EP1963239A2

EP1963239A2 - Use of an additive as an agent aiding in the removal of formwork

Info

Publication number: EP1963239A2
Application number: EP06829223A
Authority: EP
Inventors: Guillaume Francqueville; Nicolas Moins; Denis Le Cheviller; Guy Laurent; Uwe Holland
Original assignee: Construction Research and Technology GmbH
Current assignee: Construction Research and Technology GmbH
Priority date: 2005-12-01
Filing date: 2006-11-30
Publication date: 2008-09-03
Also published as: JP2009517317A; WO2007062854A2; DE102005057507A1; CN101321711A; WO2007062854A3; AU2006319360A1

Abstract

Disclosed is the use of an additive as an agent aiding in the removal of formwork when using chemical construction materials. Suspensions of inorganic particles based on aluminum oxide and/or silicon oxide, polymeric (meth)acrylic acid derivatives, saponified polyvinyl alcohols, or copolymers or terpolymers that contain water-soluble sulfonic groups and have a mean molecular weight ranging from 50,000 to 20,000,000 g/mol can be used as representatives of said additive. Preferably, aluminum-modified colloidal silica or (meth)acrylamide, methyl acrylate, or cyclohexyl acrylate is used, for example. (Partly) water-soluble polyvinyl alcohols in a partially saponified form, i.e. at a saponification rate of 60 to 96 percent, are also suitable. The respective additive can be added to the mixing water or be added to the chemical construction material after being dissolved in the dispersing agent or simultaneously with the dispersing agent. Alternatively, the additive can be applied to the area of the formwork adjoining the chemical construction material before said material is introduced into the formwork. The novel use as an agent aiding in the removal of formwork results in a simplified formwork removal process or easier pulling away of the formwork parts during in-line production when manufacturing precast concrete parts as the adhesive forces are reduced.

Description

Use of an additive as a decoating aid

description

The present invention is the use of an additive as a formwork aid in the use of building chemical compositions.

From a cost point of view, more and more processes within the construction industry, which until now have been carried out predominantly manually on site at the construction site, have been replaced by rationalization measures, for example in the form of industrial prefabrication. A variety of methods are used, which are supported by varying individual measures. The main focus is on the design of the overall process and related process optimization, whereby a wide range of special additives that influence the processability of the construction chemical mass and the quality of the construction product is used.

An important factor in the industrial prefabrication of concrete components is the time that must be minimally spent in order to leave the corresponding manufactured articles in the formwork. The shorter the formwork period, the more efficient and cost-effective the production is.

Thus, for example, in the production of green-strength concrete parts, which can also be provided with prestressed steel reinforcements, processes are used in which extrusion processes or a line production of components play an important role. In such processes, one of the main focus is on the adhesion of the manufactured body to the formwork used. Only by an absolute minimization of the adhesion forces can those forces that have to be spent for stripping the green concrete elements or for advancing the casing in the line production, keep so low that the number destroyed during stripping or Damaged components can be kept within a reasonable range with a correspondingly fast driving style and sufficiently good compaction of the construction chemical mass. The specialist on site is well aware of the fact that for this air entrainment agents often have to be used as an aid. By their use, however, the strength of the components is significantly reduced by the registered air on the other side. This should be counteracted by adapted process conditions, but this is predominantly a poor compromise.

Numerous documents are known from the prior art as to how building chemical compositions can be positively influenced by the addition of additives with regard to their processability and product properties. At this point, in addition to the already mentioned air entrainers, dispersants (flow agents), accelerators, retarders, stabilizers but also so-called fluidloss additives, rheology modifiers and anti-blooming agents may be mentioned as examples.

Also, many representatives of silica derivatives have long been used in the construction industry for the production of concrete compounds.

Thus, from US 3,135,617 a cement mortar is known which contains 0.25 to 2 wt .-% of fumed silica. Among the properties of the mortar mentioned therein are also called a high early strength and the avoidance of so-called bleeding.

In the German patent DE 25 10 224 a process for the production of concrete objects using a special concrete additive is described, which contributes to increase the early strength. This patent also includes a concrete admixture which is a stable suspension of 10 to 50% by weight of finely divided silica having a preferred particle diameter of colloidal silica <0.1 μm.

