Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~2~S~ 6925-292
ADMIXTURE FOR HYDRAULIC CEMENT COMPOSITIONS
. . .
BACKGROUND OF THE INVENTION
This invention relates to admixtures for hydraulic
cement compositions and more particularly to water-reducing
admixtures which provide improved slump retention in hydraulic
cement compositions with relatively minimal increases in
initial and final setting times.
The use of various water-reducing admixtures in hy-
draulic cement compositions, e.g., mortars, grouts, and
concrete, is well known. These admixtures allow the use of
lesser amounts of water to achieve a desired plasticity or
workability. The admixture also provides higher compressive
strengths in the cement composition after setting, due either
to the use of less water in the mix or to a more complete
dispersion oE the cement particles in the plastic cement mix
by the admixture.
A major problem associated with the use of conventional
water-reducing admixtures is that the length of time during which
the admixture is able to maintain a desired high level of
plasticity or workability in the cement mix is relatively short,
lastlng an average of 25 to 45 minutes after addition of the
admixture. In most job situations, this generally requires
that the admixture be added just prior to placement, i.e., at
the job site, thus requiring the equipping of delivery trucks
with specially designed dispensing equipment. In addition to
the expense associated with the installation and maintenance
of this equipment, its use can be problemmatic where local work
specifications or conditions prohibit on site addition of
admixtures. In addition, the relatively short duration of
~Z2~0~ 6925-292
increased plasticity limits the amount of time the applicator
has to place and work the mixture. This can be a particularly
troublesome constraint under difficult placement or job
conditions.
la
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~sè 2764 ~Z2750~i
The problem of a relatively short duration of increased plastlcity
can sornetimes be lessened by a high dosage of the water-reduclng
admixture. However, this tends to provide too fluid a mix immediately
following addition and generally results in excessive set retardation.
This latter disadvantage, in turn, can delay strength gain in the
cement mix after setting.
The plasticity of a hydraulic cement mixture is normally evaluated
by slump measurement, e.g., in accordance with ASTM C143. The
slump is measured by filling a truncated cone with the mixture,
removing the cone, and measuring the drop Tn l1elght of the
unsupported mlxture. As a measure of the decrease in plasticity of the
mixture over time, slump measurements are made on the aglng mlxture
at spaced time intervals. The decreasing plastlcity is thus quantified
as the decrease In slump with tlme. A lesser decrease in slump with
time i.e,, Increased slump retention, Indlcates a greater abllity on the
part of a water-reducing admlxture to impart increased plastlcity to the
cement mixture for a longer duratlon.
SUMMARY_OF THE INVENTION
The present invention is directed toward novel water-reducing
admixture compositions for hydraulic cement materials which can provide
levels of water reduction which are at least as great as those provided
by conventional water-reducing agents and, in additlon, provide
substantially increased levels of slump retention. A particular
Case !764 12~505
advantage of the inventive admixtures is that they can be formulated to
provide significant and substantlal Increases in slump retentlon ~tth
only relativeiy minimal increases in the initial and final settlng tlmes of
the cementitious mix. The admlxture composltTons of thls Invention are
blends or mixtures which comprlse a hydraulic cement water-reducing
agent and a borate ester of a polyhydroxy compound. By the term
"polyhydroxy compound" is meant a dioi or a polyhydric compound,
i.e., one which contains more than two hydroxy groups. The
polyhydroxy compound can be an aromatic compound, such as a
catechol, or an aliphatic compound, with the latter being preferred from
the standpoint of attaining lower levels of set retardation. Most
preferably, the polyhydroxy compound is an allphatlc polyhydrlc
carboxyllc acld, e.g., a glyconlc acld.
The admixture compositlon can comprlse tile1 borate ester com,oonent
lS in combination with a single water-reduclng agent or, preferably, In
combination with two or more water-reduclnq agents. Preferred
water-reducing agents for use In the inventive admixtures are aromatic
sulfonic acid-aldehyde condensate salts and lignosulfonic acid salts.
Most preferably, both of these preferred water-reducing agents are
present in the admixture together with the borate ester.
The relative quantity of each of the admixture components can
vary over a wide range such that a variety of admixture formulations
can be provided to meet different requirements of slump retention or
set retardation. This flexibility in formulating the admixture can also
be used to compensate for variations in reactivity of different cements
Cud se 2 7 6 4 ~;LZZ75( ~5
to the admixture. This flexibility is significantiy increased by the use
of two or more different water-reducing agents in the admlxture,
inasmuch as the ratio of the water-reducing agents to each other, as
well as to the borate ester, can be adjusted. Thus, a wider variety of
formulations, with a correspondingly broader range of properties in
hydraulic cement mixes, can be provided.
