Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
7l3~2-1
The instant invention concerns imprOVeMents in mortar and concrete
mixes.
Particularly, the improvement of the instant invention consists of
admixing mortar or concrete with a small amount of a fluidizing agent, vis.
alkylsulfonated polysaccharides.
More particularly, the instant invention consists in improving the
workability of mortar and concrete mixes so as to allow very low water/cement
ratios. Mortar and concrete mixes are those mixtures of cementitous material
and aggregates defined in ASTM specifications C270 and C125 respectively.
~t is known in the art that in mortar and concrete mixes the initial
weight ratio of water to cement, more commonly referred to as W/C ratio, is an
important factor governing the so-called workability of the cement mix.
The amount of water required for a convenient workability is much
greater than that which would be necessary for the full hydration of the
hydraulic binder employed for making the mix.
The water excess, particularly in the case of high workability,
may cause serious handicaps both to the fresh mix ~excessive bleeding,
segregation, etc.) as well as to the hardened mix ~excessive shrinkage, high
porosity, lower resistance, etc.).
In order to obtain a good workability of mortar and concrete mixes
with lower W/C ratios, particular materials have long been proposed, and a
number of them have reached commercial importance.
Usually, such materials are designated as fluidizing agents. More
particularly, according to the Italian Standards for Testing Materials (UNI),
these materials are grouped into two classes, i.e. fluidizing agents and
superfluidizing agents. If the agent allows, in standard plastic mortars, a
ater reduction of not less than 6% (i.e. ~lR - VA
100-- = 6qo
~nerein VR is the water volume of the reference mix and VA is the water
~olume, inclusive of the fluidizing agent, of the fluidizing-agent-containing
~iX), then according to UNI Standard 7102-72 the material is defined as a
fluidizing agent. If, on the other hand, said material allows a water
reduction of not less than 10%, ~i.e. V - VA
100 VR ~ 10%
hherein VR is the water volume of the reference mix and VA is the water
volume, inclusive of the fluidizing agent, of the fluidizing-agent-containing-
mix), then according to UNI Standard 8145 the material is defined as a super-
fluidizing agent. Pluidizing and superfluidizing agents as above defined meet
roquirements for type A and type F concrete mixes specified in ASTM C 494-80.
Known useFul fluidizing agents are lignine-sulfonates, gluconates
and tannates.
Some known industrial carbohydrates such as, e.g. glucose syrups
~v. United States Patent 3,432,317) and modified starch hydrolizates
( v. Appli~can~s' Canadi~an Patent~No. 1,175,QA5 ~ are
commonly us~d in cement mixes both for improving the rheologic properties of
the mixes as well as-for improving their mechanical strength. Their water
reducing capability, th~ugh, is very limited and much inferior to that of the
superfluidizers.
Industrially, the use of superfluidizers has acquired importance
only during the past five yeàrs or so.
Known superfluidizers are made of polynaphthalene sulonates tv.
e.g. United States Patent 2,141,569; DE-AS 1,238,831 ; CA Patent 993,901)
48~
and of sulfonated malamine resins (v.e.g. IT Patent 801,078).
It has now been found that by sulfonating polysaccharides with
suitable sulfonating agents excellent superfluidizing agents having superior
properties with respect to all the known fluidizing and superfluidizing agents
can be obtained.
The alkyl sulfonated polysaccharide superfluidizing agents of the
invention are characterized by a degree of polymerization (D.P.) of up to lO0,
a degree of sulfonation (D.S.) as hereinafter defined and determined, of from
0.2 to 3Ø They can be further characterized by their fluidizing activity, in
as much as the addition of 0.4% of the inventive fluidizer is capable of
imparting to the mortar to which it is added a flow increase of from 6.5% to
130% whenever the D.S. value is in the range of from 0.20, inclusive, to 1.50,
inclusive.
Illustrative examples of useful polysaccharides for making the
inventive superfluidizers are e.g. cellulose, hemicellulose, starches and
hydrolizates thereof.
Illustrative examples of sulfonating agents for making the inventive
superfluidizers are, e.g. chloromethylsul~onic acid, chloroethane sulfonic
acid, chloropropane sulfonic acid and 1,3 propane-sultone.
The preferred inventive superfluidizers are those made oE hydrolized
cellulose sulfonated with chloromethane or chloroethane sulfonic acid.
