Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators or shrinkage compensating agents
  • C04B22/08—Acids or salts thereof
  • C04B22/14—Acids or salts thereof containing sulfur in the anion, e.g. sulfides
  • C04B22/142—Sulfates
  • C04B22/143—Calcium-sulfate
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators or shrinkage compensating agents
  • C04B22/08—Acids or salts thereof
  • C04B22/10—Acids or salts thereof containing carbon in the anion, e.g. carbonates
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
  • C04B28/04—Portland cements
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B7/00—Hydraulic cements
  • C04B7/02—Portland cement
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/10—Compositions or ingredients thereof characterised by the absence or the very low content of a specific material
  • C04B2111/1018—Gypsum free or very low gypsum content cement compositions
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

• the invention relates to a method for producing a hydraulic binder for use in a mortar or concrete mixture, the properties of which, such as workability, setting time, early and / or long-term strength, can be adjusted by means of additives, the binder being at least soluble salts as strength-increasing additives which contains carbonic acid.
• the invention further relates to a hydraulic binder for the production of concrete with a high early and long-term stability, bctsi reriu on a milled stone with essentially homogeneously distributed calcium sulfate phases and additives for adjusting the processability, setting time and early - and long-term strength.
• a hydraulic binder for the production of concrete with a high early and long-term stability, bctsi reriu on a milled stone with essentially homogeneously distributed calcium sulfate phases and additives for adjusting the processability, setting time and early - and long-term strength.
• the hydraulic binders comprise various standardized cements, the main representative of which is Portland cement. It essentially consists of highly basic compounds of lime with silica (Si02), aluminum oxide (A1203) and iron (III) oxide (Fe203). As ancillary components, it contains magnesium, alkalis, titanium and manganese in oxidic form.
• the mineral structure of Portland cement consists of C3S (tricalcium silicate), C2S (dicalcium silicate), C3A (tricalcium aluminate) and C4AF (tetracalcium aluminate ferrite).
• Portland cement is produced in accordance with the standard (ASTM C150, DIN 1164) by fine grinding Portland cement clinker with calcium sulfate (gypsum).
• the approximate chemical composition of Portland cements is as follows:
• High early strengths (15-20 MPa earlier than 6 h after the fresh concrete is set) are achieved with finely ground Portland cement only with the addition of chemical activators such as Calcium chloride or alkali active such as alkali hydroxides, carbonates, aluminates, silicates.
• chemical activators such as Calcium chloride or alkali active such as alkali hydroxides, carbonates, aluminates, silicates.
• the activators are often used in conjunction with plasticizers and retarders.
• the additives mentioned can also be used with hydraulic binders whose composition differs significantly from Portland cement (for example with calcium fluoroaluminate and calcium sulfoanominate cements) with the desired effect.
• Such high-strength binder formulations are used above all as shotcrete or dry mortar for concrete work, in which time savings are associated with enormous cost savings, such as. B. Repair of highway, garage and runway coverings or molds for metal foundries.
• a hydraulic binder is known from US Pat. No. 4,842,649 which cures reliably both at high and at low temperatures, in particular below the freezing point of water.
• This binder known under the brand name "Pyrament" consists of 50-80% by weight Portland cement and various additives such as. B. coal power plant fly ash, blast furnace slag, metakaolin, microsilica, and activating additives, such as alkali metal hydroxides or carbonates and, if necessary, citric acids and citrates as setting retarders.
• activating additives such as alkali metal hydroxides or carbonates and, if necessary, citric acids and citrates as setting retarders.
• the high early and final strengths of the concrete formulations are apparently caused by the activation and acceleration of the pozzolanic reaction between hydroxides and silicate or alumino-silicate materials.
• a disadvantage of the known binder is the large number and amount of z. T. expensive (microsilicate, me ⁇ takaolin) additives to Portland cement that require a required mixing process. Practical trials have also shown that the setting times are very difficult to control.
