NL8400642A - ALKYL SULPHONATED POLYSACCHARIDES AND MORTAR AND CONCRETE MIXTURES CONTAINING THEM. - Google Patents

Description

- 1 - i i

Alkyl sulfonated polysaccharides and mortar and concrete mixtures containing them.

The invention relates to improvements in mortar and concrete mixtures.

In particular, the improvement of the invention consists of mixing mortar or concrete with a small amount of a fluidizing agent, especially alkyl sulfonated polysaccharides.

More particularly, the invention consists in improving the workability of mortar and concrete mixtures, so that very low water / cement ratios are possible.

Mortar and concrete mixtures are those mixtures of cementitious material and aggregates, defined in ASTM specifications C270 and C125, respectively.

It is known in the art that in mortar and concrete mixes the initial weight ratio of water to cement, more commonly referred to as the W / C ratio, is an important factor controlling the so-called processability of the cement mix.

The amount of water required for suitable processability is much greater than that which will be necessary for the complete hydration of the hydraulic binder used to make the mixture.

The excess water, especially in the case of high processability, can cause serious drawbacks both to the fresh mixture (excessive sweating, segregation, etc.) as well as to the cured mixture (excessive shrinkage, high porosity, lower resistance, etc.).

In order to obtain a good workability of mortar and concrete mixtures with lower W / c ratios, special materials have long been proposed, and a number of them have acquired commercial importance.

8400642 - 2 - ί #

Usually such materials are referred to as fluidizing agents. According to the Italian Standard for Materials Testing (UNI), these materials are more particularly grouped into two classes, ie, fluidizing agents and superfluidizing agents. When the agent in standard plastic mortars allows a water decrease of not more than 6% (i.e. V - v 100 - = 6% '

10 R

where V is the water volume of the reference mixture and V is the Λ Ά water volume, including the fluidizing agent, of the fluidizing agent containing mixture), the material is defined as UNI standard 7102-72 as fluidizing agent.

On the other hand, when said material allows a water decrease of not less than 10% (i.e.

V - V

R A

ïoo —-—— = ίο%

R

where V is the water volume of the reference mixture and 20 R.

V the water volume, including of the fluidizing agent, of the fluidizing agent-containing mixture), the material according to UNI standard 8145 is defined as a super-fluidizing agent. Fluidizing and super-fluidizing agents, as defined above, meet requirements for Type A. and type F concrete mixes specified in ASTM C 494 - 80.

Known useful fluidizing agents are lignin sulfonate, gluconates and tannates.

Some known industrial carbohydrates, such as, for example, glucose syrups (see US Pat. No. 3,432,317) and modified starch hydrolyzates (see Applicants Italian Patent Application 21680 A / 80 filed April 28, 1980), are commonly used in cement mixes both to improve the rhe o Logical properties of the blends such as 8400642 'i - 3 - for improving their mechanical strength. However, their water reducing ability is limited and much worse than that of the superfluidizing agents.

has

Industrial ƒ the use of superfluidic-5 preservatives only gained importance in the last five years or so.

Known superfluidizing agents are prepared from polynaphthalene sulfonates (see, for example, U.S. Patent 2141569, German Patent No. 1238831 and Canadian Patent 993901} and from sulfonated melamine resins (see, for example, Italian Patent 801078).

It has now been found that by sulfonating polysaccharides with suitable sulfonating agents, excellent superfluidizing agents with superior properties can be obtained with respect to all known fluidizing and superfluidizing agents.

F

The alkyl sulfonated polysaccharide superfluidizing agents of the invention are characterized by a degree of polymerization (D.P.) to 100 and a degree of sulfonation (D.S.), as defined and determined below, of 0.2-3.0.

They can be further characterized by their fluidization activity, in that the addition of 0.4% of the inventive fluidizing agent is capable of imparting a flow increase of 6.5-130% to the mortar to which it is added. when the DS is in the range of 0.20-1.50.

Illustrative examples of useful polysaccharides for preparing the inventive superfluidizing agents are, for example, cellulose, hemicellulose, starches and hydrolysates thereof.

Illustrative examples of sulfonating agents for preparing the inventive superfluidizing agents are, for example, chloromethyl sulfonic acid, chloroethane sulfonic acid, chloropropane sulfonic acid, and 1,3-propane sulfone.

The preferred inventive superfluidizing agents are those prepared from hydrolysed cellulose sulfonated 8400642. t-4 - with chloromethane or chloroethanesulfonic acid.

Superfluidizing agents prepared from wood pulp sulfonated with chloropropane sulfonic acid as well as hydrolyzed starches sulfonated with chloroethane or chloropropane sulfonic acid are even more preferred.

