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
  • C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
  • C04B24/12—Nitrogen containing compounds organic derivatives of hydrazine
  • C04B24/123—Amino-carboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F7/00—Compounds of aluminium
  • C01F7/78—Compounds containing aluminium and two or more other elements, with the exception of oxygen and hydrogen
  • C01F7/784—Layered double hydroxide, e.g. comprising nitrate, sulfate or carbonate ions as intercalating anions
  • C01F7/785—Hydrotalcite
• • 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, shrinkage compensating agents
  • C04B22/06—Oxides, Hydroxides
• • 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
  • C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
  • C04B40/0028—Aspects relating to the mixing step of the mortar preparation
  • C04B40/0039—Premixtures of ingredients
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
  • C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
  • C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
  • C23F11/14—Nitrogen-containing compounds
  • C23F11/141—Amines; Quaternary ammonium compounds
  • C23F11/143—Salts of amines
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2002/00—Crystal-structural characteristics
  • C01P2002/20—Two-dimensional structures
  • C01P2002/22—Two-dimensional structures layered hydroxide-type, e.g. of the hydrotalcite-type
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2002/00—Crystal-structural characteristics
  • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
  • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2002/00—Crystal-structural characteristics
  • C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
  • C01P2002/82—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by IR- or Raman-data
• • 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
  • C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
  • C04B2103/60—Agents for protection against chemical, physical or biological attack
  • C04B2103/61—Corrosion inhibitors
• • 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
  • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
  • C04B2111/00482—Coating or impregnation materials
  • C04B2111/00525—Coating or impregnation materials for metallic surfaces
• • 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
  • C04B2111/20—Resistance against chemical, physical or biological attack
  • C04B2111/24—Sea water resistance
• • 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
  • C04B2111/20—Resistance against chemical, physical or biological attack
  • C04B2111/26—Corrosion of reinforcement resistance

Definitions

• the invention is directed to a corrosion inhibition system for reinforced concrete, to the use of an intercalated double layered hydroxide as corrosion inhibitor, to a process for inhibiting corrosion of reinforced concrete, and to the use of the corrosion inhibition system in reinforced concrete.
• reinforced concrete when reinforced concrete is exposed to an environment rich in chloride ions (for instance induced by sea salts, de-icing salts, etc.), the chloride ions slowly penetrate the concrete through the porous structure and accumulate. When a sufficiently high concentration of chloride ions is reached, the chloride ions can promote corrosion of the embedded reinforcement in the presence of oxygen and moisture at the reinforcement- concrete interface by damaging the passivation layer.
• de-icing salts on roadways is probably one of the primary causes of premature failure of reinforced concrete bridge decks, roadways, and parking garages.
• reinforced concrete may benefit from the use of epoxy-coated, hot dip galvanised or stainless steel
• Zinc phosphate can slowly react with the corroding agent (e.g. alkali), thereby forming a stable hydroxyapatite layer.
• Further measures of corrosion protection include the use of penetrating sealants. These are applied some time after curing of the concrete. Sealants include paint, plastic foams, films and aluminium foil, felts or fabric mats sealed with tar, and layers of bentonite clay.
• US-A-2007/0 022 916 describes a controlled release formulation for a cement-based composition, in which an admixture for the cement-based composition (such as a corrosion inhibitor) is intercalated in a layered inorganic material.
• an admixture for the cement-based composition such as a corrosion inhibitor
• de-intercalation or release of the admixture can be actively programmed through controlled chemistry involving, for example, type of layered inorganic material, charge density, concentration, and/or pH. No specific corrosion inhibitors are mentioned.
• CN-A-1 948 207, JP-A-4 154 648, and JP-A-9 142 903 describe corrosion inhibition systems based on hydrotalcites that are directly incorporated in the mortar mix and/or concrete.
• These publications all refer to hydrotalcites intercalated with inorganic corrosion inhibitors.
• inorganic corrosion inhibitors are, however, very mobile and leach quickly. In addition, they are environmentally unfriendly and/or partly poisonous.
• JP-A-10 231 157 mentions the use of amines and acids as two separate parts of an anti- corrosion system for inhibiting concrete.
• the amines and acids are not intercalated in the inorganic ion exchange substance.