To accelerate the setting of a hydraulic and mineral binder containing an additive having hydrophilic groups is according to WO 2004/002915 A2 calcium silicate hydrate or else a silica with high surface area added. Both accelerators may additionally contain alkali metals.

A concrete composition which, in addition to the hydraulic binder, also contains aggregates, water, silica sol and a superplasticizer in the form of a polycarboxylate, is known from WO 01/90024 A1. The silica sol used here is cationically stabilized and has a particle size between 2 and 200 nanometers. Their use is intended to prevent bleeding and at the same time not affect the processability of the concrete composition too much. The European application EP 0 931 030 A1 describes a process for the production of concrete or mortar with increased early strength with a simultaneously good fatigue strength. Here, first, a mixture consisting of a hydraulic binder, aggregates, water and colloidal silica is prepared, wherein the relative standard deviation of the particle size of the colloidal silica is at least 30%.

International patent application WO 01/98227 A1 discloses a building material which comprises a hydraulic binder, water and an aluminum-modified colloidal silica, which is preferably a silica sol. It is stated in the specification that such building materials have improved strength and processability, in particular due to the aluminum-modified colloidal silicon constituents.

WO 01/98210 A1 claims a defined silica sol composition comprising a first silica sol component having a broad particle size distribution and a second silica sol component having a narrow particle size spectrum. Also included is the use of such compositions, as additives to concrete or mortar, as well as concrete and mortar compositions which, in addition to hydraulic binders, aggregates and water, also contain a silica sol composition of said grain size distributions. The use of colloidal silica components as additive to cementitious materials is described by WO 2004/035473 A1. The silica components used in this context must have been prepared by a specific process wherein at least one silane component is mixed with colloidal silica particles in the weight ratio of silane to silica component of about 0.003 to 0.2. The silica dispersion obtainable in this way has a silica content of at least 20% by weight.

Mixtures of silica with other additives are well known in the art.

Thus, the patent application US 2004/0127606 describes a hydraulic cement composition with improved bleeding resistance. This composition contains not only pozzolans but also polycarboxylate ethers, the term "pozzolans" also being able to cover fumed silica The European application EP 0 602 541 A1 describes a thixotropic and setting accelerating additive for hydraulic or latent hydraulic mixtures containing silicic acid esters as thixotropic agents Water resistance and a higher mechanical strength, self-leveling mortar compositions such as leveling compounds or leveling compounds are given, which contain calcium sulfate hemihydrate, lime and precipitated or fumed silica and reactive alumina (WO 96/20901 A1).

As already stated, the main disadvantage when stripping precast concrete parts is that the adhesion forces between the building chemical mass and the shuttering material can still not be sufficiently reduced so that damage or partial destruction of the components can be avoided.

The object of the present invention was therefore to provide an additive with which mixed-bodied masses can be better processed in the on-state and / or can be more easily switched off in the (partially) cured state. Of the the decisive aspect was to minimize the reject rate and to facilitate the shifting of the shuttering elements during line production. As far as possible, it should be possible to dispense with strength-reducing additives.

This object has been achieved by the use according to the invention of an additive containing at least one member selected from the series

1.1) suspension of inorganic particles based on aluminum and / or silicon oxide,

1.2) polymeric (meth) acrylic acid derivatives,

1.3) saponified polyvinyl alcohols, or

1.4) water-soluble sulfo-containing co- or terpolymers having a number average molecular weight of 50,000 to 20,000,000 g / mol

as a formwork aid when using chemical mixtures.

In addition to the complete fulfillment of the task, it was surprisingly found that, for example, by the addition of a silica sol as a preferred representative of the additive 1.1, the necessary initial force for the first movement of a precast concrete part in a form in the field of line production can be significantly reduced. Also, the pressing out of the (partially) cured product from the formwork is much easier compared to the prior art. In addition, due to this serious reduction of the forces required for locomotion or shuttering, the reject rate in the large-scale process could actually be significantly minimized while simultaneously improving the surface properties of the building structures. Also surprising was the fact that it is possible to dispense with further additives, such as, for example, air-entraining agents, with even the amount of hydraulic binder used being reduced, with simultaneously improved early and final strengths. This is all the more remarkable since every expert the importance of the influence of the amount of cement to be used on the final product price and the economics of the associated manufacturing process is well known.

