WO2019228882A1 - Method for plasticizing belite-calcium-sulfoalluminate-ferrite-containing cements - Google Patents

Abstract

The invention relates to a method for plasticizing a composition which comprises a belite-calcium-sulfoalluminate-ferrite cement by adding at least one polymeric dispersant, the composition comprising a product for reducing secondary plasticizing effects.

Description

 METHOD FOR LIQUIDING BELITECALIUM SULFUTALUMINATE-FERRITE-CONTAINING CEMENT

Technical area

 The invention relates to a process for the liquefaction of compositions containing belite-calcium sulfoaluminate-ferrite cement.

State of the art

 Dispersants or flow agents are used in the construction industry as liquefiers or water-reducing agents for cementitious compositions, e.g. Concrete, mortar and cement. The dispersants are generally organic polymers which are added to the make-up water or added as a solid to a dry cementitious composition. As a result, both the consistency of the composition during processing and the properties in the cured state can be advantageously changed.

 Particularly effective dispersants are, for example, polycarboxylate-based comb polymers. Such comb polymers have a polymer backbone and side chains attached thereto. Corresponding polymers are e.g. in EP 1 138 697.

The cements used in the construction industry typically contain

Portland cement or cement based on Portland cement, as they are

For example, be described in DIN EN 197-1.

 The production of Portland cement clinker requires high temperatures and releases large amounts of CO2, on the one hand from the combustion of

Heating material but also to a large extent from the decarboxylation of the necessary as raw material calcium carbonate. It is therefore the cement manufacturers' ambition to provide alternative cements that generate less CO2 during production.

One of these alternatives is belite-rich cements, such as typically belite-calcium sulfoaluminate-ferrite cement (BCSAF cement). The production of these cement clinker requires less high temperature and less calcium carbonate, which means an ecological advantage over Portland cement. to

Production of cement, the clinker is ground. Because the ground BCSAF clinker sets and / or stiffens very rapidly with water, an appropriate amount of calcium sulfate and retarders, such as boric acid or borax, are typically still added to the clinker during milling or after milling

admixed. As a result, similar processing properties and strengths as with Portland cement can be achieved.

However, such BCSAF cements, especially if they have a

Retarders, such as boric acid or borax, in combination with condensers, often have a different behavior compared to

Portland cements. Concrete or mortar mixtures with BCSAF cement often have a strong secondary liquefaction when a superplasticizer is used, even if this superplasticizer in Portland cement little or no

After-liquefaction shows. Post-liquefaction means that the flowability of the mixture increases from the time of mixing with water to 30 or 60 or more minutes after mixing and is significantly higher than directly after mixing with water. Such post-liquefaction is very undesirable in mortar and concrete works, especially in ready-mixed concrete, because the properties of the mixture are not constant and predictable. A

Re-liquefaction is significantly worse than a stiffening of the mixture. In a stiffening of the mixture, the fluidity decreases over time. The flowability can be improved again by adding water and / or further condenser. In the case of mixtures which tend to undergo secondary liquefaction, too much water is typically added during production because initially the processability of the mixture is lower. If the processability then increases due to a post-liquefaction after some time, for example during transport, this can lead to sedimentation and bleeding, but this is bad for the concrete quality. Since the concrete then also contains too much water, this leads to a lower strength of the mixture after curing.

This difficulty in being able to adjust the processability reproducibly represents a major disadvantage and can significantly reduce the acceptance and use of the new, ecologically advantageous cements. There is therefore a need for a process for the liquefaction of

Compositions containing BCSAF cement, which reduces or prevents the re-liquefaction.

Presentation of the invention

 It is therefore an object of the present invention to provide an improved process for liquefying a cementitious composition containing belite-calcium sulfoaluminate-ferrite cement (BCSAF cement).

In particular, this composition should have no or only a very small secondary liquefaction.

Surprisingly, this object is achieved by a method as described in claim 1.

 The addition of the post-condensation reducing agent causes a mortar or concrete made with BCSAF cement, particularly a BCSAF cement, containing a retarder, such as boric acid or borax, or mixed with the retarder and a superplasticizer , no or very little after-liquefaction has.