Superfluidizers made of wood molasses sulfonated with chloropropane-
sulfonic acid as Nell as hydrolized starches sulfonated with chloroethane or
chloropropane sulfonic acid are even more preferred.
At present, the most preferred inventive superfluidizers are those
obtained from water soluble st~rch hydrolizates having a polymerization degree
~2~7~
equal or lower than 100 and chloroethanesulfonic acid, as the sulfonating
agent.
It would appear that the fluidizing activity of the i-nven~ive agents
is a function of the starting polysaccharides and of the sulfonating agents
used. This statement is supported by the data shown in the following Table.
TABLE 1
FLOW TESTS
FLUIDIZER DO~AGES ~b) FLOW (mm)
referred to plain
1) hemicellulose 0.6 +12
sulfopropylate ~a) 1.5 ~24
2) Starch 0.3 +24
sulfopropylate (a) 0.5 ~35
3) Soluble starch 0.3 +24
solfoethylate (a~ 0.5 +50
_ _
(a) prepared as in Examples 1, 2 and 3 respectively.
(b) Dosages are expressed as percent (dry to dry) of the amount
of cement in the mix.
As it can be take-n from Table 1~ the fluidizers made of water
soluble starches with polymerization degree of up to 100 and chloroethane
sulfonic acid yield the best results, never achieved before with any known
fluidizers or superfluidzers. The flow tests of Table 1 have been made with
plastic mortars according to the Italian Standard UNI 8020, using P~ 325
cement (which is commonly used in industry).
The sulfonate groups of the inventive fluidizing agents can either
be in the free acid form or can be salified with a Group IA and IIA metal
cation preferably sodium, potassium or calcium. Other useful cations can be
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chosen from ammonium or the organic amines.
When the cation is derived from an organic amine, the amine may be
any suitable primary, secondary or tertiary amine, such as, e.g. amines
containing an hydroxyl group. Primary, secondary and tertiary alkanolamines
are preferred.
The inventive superfluidizers are readily prepared by per se known
methods.
The following examples are illustrative of the inventive superfluid~
izers, the way of making them as well as the way of using them in mortar and
concrete mixes.
E~MPLE 1
Hemicellulose sulfopropylate
100 g of a hemicellulose slightly soluble in water at room temperature suspended
in 300 ml water containing 75 g NaOII are added with 450 g of 1,3 propane-sultone
and reacted 16 hrs. at 50C under stirring. Then reaction mixture is allowed
to stand for 48 hrs. at ambient temperature. The pH is then adjusted to 4 with
2N sodium hydroxide and the title product is precipitated with methyl alcohol.
The yield is 80% of the theory. The substitution degree is 0.9.
~XAMPLE 2
Starch sulfopropylate
80 g of starch not soluble in water at room temperature suspended in 250 ml
water containing 60 g ~aOH are added with 350 g of 1J3 propane-sultone and
reacted 16 hrs. at 50C under stirring.
The reaction mixture is then allowed to stand ~or 48 hrs. at ambient temperature
and the pH is adjusted to 4 with 2N NaOH. Finally, the title product is
separated from the reaction mixture by precipitation with a 2.5 : 1.5 methanol/
acetone mixture; then said product :is dissolved in water and dialyzed through a
3500 Dalton cellulose acetate membrane.
The yield is 45% of the theory. The substitution degree is l.l.
E~AMPLE 3
_ = =
Water soluble starch solfoethylate~
lOO g of starch, easily solu~le in water at room temperature suspended in
lOOO ml isopropyl alcohol are added with 175 g of the sodium salt of 2-
chloroethanesulfonic acid and a solution of ~5 g of NaOH in 100 ml water is
reacted, under stirring, for 15 min. at 30C and then further 60 min. at 80C.
The reaction is interrupted by cooling at room temperature.
After neutralizing with acetic acid, the water phase is dialyzed through a
3S00 Dalton cellulose acetate membrane.
The yield is 80% of the theory. The substitution degree is 0.6.
As already said above, the fluidizing activity of the inventive
agents appears to be a function of the starting polysaccharides and of the
sul~onating agent used.
It further appears that such activity also depends on the sulfona-
tion degree, i.e. the mean number of alkyl sulfonic groups per repeating unit
of the polysaccharide chain.
It has been ~ound that 0.2 is the minimum degree of sulfonation
necessary for improving the fluidi~ing activity of the used polysaccharide,
according to the instant invention.