Furthermore, it was not to be expected at all that the desired effects according to the task can be achieved both by inorganic and by organic compounds and their arbitrary mixtures. In addition, the respective additives are essentially not limited to strictly defined compounds, but rather that the respective representatives can be selected from an unsuspectedly large number of suitable compounds.

The present invention provides as preferred component 1.1 an aluminum-modified colloidal silica wherein the colloidal silica is in particular silica sol ("silica sol"), precipitated silica, silica gel and finely divided silica.

Particularly preferred are "stable dispersion or sol of amorphous silica" type having a preferred particle size of 0.001 to 100 microns, a particularly preferred particle size of 0.01 to 30 microns, and a most preferred particle size of 0.1 to 15 microns The term "colloidal silica" is considered in accordance with the present invention as defined by K. Her, as reported in "The Colloidal Chemistry of Silica" Chapter 4, Wiley & Sons (1979, p 312) Substantive component of the present invention.

According to the invention, component 1.2 should in particular be polymers of hydroxyalkyl (meth) acrylate, acrylamide, methacrylamide, 2-acrylamido-2-methylpropanesulfonic acid (AMPS), methyl methacrylate, methyl acrylate, butyl acrylate or cyclohexyl acrylate, which are particularly preferably in each case in part - or fully cross-linked form should be available.

Water-soluble or at least partially water-soluble polyvinyl alcohols, which should preferably be present in partially saponified form and which are particularly preferred have a saponification degree of 60 to 96%, are considered in the context of the present invention as preferred representatives of component 1.3. Particularly suitable are polyvinyl alcohols having a saponification degree of from 85% to 96%, particularly preferably from 90 to 96%. In general, the polyvinyl alcohols should have an average molecular weight between 20,000 and 80,000, preferably between 25,000 and 70,000, and particularly preferably between 30,000 and 65,000.

The water-soluble sulfo-containing co- or terpolymers which characterize the alternative additive 1.4 according to the invention are essentially known from the prior art, but their use according to the invention is not disclosed. Reference is made in particular to Offenlegungsschriften DE 199 26 611 A1 and DE 190 37 629 A1 and International Patent Application WO 2005/035603 A1, whose respective disclosures with respect to additive 1.4 are a substantial part of the present disclosure.

Preferred components 1.4 used in the context of the present invention are polymer compounds having the general composition

a) 3 to 96 mol% of groups of the formula (I)

CH ₂ CR ¹

(I) where R ¹ = hydrogen or methyl

R ² , R ³ , R ⁴ = hydrogen, aliphatic hydrocarbon radical having 1 to 6 C atoms, linear or branched, optionally with

Methyl groups substituted

phenyl

V = NH or oxygen

M = hydrogen, monovalent or divalent metal cation, ammonium or an organic amine radical n = 1 to 5 a = Vz or 1,

is 96 mol% of the formula (II)

(IIa) (IIb)

wherein W = -CO-, -CO (O) - (CH ₂ ) _X -, -CO-NR ² - (CH ₂ ) _X - x = 1 to 6 R ⁵ and R ⁶ = hydrogen, optionally substituted aliphatic

Hydrocarbon radical having 1 to 20 carbon atoms, linear or branched, cycloaliphatic hydrocarbon radical having 5 to 8 carbon atoms, aryl radical having 6 to 14 carbon atoms and mean

Q = hydrogen and -CHR ⁵ R ⁷ , and in the case of Q = HR ⁵ and R ⁶ in (IIb) together form a -CH ₂ - (CH ₂ ) _y- methylene group with y = 1 to 4, R ⁷ = Is hydrogen, aliphatic hydrocarbon radical having 1 to 4 C atoms, -COOH or -COOM ₃ and R ¹ , R ² , M and a have the abovementioned meaning, and or

c) 0.05 to 75 mol% of assemblies of the formulas (III)