 The use of too much water in the concrete or

Mortar making and the associated problems such as bad

Flomogeneity, sedimentation, bleeding of the mixture and decreased

Compressive strength, thereby avoided. The with BCSAF cement and

Superplasticizer produced concrete or mortar thereby typically has comparable processing properties as a concrete or mortar made with Portland cement and superplasticizer.

The process is cost effective and can increase the acceptance of the new cements in the construction industry, which is highly desirable from an environmental point of view. The process can save costs for the development of new condenser for BCSAF cement, and in concrete plants, the same condenser can be used for Portland cement and BCSAF cement, reducing storage costs and logistics costs. Further aspects of the invention are the subject of further independent

Claims. Particularly preferred embodiments of the invention are

Subject of the dependent claims.

Ways to carry out the invention

 The invention relates to a process for liquefying a composition comprising a belit-calcium sulfoaluminate-ferrite cement by adding at least one polymeric dispersant, wherein the composition comprises a means for reducing the secondary liquefaction.

Belit-calcium sulfoaluminate-ferrite cement (BCSAF cement) is understood to mean a cement obtained by milling belite-calcium sulfoaluminate-ferrite clinker (BCSAF clinker), optionally with the addition of further additives.

Another name for Belit-calcium sulfoaluminate-ferrite clinker is also Belit-Ye'el imit-ferrite clinker (BYF clinker). Accordingly, the cement is also called BYF cement.

The BCSAF clinker is a clinker which is preferably composed of at least 50% by weight, in particular at least 80% by weight, in particular at least 90% by weight, of the mineral phases belite (dicalcium silicate), calcium sulfoaluminate and calcium aluminoferritite.

The BCSAF cement typically contains calcium sulfate to control setting. Typically, the proportion of calcium sulfate in the BCSAF cement is up to 40% by weight. The calcium sulfate is typically calcium sulfate hemihydrate, calcium sulfate dihydrate or anhydrite.

Often, when mixed with water, BCSAF cements quickly stiffen and can not or only poorly be processed. Therefore, typically a

Retarder added to ensure good processability. Especially in applications where a BCSAF cement containing calcium sulfate and a retarder is used, the process of the invention is very effective in reducing or preventing post-liquefaction when using a polymeric dispersant.

The process according to the invention is preferably used for a belite-calcium sulfoaluminate-ferrite cement comprising ground belite-calcium sulfoaluminate-ferrite clinker, calcium sulfate and a retarder.

Preferably, the retarder comprises at least one substance which reduces the pFI of a slurry of a milled belite-calcium sulfoaluminate-ferrite clinker in water. In particular, the retarder is boric acid or borax. The proportion of the retarder in the BCSAF cement is

typically at 0.01 to 3% by weight, preferably 0.05 to 2.5% by weight, in particular 0.1 to 2% by weight, based on BCSAF clinker.

Preferably, the means for reducing the secondary liquefaction comprises at least one compound selected from the group comprising water-soluble calcium salts, water-soluble magnesium salts, calcium hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide, lithium hydroxide, sodium hydroxide and

Potassium hydroxide.

 Here, the water-soluble calcium or magnesium salt is advantageously used together with an alkaline compound, in particular an alkaline earth or alkali metal hydroxide.

 Preferably, the means for reducing the Nachverflüssigung comprises

Calcium hydroxide, calcium oxide and / or alkali metal hydroxide.

 Preferably, the means for reducing the Nachverflüssigung comprises

Calcium hydroxide. Calcium hydroxide is easier to handle than calcium oxide and less violent when in contact with water. Particularly advantageously, the means for reducing the secondary liquefaction comprises calcium hydroxide and / or calcium oxide and at least one alkali metal hydroxide, in particular sodium hydroxide. Such a combination is particularly effective for suppressing the

Nachverflüssigung.

Preferably, the means for reducing the Nachverflüssigung in 0.05 to 5

% By weight, more preferably 0.08 to 3% by weight, especially 0.1 to 2% by weight, in particular 0.15 to 1% by weight, based on the weight of the milled belite-calcium sulfoaluminate-ferrite clinker, present in the composition.

 In particular, the redilution reducing agent is present in addition to possible alkali or alkaline earth hydroxides or oxides used for possible neutralization of the polymeric dispersant.

The means for reducing the secondary liquefaction is preferably present in the BCSAF cement.

