Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
3 1 ~
BACKGROUND OF Tl~l~ INVISNTION
The present invention relates to an improved
concrete composition which exhibits high flowability, low
decrease in the flowability with the progression of time
and lack of segregation over time.
The components of conventional concrete compositions
have a high tendency to segregate while being worked,
such as at the step of conveying, placing of concrete or
compaction even if it is uniformly mixed by a mixer. In
addition, due to its insufficient flowability,
conventional concrete compositions do not reaah parts of
the mold having a complicated shape, a high density of
re-bar arrangement or corners segments and, thereby,
provide a defective final concrete structure. Further,
due to lowering in the fluidity of the concrete
composition with the progression of time (hereafter
"slump loss"), the workability of such compositions
worsens over time and, thereby, inhibits the ability of
correcting defects.
In order to produce concrete structures having
durability and high reliability, construction must be
done in the field with scrupulous care by skilled workers
in the field and compaction work with the greatest
possible care is essential to achieve desired results.
In order to improve the workability of concrete,
various methods have been tried as, for example, the use
of a fluidizing agent such as a high range water reducing
agent, a high range AE (air entrained) water reducing
agent andlor the use of an admixture having a fine
particle size such as silica fume and blast-furnace slag
fine powder. However, concrete compositions containing
such substances have high slump and inferior flowability
and exhibit a high degree of slump loss with the
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-- 3 --
progression of time. With such compositions, good
filling and distribution is difficult to obtain by the
conventional methods.
Due to the present large amount of construction, the
lack of construction engineers and construction workers,
and amount of construction in special environments or
high performance structures, the technologies require the
ability to achieve a concrete structure of high
performance and reliability while using minimal manpower
and time.
In order to solve these problems, the development of
concrete composition having high flowability, small
decrease in the flowability with the progression of time
and low segregation is highly desired. Such concrete can
promote not only less manpower at the placing of concrete
and avoidance of noi~se due to compaction of concr~te but
also improvement of construction systems.
A concrete composition has now been found comprising
at most 185 Kg of water per m3 of concrete, 350 to 700 Kg
of a hydraulic cement material per m3 of concrete and
specified copolymer component substantially homogeneously
distributed therein, can impart the properties of
excellent flowability, small decrease in the flowability
with the progression of time and low segregation of the
concrete composition.
BUMMARY OF THE INVENTION
The present invention is directed to a concrete
composition which comprises
(A) 350 to 700 Kg of a hydraulic cement material per
m3 of concrete;
(B) up to 185 Kg of water per m3 of concrete;
(C) fine aggregate;
(D) coarse aggregate; and
3 :~ 0
(E) 0.05 to 3 parts by weight, based on 100 parts
by weight of the hydraulic cement material, of a
copolymer component comprising (i) an alkenyl
ether/maleic anhydride copolymer having oxyalkylene
chains with from 60 to 95 oxyalkylene units ("Copolymer
A"), as more fully described hereinbelow, or (ii) a
mixture of an alkenyl ether/ maleic anhydride copolymer
having oxyalkylene chains with from 1 to 40 oxyalkylene
units ~"Copolymer B") in combination with an alkenyl
ether/maleic anhydride copolymer have oxyalkylene chains
with from 100 to 150 oxyalkylene units ("Copolymer C"),
each as more fully described hereinbelow.
DETAIL~D D~CRIPTION
The hydraulic cement materials which can be employed
in the present invention are portland cements and the
like.
It iB preferred that the Blaine fineness of the
hydraulic cement material is from 2,500 to 200,000 cm2/g
by the specific surface area of cement. When hydraulic
cement material having a Blaine fineness of less than
2,500 cm2/g is used to form the concrete composition of
the present invention, the composition does not prevent
segregation of the composition's components. Instead
bleeding of water occurs. When the Blaine fineness of
the hydraulic cement material of the subject concrete is
greater than 200,000 cm2/g, the composition requires
excessive amount of water and cement additive composition
to provide the desired properties. The cost for the
preparation of such powder and the requirement for high
loading of cement additive does not provide a cost
effective mode of practical purposes.
