SET CONTROL COMPOSITION FOR CEMENTITIOUS SYSTEMS

Abstract

A set control composition for cementitious systems comprises a retarder (a) selected from (a-1) polymeric polycarboxylic acids selected from homopolymers and copolymers of ,-ethylenically unsaturated carboxylic acids; and copolymers of at least one ,-ethylenically unsaturated carboxylic acid and at least one sulfo group containing monomer; and salts thereof, whose milliequivalent number of carboxyl groups is 3.0 meq/g or higher, preferably 3.0 to 17.0 meq/g, and having a molecular weight 25,000 g/mol or less, assuming all the carboxyl groups to be in unneutralized form, (a-2) phosphonic acids and salts thereof, (a-3) low molecular weight polycarboxylic acids and salts thereof, and mixtures thereof, (b) at least one of (b-1) a borate source and (b-2) a carbonate source, wherein the carbonate source is selected from inorganic carbonates having an aqueous solubility of 0.1 g.Math.L.sup.1 or more at 25 C., and organic carbonates, in a weight ratio of b) to a) in the range of 0.1 to 10, (c) a polyol having at least 3 alcoholic hydroxyl groups in its molecule, in a weight ratio of c) to a) in the range of 0.2 to 4, and (d) a dispersant. The set control composition effectively improves workability of cementitious systems for prolonged periods of time without compromising early compressive strength. The compositions show sufficient open time, i.e., the time until initial setting, good workability during said open time as characterized, for example by adequate slump flow over time, and fast setting. The invention further relates to a construction composition comprising i) a cementitious binder comprising one or more calcium silicate mineral phases and one or more calcium aluminate mineral phases, ii) optionally, an extraneous aluminate source, iii) a sulfate source, and iv) the set control composition. The construction composition contains 0.05 to 0.2 mol of total available aluminate, calculated as Al(OH).sub.4.sup., from the calcium aluminate mineral phases plus the optional extraneous aluminate source, per 100 g of cementitious binder i), and the molar ratio of total available aluminate to sulfate is 0.4 to 2.0.

Claims

1. A set control composition for cementitious systems comprising a) a retarder selected from (a-1) polymeric polycarboxylic acids selected from homopolymers and copolymers of ,-ethylenically unsaturated carboxylic acids and salts thereof, and copolymers of at least one ,-ethylenically unsaturated carboxylic acid and at least one sulfo group containing monomer and salts thereof, whose milliequivalent number of carboxyl groups is 3.0 meq/g or higher and having a molecular weight 25,000 g/mol or less, assuming all the carboxyl groups to be in unneutralized form, (a-2) phosphonic acids and salts thereof, (a-3) low molecular weight polycarboxylic acids and salts thereof, and mixtures thereof, b) at least one of (b-1) a borate source, or (b-2) a carbonate source, wherein the carbonate source is selected from inorganic carbonates having an aqueous solubility of 0.1 g.Math.L.sup.1 or more at 25 C., and organic carbonates, in a weight ratio of b) to a) in the range of 0.1 to 10, c) a polyol having at least 3 alcoholic hydroxyl groups in its molecule, in a weight ratio of c) to a) in the range of 0.2 to 4, and d) a dispersant.

2. The set control composition according to claim 1, further comprising e) a co-retarder selected from hydroxy monocarboxylic acids and salts thereof.

3. The set control composition according to claim 1, wherein the polymeric polycarboxylic acid is a homopolymer of acrylic acid, a homopolymer of methacrylic acid, a copolymer of acrylic acid and maleic acid, or a copolymer of methacrylic acid and maleic acid.

4. The set control composition according to claim 1, wherein the inorganic carbonate is selected from sodium carbonate, sodium bicarbonate, potassium carbonate, lithium carbonate and magnesium carbonate; and the organic carbonate is selected from ethylene carbonate, propylene carbonate and glycerol carbonate.