• a shotcrete formulation is known from JP 59-064 551, in which carboxylic acid, in particular citric acid or citrate, is added to a mixture of Portland cement, calcium aluminate cement and alkali carbonate as a retarder. In this way, both high early and final strengths with good processability should be achieved.
• a sufficient processing time is essential for many applications.
• the reproducible setting of the setting time of high-strength concrete mixtures is therefore of central importance.
• the object of the invention is now to provide a method for producing a hydraulic binder which avoids the disadvantages existing in the prior art and which in particular the reproducible adjustability of processability, setting time, early and / or long-term strength by targeted addition of Additives.
• the object is achieved in that a ground clinker with essentially homogeneously distributed calcium sulfate phases and a ferrite content of at least 4% by weight as an activator to shorten the setting times and to increase the early and long-term strengths iron-complexing compound is admixed in the dry state.
• the essence of the invention lies in the knowledge that the clinker phase ferrite (4CaO * A1203 * Fe203), which has hitherto been regarded as little to unreactive, can be activated in an unexpectedly advantageous manner to accelerate the setting time and increase the early and long-term strengths.
• the use of iron-complexing compounds leads to shortened setting times and increased strengths, in particular increased early strengths.
• the activation of the ferrite phase according to the invention can be applied primarily to clinkers with a ferrite content of at least 4% by weight, preferably 6% by weight.
• a preferred bark is characterized by the fact that the additives contain a proportion of at least 3 mmol% of an iron-complexing compound obtained from the clinker and a carbonate donor in one to the iron-complexing compound
• the compound-related molar ratio is between 0.3 and 4.
• Contain a mortar or concrete mixture produced with such a binder is characterized by a low sensitivity of the properties to changes in the water / cement ratio.
• the ferrite clinker phase which is generally considered to be unreactive, is hydrated fastest (after 24 h to 100%) and thus contributes significantly to the development of the high early and long-term strengths.
• a clacium sulfate-containing additive is suitable as an additive to extend the setting time.
• this is in the form of gypsum, anhydrite or a mixture of both.
• the amount of the calcium sulfate-containing additive is preferably such that the calcium content of the binder, calculated as CaSO 4, is between 0.7% by weight and 8% by weight.
• the setting times between 0 and a maximum of 300 minutes can be regulated by the amount of CaS04 added without significantly influencing the development of strength.
• the molar ratio of sulfate to iron-complexing compound in a binder according to the invention is typically in a range between 1 and 20. A molar ratio between 3 and 8 is particularly preferred.
• the low sensitivity of the properties to changes in the water / cement ratio mentioned above is present in particular when the ratio of carbonate / iron complexing compound is in a range between 1 and 3 lies.
• the additives preferably contain, as carbonate donor in water, both soluble and slightly to insoluble salts of carbonic acid. Calcium carbonate, magnesium carbonate and / or dolomite are particularly suitable.
• the slightly to insoluble salts in particular have been activated beforehand by grinding and / or thermal treatment.
• the amount of the salts which are sparingly to insoluble in water is preferably between 2 and 20% by weight.
• Water-soluble salts of carbonic acid are preferably used as the carbonate donor, and water-soluble salts of polyoxycarboxylic acid or polycarboxylic acid or a diketone are used as iron-complexing compounds.
• Potassium carbonate, potassium carbonate trihydrate and potassium hydrogen carbonate are suitable as carbonate donors.
• Such carbonate donors are preferably combined with iron-complexing compounds such as tripotassium citrate monohydrate or a mixture of di-potassium u. * U .x1 u -. 4.- - ⁇ till_u_ -iiu ... nV..ru * .i.
• the proportion of di-potassium oxalate monohydrate is less than 50 mmol%.
• the iron complexes of polyoxycarboxylic acids, polycarboxylic acids and diketones according to the invention have the advantage that they are relatively strong, in particular in comparison, for example, to iron-amine complexes.
• Citric acid a polyoxycarboxylic acid
• the advantage of citrate is that the activating effect is multiplied by the alkali activators, in particular by potassium carbonate and potassium bicarbonate.