The admixture blends of this invention can be provided and used
as neat formulations in the form of a dry powder or, preferably, as
aqueous-based solutions, i.e., the admixture components can be
dissolved in an aqueous-based solvent.
The present invention is further directed to hydraulic cement
compositions comprising the admixture components.
DETA!LED DESCRIPTION OF THE INVENTION
As used hereln, the term hydraulic cement composition is
intended to refer to any composition containing a hydraulic cement
binder, e.g., an ASTM Type 1, Il, 111, IV, or V Portland cement,
inclusive of both dry cement compositions and wet cement slurries or
pastes. Included within the term are concretes, grouts, mortars,
cement pastes, and the like. The admixtures of this invention are
particularly useful in Portland cement concretes, and especially in
larger scale Portland cement concrete preparations where the concrete is
prepared at a mixing plant and transported to the Job site.
As indicated above, the admixtures of this invention provide a
longer slump life, i.e., increased slump retention, in hydraulic
cement compositions. For many larger scale applications using
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Portland cement concrete, the increased slump retention permits addition
of the admixture to the concrete at the mixing plant, rather than at the
job site. This option can be advantageous where local work
specifications or conditions prohibit on site addition of admixtures.
Moreover, it facilitates mixing during transportation to the job site and
provides greater flexibility in terms of the time alloweci for pouring,
placing, and working the concrete at the job site. i-lowever, since the
admixtures can be formulated to provide the increased slump retention
while causing only a relatively minimal increase in the initiai setting
time, (as compared, for example, to the initlal setting time obtained
with a conventional water-reducing agent) the cement mix will generally
thereafter set up in sufficient time to permit the applicator to gain
access onto the concrete and finish it within the time constraints of the
average work day,
An additional unexpected advantage provided by the inventive
admixtures is the generally excellent finishing characteristics imparted
to hydraulic cement compositions, whereby the composition assumes a
smooth, creamy consistency, for an extended duration, without
stickiness, and thus can be surface finished easily and with highly
satisfactory results.
The borate esters used in the admixtures of this invention are
believed to provide the improved finishing characteristics and slump
retention which have been observed in hydraulic cement compositions
containing the admixtures. These borate esters are cyclic esters which
are believed to involve complexation or bonding of a boron moiety to
t Yo hydroxyl groups within an esterifying polyhydroxy compound so as
to form a cyclic structure. As noted previousiy, the esterifying
polyhydroxy compound is preferably aliphatic. Tha aliphatic compound
can be, for example, an aliphatic diol, e.g. ethylene glycol,
1,2-propanediol, or 1,3-propanediol; an aliphatic polyhydric alcohol,
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a se 2 7 6 4 7S~lIS
e.g., glycerol, glucose, or mannose; an aliphatic diol carboxylic acid
e.g., 2,3-dihydroxypropionic acid or tartaric acid; or, preferab,ly, an
aliphatic polyhydric carboxylic acid, e.g., glucaric acid The preferred
aliphatic polyhydric carboxylic acids for use herein are the glyconic
acids, particularly gluconic acid and glucoheptonlc acid. The
stereospecificity of the polyhydroxy esterifying compound must, of
course, be such as to permit formation of the cyclic borate ester. The
stereospecific molecular requirements relating to borate ester formation
are well known. An early study of this subject is provided by
J. i30eseken, Advances in Carbohydrate Chemistry, 4, 189-210 (1949).
The borate esters generally used herein are belleved to be
mono-esters involving the complexation or bondlng of one molecule of
esterifying compound to one boron moiety, with the thlrd valence
positlon of the boron moiety occupled by a hydroxyl group. This
hydroxyl group may be neutrallzed wlth a cation as discussed
here7nafter,
Preparation of the mono-ester is normally facllitated by reacting
approximately equimolar amounts of boron and the esterifying compound.
i-lowever, the mono-ester may also be prepared using a molar excess of
the esterifying compound, as may prove necessary where stereospecific
or steric factors hamper the reaction of the esterifylng compound with
the boron moiety. Conversely, where the esterifylng compound is
readily reacted with the boron moiety, bis esters may be formed using a
molar excess of the esterifying compound and the present invention
broadly comtemplates the use of bis borate esters as well.