Today, the most preferred inventive superfluidizing agents obtained from water-soluble starch hydroisates having a degree of polymerization equal to or less than 100 and chloroethanesulfonic acid as sulfonating agent.

It appears that the fluidization activity of the inventive agents is a function of the starting polysaccharides and of the sulfonating agents used.

This claim is supported by the data shown in the following table.

TABLE · A

Flow Tests 20 Fluidizing Agent Dosages (b) Flow (mm) __ vs. Blank 1) Hemicellulose 0.6 +12 Sulfopropylate (a) 1.5 +24 2) Starch 0.3 +24 Sulfopropylate (a) 0.5 +35 25 3 Soluble starch 0.3 +24 solfoethylate (a) 0.5 +50 (a) prepared as in Examples 1, 2 and 3, respectively.

(b) dosages expressed as percent (dry to dry) of the amount of cement in the mixture.

As shown in Table A, the fluidizing agents prepared from water-soluble starches with a polymerization degree of up to 100 and chloroethanesulfonic acid give the best results, never before achieved with any known fluidizing or super-fluidizing agent. The flow tests of Table A.

8400642 ~ A> - 5 - were done with plastic mortars of the Italian standard ΌΝΙ 8020, using Pt 325 cement (commonly used in industry).

The sulfonate groups of the inventive fluidizing agents can be either in the free acid form or in the salt form with a group IA and IIA metal cation, preferably sodium, potassium or calcium. Other useful cations can be selected from ammonium or the organic amines.

When the cation is derived from an organic amine, it can be any suitable primary, secondary or tertiary amine, such as, for example, amines containing a hydroxyl group. Primary, secondary and tertiary alkanolamines are preferred.

The inventive superfluidizing agents are readily prepared by methods known per se.

The following examples are illustrative of the inventive super-fluidizing agents, the way to make them as well as the way to use them in mortar and concrete mixes, 20

Example 1

Hemicellulose sulfopropylate

To 100 g of a hemicellose, which is slightly soluble in water at room temperature, and is suspended in 300 ml of water, containing 75 g of NaOH, 450 g of 1,3-propane-sulfone are added and reacted at 50 for 16 hours ° C with stirring. The reaction mixture is then left to stand at room temperature for 48 hours. The pH is then adjusted to 4 with 2 N sodium hydroxide and the title product is precipitated with methyl alcohol.

30 Yield 80%. Degree of substitution 0.9.

Example II Starch sulfopropylate

To 80 g of starch, which is insoluble in 8400642 µl of v-6 water at room temperature, and suspended in 250 ml of water containing 60 g of NaOH, 350 g of 1,3-propane sulfone are added and reacted for 16 hours at 50 ° C with stirring.

The reaction mixture is then allowed to stand at room temperature for 48 hours and the pH is adjusted to 4 with 2N

I. NaOH. Finally, the title product is separated from the reaction mixture by precipitation with a 2.5: 1.5 methanol / acetone mixture. called

Then: /. product in water and dialyzed through a 3500 Dalton cellulose acetate membrane. Yield 45%.

10 Substitution degree 1.1.

Example III

Water-soluble starch sulfoethylate.

To 100 g of starch, which readily dissolves in water at room temperature, and is suspended in 1000 ml of isopropyl alcohol, 175 g of the sodium salt of 2-chloroethanesulfonic acid · water and a solution of 95 g of NaOH in 100 ml / are added and reacted. with stirring at 30 ° C for 15 minutes and then at 80 ° G for another 60 minutes. The reaction is stopped by cooling to room temperature.

After neutralization with acetic acid, the hydrogen phase is dialyzed through a 3500 Dalton cellulose acetate membrane. Yield 80%. Degree of substitution 0.6.

As stated above, the fluidization activity of the inventive agents appears to be a function of the starting polysaccharides and of the sulfonating agent used. Furthermore, it appears that such activity also depends on the degree of sulfonation, ie the average number of alkyl sulfonic acid groups per repeating unit of the polysaccharide chain.

It has been found that 0.2 is the minimum degree of sulfonation needed to improve the fluidization activity of the used polysaccharide of the invention. Further, 8400642, -7 - has been determined / that in order to obtain a fluidizing agent with excellent activity (ie an activity greater than what is considered normal in the art) the sulfonation degree must be more than one.

The degree of sulfonation (D.S.) of the tested inventive sulfoalkyl polysaccharides was determined by nuclear magnetic resonance spectroscopy (¾-NMR).

The NMR spectra shown in Figure 1 correspond to a typical water-soluble starch and its sulfoethyl-10 derivative (DS = 0.5} as well as its sulfopropyl derivative (DS = 1.1). The asterisks identify signals, which correspond with the -Cl 2 groups of the sulfoethyl and sulfopropyl substitution These signals are able to determine the degree of sulfonation by relating their area to that of the 15 anomeric signals (HI).