It has further been ascertained that in order to obtain a fluid
izing agent with outstanding activity (i.e. an activity greater than what is
considered normal in the art) the degree of sulfonation must exceed l.
The sulfonation degree (also referred to herein as D.S.) of the
tested inventive sulfoalkyl polysaccharides has been determined by means of
the nuclear magnetic resonance spectroscopy ~ NMR).
The NMR spectra shown in Figure 1 correspond to a typical water
soluble starch and to its sulfoethyl derivative (D.S. ~ 0.5) as well as to its
sulfopropyl derivative (D.S. ~ 1.1). The asterisks identify signals corres-
ponding to the -Cl-12~ groups of the sulfoethyl and sulfopropyl substitutents.
These signals permit to determine the sulfonation degree by relating their area
to that of the anomeric signals (H-l).
The following Table 2 shows the dependence of the fluidizing activity
10on the degree of sulfonation.
TABLE 2
EFFECT OF THE DEGREE OF SULFONATION
D.S. FLOW (mm) INCREASE OVER THE
~ PLAIN (mm)
plain 72
0.00* 70 - 2
0.20 77 ~ 5
0.80 ~9 +17
1.1~ 139 ~67
1.35 151 ~79
1.50 165 -~93
* This corresponds to the starting material, i.e. the unsubstituted or
non-sulfoalkylated ~ater soluble starch.
The sulfonated derivatives in Table 2 have been prepared by subject-
ing a commercial water soluble starch having a polymerization degree of 80
by sulfonation with the sodium salt of chloroethylsulfonic acid, according to
the method described in Example 3.
The flow tests are performed with plastic mortars according to UNI
Standard 8020 and using a Pt 325 cement; the amount of the fluidizer added
being 0.~ of the weight of the cement.
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'7~
The data in Table 2 shows that the addition o:E 0.4% of non-
sulfoalkylated water soluble starch to mortar causes a slight decrease in
the flowability of said mortar with respect to the plain ~or non-additioned
mortar).
The fluidizing effect becomes noticeable after addition of a 0.4%
amount of an inventive superfluidizer having a D.S. value of 0.20. The
resulting effect, though, is of little interest from an industrial point of
view.
A fluidizing effect in the range of those obtainable with known
fluidizing agents is achieved by adding 0.4% of an inventive superfluidizer,
having a D.S. value of 0.80.
With the addition of 0.4% of an inventive superfluidizer having a
D.S. value of 1.10, the fluidizing effect attained is in the range of those
obtainable with cm equal amount of commercial superfluidizers.
Finally, the addition of 0.4% of an inventive superfluidizer,
having a D.S. value of at least 1.35, the fluidizing effect attained is
outstanding, i.e. much greater than the fluidizing effect achievable with an
equal amount of any known superfluidizer.
The possibility of fluidizing the mortar and concrcte mix depends
not only on the sulfonation degree but also on the amount of fluidizing agent
added thereto and is all the lower the higher is the sulfonation degree.
According to the present invention, interesting results (with
respect to flowability) are obtained with dosages between 0.1% and 0.4% (of
the weight of the hydraulic binder) and high D.S. values, i.e. greater than 1Ø
For achieving results of the same order of magnitude using
fluidizers having a medium degree of sulfonation, i.e. with D.S. values i.n the
range of from 0.8 to 1.2, the dosage of the fluidizer shall be in the range of
7~
from 0.2% to 0.6%.
When using flu:idizers having a low degree of sulfonation, i.e.
having D.S. values ranging from between 0.2 to 0.5, dosages greater than 0.6%
are needed.
In particular, when using sulfoethylated water soluble starches
(having a polymerization degree of s 100), it has been folmd that with dosages
of from 0.35% to 0.55% (of the weight of the hydraulic binder) and a D.S. value
in thearea of 0.8, the flowability of the mortar and concrete mix is of the same
order of magnitude as that achievable using known fluidizers. When the D.S.
value of said starches is in the area of 1, then the flowability of the mortar
and concrete mix is equivalent to that of a mortar and concrete mix with a
known superfluidizer. Finally, using a sulfoethylated starch of this invention
having a D.S. value in the area of 1.3, the flo~bility of the mortar and
concrete mix containing it is greater than that obtainable with any of the
known superfluidizers.