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Ca ye 2 7 6 4 ~2~75~
The borate esters may be used in the free acid form, I . e. with an
-OH group on the boron and ~COOH group on an esterifying carboxylic
acid compound. However, the salt form of the ester can provide less
set retardation in concrete formulations and is thus generally preferred
for use herein. Where the esterifying polyhydroxy compound is a
pclyhydroxy alcohol, the salt form incorporates a cation which displaces
the hydrogen of the remaining hydroxyl group on the boron moiety.
Where the esterifying polyhydroxy compound is a polyhydroxy
carboxylic acid, this salt form incorporates a cation associated with the
carboxyl group(s) of the esterifying compound and, optionally, a cation
which displaces the hydrogen of the remaining hydroxyl group on the
boron moiety. The cation can be an alkali metal, e.g., sodium or
potassium, or an alkaline earth metal, e.g., calclum or magnesium.
Preferably, however, the catlon is ammonium: alkylammonium, e.g.,
triethylammonium; alkanolammonlum, e.g. dlethanolammonium,
triethanolammonium, or mixtures of the same. Utillzation of
alkanolammonlum borate ester salts in particular has been found to
result in admixtures which provide lesser increases In initial and final
setting tlmes as compared, for example, to similar admixtures comprising
alkaline earth ester salts. A particularly preferred cationic grouping
is that provided by neutralization of the borate ester with a
mixture of monoethanolamine, diethanolamine and triethanolamine.
The borate esters can be prepared by known methods. Thus,
boric acid can be reacted with the esterifying compound in an aqueous
medium, using mild heating to facilitate completion of the reaction.
Case 2764 ~2~'7SOS
Where the esterifying compound is not readily reactive with borlc acid it
may prove desirable to employ an anhydrous polar reaction solvent,
e.g., tetrahydrofuran, or hlgher reaction temperatures in order to
promote ester formation. An esterifying carboxylic acid may be reacted
in its salt form, e.CJ., calcium gluconate may be reacted with boric acid
to provide the correspondingly neutralized calclum borogluconate. A
precursor to the carboxylic acid esterifying compound, e.g. a precursor
lactone, may also be utilized as an esterifying reagent.
The esters may also be prepared by reaction of a borate salt such
as zinc borate or calcium borate wlth the esterJfying compound, e.g.,
as described in U. S. Patent No. 3,053,674.
After formation of the ester, a base may be added to the reaction
solution to neutralize the ester or as desired for cation exchange.
However, the pH of the solution should be maintained at less than pH
10-11, and preferably less than about pH 8, In order to provlde a
stable solution which can be stored for extended periods.
Any of the known hydraulic cement water-reducing agents, can be
used in the Inventive admixtures. It Is preferred to use as the
water-reducing agent component elther an aromatic sulfonlc
? acid-aldehyde condensate salt or a lignosulfonic acid salt. Most
preferably, the admixture comprises both of these preferred
water-reducing agents. The aromatic sulfonic acid-aldehyde condensate
salt which can be used in the present admixtures can be any such
polymeric condensate which meets the ASTM C494 standard for a Type
A or Type F water-reducer. SUCh condensates and their use as
dispersants or water-reducers in hydraulic cements are disclosed, for
example, in U. S. Patent Nos, 2,141 ,569; 2,690,975; 3,359,225;
3,582,375 4,125,410; 4,391,645; and 4,424,074.
Case 2764 5
Exemplary aromatic moieties which can be present in the condensate
polymer are phenyl, tolyl, xylyl, benzoic acid, phthalic acid, phenol,
melamine, diphenyl, naphthalene, methylnaphthalene or anthracene
moieties. The condensate polymer may contain a slngle aromatic moiety
or two or more different aromatic moieties in the polymer chain.
The aldehyde used in preparation of the condensate is an
alkylaldehyde~ e.g. acetaldehyde, or preferably formaldehyde. The
formaldehyde condensates are particularly well known water-reducing
agents and are generally preferred from an availability, cost, and
performance standpoint .