 The means for reducing the Nachverflüssigung but can also

Composition may be added separately from the cement, in particular in or together with the polymeric dispersant.

 In a preferred embodiment, the means for reducing the

After liquefaction in the polymeric dispersant, wherein this mixture may be present as a powder or as an aqueous solution.

Preferably, the polymeric dispersant comprises an anionic polymer comprising -COOM, -SO2-OM, -O-PO (OM) 2 and / or -PO (OM) 2 groups, wherein M, each independently, is FT, alkali metal ion, alkaline earth metal ion, divalent or trivalent metal ion, ammonium ion or an organic ammonium group.

Suitable anionic polymers are, for example, in the concrete technology known condenser or superplasticizer such as in particular lignosulfonates, sulfonated naphthalene-formaldehyde condensates, sulfonated melamine-formaldehyde aldehyde condensates, sulfonated vinyl copolymers, polyalkylene glycols with

Phosphonate groups, polyalkylene glycols with phosphate groups, polycarboxylates or comb polymers having anionic groups on the polymer backbone and

Polyalkylene glycol side chains.

The polymeric dispersant preferably comprises a comb polymer comprising anionic groups on the polymer backbone and polyalkylene glycol side chains, the molar ratio of anionic groups to polyalkylene glycol side chains preferably being 0.7-15: 1, more preferably 1-6: 1, in particular 1-4. 1, is. The comb polymer preferably comprises structural units of the formula I.

and structural units of the formula II

wobei

in which

R ¹ , each independently of one another, is -COOM, -SO 2 -OM, -O-PO (O) 2 and / or -PO (OM) 2, preferably -COOM,

R ² and R ⁵ , each independently, is Fl, -CFI 2 -COOM or a

Alkyl group having 1 to 5 carbon atoms,

R ³ and R ⁶ , each independently of one another, are Fl or an alkyl group having 1 to 5 carbon atoms,

R ⁴ and R ⁷ , each independently of one another, are Fl, -COOM or an alkyl group having 1 to 5 carbon atoms,

or where R ¹ forms a ring with R ⁴ to give -CO-O-CO- (anhydride),

M, each independently, for FT, alkali metal ion, alkaline earth metal ion, two or trivalent metal ion, ammonium ion or an organic

Ammonium group stands,

p = 0, 1 or 2,

o = 0 or 1,

m = 0 or an integer from 1 to 4,

n = 2-250, especially 10-200,

 X, in each case independently of one another, represents -O- or -NH-,

R ⁸ , each independently, is H, a C 1 to C 20 alkyl group, cyclohexyl group or alkylaryl group, and

A is C 2 to C 4 alkylene.

Preferably, the polymeric dispersant comprises a comb polymer comprising carboxylate groups and polyethylene glycol side chains.

 In particular, the polymeric dispersant is a comb polymer composed of structural units I derived from ethylenically unsaturated

Carboxylic acids, in particular monocarboxylic acids, or salts thereof, and structural units II derived from ethylenically unsaturated

Polyalkylene glycols, in particular polyethylene glycols, are. The comb polymer preferably contains no further structural units otherwise.

Preferably, the weight average molecular weight M w of the comb polymer, measured against polyethylene glycol standards at pH 12, between 8Ό00 and 200Ό00 g / mol, more preferably between 10Ό00 and 150Ό00 g / mol, in particular between 12Ό00 and 130Ό00 g / mol, in particular between 15Ό00 and 80Ό00 g / mol.

The comb polymer is advantageously prepared by free radical copolymerization of monomers containing acid groups and monomers containing polyether chains. Corresponding polymers are described, for example, in EP 2 522 680.

 Likewise advantageously, the comb polymer by polymer-analogous esterification and / or amidation of polymers containing carboxyl groups with

Polyethers having at one end a hydroxyl group or an amino group have to be produced. Corresponding polymers are described, for example, in EP 1 138 697.

 Also advantageously, the comb polymer is a block or gradient polymer. Such polymers are typically obtained by living radical polymerization. Corresponding polymers are described, for example, in WO 2015/144886 and in WO 2017/050907.

Preferably, the polymeric dispersant is present in 0.04 to 2.5% by weight, calculated as a solid by weight of the belite-calcium sulfoaluminate-ferrite cement.