5. The set control composition according to claim 1, wherein the polyol is selected from sugar alcohols and saccharides.

6. The set control composition according to claim 1, wherein the polyol, in a calcium aluminate precipitation test in which a test solution, obtained by supplementing 400 mL of a 1 wt.-% aqueous solution of the polyol with 20 mL of a 1 mol/L NaOH aqueous solution and 50 mL of a 25 mmol/L NaAlO.sub.2 aqueous solution, is titrated with a 0.5 mot/L CaCl.sub.2 aqueous solution at 20 C., inhibits precipitation of calcium aluminate up to a calcium concentration of 75 ppm.

7. The set control composition according to claim 6, wherein the polyol is selected from monosaccharides, oligosaccharides, water-soluble polysaccharides, compounds of general formula (P-I) or dimers or trimers of compounds of general formula (P-I): ##STR00019## wherein X is ##STR00020## wherein R is CH.sub.2OH, NH.sub.2, n is an integer from 1 to 4, m is an integer from 1 to 8.

8. The set control composition according to claim 1, wherein the dispersant is selected from the group of comb polymers having a carbon-containing backbone to which are attached pendant cement-anchoring groups and polyether side chains, non-ionic comb polymers having a carbon-containing backbone to which are attached pendant hydrolysable groups and polyether side chains, the hydrolysable groups upon hydrolysis releasing cement-anchoring groups, colloidally disperse preparations of polyvalent metal cations and a polymeric dispersant which comprises anionic and/or anionogenic groups and polyether side chains, and the polyvalent metal cation is present in a superstoichiometric quantity, calculated as cation equivalents, based on the sum of the anionic and anionogenic groups of the polymeric dispersant, sulfonated melamine-formaldehyde condensates, lignosulfonates, sulfonated ketone-formaldehyde condensates, sulfonated naphthalene-formaldehyde condensates, phosphonate containing dispersants, preferably the phosphonate containing dispersants comprise at least one polyalkylene glycol unit, and mixtures thereof.

9. A construction composition comprising i) a cementitious binder comprising one or more calcium silicate mineral phases and one or more calcium aluminate mineral phases, ii) optionally, an extraneous aluminate source, iii) a sulfate source, wherein the construction composition contains 0.05 to 0.2 mol of total available aluminate, calculated as A(OH).sub.4.sup., from the calcium aluminate mineral phases plus the optional extraneous aluminate source, per 100 g of cementitious binder i), and the molar ratio of total available aluminate to sulfate is 0.4 to 2.0, wherein the construction composition additionally comprises iv) a set control composition comprising iv-a) a retarder selected from (a-1) polymeric polycarboxylic acids selected from homopolymers and copolymers of ,-ethylenically unsaturated carboxylic acids and salts thereof, and copolymers of at least one ,-ethylenically unsaturated carboxylic acid and at least one sulfo group containing monomer and salts thereof, whose milliequivalent number of carboxyl groups is 3.0 meq/g or higher, having a molecular weight in the range of 25,000 g/mol or less, assuming all the carboxyl groups to be in unneutralized form, (a-2) phosphonic acids and salts thereof, (a-3) low molecular weight polycarboxylic acids and salts thereof, and mixtures thereof; iv-b) at least one of (b-1) a borate source, or (b-2) a carbonate source, wherein the carbonate source is selected from inorganic carbonates having an aqueous solubility of 0.1 g.Math.L.sup.1 or more at 25 C., and organic carbonates; iv-c) a polyol having at least 3 alcoholic hydroxyl groups in its molecule; and iv-d) a dispersant.

10. The construction composition according to claim 9, comprising, relative to the amount of cementitious binder i) iv-a) in an amount of 0.1 to 2 wt.-%, iv-b) in an amount of 0.2 to 1 wt.-% and iv-c) in an amount of 0.2 to 2.5 wt.-%.

11. The construction composition according to claim 9, wherein the calcium silicate mineral phases and calcium aluminate mineral phases constitute at least 90 wt.-% of the cementitious binder i), and the calcium silicate mineral phases constitute at least 60 wt.-% of the cementitious binder i).