CH ₂ - CR ¹ -

(DDLa) (mt>)

where Y =

SO ₃ ^e M _a ,

X = halogen, C 1 to C ₄ alkyl sulfate or d-bis

C ₄ alkyl sulfonate, and

R ¹ , R ² and R ³ , M and a are as defined above,

d) 0.01 to 50 mol% of groups of the formula (IV) CH ₂ CR ¹

(IV) where Z = -COO (C _m H _2m O) _n -R ⁹ , - (CH ₂ ) pO (C _m H _2m O) _n -R ⁹ , R ⁹ = H,

R 12 ¹ wherein at least one radical R ¹⁰ , R ¹¹ and / or R ¹² must be present, and a saturated or unsaturated, linear or branched, aliphatic hydrocarbon radical having 1 to 40 C atoms R ¹⁰ = H ₁ C ₁ -C ₄ -AlkVl- , Phenyl, benzyl, C ₁ -C ₄ -alkoxy,

Halogen, cyano, -COOH, -COOR ⁵ , -CO-NH ₂ , -OCOR ⁵ R ¹¹ = arylalkyl group with C ₁ -C ₁₂ -alkyl, linear or branched, and C ₆ -

C ₁₄ aryl radical R ¹² = alkylaryl group with C ₁ -C ₁₂ -alkyl, linear or branched, and C ₆

C-ι ₄ -aryl m = 2 to 4 n = O to 200 p = 0 to 20 and R ¹ and R ^{5 have the} abovementioned meaning.

In preferred embodiments, n = 1 to 150, more preferably 1 to 100, and P = 1 to 15, more preferably 1 to 10.

In specific variants of the present invention, up to 50 mol% of the components a) in component 1.4 are replaced by other sulfo-containing structural units derived from methallylsulfonic acid or allylsulfonic acid monomers. The component 1.4 can according to the present invention also from 30 to 80 mol%, preferably 35 to 70 mol%, of the assembly a), 5 to 55 mol%, preferably 10 to 45 mol% of the assembly b), 2nd to 30 mol%, preferably 5 to 25 mol%, of the assembly c) and / or 0.2 to 15 mol%, preferably 0.5 to 10 mol%, of the assembly d). The present invention comprises a further variant of component 1.4 which has a number-average molecular weight of 50,000 to 10,000,000 g / mol.

The proposed additive should find use as a formwork aid, in particular when using construction-chemical compositions containing at least one member of the series hydraulic binder, filler, accelerator and dispersing additive. Of course, the proposed additive can also be used according to the invention in building chemical compositions, which further contain functional additives. Particularly positive effects succeed with the use according to the invention in connection with construction chemical compositions containing as hydraulic binder cement, lime, gypsum, anhydrite or other calcium sulfate-based binder, with cements of type CEM I to CEM V and aluminate cements and any mixtures thereof as are particularly preferred. From the series of other ingredients of the construction mixture mass, the present invention takes into account dispersing additives in the form of a water reducer and / or a superplasticizer according to standard EN 934/2. With regard to the fillers also already mentioned representatives have been found to be particularly suitable, which have a particle size of 0.1 to 100 mm.

The breadth of uses according to the invention is reflected in various variants, which are claimed by the present invention as being preferred. Thus, the respective additive can be added to the mixing water and introduced with this in the bauchemische raw mass. However, it is also possible to dissolve the respective additive in a dispersant and / or to introduce the additive at the same time as the dispersant but separately from it. Alternatively or additionally, the additive which is to be used according to the invention as a formwork aid can also be applied to the boundary layer of the formwork prior to introduction of the construction chemical raw material into the formwork. In this case, it is particularly evident as a release agent to either easier to solve the partially or completely cured building chemical product from the formwork or to move the shuttering in the course of a line production without affecting the surface of the construction chemical product. Of course, the application of the new Entschalungshilfsmittels on the Formungswandung is the most economical, since in this case much smaller amounts are needed in comparison with the mixing in the construction chemical mass. On the other hand, the introduction of the additive serving as a release agent into the construction mixture mass can also have the advantage that the respectively used component 1.1, 1.2, 1.3 and / or 1.4 the processability or the properties of the cured product additionally positively influence, by the respective component unfolds their already known from the prior art additive effect, for example. As a condenser, retarder or dispersant.

Finally, a use variant is also included in the present invention, in which the additive is used as a formwork removal aid in the production of precast concrete parts, preferably for the production of green-strength-resistant and in particular prestressed precast concrete parts.