The condensates can be prepared by reaction of an aromatic
sulfonic acid with an aldehyde to form a condensation polymer, followed
by neutralization with a basic material, e.g., sodium hydroxide, or
they can be prepared by condensation of an aromatic compound with the
aldehyde followed by sulfonation of the condensation product and
neutralization of the sulfonated material. Processes for preparing the
condensates are disclosed in U. S. Patent Nos. 2,141,589; 3,0~57,243;
3,193,575; 3,277,162; and 4,125,410,
The condensates used on the present admixture are in the sait
2~ form, so as to possess desired water solubility, and can comprise, as
the salt forming cation, sodium, potassium, calcium, zinc, aluminum,
magnesium, manganese, ferrous, ferric, or ammonium cations.
Alkylammonium or alkanolammonium cations can also be used such as
methylammonium, dimethylammonium, ethanolammonium or
diethanolammonium cations.
Naphthalenesulfonic acid-formaldehyde condensate salt is the
preferred condensate polymer for use in the admixture of this
invention. A commercial naphthaienesulfonic acid-formaldehyde
condensate which has been found particularly useful in the inventive
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Case 2764
admixtures is that sold under the trademark "WRI)A-l9" by W. R. Grace
Co., Cambridge, Massachusetts.
With respect to the the use of a lignosulfonate component In the
present admixtures, lignosulfonates, as a class, are well known
materials which have been used as water-reducing agents, plasticizers,
and set-retarding agents in Portland cement compositions.
Lignosulfonates are commonly obtained as water-soluble salt derivatTves
of conventional sulfite wood-pulping processes. These derivatives may
be subsequently treated to provide "desugarized" lignosulfonates and
these desugarized materials are preferred for use herein. The
lignosulfonate used herein can be a salt of any alkali metal such as
sodium or potassium or any alkaline earth metal such as caicium or
magnesium.
As previously indicated, the relative quantlty of each admixture
component can be varied as approprlate to meet different requirements
of slump retention or set retardation or to compensate for variations in
reactivity of different cements to the admixture. Accordingly, any
ratio of the aforementioned components can be employed, as necessary
for particular applications. In general, it is preferred to employ less
than about 30% by weight of the borate ester component, based on the
total weight of admixture components, in order to minimize any set
retardation imparted by the admixture.
The set retardation encountered by use of the present admixtures
can be modulated by adlustment in the relative proportion of the borate
ester in the admixture, with a lower proportion generally resulting in a
iesser degree of set retardation by use and adjustment of the relative
proportion of a set retarding water-reducing agent, e.g.,
lignosulfonate by use of differently neutralized borate esters, with
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ammonium, alkylammonium, anci alkanolammonium neutralized borate
esters tending to provide lesser degrees of set retardation than
alkali metal and alkaline earth metal neutralized borate esters; and by
adjustment of the concentration or "dosage" of the admixture in the
cementitious mix.
The initial slump and the slump retention obtained by use of the
present admixtures can be modulated by adjustment in the relative
proportion of the borate ester, with a higher proportion generally
providing a higher initial slump and increased slump retention; and by
adjustment of the dosage of admixture in the cementitious mix.
For most applications, it will be desired to obtain a maximal
increase in slump retention with minimal set retardatlon. Any of the
above methods of modulating set retardation and slump retention may be
used, either individually or in combination, to obtain the desired
performarlce, In general, optimal combinations of slump retention and
set retardation are most readily obtained utilizing the preferred
admixtures of this invention comprising both the naphthalene sulfonic
acid-formaldehyde condensate polymer salt and lignosulfonic acld salt.
Most preferably, from the standpoint of minimizing set retardation,
- these preferred admixtures should comprise as the borate ester
component an ammonium, alkylammonium, or alkanolammonium neutralized
bo ra te este r .
Although it is generally preferred to formulate the admixture so as
to provide minimal set retardation, for some applications, such as hot
weather applications, a greater degree of set retardation may be desired
and adjustments can be made in the admixture formulation or dosage, as
described above, in order to meet this need.
A particularly preferred admixture of this invention comprises
about 30 to 90 percent b`y weight of an aromatic sulfonic acid-aldehyde
condensate, about 15 to 70 percent by weight of a lignosulfonic acid
salt, and about 1 to 15 percent by weight of borate ester, where the
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Case 2764 12~7~;0~i
percentage is of the total weight of the three components. A more
preferred admixture formulation comprises about 50 to 70 percent by
weight of the condensate, about 25 to 45 percent by weight of the
lignosulfonate, and about 3 to 10 percent by weight of the borate
ester. In general, it is desirable to employ less than about 10 percent
by weight of the borate estsr in the admixture compositions containing
both the condensate and lignosulfonic acid salt in order to provide
desirably low levels of set retardation, although higher proportions of
the borate ester may be employed where the admixture Is to be used at
a low concentration In the cementitious mix.