12. The construction composition according to claim 9, wherein the construction composition additionally comprises v) at least one of a latent hydraulic binder, a pozzolanic binder and a filler material.

13. The construction composition according to claim 9, wherein the extraneous aluminate source ii) is selected from non-calciferous aluminate sources selected from aluminum(III) salts, aluminum(III) complexes, crystalline aluminum hydroxide, amorphous aluminum hydroxide; and calciferous aluminate sources selected from high alumina cement, sulfoaluminate cement or synthetic calcium aluminate mineral phases.

14. The construction composition according to claim 9, wherein the sulfate source iii) is a calcium sulfate source.

15. The construction composition according to claim 9, in freshly mixed form, wherein the ratio of water to cementitious binder i) is in the range of 0.2 to 0.7.

Description

[0248] FIG. 1 shows a plot of the photo current signal in mV against the time of dosage of CaCl.sub.2 in the calcium aluminate precipitation test according to one embodiment of the invention.

METHODS

[0249] Calcium Aluminate Precipitation Test

[0250] For the calcium aluminate precipitation test, an automated titration module (Titrando 905, available from Metrohm) equipped with a high performance pH-electrode (iUnitrode with Pt 1000, available from Metrohm) and a photosensor (Spectrosense 610 nm, available from Metrohm) was used. First, a solution of 400 mL of a 1 wt.-% aqueous solution of a polyol to be investigated and 20 mL of a 1 mol/L NaOH aqueous solution was equilibrated for 2 min under stirring in the automated titration module. Then, 50 mL of a 25 mmol/L NaAlO.sub.2 aqueous solution was added thereto, followed by equilibration for another 2 min, obtaining an essentially clear test solution. In a next step, the test solution is titrated with a 0.5 mol/L CaCl.sub.2 aqueous solution which is dosed with a constant rate of 2 mL/min. During the whole experiment, the temperature is hold constant at 20 C. The elapsed time to a turbidity inflection is recorded. To this end, the photo current signal in mV is plotted against the time of dosage of the CaCl.sub.2 aqueous solution. From the diagram, the onset point is determined as the intersection of the baseline tangent with a tangent to the curve after the inflection of the curve.

[0251] Molecular weight determination of the polymeric polycarboxylic acids

[0252] The molecular weights of the polymeric polycarboxylic acids used in the examples are based on the information provided by the supplier. The molecular weight was determined by gel permeation chromatography (GPC) with aqueous eluents (Column combination: OH-Pak SB-G, OH-Pak SB 804 HQ and OH-Pak SB 802.5 HQ by Shodex, Japan; eluent: 80 vol.-% aqueous solution of HCO.sub.2NH.sub.4 (0.05 mol/I) and 20 vol.-% methanol; injection volume 100 l; flow rate 0.5 ml/min). The molecular weight calibration was performed with poly(acrylate) standards for the RI detector. Standards were purchased from PSS Polymer Standards Service, Germany.

[0253] Testing ProcedureMini-Slump

[0254] The used procedure is analogous to DIN EN 12350-2, with the modification that a mini-slump cone (height: 15 cm, bottom width: 10 cm, top width: 5 cm) was used instead of a conventional Abrams cone. 2 L of the aqueous freshly mixed construction composition were filled into the mini-slump cone. The cone was filled completely immediately after mixing. Afterwards, the cone was placed on a flat surface, and lifted, and the slump of the mortar mix was measured. The slump of all mixes was adjusted to 11 cm by adjusting the dosage of the superplasticizer to allow for comparability.

[0255] Testing ProcedureEarly Strength Development for Mortars

[0256] The adjusted mortar mixes were each filled into mortar steel prisms (16/4/4 cm), and after 3 h at a temperature of 20 C. and relative humidity of 65%, a hardened mortar prism was obtained. The hardened mortar prism was demolded and compressive strength was measured according to DIN EN 196-1. The mortar prism was measured again after 24 h.

