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
  • C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
  • C04B20/10—Coating or impregnating
  • C04B20/1055—Coating or impregnating with inorganic materials
  • C04B20/1066—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
  • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
  • C04B14/02—Granular materials, e.g. microballoons
  • C04B14/30—Oxides other than silica
  • C04B14/305—Titanium oxide, e.g. titanates
• • 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
  • 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
  • C04B40/0042—Powdery mixtures

Definitions

• the invention relates to the use of a pulverulent composition which comprises titania and an inorganic binder to increase the early strength of products prepared therewith .
• the titania is used to obtain colour and brilliance of special concretes. It is especially explained that the compressive strength of concretes is not influenced by the titania.
• JP2000117117 a mixture is disclosed which comprises 100 parts by weight of cement and 10 to 150 parts by weight of titania .
• a coating composition for concrete is, which of white cement and comprises up to 3% by weight of titania .
• titania is only disclosed as a photocatalytically active substance in cement mixtures.
• the invention relates to the use of a pulverulent composition which comprises an inorganic binder and, based on the binder, 0.25 to 5% by weight of finely divided titania, for the preparation of products having high early strength.
• the content of titania is 0.25 to 2% by weight, a content of 0.25 to 1% by weight being particularly preferred.
• a product having high early strength comprising inorganic binder is here to be understood as meaning a product which at any desired point in time in the first 48 hours of hardening of the product achieves strengths which are at least 30% higher than the reference value of a product without titania.
• an inorganic binder inorganic substances processable in the plastic state are meant, which in the course of a certain time harden and at the same time firmly cement other substances to one another, for example relatively coarse or relatively fine aggregates.
• the inorganic binders according to the invention include hydraulic binders which spontaneously harden in the presence of water (e.g. cement, hydraulic limes), latent hydraulic binders which exhibit solidification reactions only after a pretreatment, pozzolanic materials which react to give stable products in the presence of water and calcium hydroxide (e.g. silica dust), non-hydraulic binders which only harden in air (e.g. gypsum plaster, anhydrous binders, magnesia binders, non- hydraulic mortars, phosphate binders and water glass) .
• hydraulic binders which spontaneously harden in the presence of water
• latent hydraulic binders which exhibit solidification reactions only after a pretreatment
• pozzolanic materials which react to give stable products in the presence
• hydraulic binders such as cement and hydraulic limes
• Finely divided titania is to be understood as meaning one which has a BET surface area of 20 to 400 m 2 /g.
• a titania can be employed which has a BET surface area of 40 to 120 m 2 /g.
• Particles of this type can be produced, for example, by flame oxidation or flame hydrolysis.
• oxidizable and/or hydrolysable starting substances are as a rule oxidized or hydrolysed in a hydrogen-oxygen flame.
• Suitable starting substances are organic and inorganic substances.
• titanium tetrachloride is particularly suitable.
• the particles of the titania powder thus obtained are as far as possible pore-free and have free hydroxyl groups on the surface.
• a highly suitable, commercially obtainable titania powder is, for example, AEROXIDE® TiO 2 P25, Degussa, having a BET surface area of 50 ⁇ 15 m 2 /g. Furthermore, the titanias disclosed in WO2005/054136 having a very narrow distribution of the primary particle diameters can advantageously be used.
• mixed oxide powders which, in addition to titania as the main constituent, contain a further metal oxide.
• These can be, for example, titanium- silicon (for example from DE-A-4235996) , titanium-aluminium (for example from the German patent application having the application number 102004062104.7 of 23 December 2004) or titanium-zirconium mixed oxide powders, for example from the German patent application having the application number 102004061702.3 of 22 December 2004 or doped titania powders as disclosed in EP-A-1138632.
