Search

EP-4204381-B1 - SET CONTROL COMPOSITION FOR CEMENTITIOUS SYSTEMS

EP4204381B1EP 4204381 B1EP4204381 B1EP 4204381B1EP-4204381-B1

Inventors

  • LORENZ, KLAUS
  • BANDIERA, Massimo
  • HIMMELEIN, Sabine
  • SACHSENHAUSER, Bernhard

Dates

Publication Date
20260506
Application Date
20210825

Claims (15)

  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 α,β-ethylenically unsaturated carboxylic acids; and copolymers of at least one α,β-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 having a molecular weight of 500 g/mol or lower, 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·L -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 or 2, 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 any one of the preceding claims, 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 any one of the preceding claims, wherein the polyol is selected from sugar alcohols, in particular glycerol, and saccharides.
  6. The composition according to any one of claims 1 to 4, 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 2 aqueous solution, is titrated with a 0.5 mol/L CaCl 2 aqueous solution at 20 °C, inhibits precipitation of calcium aluminate up to a calcium concentration of 75 ppm, preferably 90 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): wherein X is wherein R is -CH 2 OH, -NH 2 , n is an integer from 1 to 4, m is an integer from 1 to 8.
  8. The set control composition according to any one of the preceding claims, 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, such as Al 3+ , Fe 3+ or Fe 2+ , 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 Al(OH) 4 - , 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 α,β-ethylenically unsaturated carboxylic acids; and copolymers of at least one α,β-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, 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 having a molecular weight of 500 g/mol or lower, and mixtures thereof; iv-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·L -1 or more at 25 °C, and organic carbonates, in a weight ratio of iv-b) to iv-a) in the range of 0.1 to 10; iv-c) a polyol having at least 3 alcoholic hydroxyl groups in its molecule, in a weight ratio of iv-c) to iv-a) in the range of 0.2 to 4; 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.-%, preferably 0.3 to 0.6 wt.-%, and - iv-c) in an amount of 0.2 to 2.5 wt.-%.
  11. The construction composition according to claim 9 or 10, 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 any one of claims 9 to 11, 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 any one of claims 9 to 12, wherein the extraneous aluminate source ii) is selected from non-calciferous aluminate sources, such as aluminum(III) salts, aluminum(III) complexes, crystalline aluminum hydroxide, amorphous aluminum hydroxide; and calciferous aluminate sources such as high alumina cement, sulfoaluminate cement or synthetic calcium aluminate mineral phases.
  14. The construction composition according to any one of claims 9 to 13, wherein the sulfate source iii) is a calcium sulfate source.
  15. The construction composition according to any one of claims 9 to 14, in freshly mixed form, wherein the ratio of water to cementitious binder i) is in the range of 0.2 to 0.7.

Description

The present invention relates to a set control composition for cementitious systems and a construction composition comprising the set control composition. It is known that dispersants are added to aqueous slurries or pulverulent hydraulic binders for improving their workability, i.e. kneadability, spreadability, sprayability, pumpability or flowability. Such admixtures are capable of preventing the formation of solid agglomerates and of dispersing the particles already present and those newly formed by hydration and in this way improving the workability. This effect is utilized in the preparation of construction compositions which contain hydraulic binders, such as cement, lime, gypsum, hemihydrate or anhydrite. In order to convert the pulverulent binders into a freshly mixed processible form, substantially more mixing water is required than would be necessary for the subsequent hydration and hardening process. The voids formed in the concrete body by the excess of water which subsequently evaporates lead to poor mechanical strength and resistance. In order to reduce the excess proportion of water at a predetermined processing consistency and/or to improve the workability at a predetermined water/binder ratio, admixtures are used which are generally referred to as water-reducing agents or plasticizers. Upon hydration of the cementitious system, generally ettringite is generated in a rapid reaction. This reaction is responsible for the development of early compressive strength of the cementitious composition. However, the newly formed minute ettringite crystals tend to deteriorate the workability or flowability of the cementitious composition. It has been known to add set control agents or retarders to the composition in order to delay the reaction and improve workability. The retarders delay the hydration onset by inhibiting the dissolution of the reactive cement components, in particular aluminates, and/or by masking the calcium ions thereby slowing down the hydration reaction. US 5,792,252 relates to cement admixtures containing an alkali metal carbonate and a mono- or di-carboxylate acid or alkali metal salt thereof or an alkali metal salt of a tricarboxylic acid. US 4,175,975 relates to water-soluble salts of low-molecular weight polyacrylic acids functioning with inorganic salts to reduce water demand of dispersed inorganic solids, such as Portland cement. WO 2019/077050 describes a set control composition for cementitious systems comprising an amine-glyoxylic acid condensate and at least one of a borate source and a carbonate source. Under certain conditions, the amine-glyoxylic acid condensate may be susceptible to hydrolysis. There is a need for further set control compositions for cementitious systems. In particular, there is a need for set control compositions that effectively improve workability of cementitious systems for prolonged periods of time without compromising early compressive strength. In particular the compositions should 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 above problems are solved by a set control composition for cementitious systems comprising a) a retarder selected from (a-1) polymeric polycarboxylic acids selected from homopolymers and copolymers of α,β-ethylenically unsaturated carboxylic acids; and copolymers of at least one α,β-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, more preferably 5.0 to 17.0 meq/g, most preferably 5.0 to 14.0 meq/g, and having a molecular weight 25,000 g/mol or less, preferably in the range of 1,000 to 25,000 g/mol, 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 having a molecular weight of 500 g/mol or lower, 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·L-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, andd) a dispersant. By the term polymeric polycarboxylic acid, as used herein, is meant a polymeric compound constituted of monomeric units incorporating carboxylic acid functionalities, and, optionally, further monomeric units. Although the above ingredients a) through d) have been used individually or as subcombinations, lacking at least one of the above ingredients, it has surprisingly been found that a combination of all ingredients a), b), c) and d) according to the invention act in a syne