[0257] Testing ProcedureSetting Time

[0258] Setting time was determined with a Vicat needle according to DIN EN 480.

EXAMPLES

Reference Example: Calcium Aluminate Precipitation-Inhibiting Properties of Polyols

[0259] Various polyols were assed for their precipitation-properties in the calcium aluminate precipitation test. The results are shown in the table that follows. For the control, 400 mL of bidestilled water was used instead of 400 mL of a 1 wt.-% aqueous solution of a polyol. The titration endpoint, expressed as the maximum calcium concentration (as Ca.sup.2+) before the onset of turbidity, is calculated from the elapsed time to the onset point. FIG. 1 shows a plot of the photo current signal in mV against the time of dosage of CaCl.sub.2. Curve a) of FIG. 1 shows the results in the absence of a polyol (blank). Curve b) of FIG. 1 shows the results for addition of 1% of triethanolamine. For curve b), a first tangent 1, referred to as baseline tangent, and a second tangent 2 are shown. From the baseline tangent 1 and the second tangent 2, the onset point in s may be determined as the intersection of the baseline tangent 1 with the second tangent 2.

TABLE-US-00001 control (without ethylene triethanol- Polyol polyol) glycol glycerol amine erythrit Onset point [s] 42 42 64 500 686 Ca endpoint [ppm] 59 59 93 682 924

[0260] Calorimetry Measurements on Cement Pastes

[0261] Various mortar mixes were prepared, adjusted to the same slump and their early strength development was measured. The basic recipe is as follows, to which further ingredients were added as described in detail below.

TABLE-US-00002 Amount Material [kg/m.sup.3] Cementitious binder 542 Limestone powder 68 Anhydrite (CAB 30) 54 Water 209 Quartz sand (0.1-0.3 mm) 155 Quartz sand (0.3-1 mm) 118 Natural sand (0-4 mm) 977 Crushed stones (2-5 mm) 279

[0262] Cement pastes were prepared with 47.5 g of Mergelstetten CEM 142.5 N, 2.5 g of anhydrite (CAB 30, available from Lanxess) and a total amount of water of 20 g (water/cement=0.42). Retarder 7 of WO 2019/077050 was used as glyoxylic acid urea polycondensate.

[0263] The calorimetric results summarized in Table 1 were obtained with a Tam Air calorimeter operated in isothermal conditions at 20 C. Calorimetric analytical techniques involve the measurement of heat that is evolved or absorbed during a chemical reaction. The dissolution of the aluminate phase is accompanied by heat evolution. The time until the peak of the heat evolution is reached is indicative of the open time.

TABLE-US-00003 TABLE 1 Cement pastes Time for Sodium peak of carboxyl Retarder NaHCO.sub.3 gluconate Glycerol aluminate groups M.sub.W Dosage .sup.[1] (iv-b) (e-1) (iv-c) reaction # Retarder [meq/g] [g/mol] [g] [g] [g] [g] [h] 1 0 0 0 <0.25 2 0.15 0.0314 0.126 <0.25 3* glyoxylic acid 8.6 6,000 0.0940 0.15 0.0314 0.126 1.75 urea polycondensate 4 Sokalan PA 20 13.9 2,500 0.0431 0.15 0.0314 0.126 3.25 5 Sokalan PA 15 13.9 1,200 0.0431 0.15 0.0314 0.126 0.75 6 Sokalan CP 10S 13.9 4,000 0.0431 0.15 0.0314 0.126 1.25 7 Sokalan PA 25 13.9 4,000 0.0431 0.15 0.0314 0.126 0.75 CL PN 8 Sokalan CP 12S 15.9 3,000 0.0431 0.15 0.0314 0.126 0.50 9 Sokalan PA 40 13.9 15,000 0.0431 0.15 0.0314 0.126 0.50 10 Polymer 1 .sup.[2] 10.7 2,500 0.0431 0.15 0.0314 0.126 0.75 11 Polymer 2 .sup.[3] 2.9 2,500 0.0431 0.15 0.0314 0.126 0.25 12 Polymer 3 .sup.[4] 9.9 1,500 0.0431 0.15 0.0314 0.126 0.75 .sup.[1] doseage calculated as active substance .sup.[2] low molecular weight co-polymer of acrylic acid, methacrylic acid and methallyl sulfonic acid (wt.-%-ratio 0.42:0.42:0.16). .sup.[3] low molecular weight co-polymer of hydroxy propyl acrylate, methacrylic acid and methallyl sulfonic acid (wt.-%-ratio 0.59:0.25:0.16). .sup.[4] low molecular weight co-polymer of methacrylic acid and methallyl sulfonic acid (wt.-%-ratio 0.85:0.15).