The amounts in which the particular additive is added to the construction chemical mass, of course, depend on the specific composition of the construction chemical mass; However, it is advisable to choose amounts which are between 0.001 and 1, 0 wt .-% and preferably between 0.01 and 0.5 wt .-%, each based on the total composition.

In summary, it should be noted that although the components 1.1 to 1.4 proposed as sheathing aids according to the present invention are largely known from the prior art regarding their ability to function as construction-chemical additives, they astonishingly coexist with their respective known ones Effect now especially in connection with the production of precast concrete parts or more generally components, in the production of formwork parts are used, have a completely new effect, which can be used especially to run known methods even more economical. Namely, the additives used in each case are amazingly able to reduce the adhesion forces acting at the interface between building chemical mass and formwork to such an extent that the formwork now removed without major damage or destruction of the component of this or in the Line production can be moved easier. Important in this context is above all the fact that with a delay of formwork parts previously known as negative larger adhesion forces now no longer need to be overcome, so that the parts easier on or slide together. The following examples illustrate the advantages of the present invention.

Examples

The switch-off test and the determination of the compressive strength DF after heat treatment are carried out according to the following procedure:

The concrete to be characterized is freshly prepared and transferred immediately after mixing in a corresponding Gleitform (open top and bottom mold of the corresponding molded part, which is closed at the front and provided at the rear with a removable closure) and compacted by appropriate vibration. The front side of the slipform is connected to a dynamometer by a steel cable and this with a corresponding hand crank. For shuttering of the molding of the rear closure of the slip formwork is removed and the remaining slip formwork by means of the hand crank forward pulled off from the mold body down. In this case, Fi describes the measurand of the dynamometer, which is needed to set the slipforming in motion for the first time; Ffb describes the measurand of the dynamometer in order to move the slipform at a constant speed.

Parallel to the filling of the slip form molds are filled to determine the compressive strength of concrete with the appropriate concrete, appropriately compacted and then heat treated for 5 h 30 min at 80 ⁰ C in the covered state. Part of the test specimen thus obtained is measured immediately after completion of the heat treatment; the remaining part is stored until the age of 28 days in standard climate and then measured accordingly.

Claims

claims

1. Use of an additive containing at least one member selected from the series

1.2) polymeric (meth) acrylic acid derivatives,

1.3) saponified polyvinyl alcohols, or

as a formwork aid when using chemical mixtures.

2. Use according to claim 1, characterized in that the component 1.1) represents an aluminum-modified colloidal silica, wherein the colloidal silica to silica sol ("silica sol"), precipitated silica, silica gel and finely divided silica, in particular of the type "stable Amorphous silica dispersion or sol "having a preferred particle size of 0.001 to 100 microns.

3. Use according to claim 1, characterized in that in the component 1.2) are polymers of hydroxyalkyl (meth) acrylate, acrylamide, methacrylamide, 2-acrylamido-2-methylpropanesulfonic acid (AMPS), methyl methacrylate, methyl acrylate, butyl acrylate or cyclohexyl acrylate, especially in each case in partially or fully cross-linked form.

4. Use according to claim 1, characterized in that the component 1.3) is selected from the series of water-soluble or partially water-soluble Polyvinyl alcohols, preferably in teilverseifter form and particularly preferably with a degree of saponification of 60 to 96%.

5. Use according to claim 1, characterized in that as component 1.4) polymer compounds are used having the general composition a) 3 to 96 mol% of the formula (I)

CH, - CR ¹

SO ₃ - M _a

(I)

wherein R ¹ = hydrogen or methyl

Methyl groups substituted

phenyl

V = NH or oxygen

M = hydrogen, monovalent or divalent metal cation, ammonium or an organic amine radical n = 1 to 5 mean,

b) 3 to 96 mol% of groups of the formula (II)

(IIa) (IIb)

wherein W = -CO-, -CO (O) - (CH ₂ ) _X -, -CO-NR ² - (CH ₂ ) _X - x = 1 to 6

R ⁵ and R ⁶ = hydrogen, optionally substituted aliphatic hydrocarbon radical having 1 to 20 C atoms, linear or branched, cycloaliphatic hydrocarbon radical having 5 to 8 C atoms, aryl radical having 6 to 14 carbon atoms and