The admixture can be provided as a dry powder mixture of the
aforementloned components but preferably, for purposes of easy
dispensing into cement formulations, Is provlded In an aqueous solution,
generally at a concentratlon of 30 to 50 percent by weight of the
admixture, based on the total weight of the solution, The admixture
can be dissolved in water at these concentratlon levels at a pH ranging
between about 3 to 10 to provlde a stable, homogeneous solution.
The admixtures of this Invention can be used as either low range
water-reducing agents, as defined by ASTM C494, Type A, or as high
range water-reducers, defined by ASTM C494, Type F or Type G . I n
general, the functioning of the admixture as a low range or high range
water-reducer is dependent on the dosage level, although performance
in this regard may also be dependent on the particular admixture
formulation and hydraulic cement type. As a general guide for Portland
2i cement concretes, the admixture will function as a low range
water-reducer at dosage levels of less than about 0 . 20% solids of the
admixture, based on the weight of Portland cement binder in the
concrete, and as a high range water-reducer at dosage levels
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Ca se 2 7 6 4 3L~2~5~5
above about 0.20%, similarly based. It is generally preferred to employ
the admixture as a high range water-reducer in Portland cement
concretes utilizing dosage levels in the range of about 0,20% to 0.50%.
At these levels, the admixtures have been found to provide initial
slumps in the desired range of approximately 8 to 10 inches (ASTM
C143) and improved slump retention (as quantified in the following
Examples), while retarding initial setting times by approximately 112
hour to 2 hours as compared to the initial setting tlme of the same
concrete containing comparable dosages of conventlonal water-reducing
agents. Accordlngly, a high slump concrete is provided which retains
its slump for !onger durations but is generally capable of setting and
being surface finished within the tlme constrlctlons of a typical work
day .
The admlxture may be added to the dry cementitious mixture or to
the wet cement slurry. In general, the admlxture wlll be added In its
dry powder form to a dry cementltious mix while an aqueous solution of
the admlxture is used in the case of additlon to a wet cement slurry.
While the admixture may be dissolved in the mix water used to prepare
the cement slurry, it preferably is added as a separate solution
following preparation of the slurry. After addition, sufficient mixing
should be provided to assure a substantially uniform distribution of the
admixture throughout the cement composition.
Consistent with the foregoing, the present invention is further
directed toward hydraulic cement compositions comprising a hydraulic
cement binder and the admixture components of this invention. The
total arnount of the admixture components in the cement compositions is
preferably about 0.0S% to 0.50% by weight, based on the weight of
hydraulic cement binder. The cement composition can be in an
essentially dry, free-flowing powder form or a wet slurry form. The
cement composition can be formed by individual addition of
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each of the admixture components to the hydraulic cement binder
or by addition the multicomponent admixture, either in dry form,
or, preferably, in solution. The preferred hydraulic cement
binder is Portland cement and the inventive cement compositions
may comprise additional materials such as fine or course
aggregate or additional admixture materials. Consistent with
the foregoing, in Portland cement concretes the admixture
components, in total, will generally be present in a weight
concentration of about 0.05% to about 0.20%, based on the weight
of Portland cement binder, where performance of the admixture
as a low range water-reducer is desired and in a weight concen-
tration of about 0.20% to about 0.50%, where performance as a
high range water-reducer is desired.
The admixtures of this invention can be prepared by
mixing the respective components in dry form or, preferably,
by blending aqueous solutions of the respective components
followed by adjustment O:e the blended solution to a desired con-
centration by water addition.
The following Examples are given to further describe
and illustrate the present invention. The following Examples
are illustrative only and are not intended to limit the present
invention in any sense. All parts and percentages are by weight
unless otherwise indicated.
EXAMPLE 1
Preparation of calcium borogluconate solution:
860.5 grams of calcium gluconate minohydrate and 244
grams o e technical grade boric acid were added to 1100 grams
of water at room temperature. The resultant mixture was stirred
and warmed to a temperature of about 50C until a dark brown
solution was obtained. The solution was allowed to cool to
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room temperature. The solution can be used as is or the water
can be evaporated to provide the calcium borogluconate as a
brownish solid.