• this staining can be achieved by adding 0.1-1% by weight of oxalic acid or. their alkali salts are prevented.
• the additives contain a proportion of at least 4.5 mmol, preferably at least 7.5 mmol% of potassium citrate (K3C6H507 * H20) based on the clinker.
• the additives may contain at least 11 mmol% of citric acid, based on the clinker.
• the carbonate fraction is between at least 5 mmol% and at most 25 mmol%. This enables high early strengths to be achieved.
• the additives contain a proportion of at least 9 mmol% and at most 30 mmol% of potassium bicarbonate, based on the clinker.
• a mortar or concrete mixture produced with the binder according to the invention is largely independent of the ambient temperature, in particular also at temperatures sets below the freezing point, pozzolans, clay minerals, fly ash and / or finely divided reactive silica can also be added as additives.
• a mortar or fresh concrete according to the invention is characterized by a hydraulic binder of the type mentioned above and a water / cement value in the range from 0.25-0.4, in particular from 0.3-0.37.
• the strength development of a mortar or fresh concrete mixture according to the invention is characterized by the fact that with the usual workability (spreading width 45-50 cm, slump 15-20 cm) approx. 30 minutes after the setting strength of typically 19 MPa, but at least 15 MPa can be achieved, this corresponds to approx. 80% of the 6 h strength. After 28 days, the strengths are typically around 75 MPa. On the other hand, analogous early strengths can be achieved 90 minutes after the end of setting, but less heat development occurs during hardening and comparatively higher long-term strengths of approximately 90 MPa are achieved after 28 days.
• the development of early strength and the development of heat during the early phase of hardening are adjusted by simply changing the initial pH of the binder mixture.
• the binder composition has a significant influence on the strength development, in particular on the early strength.
• the early strengths (2-4 h) are approximately as sensitive to changes in the water / cement value as the 24-48 h strengths of common Portland cements. The same applies analogously to the consistency and setting times of fresh concrete. Compared to conventional high-strength binders, this has the great advantage that very liquid (spreading width> 50 cm) or liquid (spreading dimension 45-50 cm) concrete mixtures such as
• the strengths, setting times and consistency of the known high-strength binders which are based on Portland cement, liquefiers and activators and possibly additives such as fly ash, metakaolin and microsilica, are very sensitive to changes in the water / Cement ratio.
• the low water / cement ratio of 0.20-0.26 necessary for the achievement of the known characteristic early strengths results in strongly tixothropic behavior of the fresh concrete and thus severely limits its workability and range of application.
• Fig. 3 is an illustration of the dependence of the 6 hour compressive strength from C4AF content when using Vai ⁇ • umbikarbona ⁇ - ls a K * a r ' ⁇ "" ** natdonor " 4 shows a representation of the dependence of the 6 h compressive strength on the C4AF content when using potassium carbonate as carbonate donor;
• Tab. 1.1-1.3 A compilation of the clinker and Portland cement used in the exemplary embodiments.
• Tab. 12 some particularly preferred exemplary embodiments
• Tab. 13 exemplary embodiments with particularly high early strengths
• the basis for a binder according to the invention is formed by a ground clinker with a ferrite content of at least 4% by weight, preferably a ground Portland cement clinker, and a calcium sulfate-containing additive which has either been ground together with the clinker or separately.
• the cement or the gypsum mixed with the gypsum-free clinker make up 80-95% by weight of the binder.
• the remaining parts by weight are provided by the activators according to the invention.
• the temperature does not exceed 120 ° C., preferably 70 ° C.
• excessive temperatures can lead to undesirable side effects (such as uncontrolled variation in the setting times).
• additives are used as activators which on the one hand contain soluble salts of carbonic acid and on the other hand iron-complexing, preferably pH-neutral to basic compounds.
• iron-complexing preferably pH-neutral to basic compounds.
• the iron-complexing compound eg potassium citrate monohydrate or citric acid
• the iron-complexing compound surprisingly does not act as a retarder but as an activator, i. H. it speeds up the setting process and increases strength.