In order to further increase the flowability and
resistance to segregation of the subject concrete
~131~
composition, it is preferred that at least one fine
powder material selected from the group consisting of
blast-furnace slag, fly ash, silica stone powder, natural
mineral powder and superfine siliceous powder be employed
as part of the hydraulic cement component of the present
composition. The amount of fine powder (Blaine fineness
of from 2,000 to 200,000 cm2/g) to be used is not limited
and is preferably up to 50% by weight, more preferably 5
to 40% by weight of the total hydraulic cement material
(e.g. portland cement) used.
The amount of the hydraulic cement material to be
used is from 350 to 700 Kg per m3 of concrete composition
formed and the amount of mixing water is up to 185 Kg per
m3 of concrete. The fine aggregate (sand) and coarse
aggregate (stone) should be used in conventional amounts
to form the concrete composition of the present
invention. When the above concrete composition contains
the cement additive described hereinbelow, it has been
found that the concrete composition is capable of
exhibiting high flowability, retention of low slump over
extended periods of time and high resistance to the
segregation. In contrast, concrete compositions
containing the above described fine powder in the
specified amount, either alone or together with
conventional high range reducing agents or conventional
high range AE water reducing agents, do not readily
maintain sufficient flowability, slump retention and
resistance to the segregation.
The copolymer component reguired by the present
invention is a copolymer of an alkenyl ether and maleic
anhydride. Three specific copolymers, when used in the
manner described hereinbelow, have been found to achieve
the desired combination of properties. Each copolymer,
,s~
respectively, has an alkenyl ether comonomer represented
by the formula:
R10(AO)~R2 (I),
R10(AO)~R2 (II),
RlO(AO)~R2 (III),
wherein in each of the above formulae
R1 represents a C25 alkenyl group;
R2 represents a Cl_4 alkyl group;
A0 represents a C218 oxyalkylene group in
which 0 represents an oxygen atom and A
represents an alkylene group;
n represents an average adduct mole number of
from 60 to 95 for the oxyalkylene group;
m represents an average adduct mole number of
from 1 to 40 for the oxyalkylene group; and
p represents an average adduct mole number of from
100 to 150 for the oxyalkeylene group.
In the present description and in the appended
claims, the term "Copolymer A" shall mean a copolymer of
alkenyl ether I and maleic anhydride, as the anhydride,
or a partially or completely hydrolyzed product or as a
salt (alkali or alkaline earth metal) of the hydrolyzed
product and the mole ratio of alkenyl ether I to maleic
anhydride being from 30:70 to 70:30;
"Copolymer B" shall mean a copolymer of alkenyl
ether II and maleic anhydride, as the anhydride, or a
partially or completely hydrolyzed product or as a salt
(alkali or alkaline earth metal) of the hydrolyzed
product and the mole ratio of alkenyl ether II to maleic
anhydride being from 30:70 to 70:30; and
"Copolymer C" shall mean a copolymer of alkenyl
ether III and maleic anhydride, as the anhydride, or a
partially or completely hydrolyzed product or as a salt
~1310
(alkali or alkaline earth metal) of the hydrolyzed
product and the molar ratio of alkenyl ether III to
maleic anhydride being from 30:70 to 70:30.
C25 alkenyl groups represented by Rl in each of the
above described formulae (I), (II), and (III), include,
for example, vinyl, allyl, methallyl,
1,1-dimethyl-2-propenyl and 3-methyl-3-butenyl groups and
of these groups, allyl group is preferably employed.
C218 oxyalkylene groups represented by A0 in the
above described formulae (I), (II) and (III) include, for
example, oxyethylene, oxypropylene, oxybutylene,
oxytetramethylene, oxydodecylene, oxytetradecylene,
oxyhexadecylene and oxyoctadecylene groups. Of these
oxyalkylene groups, C24 oxyalkylene groups such as
oxyethylene, oxypropylene and oxybutylene are preferred.
The A0 may include two or more types of oxyalkylene
moieties and such oxyalkylene moieties may be linked in
block or at random.
Cl4 alkyl groups represented by R2 in the above
described formulae (I), (II) and (III) include, for
example, methyl, ethyl, propyl, isopropyl, n-butyl,
isobutyl and tertiary butyl groups. When the carbon
atoms is more than 4 in the R2, the amount of air
entrained in the mortar or concrete admixture is
increased, and accordingly, it is preferred to select a
C14 alkyl group when air entrainment is not desired.