EXAMPLE 2
Preparation of calcium borogluconate solution:
28 grams of calcium oxide were added to water to form
a thick slurry. This slurry was slowly added with stirring
to 392 grams of a 50% aqueous solution of technical grade
gluconic acid. After all of the slurry was added the resultant
mixture was cooled and 61.8 grams of technical grade boric
acid added. The mixture was stirred until a dark brown solution
was obtained and then adjusted by water addition to provide a
40% solids solution.
EXAMPLE _
Preparation of sodium boroglucoheptonate solution:
123.7 grams of technical grade boric acid were added
slowly to 1417 grams of a 35% aqueous solution of technical
grade sodium glucoheptonate. The mixture was stirred at room
temperature until a dark brown solution was obtained.
EXAMPLE 4
-
Preparation of triethanolammonium borogluconate
solution:
35.6 grams of gluconolactone and 12.2 grams of
technical grade boric acid were added to 50 ml. of water at room
temperature. The resultant mixture was stirred and heated at
about 50C. for about 4 hours and the water allowed to evaporate
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6925-292
to reduce the mixture volume to about 45 ml. The mixture was
then cooled to room temperature and 28 grams of triethanolamine
were added with stirring.
EXAMPLE 5
2584 grams of a 35% solids aqueous solution of
technical grade sodium glucoheptonate were adjusted to about
pH 6 by addition of 20.5 grams of an 88~ formic acid solution.
226 grams of technical grade boric acid were then added to the
pH adjusted solution and the resultant mixture stirred overnight
at room temperature. 476 grams of a mixture of monoethanolamine,
diethanolamine, and triethanolamine were then added with stir-
ring, bringing the pH of the resultant solution to pH I. The
alkanol amine mixture was reported by the supplier to contain
0-15% monoethanolamine, 13-~5~ diethanolamine, 55-76% triethanol-
amine, and 0-5~ of other materials.
The borate ester prepared in this Example is herein-
after referred to as sodium-mixed alkanolamine boroglucohepton-
ate and is believed to comprise a mixture of both the sodium
and alkanolamine borate ester salts.
EXAMPLE 6
Preparation of mixed alkanolamine borogluconate
solution:
500 grams of gluconolactone and 173.6 grams of
technical grade boric acid were added to 500 ml. of water and
the resultant mixture stirred and warmed until a dark brown
solution was obtained. The solution was cooled to room
temperature and 418 grams of the alkanolamine mixture of Example
5 were added with cooling. The resultant solution was diluted
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with water to a total weight of 1980.4 grams to provide a 50%
solids solution of the mixed alkanolamine borogluconate.
16a
Case 2764 ~;~27$~
XAMPLE 7
The following admixtures were prepared by blending a 40% soiids
aqueous solution of naphthalene sulfonic acid-formaldehyde condensate
salt ("WRDA-lg", available from W, R, Grace Co., Cambridge,
Massachusetts), a 50sg solids aqueous solution of sodium lignosulfonate,
and an aqueous solution of a borate ester, as indicated below. The
weight ratios given below are solids weight ratios of the condensate:
lignosulfonate: borate ester. The resultant blends were adjusted to a
concentration of 40% solids by addition of water to provide a final
admixture solution,
Admixture Weight Ratio Borate Ester
___ _. _
A 65:25:10 Mixed alkanolamine borogluconate (Example 6)
B 65: 25: 10 Calcium borogluconate
C 65:30:5 Mixed alkanolamine borogluconate (Example 6)
D 65: 30: 5 Sodium-mixed alkanolamine
boroglucoheptonate (Example 5)
E 65: 30: 5 Calcium borogiuconate
F 65:30:7 Mixed alkanolamine borogluconate (Example 6)
G 65:30:7 Triethanolammonium borogluconate (Example 4)
H 15:80:5 Mixed alkanolamine borogluconate (Example 6)
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EXAMPLE 8
Admixtures A and B were added to individual batches of a
Type l l Portland cement concrete slurry which had been prepared with
a water/cement ratio of 0.49 and mixed for about 11 minutes prior to
addition of the admixture. The amount of admixture added to the
cement in this and the following Examples is given in terms of the total
weight of solid admixture components expressed as a percentage of the
weight of Portland cement binder present in the concrete formulation,
hereinafter termed "percent solîds on solids" (% s/s). In this Example,
each of the admixture solutions was added to the individual concrete
batches in an amount sufficient to provide an admixture concentration of
0,40% s/s.