• the iron-complexing compound is advantageously added in an amount of at least 3 mmol% (based on the clinker).
• the soluble salts of the carbonate donor Carbonic acid e.g. potassium carbonate
• the choice of the molar ratio according to the invention results in advantageous properties which are explained below using an example.
• a binder according to the invention is achieved when 80-95 parts of Portland cement clinker are mixed with a calcium sulfate-containing additive and an effectively strengthening additive in a dry state
• Portland cement clinker is ground without gypsum additive to an amount of 44000000-6600 (00 cm 2 / g, preferably to approx. 5000 cm2 / g according to Blaine.
• the calcium sulfate additive contains gypsum (CaS04 * 2H20) and / or anhydrite (CaS04). It is produced by grinding gypsum and / or anhydrite, possibly with limestone and / or other inert additives, to grain sizes less than 120 ⁇ , preferably less than 60 ⁇ and 90% greater than 2 ⁇ .
• the calcium sulfate-containing additive can be ground in a conventional, open ball mill, in a roller bowl mill, in a micro vortex mill or in some other way. The grinding temperatures and the storage temperature should be below the formation temperature of hemihydrate (lower 70-80 ° C).
• calcium sulfate additives such.
• B. also residues of the chemical industry (citro plaster, phosphogypsum, gypsum from titanium dioxide processing etc.) or residues from flue gas desulfurization can be used. If these additives are obtained in the required fineness, they can be added directly. Otherwise they are to be ground as described above.
• the calcium sulfate-containing additive is added in an amount such that the binder contains 0.7-8% by weight of gypsum and / or anhydrite (calculated as C ⁇ .S04). With this additive, the setting time is set to a certain basic value between 0 and 300 minutes. The strength development is not significantly influenced by this.
• the effective strength-increasing additive contains at least one iron-complexing compound and at least one carbonate donor. Carbonate generator.
• any compound which forms stable, soluble complex compounds with iron (III) in an aqueous solution in alkaline medium can be used as the iron-complexing compound.
• These include the representatives of polyoxycarboxylic acids such as citric acid, tartaric acid, lactic acid. Gluconic acid, malic acid etc. and their salts.
• representatives of polycarboxylic acids such as oxalic acid, maleic acid, malonic acid, succinic acid etc. and their salts.
• representatives of diketones such as pyruvic acid, acetyl acetoacetate, dimethyl acethyl succinate etc. and their salts are also suitable.
• hydroquinoline, amine, pyridine, glyoxime and similar compounds can also be used. The latter are less preferred because of certain disadvantages such as toxicity, smell or cost.
• Particularly preferred properties are e.g. B. achieved with the salts of citric acid, especially with tri-potassium citrate mononhydrate (K3C), the latter partly by a polycarboxylic acid, such as. B. oxalic acid and / or potassium oxalate can be replaced.
• K3C tri-potassium citrate mononhydrate
• carbonate donor or generator compounds can be used which release or release carbonate ions in an alkaline aqueous environment. with reactive calcium compounds such as Portlandite Ca (OH) 2, C3A, C3S etc. to calcium carbonate and / or calcium carbonate, the compounds react, such as.
• Those compounds which release carbon dioxide and / or carbonate in aqueous media, such as carbon dioxide act as carbonate generators.
• Potassium carbonate trihydrate 2K2C03 * 3H20 can also be used to increase storage stability.
• the effective strength-increasing additive is produced by mixing its components, preferably in powder form, optionally with fillers and / or other strength-increasing additives (such as, for example, microsilica, alkali silicates, etc.).
• the components of the strength-increasing to r set by means of the binder can also separately be zuge ⁇ sets.
• the amount of the strengthening additive is such that the binder mixture contains 3-12 mmol% iron-complexing compounds (e.g. 0.1-4% by weight potassium citrate monohydrate) and 1-40 mmol% carbonate donors (e.g. 0.1-4 wt .-% potassium hydrogen carbonate) contains.