The following Table 3 outlines the results attained with a
commercial water soluble starch having a polymerization degree of ~ 100, at
increasing D.S. values, in comparison with fluidizers known in the art.
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TABLE 3
COhJPARISON OF TIIE INVENrl`IVE SU~ERFLUIDIZERS WITII KNOWN
FLUIDIZERS AND SUPERFLUIDIZERS OF TIE COh~ERCE
_ . COMPRESSIVE
FLUIDIZER FLOW (mm) STREN2GTH
(Kg/cm ) at 7 days
_ . _ _ . ... .. ~
~bsolute Referred Absolute Referred
value to plain value to plain
1- Commercial water soluble
starch sulfoethylate (of
the invention)
D.S. = 0.8 8g + 17 292 + 66
2- Raw calcium lignine sulfo-
nate liquor 85 + 13 260 t 34
_
3- sodium gluconate mother
liquor 90 + 18 253 -~ 27
_ _
4- Commercial water soluble
starch sulfoethylate (of
the invention)
D.S. = l.O 129 + 47 ?89 ~ 63
5- Sodium polynaphthalene
sulfonate 120 + 38 280 + 54
6- Sulfonated melamine resin 115 + 33 295 + 69
7- Commercial water soluble
starch sulfoethylate ~of
the invention)
D.S. = 1.30 159 + 67 267 -~ 41
,, _ . __ _
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Tlle following Table 4 outlines the superlor reduction of water
demand obtained with a commercial water soluble starch having a polymerization
degree of ~ 100 and a D.S. value of 1.25, in comparison with a commercial known
superfluidizer (polynaphthalene sulfonate).
TABLE 4
FLUIDIZER ~ W/C flow ; ~ " ~ )
Plain 225 0.5 85 260
Sulfoalkylated starch 1~4 0.43 86 358
Naphthalene sulfonate 200 0.44 86 342
According to UNI Standard 8145, the water reduction, as hereinafter
defined, obtained with the sulfoalkylated starch:
100. 225 1~4 = 14%
225
is greater than the water reduction obtained with the known superfluidizer
(polynaphthalene sulfonate):
100. 225 - 200 = 11
225
Tests summarized in Table 3 and 4 are carried out with plastic mortar, according
to UNI Standard 8020, using a Pt 325 commercial cement.
The quantity of fluidizer added to the mix is the same for all the
samples, i.e. 0.40% (referred to the weigh* of hydraulic binder).
The following Table 5 shows data obtained with concrete tests carried
out according to Italian Standards (UNI 7163), using Pt425 cement of the commerce.
: - 11-
~ABLE _
Cement type ¦ CementW/C ¦ slump Compressive strengths
dosa3gevalue (kg/cm2)
kg/m (cm) 3 days 7 days 28 d~ys
425 Portland 350 0.55 ¦ 8 230 336 400
idem + polynaph-
thalene sulfonate 350 0.44 8 388 449 590
idem ~ sulfoalkyl-
starch 350 0.44 10 368 460 605
The inventive alkylsulfonated polysaccharides are useful for making
mortar and concrete mixes containing any type of hydraulic binder such as
Portland cement and blended cements (Portland blast-furnace slag cement, Port-
land-Pozzolan or fly ash cement, slag cement). The inventive mortar or concrete
mix may contain other additives, such as hardening agents, air-entraining agents,
plasticizers, accelerators and retarders known in the art.
It is expedient to note that the hydraulic binders used for making
mortar and concrete mixes of the invention may already contain additives used
in the clinker-grinding process and/or in the hydraulic binder manufacturing
process.
The inventive superfluidizers can be incorporated into the mortar
and concrete mix by any convenient method. Thus, they can be added directly
to the mix, advantageously as a water solution.
Alternatively, the inventive fluidizers can be pre-mixed with one
or more of the ingredients of the mix. If it is pre-mixed with cement, the
fluidizer must necessarily be in the dry state.
The inventive fluidizers can also be added to the clinker during
grinding. In this case, it can be mixed with known grinding aids such as~ e.g.
alkanolamines and glycols.
~;~1'7~
Although the instant invention is advantageously applicable to the
production of any kind of mortar and concrete, this invention is particularly
clirected to the field of the additives which improve the workability of the
concrete used in civil buildings or massive buildings ~as bridges or roads),
as well as for pre-cast concrete manufacturing.
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