Q = hydrogen and -CHR ⁵ R ^{7 together} and in the case of Q = H, R ⁵ and R ⁶ in (IIb) together form a -CH ₂ - (CH ₂ ) _y- methylene group with y = 1 to 4, R ⁷ Is hydrogen, aliphatic hydrocarbon radical having 1 to 4 C atoms, -COOH or -COOM _a and R ¹ , R ² , M and a have the abovementioned meaning,

and or

c) 0.05 to 75 mol% of assemblies of the formulas (III)

CH ₂ - CR ¹ -

(EIA) (IDb)

wherein Y = O ₁ NH or NR ⁵

R ⁸ = R ⁵ or R ⁶ , - (CH ₂ ) X-SO ₃ ⁹ Ma, SO ₃ ⁶ Ma,

SO ₃ ⁹ M ₃

X = halogen, C 1 to C ₄ alkyl sulfate or ci bis

C ₄ alkyl sulfonate and R ¹ , R ² and R ³ , M and a are as defined above;

d) 0.01 to 50 mol% of groups of the formula (IV) CH ₂ CR ¹

(IV) where Z = -COO (C _m H _2m O) _n -R ^9, - (CH ₂₎ _p -O (C _m H _2m O) n R ^9, R ⁹ = H,

_R 12 ^" ^ ^ ^* R"

where at least one radical R ¹⁰ , R ¹¹ and / or R ¹² must be present, and a saturated or unsaturated, linear or branched, aliphatic hydrocarbon radical having 1 to 40 C atoms R ¹⁰ = H, C 1 -C ₄ -alkyl, Phenyl, benzyl, C 1 -C ₄ -alkoxy,

Halogen, cyano, -COOH, -COOR ⁵ , -CO-NH ₂ , -OCOR ⁵ R ¹¹ = arylalkyl group with linear or branched Ci - Ci ₂ -

Alkyl and C ₆ - C ₄ aryl radical R ¹² = alkylaryl group having a linear or branched Ci - C ₂ -

Alkyl and C ₆ -Cu-aryl m = 2 to 4 n = 0 to 200 p = 0 to 20 and R ¹ and R ^{5 have the} abovementioned meaning contains.

6. Use according to claim 5, characterized in that in component 1.4) up to 50 mol% of the structural groups a) are replaced by other sulfo-containing structural units derived from Methallylsulfonsäure- or allylsulfonic acid monomers.

7. Use according to one of claims 5 or 6, characterized in that the component 1.4) from 30 to 80 mol% of the assembly a), 5 bis

55 mol% of the assembly b), 2 to 30 mol% of the assembly c) and / or 0.2 to 15 mol% of the assembly d).

8. Use according to one of claims 5 to 7, characterized in that the component 1.4) has a number average molecular weight of 50 000 bis

10 000 000 g / mol.

9. Use according to one of claims 1 to 8, characterized in that the construction mixture contains at least one member of the series hydraulic binder, filler, accelerator and dispersing additive.

10. Use according to claim 9, characterized in that the hydraulic binder is selected from the series of cement, lime, gypsum, anhydrite or other calcium sulfate-based binder and in particular cements of the type CEM I to CEM V and aluminate cements and any mixtures thereof.

11. Use according to one of claims 9 or 10, characterized in that the dispersing additive is a water reducer and / or a superplasticizer according to standard EN 934/2.

12. Use according to any one of claims 9 to 11, characterized in that the filler has a particle size of 0.1 to 100 mm.

13. Use according to one of claims 1 to 12, characterized in that the additive is added to the mixing water and / or pre-dissolved in the dispersing additive and / or used simultaneously with the dispersing additive and / or prior to introducing the building chemical mass into the formwork on the interface of Formwork is applied to the building chemical mass.

14. Use according to one of claims 1 to 13 for the production of precast concrete parts, in particular for the production of green-strength and in particular pre-stressed precast concrete parts.

15. Use according to one of claims 1 to 14, characterized in that the additive of the construction mixture mass in amounts of 0.01 to

1, 0 wt .-% and preferably from 0.01 to 0.5 wt .-% is added.