• the invention is based on the insight that the use of specific corrosion inhibitors intercalated in a layered double hydroxide is particularly advantageous in view of their limited leaching, their ease of degradation when exposed to the environment and particularly in view of their efficiency as corrosion inhibitor.
• the invention is directed to a corrosion inhibition system for concrete reinforced with a corrosion sensitive
• Y is NH 2 or COO ;
• R is an optionally substituted aromatic, aliphatic, or cycloaliphatic moiety having 5-18 carbon atoms.
• the corrosion inhibition system of the invention is based on layered double hydroxide particles that are intercalated with organic anions capable of effectively protecting the reinforced concrete against corrosion.
• the intercalated layered double hydroxides can advantageously be applied directly as an aqueous emulsion, in the form of a spray, on the corrosion sensitive reinforcement material that is employed in the concrete, or alternatively be mixed in the concrete mortar. There is no need for using a paint or polymeric carrier.
• the intercalated layered double hydroxides are able to free the corrosion protective organic anions as a response to the increase of the chloride ion concentration in the aqueous media close to the reinforcing steel.
• the corrosion inhibition system of the invention is able to work as a smart storage of active corrosion protective agent.
• the corrosion inhibition system of the invention keeps the chloride ion concentration below the limit that is considered dangerous due to the damage induced on the passivated oxide layer of the steel, preferably during the concrete service life.
• the invention is relates to the use of layered double hydroxides. These are typically capable of ion exchange.
• ion exchanger compounds comprise a host structure with one or more guest species that can be exchanged by other species of the surroundings.
• the host is formed by hydroxide layers of divalent metallic cations that are partly substituted by trivalent cations, therefore having a net positive charge. Electrical neutrality is obtained by anions that are present between the layers, which are the guest or exchangeable species.
• the host has open channels that can accommodate anions and solvent molecules. It can also incorporate cations in such channels in order to maintain electrical neutrality of the solid.
• the ion exchange is illustrated by the equation below. Initially, the system LDH-Inh has inhibitor anions (Inh) in the channels. In contact with an electrolyte that contains e.g. chloride anions, the exchange reaction is ruled by an equilibrium constant and an exchange isotherm, which can be measured: LOH-Inh + NaCl (aq) ⁇ LDH-Cl + Nalnh ⁇
• LDH-ira/i is the synergistic corrosion active system consisting of chloride scavenger (the layered double hydroxide) and active corrosion protective agent (the corrosion inhibitor according to formula (I)), and LDH-Cl is the layered double hydroxide with chloride in the layered double hydroxide channels.
• the anionic counter ions that are originally present between the layers of the double layer hydroxide (and compensate for the net positive charge) are exchanged (substituted) for compounds of general formula (I).
• distinct double layer hydroxide particles are linked together via compounds of general formula (I) to form larger aggregate particles.
• the layered double hydroxide is preferably identified by the general formula M 2 - X M 3+ X ⁇ OH) 2 ((A" " ) m )_ * _ ⁇ y H 2 0 ,
• M 2+ represents one or more divalent metal cations; 3+ represents one or more trivalent metal cations;
• i° " ) m ) ⁇ is an interlayer n m
• anion with valence n n is an integer in the range of 1-4; m is an integer in the range of 1-5000. In case m is two or more, the anion is a polyanion having multiple repeating units A n ⁇ .
• x is a value in the range of 0.1-0.5; and y is a is an integer in the range of 0-20.
• the anion may a polyanion, having multiple repeating units A n ⁇ .
• 2+ is preferably Ni 2+ , Zn 2+ , Mn 2+ , Ca 2+ , Mg 2+ , Fe 2+ , or mixtures thereof.
• Especially preferred divalent metal cations are Mg 2+ , Ca 2+ , Fe 2+ , and Zn 2+ .
• M 3+ is preferably Al 3+ , Ga 3+ , Fe 3+ , Cr 3+ , or mixtures thereof.
• Especially preferred trivalent metal cations are Al 3+ and Fe 3+ .
• the value x is preferably in a range of 0.1-0.5, more preferably, x is in the range of 0.17-0.33.
• the molar ratio between M 2+ and 3+ can be between 2 and 4, and is preferably about 2.