• 3-12 mmol% iron-complexing compounds e.g. 0.1-4% by weight potassium citrate monohydrate
• 1-40 mmol% carbonate donors e.g. 0.1-4 wt .-% potassium hydrogen carbonate
• the hydraulic binder according to the invention is preferably produced by mixing its components in a conventional dry mixer. As already mentioned, the Temperature when mixing do not exceed 120 ° C or preferably 70 ° C.
• Tables 1.1, 1.2, 1.3 show the elementary compositions of the clinker and cement used in the examples (calculated as oxides) and the corresponding clinker phase compositions, calculated according to Bogue (ASTM C150 modified).
• Y ' measured variable (6 h compressive strength), standardized to Y0 (measured variable at the central point)
• Binders according to the invention which are based on Portland cement clinkers of widely differing compositions, potassium citrate (in particular in the presence of potassium carbonate) is the component determining the 6 h strength development.
• 3 and 4 show the correlation of the 6 h strengths with the C4AF content (determined according to Bogue) of a number of clinkers activated according to the invention.
• a mixture of citrate and bicarbonate was used as the activating additive in the examples in FIG. 3 and a mixture of citrate and carbonate in those in FIG.
• citric acid and alkali salts of citric acid have an accelerating and strengthening effect by activating the ferrite phase of the clinker according to the invention. This should be explained using Tables 2-5.
• Table 2 shows the influence of potassium citrate on the 2 Hardening behavior of Portland cement (Blaine 5000 cm / g,
• Table 3 shows the influence of potassium bicarbonate and potassium citrate on cement hardening.
• Table 4 shows the influence of alkali carbonate and potassium citrate on cement hardening.
• Table 5 shows an example with citric acid and potassium carbonate as an additive to increase the strength.
• Tables 3 and 4 show that potassium citrate in combination with alkali carbonates, respectively. Alkalibikarbonat significantly higher strengths (factor 2) can be achieved. At the same time, the plasticizing effect is increased.
• alkali carbonate in particular of alkali bicarbonate, causes an increase in the setting times in comparison to the carbonate-free binders (Table 2).
• the setting time is reduced from 240 minutes (0% by weight of potassium citrate) to 120 minutes (2.7% by weight of potassium citrate).
• the setting time is reduced from 220 minutes (1.7% by weight of potassium citrate) to 70 minutes (at 3% by weight of potassium citrate).
• the citrate is also in the presence of carbonates resp. Bikar bonates, the essential component for achieving high early strengths.
• the effect of citrate (high early strength, reduction in water consumption) is due to the Carbonates increased.
• the setting-retarding effect of carbonate, in particular potassium bicarbonate, in the presence of citrate allows the setting time to be regulated, which is useful for commercial applications.
• Table 5 shows the extent of hydration of the clinker phases, determined by means of X-ray diffractometry (clinker 1.6% by weight of gypsum).
• a 30% hydration of the C3S phase is also quite common in non-activated Portland cements, but the alkali carbonate or bicarbonate present in the binder according to the invention as carbonate donor leads to the formation of unusually dense, quasi-amorphous silicate hydrates, as is the case in conventional hydrated ones Portland cements cannot be observed.
• These very dense, partially sulfate, potassium, iron and carbonate-containing silicate phases certainly contribute to the increased early and in particular long-term strength.
• An alkali activation of the silicate phases in the early stage of the hydration (up to 24 h) cannot be determined in the presence of citrate.
• Tables 2 to 6 show that potassium citrate, as a representative of a polyoxy or a polycarboxylic acid, is the essential component for achieving the high early strengths in the binder according to the invention.
• the hydration of the ferrite phase activated by potassium citrate makes the greatest contribution to the strengths within the first 24 hours after the start of hydration (cf. FIG. 2).
• Potassium carbonate or bicarbonate as a carbonate donor increases the activation of the ferrite and increases the plasticizing effect of the citrate.
• the carbonate donors mentioned delay the setting. The prolongation of the rest (duration of workability) of the cement paste or mortar is very likely due to the formation of a protective layer of calcium carbonate on the surface of the CaO-containing clinker phase ("carbonate effect").
