanic Ash 283.2 g
Lime (Calcium Hydroxide) 11.8 g
Water 424.06g
Silica Sand 1300 g
The mortar cube composition was mixed with a superplasticizer and cast into 2
x 2
inch cubes, which were tested and had a compressive strength of 7290 psi at 28
days.
Example 22
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A mortar cube composition was made using the following components.
White Cement 524 g
GGBFS (Grade 120) 524 g
Interground Limestone-Volcanic Ash 246.6 g
Lime (Calcium Hydroxide) 13.1 g
Water 381 g
Silica Sand 1314 g
The mortar cube composition was mixed with a superplasticizer and cast into 2
x 2
inch cubes, which were tested and had a compressive strength of 10,670 psi at
28 days.
Example 23
A mortar cube composition was made using the following components.
White Cement 554 g
GGBFS (Grade 120) 554 g
Interground Limestone-Volcanic Ash 123.7 g
Type S Lime 6.19 g
Latex adhesive 30.17
Water 337g
Coarse Silica Sand 447.65 g
Fine Silica Sand 654.25 g
Marble White 80 242 g
Glass Fibers 98g
The mortar cube composition was mixed with a superplasticizer and cast into 2
x 2
inch cubes, which were tested and had a compressive strength of 12,860 psi at
28 days.
Example 24
A ready mixed concrete composition was made using the following components,
expressed in quantity per cubic yard of concrete.
Portland Cement 429 lb
Class F Fly Ash 102 lb
Interground Limestone-Volcanic Ash 125.72 lb
Type S Lime 1.65 lb
Plaster of Paris 1.65 lb
Water 283.8 lb
Air Entraining Agent 13.27 oz
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Low Range Water Reducer 15.93 oz
Mid Range Water Reducer 21 oz
Coarse Aggregate (1 inch minus) 1675 lb
Fine Aggregate (ASTM C33 sand) 1215 lb
The concrete composition was made in a concrete mixing/delivery truck with a
slump
of 6 inches. The majority of the composition was poured into a form as part of
a driveway
slab 6 inches thick and reinforced with rebar. The concrete had placement and
finishing
properties similar to conventional concrete and was ready for final surface
finishing in
approximately 2-3 hours after pouring. The concrete slab was exposed to
periodic freeze-
thaw cycles and driven over with a car for an entire winter without showing
any signs of
spalling or other damage.
A portion of the concrete was cast into 4 x 8 inch cylinders, which were
tested and
had a compressive strength of 4000 psi at 28 days and 4500 psi at 91 days.
While the strength
was lower than expected, this may have been due to excessive air entrainment
owing to the
combined use of air entrainment agent and mid-range water reducer.
Example 25
A ready mixed concrete composition was made using the following components,
expressed in quantity per cubic yard of concrete.
Portland Cement 366 lb
Class F Fly Ash 91.5 lb
Shale Dust 91.5 lb
Mine Rock Dust 75.5 lb
Type S Lime 6.1 lb
Plaster of Paris 4.6 lb
Water 274.5 lb
Low Range Water Reducer 13.27 oz
Air Entrainment Agent 7.32 oz
Coarse Aggregate (1 inch minus) 1675 lb
Fine Aggregate (ASTM C33 sand) 1260 lb
The concrete composition was made in a concrete mixing/delivery truck with a
slump
of 6 inches. The majority of the composition was poured into a form as part of
a driveway
slab 6 inches thick and reinforced with rebar. The concrete had placement and
finishing
properties similar to conventional concrete and was ready for final surface
finishing in
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approximately 2-3 hours after pouring. The cost savings were $10.73 per cubic
yard
compared to a commercial mix with design strength of 4500 psi at 4-inch slump.
The
concrete slab was exposed to periodic freeze-thaw cycles and driven over with
a car for an
entire winter without showing any signs of spalling or other damage.
A portion of the concrete was cast into 4 x 8 inch cylinders, which were
tested and
had a compressive strength of 4270 psi at 28 days and 5270 psi at 56 days. The
strength was
lower because of higher slump achieved by adding more water. By 56 days, the
strength far
exceeded the design strength. The strength can be increased by increasing the
ratio of coarse
to fine aggregate.