In one embodiment of the present invention, the
concrete composition contains a copolymer component
composed of at least one Copolymer A where the average
adduct mole number of the oxyalkylene group represented
by n is 60 to 95. This copolymer component exhibits the
properties of affecting the initial short term dispersion
of the particles comprising the cement composition
L31~
- 8 -
similarly to that caused by conventional slump loss
admixtures, such as naphthalene sulfonate formaldehyde
high range condensate types, sulfonated melamine resin
type or lignosulfonate type admixtures. The present
Copolymer A further unexpectedly increases slump with the
progression of time. Thus, the present admixture concrete
composition containing at least one Copolymer A provides
both initial and progressive increases in slump to the
composition.
Furthermore, the concrete composition containing
Copolymer A surprisingly shows a tendency of reducing the
segregation of components and bleeding water and reducing
setting retardation. Accordingly, it is not necessarily
required to add to the concrete composition of the
present invention a water ~oluble high molecular weight
substance which is essential for the resistance to the
segregation of concrete or the suppression of bleeding as
described in Japanese Patent Publication (Kokai) No.
237049/1991.
Furthermore, depending on the types of hydraulic
cement material and aggregate and the concrete
compositions formed therewith, the copolymer component of
Copolymer A may also contain small amounts (5 to 30 parts
by weight, based on 100 parts by weight of Copolymer A,
its hydrolyzed product or a salt of the hydrolyæed
product of the present invention), of Copolymer B or
Copolymer C, their hydrolyzed product or a salt of the
hydrolyzed product. The desire to incorporate Copolymer
B or Copolymer C can be readily determined by conducting
slump tests of cement composition to achieve the specific
characteristic desired.
~9:~31~
In a second embodiment of the subject invention, the
concrete composition contains a mixture of Copolymer B
and Copolymer C. Thus, it has been unexpectedly found
according to the present invention that a balanced
combination of the Copolymer B with the Copolymer C ,
when used in the subject concrete composition, produce a
concrete composition having excellent flowability and
slump retention. Furthermore, the concrete composition
comprising such a combination of Copolymer B with
Copolymer C surprisingly shows a tendency of
substantially inhibiting segregation of components and
bleeding water. Accordingly, it is not necessarily
required to add to the concrete composition of the
present invention a water soluble high molecular weight
substance which is essential for the resistance to the
segregation of concrete or the suppression of bleeding,
as described in Japanese Patent Publication (Kokai) No.
237049/1991.
The mixing ratio of Copolymer B and Copolymer C may
vary from 97-50 : 3-50.
The Copolymers A, B, and C of the present invention
can be prepared by the polymerization of an alkenyl ether
of the formula (I), (II), or (III) and maleic anhydride
in the presence of a peroxide catalyst in accordance with
the method described in Japanese Patent Publication
(Kokai) No. 297411/1989. The mol ratio of the alkenyl
ether of the formula (I), (II), or (III) to maleic
anhydride is typically 30 - 70 : 70 - 30 and preferably
50 : 50. If desired, each of the copolymers may contain
another monomer which is copolymerizable therewith, such
as styrene, an alpha-olefin or vinyl acetate in amounts
of up to 30 percent by weight of the total weight of the monomers.
~9:13~
-- 10 --
The referred to hydrolyzed products of Copolymers A,
B, and C are products having a hydrolyzed maleic acid
unit resulting from the hydrolysis of the maleic
anhydride unit in the copolymer.
The referred to salts of the hydrolyzed product of
Copolymers A, B, and C are salts formed by the maleic
acid unit. Exemplary salts include alkali metal salts
and alkaline earth metal salts such as lithium salts,
sodium salts; ammonium salts; and organic amine salts.
The amount of cement additive (either Copolymer A or
a mixture of Copolymer B and Copolymer C required to
provide the desired effects is from 0.05 to 3 parts by
weight, preferably from 0.1 to 1 parts by weight based on
100 parts by weight of the hydraulic cement material
contained in the concrete composition.