• Ordinary Portland cement usually contains 4-7% by weight of gypsum as a setting retarder. It is added to the Portland cement clinker in the form of natural gypsum and / or chemical gypsum before grinding.
• the gypsum is present in Portland cement as a mixture of dihydrate, hemihydrate and anhydrite. The quantitative ratios of the calcium sulfate phases depend very much on the grinding conditions.
• the amount of calcium sulfate rabbits and the manner in which the calcium sulfate-containing additives are admixed have an influence on the strength development and the setting behavior.
• Dihydrate is advantageously used as the additive containing calcium sulfate (CaS04 * 2H20) is used, which can also be mixed with fillers such as limestone.
• anhydrite (CaS04) can also be used.
• the achievable early strengths are 10-30% lower than with dihydrate.
• the binder according to the invention contains hemihydrate (CaS04 * 0.5H2O or CaS04 * 0.8H2O), the development of strength and the degree of setting depend on the type of printer.
• Tables 7 and 8 illustrate the influence of the handle hydrate in the presence of dihydrate on the properties of the binder depending on the formulation of the activating additive.
• Commercial Portland cement is compared to the corresponding clinker with added dihydrate, which is ground according to the invention in a gypsum-free manner.
• Potassium citrate and on the other hand citric acid are used as the iron complexing compound and on the one hand potassium carbonate and on the other hand potassium bicarbonate as the carbonate donor.
• A1 4.6% by weight, 40% K2C03, 60% potassium citrate monohydrate A2: 4.7% by weight, 43% K2C03, 57% potassium citrate monohydrate A3: 3.5% by weight, 71% K2C03, 29% citric acid
• Table 9 The examples in Table 9 are based on gypsum-free ground
• Table 10 The examples in Table 10 are based on gypsum-free ground
• the binder mixtures in Table 11 are based on gypsum-free clinker (PK1 / 5) and 0-6% by weight of gypsum and 6-0 % By weight hemihydrate.
• the following activating additives were used:
• A1 4.6% by weight, 40% K2C03, 60% potassium citrate monohydrate A2: 3.5% by weight, 71% K2C03, 29% citric acid
• citric acid acts as an efficient retarder in formulations containing Portland cement, but in formulations which are free of semihydrates, it acts as an activator with regard to setting times and strength development.
• potassium citrate acts as an activator in both formulations.
• the water requirement and the sensitivity to changes in the water / cement ratio are significantly and significantly higher in formulations containing citric acid than in formulations containing K3C (in particular in the case of binder mixtures containing Portland cement).
• binder formulations which contain potassium carbonate / citric acid and commercial Portland cement are generally sensitive to the setting times and the development of strength Changes in the water / cement ratio and by significantly lower strengths.
• the described in US 4,842,649 The retarding effect of citric acid could only be confirmed in formulations containing Portland cement, but not in formulations with a low hemihydrate content.
• the citric acid acts as an activator both on the setting times and on the development of strength.
• the retarding effect of potassium citrate which is equivalent to citric acid in US Pat. No. 4,842,649, could not be confirmed either in mixtures containing Portland cement or in formulations with a low hemihydrate content (especially not in formulations containing clinker gypsum-free).
• Table 12 shows a compilation of preferred exemplary embodiments. The following activators were used as additives:
• CaS04 5.0-5.8% by weight dihydrate, anhydrite, hemihydrate (calculated as dihydrate)
• A1 3.85-5.0% by weight, 40-56% K2C03, 40-60% potassium citrate monohydrate
• Table 13 summarizes four particularly preferred exemplary embodiments of the invention.
• 3 binder was in standard concrete (400 kg cement per m,
• Standard aggregate is used with different water / cement ratios or different workability of the fresh concrete.
• the line of sight of the standard., Expelled materials corresponds to the Fuller curve.
• the binder used had the following formulation: gypsum-free clinker PK1 / 5
• Table 14 shows the influence of the addition of dipotassium oxalate on the binder properties in iso-mortar mixtures. All binders are based on the PK1 / 5 clinker type, which was mixed with 6% by weight dihydrate.