The concrete of this Example and the concretes of the following
Exampies 9-13 were prepared at a cement factor of 611 Ibs/yd.
To provide a reference sample, an individual portion of the
concrete was also admixed with WRDA-19 alone at a concentration of
O . 40% s/s . This commerciai matertal has been widely used as a high
range water-reducer.
Slump measurements were carried out on the concrete before and
after addition of the admixtures in accordance with ASTM C143. The
measured slumps are presented in Table i. The times given in Table i
and in the following Examples are the times at which slump
measurements were made and denote the total mixing time of the
concrete. As noted above, the admixtures were added at about 11
minutes into the mix cycle.
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Case 2764
Table I
Admixture Slump (inches)
9 Min15 Min 30 Min . 45 Min . 60 Min .
Reference 4.2510.00 8.25 5.25 3.25
S A 4.0010.50 8.75 7.25 4.50
B 4.2510.25 8.75 7.50 5.50
The results presented in Table I indicate approximately equal
initial ( l 5 Mln . ) slumps among the three samples and substantlally
improved slurnp retention in the samples containlng the admixtures of
this inventlon,
The concretes of this Example and of the foliowlng Examples were
also measured for alr content (ASTM C231), Inltlal and final setting
times (ASTM C403), and compressive strength (ASTM C192) at 1, 7,
and 28 days (average of two cylinders). These measurements on the
concretes of this Example are presented in Table l l .
19
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Case 2764
Table l l indicates the generally observed result of lesser increases
in setting time where the borate ester is neutralized with an
alkanolamine (Admixture A) rather than an alkaline earth metal
(Adrnixture B).
EXAMPLE 9
Admixture solutions A and C were added to individual batches of a
Type l / l l Portland cement concrete slurry in amounts sufficient to
provide admixture solids concentrations of 0.40~ s/s, 0.33% s/s, and
0.25% s/s. The concrete was prepared wlth a water/cement ratio of
0.48 and the admixtures were added at 11 minutes as in Example 8.
Reference samples were prepared ivy addition of WRDA-19 alone at
the three different concentratlon levels. Measurements were taken as in
Example 8 and are presented in Tables l l l and IV.
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Case 2764 ~22~7~iO~
Table l l l
Admixture Slump (inches)
Admixture Concentration (%s/s? 9 Min,~15 Min. 30 Min. 45 Min, 60 Min.
Reference 0.40 3.00 9.75 8.00 6.00 3.50
A 0.40 2.75 9.50 7.00 5.75 4.25
C 0.40 3.25 9.50 .50 7.00 5.00
Reference 0.33 2.25 9.75 6.00 3.75 2.50
A 0.33 3.50 9.75 6.50 5.00 4.00
C 0.33 2.50 9,00 7,75 4,50 3.50
Reference 0.25 3.25 8.25 4.50 3.50 3.00
A 0.25 3,75 8.25 6.00 4.75 3.50
C 0.25 3.00 8.00 6`.00 3.50 3.50
22
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Case 2764
The results presented in Tables lll and IV indicate increased slump
- retention over the reference at all admixture concentration levels.
Compressive strengths and air content are close to those of the
reference samples at all admixture concentration levels. The increases in
initial and final setting times resulting from use of the admixtures
decreases with decreasing concentration, with the setting time with
Admixture A at 0.25% s/s being about equal to that of the reference.
EXAMPEE 1 0
Admixtures solutions C and D were each added to batches of two
concretes which respectively contained Type 1/11 and Type 11 Portland
cement binders, respectively designated as Concretes I and 11.
Admixture concentration was 0.33% s/s for all batches and the admixtures
were added at 11 minutes into the mix cycle. The concretes were each
prepared at a water/cement ratio of 0.57.
For comparison, reference sarnples were prepared as in Examples 8
and 9 (WRDA-19 alone) at an admlxture concentration of 0.33% s/s
("Reference l In addition, a second reference ("Reference 2") was
prepared in which WRDA-19 was acided at 11 minutes into the mix cycle
to Concretes I and 11 which contained 0.1~ s/s of a commercial
low range water-reducer sold under the ye "Hycol" by W. R .
Grace Co. The combined concentration of the water-reducers was thus
0. 43% s/s.
Slurnp measurements were conducted as in Examples 8 and 9 and are
presented in Table V.
I.
C a s e 2764 3L2Z7~;0~ 1
Table V
Slump ( inches)
ConcreteAdmixture 9 Min .15 Min . 30 Min, 45 Min . 60 Min .