Another aspect of the present invention relates to the use of a polymeric dispersant for liquefying a composition

comprising a belite-calcium sulfoaluminate-ferrite cement, the composition comprising a means for reducing the after-liquefaction.

 The polymeric dispersant may be added to the composition as a powder or as an aqueous solution.

Another aspect of the present invention relates to a composition comprising

 a milled belite-calcium sulfoaluminate-ferrite clinker,

 Calcium sulfate,

 a retarder, in particular comprising boric acid or borax,

 - A means for reducing the secondary liquefaction, in particular comprising

Calcium hydroxide and / or calcium oxide and

 a polymeric dispersant, in particular a comb polymer comprising carboxylate groups and polyethylene glycol side chains.

Preferred is a composition comprising

 a milled belite-calcium sulfoaluminate-ferrite clinker (BCSAF clinker),

Calcium sulfate,

0.01 to 3% by weight, based on the weight of the BCSAF clinker, of a retarder, 0.05 to 5% by weight, based on the weight of the BCSAF clinker, of a composition for the reduction of the secondary liquefaction, in particular comprising

Calcium hydroxide and / or calcium oxide, and

 0.04 to 2.5% by weight, based on the weight of the BCSAF clinker, of a polymeric dispersant.

Here, the ingredients and their proportions of the composition are as previously described for the process.

In addition to the constituents mentioned, the composition may also contain additives, additives or additives. Such additives are known in the art.

 Suitable aggregates are in principle all sands, gravel and stones that are commonly used for concrete and mortar.

 Suitable additives are, in particular, fly ash, flash sand, metakaolin, silica fume, quartz flour, fine calcium carbonate and / or inert rock flour. Suitable additives are in particular further dispersants, defoamers, wetting agents, dyes, preservatives, flow agents, retarders,

Accelerators, film-forming polymers, air-entraining agents, rheology aids, viscosity modifiers, pumping aids, pigments, shrinkage reducers or corrosion inhibitors.

Another aspect of the present invention relates to a composition comprising a belite-calcium sulfoaluminate ferrite cement, a polymeric dispersing agent, a post-liquefaction reducing agent and water, wherein the belite-calcium sulfoaluminate-ferrite cement is a milled belite-calcium sulfoaluminate-ferrite clinker , Calcium sulfate and a retarder. Typically, such a composition is prepared for use by mixing the dry ingredients with water.

The composition of the invention is very suitable for the

Production of concrete or mortar with predictable flow behavior, in particular without strong secondary liquefaction. An additional aspect of the present invention relates to a

Shaped body, in particular a building or a part of a building, obtainable by curing the composition with water.

 A building can e.g. a bridge, a building, a tunnel, a lane, or a runway.

From the following embodiments, further advantageous embodiments of the invention result.

Examples

 In the following, exemplary embodiments are listed which are intended to explain the described invention in more detail. Of course, the invention is not limited to these described embodiments.

 "Ref." stands for "reference example"

 "Ex." stands for "inventive example"

 "W / Z" stands for water-cement value and indicates the weight ratio of water to cement.

1. Used materials

 BCSAF cement: BCSAF cement containing 4% by weight of anhydrite and 0.36% by weight of boric acid.

 Condenser V1: 30% by weight solution of a comb polymer composed of structural units a) derived from acrylic acid and structural units b) the side chains of polyethylene glycol (average molecular weight of

Polyethylene glycol chain about 2,500 g / mol), with a molar ratio of carboxylic acid groups to polyether chains of 2.3 and a middle

Molecular weight Mw of 28Ό00 g / mol. 2. Mortar mixtures

2.1 Production

 The mortar mixture used for test purposes has the in Table 1

described dry composition on.

Table 1

For making a mortar mix, the sands, the limestone filler and the cement, as well as the additives given in Table 2 and Table 3 were used

Calcium hydroxide (Ca (OH) 2), calcium oxide (CaO) and / or sodium hydroxide (NaOH), mixed for one minute in a Hobart mixer. Within 30 seconds, the mixing water, to which previously 4.5 g of liquefier V1 had been added, was added and mixed for a further 2.5 minutes. The total mixing time wet took 3 minutes each. 2.2 Determination of the spread

 To determine the dispersing behavior of the polymers, in each case the slump of prepared mortar mixtures was measured at different times. The slump of the mortar was determined according to DIN-EN 1015-3. Before each measurement, the mortar mix was mixed for 15 seconds with the Hobart mixer.