• the titania or the titanium mixed oxide powder can also be employed in surface-modified form.
• the following silanes, individually or as a mixture, can be employed for this:
• Cyclic polysiloxanes D3, D4, D5 where D3, D4 and D5 is understood as meaning cyclic polysiloxanes having 3, 4 or 5 units of the type -0- Si (CH 3 ) 2 , e.g. octamethylcyclotetrasiloxane D4
• R alkyl, aryl, (CH 2 ) n -NH 2 ,H
• R' alkyl, aryl, (CH 2 ) n -NH 2 ,H
• R" alkyl, aryl, (CH 2 ) n -NH 2 ,H
• R'" alkyl, aryl, (CH 2 ) n -NH 2 , H
• the following substances can be employed as surface modification agents: octyltrimethoxysilane, octyltriethoxysilane, hexamethyldisilazane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, dimethylpolysiloxane, glycidyloxypropyltrimethoxysilane, glycidyloxypropyltriethoxysilane, nonafluorohexyl- trimethoxysilane, tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, aminopropyltriethoxysilane .
• octyltrimethoxysilane, octyltriethoxysilane and dimethylpolysiloxanes can be employed.
• a suitable surface-modified titania powder is, for example, AEROXIDE ® TiO 2 T805, Degussa, having a BET surface area of 45 ⁇ 10 m 2 /g and a carbon content of 2.7 - 3.7% by weight.
• a pulverulent composition can also be used in which titania is present sprayed onto the inorganic binder.
• the moistness of the composition in comparison to the moistness of the composition before spraying on the dispersion increases by at most 5% and particularly preferably at most 1.5%.
• the inorganic binder can have a moistness of 2%, after spraying of at most 7% and particularly preferably at most 3.5% moistness.
• the spraying can be carried out by means of atomization of aqueous dispersions according to processes known to the person skilled in the art.
• the dispersions are highly filled, aqueous dispersions of small particle size. Titania dispersions are particularly preferred, having a titania content of at least 30% by weight, based on the dispersion. Furthermore, those dispersions are preferred in which the titania particles have an average aggregate diameter in the dispersion of not more than 2 ⁇ m. Particularly preferably, dispersions having an average aggregate diameter of less than 300 nm can be employed.
• the pH of the dispersion is preferentially 2 to 4 or 9 to 13. However, dispersions in the range from 4 to 9 can also be employed. The pHs are adjusted by addition of acids or bases.
• the dispersions can furthermore contain additives which counteract sedimentation and reagglomeration . Acids, bases and/or additives should be chosen such that no adverse interactions occurs with the constituents of the hydraulic binder. As a rule, the liquid phase of the dispersion is aqueous .
• Table 1 shows suitable dispersions by way of example.
• the median values of the particle size distribution (d 5 o) were determined by means of dynamic light scattering using a measuring instrument from Horiba (LB 500) .
• titania dispersion for example, VP Disp W 740 X (40% by weight of TiO 2 , d 50 ⁇ 0.2 ⁇ m, pH 6-9) and VP Disp W 2730 X (30% by weight of TiO 2 , d 50 ⁇ 0.1 ⁇ m) .
• TiO 2 -2 titania powder according to WO2005/054136, Example A7, BET surface area 91 m 2 /g.
• pigmentary titania BET surface area ⁇ 10 m 2 /g.
• silicon-titanium mixed oxide according to DE-A- 102004001520, Example 12, BET surface area 43 m 2 /g, content of titania 49% by weight, content of silica 51% by weight.
• TiO 2 dispersion 1 (aqueous) TiO 2 BET surface area:
• An inorganic binder (CEM I 52.5R HS/NA from Holcim) containing 1.5% by weight of the cement of AEROXIDE® TiO 2 P25 is first mixed intensively in a powder mixer. Using this pulverulent composition, a standard mortar (water-cement value 0.45) is prepared according to DIN EN 196. After 24 h and 48 h, the compressive strength of the mortar is measured on prisms of size 1 x 1 x 4 cm following DIN 1164. The experiment is repeated without use of titania. The results of the comparison are shown in Table 1.