The following Table B shows the dependence of the fluidization activity on the degree of sulfonation.

I'ABEL B

20 Effect of the sulphonation degree DS Flow (mm) Increase compared to blank _ _ _ (mm) _ 72 25 0.001 70 - 2 0.20 77 +5 0.80 89 +17 1.10 139 +67 1.35 151 +79 3Q 1.50 165 +93 8400642

It corresponds to the starting material, i.e. the unsubstituted or unsulfoalkylated water-soluble starch.

The sulfonated derivatives in Table B are prepared by subjecting a commercial water-soluble starch having a polymerization degree of 80 to sulfonation with the sodium salt of chloroethyl sulfonic acid according to the method described in Example III.

The flow tests were carried out with plastic mortars according to UNI standard 8020 and using a Pt 325 cement; the amount of fluidizing agent added is 0.4% by weight of the cement.

The data of Table B show that the addition of 0.4% non-sulfoalkylated water-soluble starch to mortar causes a slight decrease in flowability of said mortar with respect to the blank (mortar to which nothing has been added).

The fluidization effect becomes noticeable after adding a 0.4% amount of an inventive superfluidizing agent with a D.S. value of 0.20. The effect obtained is therefore of little importance from an industrial point of view.

A fluidization effect in the range of those obtainable with known fluidizing agents is obtained by adding 0.4% of an inventive superfluidizing agent with a D.S. value of 0.80.

When adding 0.4% of an inventive superfluidizing agent with a D.S. of 1.10, the fluidization effect is in the range of that, achievable with an equal amount of commercial fluidizing agents.

Finally, when adding 0.4% of an inventive superfluidizing agent with a DS value of at least 1.35, the fluidization effect to be achieved is excellent, i.e. much greater than the fluidization effect, which is achievable by an equal amount to that known super fluidizing agent.

The possibility of fluidizing the mortar and concrete mixture depends not only on the degree of sulfonation but also on the amount of fluidizing agent added to it 4 8 0 0 6 4 2 - 9 - and the lower the degree of sulfonation being higher .

According to the invention, important results (with respect to flowability) are obtained at 5 dosages between 0.1-0.4% (by weight of the hydraulic binder) and higher D.S. values, i.e. more than 1.0.

To obtain results of the same magnitude using medium sulfonation degree fluidizing agents, i.e., with DS values 10 in the range 0.8-1.2, the fluidizing agent dosage should be in the range 0 , 2-0.6% lie.

When using low sulfonation fluidizers, i.e., with D.S. values between 0.2-0.5, dosages greater than 0.6% are required.

When using sulfoethylated water-soluble starches (with a degree of polymerization less than or equal to 100), it has been found in particular that at dosages of 0.35-0.55% (by weight of the hydraulic binder) and a DS value in the range of 0.8, the flowability of the mortar and concrete mixture is of the same order of magnitude as that comparable by known fluidizing agents. When the D.S. value of said starches is in the range of 1, the flowability of the mortar and concrete mixture is equivalent to that of a mortar and concrete mixture with a coated super-fluidizing agent. Finally, when using a sulfoethylated agent of the invention having a D.S. value in the range of 1.3, the flowability of the mortar and concrete mixture containing it is greater than that obtained with any of the known superfluidizing agents.

The following Table C shows results achievable with a commercial water-soluble starch having a degree of polymerization less than or equal to 100, with increasing D.S. values, compared to known fluidizing agents.

8400642 - 10 -

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The following Table D shows the superior decrease in water requirement obtained with a commercial water-soluble starch with a degree of polymerization less than or equal to 100 and a DS value of 1.25 compared to a commercially known superfluidizing agent (polynaphthalene sulfonate).

TABLE · D

10 Fluidizing agent ml w / C Flow Compressive strength after __water___7 days (kg / cm2)

Blank 225 0.5 85 260

Sulphoalkylated starch 194 0.43 86 358

Naphthalene sulfonate 200 0.44 86 342 15 __L_J___

According to UNI standard 8145, the water decrease, defined as 100. 225 194 = 14% 225, obtained with the sulfoalkylated starch is greater than that obtained with the known superfluidizing agent (polynaphthalene sulfonate), which is 100. 225 - 200 = 11% .

225 25

The tests are summarized in Tables C and D.

are made with plastic mortars according to üNI standard 8020 using a Pt 325 cement.

The amount of fluidizing agent added to the mixture is the same for all samples, that is, 30

Say 0.40% (relative to the weight of hydraulic binder).