-- j
Reference 1 2.258.50 5.50 3.25 2.25
I Reference 2 5.7510.00 7.75 4.75 4.25
C 3.509.50 8.00 6.25 4.50
D 3.509.75 8.00 6.25 4.50
I lReference 1 2.005.50 3.50 2.50 2.50
IlReference 2 2.508.00 3.50 2.75 2.50
ll C 1.757.50 3.50 2.75 2.00
I l D 2.256.75 4.25 3.25 2.75
The results of Table V Indicate Improved slump retention over
Reference I in both concretes by both admlxtures. The slump retention
provided by both admixtures is comparable to or better than that
provided by Reference 2 notwithstanding the higher total concentration
of water-reducers in Reference 2, with this result being more
pronounced in Concrete 1.
The air content, setting times, and compressive strengths of the
concretes were measured as in Example 8 and are provided in Table Vl.
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Case 2764 7505
Example l l
Admixtures E, F, and G werè added to concrete batches at a
concentration of 0.40% s/s at 11 minutes into the mix cycle. The
concrete was prepared using the Type i / l l Portland cement binder of
Example 9 at a water/cement ratio of about 0.48. Slump retention
measurements are presented in Table Vi I .
Table Vl l
Slump tinches)
Admixture 9 min . l S min . 30 min . 45 min . 60 min,
__ _
E 3.00 lO,00 8,50 7,00 5.25
F 3.50 10.25 8,50 6.75 4.75
G 3.50 9.75 8.75 7.75 5.00
leasurement of air content, setting times, and compressive
strengths are given in Table Vl l l .
27
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Case 2764
As shown in Tahle Vl l l, setting times are less using the mixed
alkanolamine borogluconate (Admixture F) rather than calcium
borogluconate (Admixture E), notwithstanding the higher dosage of the
borogluconate component in Admixture F. Admixture F also provides
lower setting times than Admixture G, which is consistent with a
generally observed trend of lower setting times using a borate ester
neutralized with the alkanolamine mixture, as opposed to a borate ester
neutralized solely with triethanolamine. However, the setting times
provided with Admixture C are still approximately equal to those
provided with Admixture E, notwithstanding a higher dosage of the
borogluconate component.
Example 1 2
In order to demonstrate a water-reducing capability at low dosage,
admixtures C and H were each added to concrete slurry batches in
concentrations of 0,10% s/s and 0,16% s/s. The admixtures were added
with the mix water used to prepare the slurries and slump measurements
were taken at 9 minutes into the mix cycle. The concrete was prepared
using the Type l / l l Portland cement binder of Example 9 at a
water/cement ratio of about 0.49.
The experimental concretes were compared against a batch with no
admixture added ("Blank")and a batch to which were added the same
dosages of the commercial low range water-reducing agent "Hycol". The
9 minute slumps and results of similar measurements as in the above
Examples are provided in Table I X .
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Case 2764
As shown by Table IX, significant water reduction was provided by
both Admixtures C and H. The increases in setting time over the blank
sample were least with Admixture C and greatest with the Hycol samples.
Examp!e 13
Two 40% solids admixture solutions of this invention were prepared
by blending lNRDA-19 and an aqueous solution of calcium borogluconate
at WRDA-19: calcium borogluconate solids weight ratios of 50:50 and
75: 25 and adjusting the final concentration with water. These
admixtures were added to concrete batches at 11 minutes into the mix
cycle at a dosage of 0.2~ s/s and compared against a reference concrete
dosed with 0.2~ s/s WRDA-19 alone. The concretes were prepared using
the Type l l Portland cement binder of Example 8 at a water/cement ratio
of 0.51. Slump retention measurements and air content, setting times,
and compressive strengths are provided in Tables X and X 1.
Table X
S!ump (inches
Admixture 9 min .15 min . 30 min .45 min .60 min .
Reference 3.00 6.25 4.00 3.00 2.25
75:25 2.508.50 5.()0 4.00 3.00
50:50 4.00 8.00 5.25 4.00 2,75
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Case 2764
The results provided in the above Examples should be taken as
exemplifying the performance which can be obtained employing the
admixtures of this invention. As previously indicated, the admixture
performance will vary as a function of admixture composition and the
5 variables associated with formulation of the cementitious mix such as
cement type and source, water/cement ratio, and aggregate size and
amount .