[0264] It is evident that the presence of polymeric polycarboxylic acids markedly delays the exothermic aluminate phase dissolution.

[0265] Evaluation of Open Time and Compressive Strength of Mortar Mixes

[0266] Mortar mixes 1 to 21 were prepared, adjusted to the same slump and their early strength development was measured. As cementitious binder, Karlstadt CEM 142.5 R (0.092 mol total available aluminate per 100 g) or Mergelstetten CEM 142.5 N (0.084 mol total available aluminate per 100 g) was used.

[0267] Mixing Procedure

[0268] Crushed stones (2 to 5 mm) were dried in an oven at 70 C. for 50 h. Sand (0 to 4 mm) was dried for 68 h at 140 C. Afterwards, the crushed stones and sand were stored at 20 C. for at least 2 days at 65% relative humidity. A retarder (retarder 7 of WO 2019/077050 as glyoxylic acid urea polycondensate or MasterRoc HCA 10, a mixture of citric acid and phosphonobutantricarboxylic acid, available from Master Builders Solutions Deutschland GmbH), sodium gluconate, Na.sub.2CO.sub.3 and a polycarboxylate based superplasticizer (Master Suna SBS 8000 or Master Glenium ACE 30, both available from Master Builders Solutions Deutschland GmbH) according to Table 2 were added to the total amount of mixing water, so as to obtain a liquid aqueous component. Subsequently, crushed stones, sands, cementitious binder and anhydrite were added to a 5 L Hobbart mixer. The liquid aqueous component was added thereto and the mixture was stirred for 2 min at level 1 (107 rpm) and for further 2 min at level 2 (198 rpm) to obtain an aqueous freshly mixed construction composition.