The following Table E shows data obtained with concrete tests conducted according to the Italian standard DNI 7163 using commercial Pt 425 cement.

8400642 - 12 -

TABLE E

Cement type Cement W / C ZcSkings Compressive strength dosage value (kg / cm2) ___ kg / cm3 ___ (cm) 3 days 7 days 28 days 425 Portland 350 0.55 8 230 336 400 idem + polynaphthalene sulfonate 350 0.44 8 388 449 590 idem + sulfoalkyl starch 350 0.44 10 368 460 605

The inventive alkyl sulfonated polysaccharides are useful for making mortar and concrete mixes, which can contain any type of hydraulic binder such as Portland. cement and mixed cement (Portland blast furnace 5 slag cement, Portland-Pozzolan or fly cement, slag cement). The inventive mortar or concrete mixes may contain other additives, such as hardeners, air entrains, plasticizers, accelerators and retarders, which are known in the art.

It can be noted that the hydraulic binders used for making mortar and concrete mixtures according to the invention may already contain additives that are used in the clinker grinding process and / or in the hydraulic binder manufacturing process.

The inventive superfluidizing agents can be incorporated into the mortar and concrete mixtures in any suitable manner.

They can thus be added directly to the mixture, advantageously as an aqueous solution.

Alternatively, the inventive fluidizers can be premixed with one or more of the ingredients of the mixture. In the event that . it is premixed with cement, the fluidizing agent must necessarily be in the dry state.

8400542 - 13 -

The inventive fluidizing agents can also be added to the clinker during grinding. In this case, it can be mixed with known grinding agents such as, for example, alkanolamines and glycols.

Although the invention can be used advantageously for the production of any type of mortar or concrete, the invention is particularly directed to the field of additives, which use the workability of the concrete in civilian houses or solid structures (such as bridges or weighing) 10. improve as well as for precast concrete fabrication.

8400642

Claims (15)

Superfluidizing agent for mortar or concrete, characterized in that it contains an alkyl sulfonated polysaccharide with a degree of polymerization of up to 100 and a sulfonation degree of 0.2-3.0. 5 Superfluidizing agent according to claim 1, characterized in that said sulfonation degree is 0.2-1.5. Superfluidizing agent according to claim 1, 10, characterized in that said alkyl sulfonated polysaccharide is an alkyl sulfonated cellulose, hemicellulose, hydrolysed cellulose, wood pulp or starch. A superfluidizing agent according to claim 1, characterized in that said alkyl sulfonated polysaccharide is an alkyl sulfonated water soluble starch. Superfluidizing agent according to claim 4, characterized in that said alkyl sulfonated water-soluble starch has been prepared by a process consisting of alkyl sulfonation of a water-soluble starch with chloroethanesulfonic acid. Super-fluidizing agent according to claim 4, characterized in that said sulfonation degree is about 1.3 or more. 7. Hydraulic cementitious composition, characterized in that it contains a hydraulic cement binder and an alkyl sulfonated polysaccharide with a degree of polymerization of up to 100 and a sulfonation degree of 0.3-3.0. 8400642 - 15 - A composition according to claim 7, characterized in that said alkyl sulfonated polysaccharide is present / an amount of 0.1-1.4% by weight of said binder and ". said degree of sulfonation is more than 1.0. 9. A composition according to claim 7, characterized in that said alkyl sulfonated polysaccharide is present in an amount of 0.2-0.6% by weight of said binder and said sulfonation degree is 0.8-1.2. 10. A composition according to claim 7, characterized in that said alkyl sulfonated polysaccharide is present in an amount of more than 0.6% of said binder and said sulfonation degree is 0.2-0.5. Composition according to claim 7, characterized in that said alkyl sulfonated polysaccharide is an alkyl sulfonated water soluble starch. 20 A composition according to claim 11, characterized in that said alkyl sulfonated polysaccharide is a sulfogethylated water soluble starch present in an amount of 0.35-0.55 wt% of said hydraulic binder and said sulfonation degree 0.8 -1.3. 25 13. A method of increasing the flowability of a mortar or concrete mixture containing a hydraulic cement binder, characterized in that in said mixture approximately 0.1-1.0% by weight, based on the weight of 30 said binder, to an alkyl sulfonated polysaccharide, with a polymerization degree of up to 100 and a sulfonation degree of 0.2-3.0. 8400642 «- 16 - A method according to claim 13, characterized in that said sulfonation degree is 0.2-1.5. A method according to claim 13, 5, characterized in that said alkyl sulfonated polysaccharide is a sulfogethylated water soluble starch incorporated in said mixture in an amount of 0.35-0.55 wt% of said binder and a sulfonation degree has 0.8-1.3. 8400642 T