• Fig. 5 shows the dependence of the 4 h strength on water / cement ratio.
• Activated Portland cements PK1 / 5, 400 kg / m
• HPC Untervaz and PC55 small creams HPC Untervaz and PC55 small creams
• FIG. 6 illustrates that the invention clearly stands out from known high-strength binders in terms of sensitivity to changes in the water / cement value.
• the pyrament binder used for comparison (according to US 4,842,649), which is designated T505 in the figure, is significantly more sensitive. If the water / cement ratio changes by 10% from 0.33 to 0.30, the 4-hour strength changes by a factor of 2. In contrast, a corresponding change in the water / cement ratio leads from 0.37 to 0.34 a binder according to the invention for an increase in compressive strength of only a good 15%. The same applies to the 24 h strength.
• FIG. 7 shows the temperature dependence of the early strength development in ISO mortar mixtures.
• the temperature in degrees C is plotted on the abscissa and the compressive strength in MPa is plotted on the ordinate.
• the binder according to the invention (PK1 / 5 gypsum-free ground on Blaine 5300 cm / g) was compared with a known early-strength cement of the type P50.
• the 4 h and in particular the 6 h strength which is achieved with the binder according to the invention is significantly less dependent on the temperature than the 48 h strength relevant for the P50.
• the invention relates to a hydraulic binder which contains Portland cement clinker, a calcium sulfate-containing additive, strength-increasing additives and, if appropriate, fillers or additives, as are usually found in mixed cements, and with which, compared to previous binders, increased early and final strengths (> 28 days) in concrete and mortar mixtures can be achieved.
• the invention in particular avoids the following disadvantages of known binders:
• the binder according to the invention is characterized by a hemihydrate content of less than 50%, in particular less than 20%, calculated as dihydrate.
• strength-increasing additives preferably at least at least one iron complexing compound and at least one carbonate donor are used.
• the invention also specifies advantageous methods for producing Portland cements with a defined maximum half-hydrate content.

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• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)
• Basic Packing Technique (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Pistons, Piston Rings, And Cylinders (AREA)
• Pressure Welding/Diffusion-Bonding (AREA)
• Powder Metallurgy (AREA)
• Piles And Underground Anchors (AREA)
• Lubricants (AREA)
• Nonmetallic Welding Materials (AREA)
• Paper (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

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• 1991
  • 1991-12-30 EP EP92901334A patent/EP0517873A1/de not_active Withdrawn
  • 1991-12-30 HU HU922763A patent/HUT62538A/hu unknown
  • 1991-12-30 BR BR9106243A patent/BR9106243A/pt unknown
  • 1991-12-30 WO PCT/CH1991/000281 patent/WO1992012103A1/de not_active Application Discontinuation
  • 1991-12-30 WO PCT/CH1991/000280 patent/WO1992012100A1/de active IP Right Grant
  • 1991-12-30 AU AU91123/91A patent/AU9112391A/en not_active Abandoned
  • 1991-12-30 PL PL29579291A patent/PL295792A1/xx unknown
  • 1991-12-30 DE DE59108990T patent/DE59108990D1/de not_active Expired - Fee Related
  • 1991-12-30 HU HU922764A patent/HUT62540A/hu unknown
  • 1991-12-30 AU AU90909/91A patent/AU9090991A/en not_active Abandoned
  • 1991-12-30 CA CA 2076868 patent/CA2076868A1/en not_active Abandoned
  • 1991-12-30 CA CA 2076869 patent/CA2076869A1/en not_active Abandoned
  • 1991-12-30 AT AT92901131T patent/ATE166330T1/de not_active IP Right Cessation
  • 1991-12-30 BR BR9106242A patent/BR9106242A/pt unknown
  • 1991-12-30 PL PL29579391A patent/PL295793A1/xx unknown
  • 1991-12-30 EP EP92901131A patent/EP0517869B1/de not_active Expired - Lifetime

Non-Patent Citations (1)

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