3. Results of the mortar tests

Ao is the slump measured in mm immediately after mixing with water, AQO is the slump measured in mm 60 minutes after mixing with water. Table 2 shows the type and amount of added additives in the mortar tests with W / Z = 0.57 and the results obtained. Table 2

Table 3 shows the type and amount of added additives in the mortar tests with a W / Z = 0.46 and the results obtained. Table 3

^* as a 50% by weight solution

4. Test with Portland cement CEM I

The mortar test was repeated with the composition of the dry mortar as indicated in Table 1, but Portland cement CEM I 42.5 was used instead of BCSAF cement in the mortar mix. For mixing, water (W / Z = 0.45) and 4.5 g of liquefier V1 were added to the mortar. The results of the mortar test are given in Table 4.

Table 4

Claims

claims: A process for liquefying a composition comprising a belite-calcium sulfoaluminate-ferrite cement by adding at least one polymeric dispersant, said composition comprising a means for reducing post-liquefaction. 2. The method according to claim 1, characterized in that the Belit- calcium sulfoaluminate-ferrite cement comprises milled Belit-calcium sulfoaluminate ferrite clinker, calcium sulfate and a retarder. A process according to claim 2, characterized in that the retarder comprises at least one substance which reduces the pFI value of a slurry of a milled belite-calcium sulfoaluminate-ferrite clinker in water, in particular boric acid. 4. The method according to any one of the preceding claims, characterized  in that the means for reducing the secondary liquefaction comprise at least one compound selected from the group comprising water-soluble calcium salts, water-soluble magnesium salts,  Calcium hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide,  Lithium hydroxide, sodium hydroxide and potassium hydroxide. 5. The method according to claim 4, characterized in that the means for reducing the secondary liquefaction comprises calcium hydroxide, calcium oxide and / or alkali metal hydroxide. 6. The method according to claim 5, characterized in that the means for reducing the secondary liquefaction calcium hydroxide and / or calcium oxide and at least one alkali metal hydroxide, in particular sodium hydroxide comprises. 7. The method according to any one of the preceding claims, characterized characterized in that the means for reducing the post-liquefaction in 0.05 to 5% by weight, preferably 0.08 to 3% by weight, in particular 0.1 to 2% by weight, in particular 0.15 to 1% by weight, based on the weight of the milled belite-calcium sulfoaluminate-ferrite clinker. 8. The method according to any one of the preceding claims, characterized in that the polymeric dispersant comprises an anionic polymer comprising -COOM, -SO2-OM, -O-P0 (O) 2 and / or -PO (OM) 2 groups, wherein M, independently of one another, represents H ⁺ , alkali metal ion , Alkaline earth metal ion, divalent or trivalent metal ion, ammonium ion or a  organic ammonium group is. 9. The method according to claim 8, characterized in that the polymeric dispersant is a comb polymer comprising anionic groups on  Polymer backbone and polyalkylene oxide side chains, wherein the molar ratio of anionic groups to polyalkylene glycol side chains is preferably from 0.7 to 15: 1, more preferably from 1 to 6: 1, especially from 1 to 4: 1. 10. The method according to claim 9, characterized in that the polymeric dispersant is a comb polymer comprising carboxylate groups and  Polyethylene glycol side chains includes. 11.Verfahren according to any one of the preceding claims, characterized  characterized in that the polymeric dispersant is present in 0.04 to 2.5% by weight, calculated as a solid on the weight of the belite-calcium sulfoaluminate-ferrite cement. 12. Use of a polymeric dispersant for the liquefaction of a A composition comprising a belite-calcium sulfoaluminate-ferrite cement, said composition comprising a means for reducing post-liquefaction. 13. Composition comprising  a milled belite-calcium sulfoaluminate-ferrite clinker,  Calcium sulfate,  - a retarder,  a means of reducing secondary liquefaction and  a polymeric dispersant. 14. The composition according to claim 13 additionally comprising water. 15. Shaped body, in particular a building or a part of a building, obtainable by curing a composition according to any one of claims 13 and 14 with water.