• Pulverulent compositions of inorganic binder (CEM I 42.5 R, Buderus) and various titanias (see Table 2) are first prepared by intensive blending in a powder mixer. All preparations contain an amount of titania of 0.5% by weight of the cement. Using this pulverulent composition, a standard mortar (water-cement value 0.45) is prepared according to DIN EN 196. After 24 h, the compressive strength of the mortar is measured on prisms of size 1 x 1 x 4 cm following DIN 1164. The experiment is repeated without use of titania.
• Table 2 shows that as a result of the use of finely divided titania a very considerable increase in the early strength can be achieved. This turns out to be higher, the higher the specific surface area. As a result of the use of low- surface area, pigmentary titania, however, only a slight increase in the early strength is achieved. The early strength can also be markedly increased by the use of finely divided titania-containing mixed oxides.
• Pulverulent, titania-containing compositions are first prepared by spraying various titania dispersions (see Table 3) onto CEM I 42.5 R (Buderus) in an intensive mixer (15 1 volume, Maschinenfabrik Gustav Eirich GmbH & Co KG) . Using this pulverulent composition, a standard mortar (water- cement value 0.45) is prepared according to DIN EN 196. After 24 h, the compressive strength of the mortar is measured on prisms of size 1 x 4 x 4 cm following DIN 1164 The experiment is repeated without use of titania.
• titania dispersion 1 &) titania dispersion 2 ; based on cement;
• Table 3 shows that a marked increase in the early strength can also be achieved using compositions which comprise a sprayed-on titania dispersion.
• Example 4 Investigation of the strength-increasing action of a titania addition in standard mortar samples
• the cement and Aeroxide TiO 2 P25 are first mixed with intensive mixing.
• the test articles are then prepared according to DIN EN 196 (water-cement value: 0.45) .
• the strengths of the mortar prisms (1.5 x 1.5 x 6.0 cm) are determined according to DIN 1164.
• Table 4 Flexural/compressive strengths (in N/mm 2 ) as a function of the amount of titania added (in % by weight)
• Table 4 shows that very low concentrations of 0.1% by weight of cement only cause a slight increase in the early strength. On addition of 0.5% by weight of titania based on the binder content, however, a considerable increase in strength of the samples is to be observed.
• the strengths measured in Table 4 after day 1 also show clearly that the early strength cannot always be increased further as a result of increase in the titania concentration.
• the strength after 2 days (2d) decreases noticeably even at concentrations of 5%. In summary, it can be said that there is an optimum between amounts of titania which are not yet active and amounts of titania which no longer increase early strength.
• FIG 1 shows the hydration course of CEM 42.5 R I (Curve a) and the pulverulent composition of CEM 42.5 R I with a 2% by weight titania addition (Curve b) . It is seen that the heat development per time is markedly higher in the initial peak of the sample with a titania addition. Furthermore, an earlier increase and decrease in the evolution of heat in the acceleration phase as a result of a shorter induction period is to be seen, whereby the acceleration of the hydration of the cement and thus the early strength-increasing action as a result of titania addition is demonstrated.
• FIG. 2 shows the hydration course of CEM 42.5 R I (Curve a) and CEM 42.5 R I with a 2% by weight titania addition (Curve b) .
• the amount of heat given off after 24 hours is nearly identical in both samples.
• the earlier heat development in the acceleration phase in the case of the sample with a titania addition is also clearly to be seen here .

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Civil Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Paints Or Removers (AREA)
• Catalysts (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=38134203

Family Applications (1)

Country Status (4)

Families Citing this family (1)

Family Cites Families (6)

• 2006
  • 2006-05-05 DE DE102006020878A patent/DE102006020878A1/de not_active Withdrawn
• 2007
  • 2007-04-04 EP EP07727753A patent/EP2018355A1/de not_active Withdrawn
  • 2007-04-04 WO PCT/EP2007/053282 patent/WO2007128630A1/en active Application Filing
  • 2007-05-02 TW TW096115606A patent/TW200815303A/zh unknown

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events