Conventional cement additives such as air
entrainers, water proofing agents, strength enhancers,
curing accelerators and, if desired or necessary,
antifoaming agents can also be added to the concrete
composition of the present invention.
The above described copolymers as well as
conventional cement additives, if employed, can be added
to the other components in any conventional manner. For
example, they can be added to the mixing water used for
the preparation of the subject concrete composition or to
an already mixed concrete composition or as an aqueous
solution or suspension.
The concrete composition of the present invention
has high flowability and high resistance to the
segregation and, in addition, the slump retention with
the proqression of time is extremely improved.
Accordingly, the concrete composition having the high
flowability of the present invention can have various
~313~0
applications. For example, it can effectively be used for
general construction work; architectural construction
work; lining of tunnels; structure mass concrete;
refilling of side ditches; placing of concrete into
narrow spaces or frames of complicated shapes; and
construction of concrete structures having a high density
of re-bar arrangement.
The present invention is further explained by the
following examples which are given for illustrative
purposes and are not meant to limit the invention. All
other parts and percentages are by weight unless
otherwise stated.
Examples 1 to 30 and Comparative ExamDles 1 to 11
Forty liters of the concrete composition as shown in
Table 1 and Table 2 (for comparative samples) and the
copolymer additives, as shown in Table 3, were added in a
50 liter forced mixing type mixer and mixed at a mixing
ratio as shown in Tables 1 and 2 for 3 minutes to prepare
fluidized concrete having a lump of 21 to 25 cm, a slump
flow of 40 to 60 cm and an air content of at most 2% by
volume. After mixing, the mixture was transferred into a
mixing boat and retempering was conducted at a
predetermined number and the slump, slump flow and air
content with the progression of time was measured for up
to 60 minutes.
The procedure specified in JIS-A6204 were employed
to measure slump, air content, setting time and
compressive strength and to prepare test specimens for
measuring the compressive strength. The results are
shown in Tables 4 and 5 (comparative).
~S ~ 3~
- 12 -
The flowability of concrete was evaluated by
measuring slump and slump flow and by calculating flow
rate, and as the index for the resistance to segregation,
the state of concrete during the above described
measurements were observed by naked eyes and the judgment
was as follows:
A: No segregation was observed
B: Segregation was hardly observed
C: Some segregation was confirmed
D: Clear segregation was confirmed
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Table 1 (-continued)
1) Cement: Commercial portland cement (an equi-amount
mixture of 3 types of commercial portland cement);
Specific gravity: 3.16
2) Blast-furnace slag: Fineness: 8,000 cm2/g by the
specific surface area of cement by blaine; Specific
gravity: 2.90
3) Fly ash: Fineness: 2,880 cm2/g by the specific surface
area of cement by blaine; Specific gravity: 2.19
4) Silica fume: Fineness: 200,000 cm2/g by the specific
surface area of cement by blaine; Specific gravity 2.20
5) Water: Tap water
6) Fine aggregate: Sand from the Ohi River in Japan;
Specific gravity: 2.60; Fineness modulus: 2.76
7) Coarse aggregate: Crushed stone produced at Oume in
Tokyo; Specific gravity: 2.64; Fineness modules: 6.60
2~9131~
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-17-
Table 3
Number
Average
Alkenyl Ethers of Formulae Molecular
Copol~mer ~ & (III~ Weight
Formula (I)
(a) CH2=CHCH20(C2H40)66CH3 30,000
(b) CH2~cHcH2o(c2H4o)9lcH3 40~000
Formula (II)
(c) CH2=CHCH20(C2H40)llcH3 20,000
(d) CH2=CHCH20 (C2H4O) 33CH3 20, 000
(e ) cHa=cHcH2o ( C3H60) 15 ( CaH4O) l5C4Ng~l) 35,000
( f ) CH2=CHCH2O ( C3H60 ) 6 (C2H40)12CH3~2) 30,000
Formula (III)
(g) CH2=CHCH20(C2H40)ll5CH3 45,000
*l): (C3H6O) (C2H4O): 15: 15 random adduct
*2 ): (C3H6O) (C2H4O): 6 :12 block adduct
-18-
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