TABLE-US-00004 TABLE 2 Mortar mixes Ratio Dosage Cementitious CAB 30 Aluminate/ Water/ [wt.-%] # binder [wt.-%] Sulfate Cement Retarder .sup.[1] 1* Karlstadt 15.0 0.61 0.37 urea-glyoxylic 0.50 CEM I 42.5 R acid condensate 2* Karlstadt 15.0 0.61 0.37 urea-glyoxylic 0.50 CEM I 42.5 R acid condensate 3* Karlstadt 15.0 0.61 0.37 Sokalan PA 15 0.50 CEM I 42.5 R 4* Karlstadt 15.0 0.61 0.37 Sokalan PA 15 1.00 CEM I 42.5 R 5* Karlstadt 15.0 0.61 0.37 Sokalan PA 15 0.30 CEM I 42.5 R 6* Karlstadt 15.0 0.61 0.37 Sokalan PA 15 0.10 CEM I 42.5 R 7* Karlstadt 15.0 0.61 0.37 urea-glyoxylic 1.00 CEM I 42.5 R acid condensate 8 Karlstadt 15.0 0.61 0.37 Sokalan PA 15 1.00 CEM I 42.5 R 9* Karlstadt 15.0 0.61 0.37 Sokalan PA 15 1.00 CEM I 42.5R 10* Karlstadt 15.0 0.61 0.37 Sokalan PA 15 1.00 CEM I 42.5R 11* Karlstadt 0 2.02 0.37 urea-glyoxylic 0.50 CEM I 42.5 R acid condensate 12* Karlstadt 0 2.02 0.37 Sokalan PA 15 0.50 CEM I 42.5 R 13* Karlstadt 5.0 1.19 0.37 urea-glyoxylic 0.30 CEM I 42.5 R Hemi- acid condensate hydrate Sodium gluconate 0.10 14 Karlstadt 5.0 1.19 0.37 Sokalan PA 15 0.20 CEM I 42.5 R Hemi- Sodium gluconate 0.10 hydrate 15 Karlstadt 5.0 1.19 0.37 Sokalan PA 20 0.20 CEM I 42.5 R Hemi- Sodium gluconate 0.10 hydrate 16 Karlstadt 15.0 0.61 0.37 MasterRoc 0.50 CEM I 42.5 R HCA 10 17 Karlstadt 15.0 0.61 0.37 MasterRoc 0.50 CEM I 42.5 R HCA 10 18* Karlstadt 15.0 0.61 0.37 0 CEM I 42.5 R 19* Mergelstetten 10.0 0.76 0.37 urea-glyoxylic 0.23 CEM I 42.5 acid N polycondensate 20 Mergelstetten 10.0 0.76 0.37 Sokalan PA 20 0.23 CEM I 42.5 N 21 Mergelstetten 10.0 0.76 0.37 Sokalan PA 15 0.23 CEM I 42.5 N Comp. Dosage Open strength Na.sub.2CO.sub.3 Dosage [wt.-%] time [MPa] # [wt.-%] Polyol [wt.-%] Dispersant .sup.[1] [min] 3 h 24 h 1* 0.90 Glycerol 0.30 Master Suna 0.20 15 10.8 19.7 SBS 8000 2* 0 Master Suna 0.13 20 0 14.8 SBS 8000 3* 0 Master Suna 0.20 <5 0 0 SBS 8000 4* 0 Master Glenium 0.30 <5 0 0 ACE 30 5* 0 Master Glenium 0.30 <5 0 0 ACE 30 6* 0 Master Glenium 0.30 <5 0 0 ACE 30 7* 0.90 Glycerol 0.30 Master Suna 0.20 90 10.6 21.9 SBS 8000 8 0.90 Glycerol 0.30 Master Suna 0.15 40 11.7 13.4 SBS 8000 9* 0 Glycerol 0.30 Master Suna 0.20 <5 3.3 3.6 SBS 8000 10* 0.90 Master Suna 0.12 30 5.2 8.1 SBS 8000 11* 0 Master Suna 0.13 30 0 24.0 SBS 8000 12* 0 Master Suna 0.20 <5 0 0 SBS 8000 13* 0.90 Glycerol 0.30 Master Suna 0.15 70 13.0 19.8 SBS 8000 14 0.90 Glycerol 0.30 Master Suna 0.11 80 13.2 25.9 SBS 8000 15 0.90 Glycerol 0.30 Master Suna 0.12 80 11.0 24.6 SBS 8000 16 0.90 Glycerol 0.30 Master Suna 0.26 20 15.5 15.4 SBS 8000 17 0.90 Sucrose 0.30 Master Suna 0.26 50 10.4 n.d. SBS 8000 .sup.[2] 18* 0.9 Glycerol 0.30 Master Suna 0.26 <5 10.4 n.d. SBS 8000 19* 0.37 Glycerol 0.31 Master Suna 0.13 60 7.8 31.5 SBS 8000 20 0.37 Glycerol 0.31 Master Suna 0.09 40 7.1 26.9 SBS 8000 21 0.37 Glycerol 0.31 Master Suna 0.09 50 7.3 28.1 SBS 8000 *comparative example .sup.[1] doseage calculated as active substance .sup.[2] n.d. = not determined

[0269] Construction Research & Technology GmbH The inventive mixes show rapid strength development once setting commences. Hence, the open time largely corresponds to the setting time.

[0270] It is evident that the carbonate source and the polyol act in a synergistic fashion, evidenced by comparison of examples with both compounds and examples lacking one of the two (e.g., comparison of examples 8 to 10).