• the anion ([A n ⁇ ) m ) ⁇ has n m a direct influence on the basal spacing between the layers of the layered double hydroxide.
• ⁇ " " D— i s an inorganic anion more preferably selected from the group
• n is an integer in the range of 1-4.
• the layered double hydroxide is a hydrotalcite, more preferably a hydrotalcite having Mg(OH)2 brucite layers wherein part of the Mg 2+ ions are substituted with Al 3+ ions.
• the layered double hydroxides are intercalated with compounds according to general formula (I). It is preferred that R in formula (I) is (CH2)n wherein n is an integer in the range of 5- 18, preferably 5- 12. Examples of such compounds include 4-aminobenzoate and 11-aminoundecanoate. Without wishing to be bound by theory, the inventors believe that the longer aliphatic chains result in somewhat lower water solubility, which in turn provides resistance against quick leaching.
• Y in formula (I) is NH2.
• Layered double hydroxides that are intercalated with these compounds can be prepared using a co-precipitation method at controlled pH, and under inert atmosphere to avoid the contamination with carbonate ions.
• the thus prepared layered double hydroxides can be intercalated with compounds according to general formula (I) at a level ranging between 1.5 and 4.5 meq/g.
• the invention is directed to the use of an intercalated double hydroxide as defined herein as corrosion inhibitor for concrete reinforced with a corrosion sensitive reinforcement.
• the corrosion sensitive reinforcement is usually steel, typically in the form of steel plates, steel bars, steel fibres, steel rods, steel fabric, steel wire, welted steel wire netting, welted steel fabric, and/or mesh steel reinforcement.
• the invention is directed to a process for corrosion in concrete comprising corrosion sensitive reinforcement, said process comprising:
• the intercalated layered double hydroxide can be applied onto the corrosion sensitive reinforcement by spraying, coating, dipping, or the like. To this end, for instance, an aqueous emulsion of the intercalated layered double hydroxide can be prepared. Alternatively or additionally, the intercalated layered double hydroxide can be directly admixed with the concrete mortar components.
• the invention does not require a polymeric carrier, which in the prior art was essential for applying the corrosion inhibition system and protected prior art corrosion inhibitors from quick leaching.
• the intercalated layered double hydroxide When admixed with the concrete mortar, the intercalated layered double hydroxide can be applied in a concentration of 0.5-20 wt.% of intercalated layered double hydroxide based on dry weight of the concrete mortar, preferably 1-5 wt.%.
• the concrete mortar has a water/cement ratio in the range of 0.2-0.7.
• the invention may be applied to reinforced concrete in structures exposed to seawater, or in structures exposed to de-icing salts. Such use is particularly advantageous, because in such structures the reinforced concrete is usually exposed to exceptionally high chloride ion concentrations.
• the invention provides a smart and solution in reducing or preventing corrosion of the corrosion sensitive reinforcement under such conditions.
• Electrochemical measurements were carried out by the Open Circuit Potential (OCP) according to the ASTM C 876 standard test method for half-cell potentials, measuring the OCP versus a saturated calomel electrode. According to this norm, potentials more positive than -120 mV indicate that corrosion process will not occur in the reinforcement bars with a probability higher than 90 %. A potential between -120 mV and -270 mV means that the corrosion probability is uncertain; while a potential more negative than -270 mV corresponds to a corrosion process probability higher than 90 %.
• OCP Open Circuit Potential
• the first reflection in the low angle region corresponds to the interlayer distance.
• the IR spectra show characteristic frequencies associated with the presence with of the corresponding anions (around 1350 cm 1 for the inorganic anions and in the range 1400-1600 cm 1 for the organic anions). The presence of these characteristic absorption bands with the X-ray diffraction results confirms the formulations proposed.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Ceramic Engineering (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Inorganic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Preventing Corrosion Or Incrustation Of Metals (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)

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• 2009
  • 2009-11-25 EP EP09177115A patent/EP2327670A1/de not_active Withdrawn
• 2010
  • 2010-11-25 EP EP10787580A patent/EP2504292A1/de not_active Withdrawn
  • 2010-11-25 WO PCT/NL2010/050791 patent/WO2011065825A1/en active Application Filing

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