Foaming agent and method for the foaming and stabilizing of a building material slurry for porous lightweight building materials

Abstract

A foaming agent is used for foaming a building material binder paste or a building material slurry for producing porous lightweight-construction and insulating materials. On curing of the foamed slurry, the foam bubbles generate pores in the building material. The foam obtained from the foaming agent is stabilized using a long-chain or medium-chain polycarboxylate ether (PCE). The foaming agent includes a foam-forming ionic surfactant component, at least one fatty alcohol and at least one PCE in an aqueous-organic solvent which is selected from the group of alkyl glycols, alkylene glycols up to C6 alkyl, diglycols and diglycol ethers, and also, optionally, up to a maximum of 20 wt %, based on the mixture, of further ingredients.

Claims

1. A method for producing porous lightweight-construction and insulating materials, comprising the step of using a long-chain or medium-chain polycarboxylate ether (PCE) for stabilizing a foam from a foaming agent for building materials on the basis of ionic foaming surfactants.

2. The method according to claim 1, wherein the amount of the polycarboxylate ether (PCE) in the foaming agent before combining with a building material component is at least 0.1 wt %.

3. The method of claim 1, wherein the polycarboxylate ether (PCE) is used in combination with at least one glycol and at least one fatty alcohol.

4. A foaming agent for foaming of a building-material binder paste or a building material slurry for producing pory lightweight-construction and insulating materials, comprising:, a foam-forming ionic surfactant component; at least one fatty alcohol; and at least one polycarboxylate ether for stabilization in an aqueous-organic solvent, wherein the aqueous-organic solvent is selected from the group of alkyl glycols, alkylene glycols up to C6 alkyl, diglycols and diglycol ethers, and also, optionally, up to a maximum of 20 wt % of the mixture, of further ingredients.

5. The foaming agent according to claim 4, comprising: a) at least 2 wt % of said ionic, foam-forming surfactant, b) at least 10 wt % of said aqueous-organic solvent, c) at least 0.1 wt % of the at least one polycarboxylate ether (PCE), d) at least 0.5 wt % of the at least one fatty alcohol, e) at least 10 wt % of water, and f) 0-20 wt % of other organic-chemical adjuvants and/or organic or inorganic acids or bases for pH adjustment, the mixture giving a total of 100 wt %.

6. The foaming agent according to claim 5, further comprising additional water up to 25 times a volume of the foaming agent.

7. The foaming agent according to claim 4, wherein the foaming agent is present in a pasty or pulverulent solid form obtainable by freeze drying or vacuum evaporation of the foaming agent.

8. A method for producing a pory lightweight-construction and insulating material by means of a binder paste foam or a foamed building material slurry, comprising the steps of foaming a foaming agent comprising a foam-forming ionic surfactant component; at least one fatty alcohol; and at least one polycarboxylate ether for stabilization in an aqueous-organic solvent, wherein the aqueous-organic solvent is selected from the group of alkyl glycols, alkylene glycols up to C6 alkyl, diglycols and diglycol ethers, and also, optionally, up to a maximum of 20 wt % of the mixture, of further ingredients, and optionally with additional water, to produce a resulting foam; and combining the resulting foam with mixing water for a binder, with a binder paste composed of binder and mixing water and also, optionally, additives, or with a building material slurry composed of the binder paste and aggregates, to produce the binder paste foam or the foamed building material slurry.

9. The method according to claim 8, wherein the resulting foam from the foaming agent is supplied, within a binder paste preparation method, to at least one starting material in a container or to a transfer line, to a mixer or foam generator, to a pump, or to a fresh building material delivery line.

10. The method of claim 8 wherein the foaming agent is added to dry binder or to mixing water, and wherein the binder paste foam is generated on mixing of the binder with the mixing water.

11. The method according to claim 8 wherein the binder includes one or more of cement, gypsum, and lime, alone or in any desired mixture with one another or with other mineral constituents.

12. The method according claim 8 further comprising the step of either transporting the binder paste foam or the foamed building material slurry, prior to setting and curing, to a construction point, or pouring the binder paste foam or the foamed building material slurry into a mold and curing the binder past foam or the foamed building material slurry in the mold.

13. The method according to claim 12, wherein the step of curing in the mold takes place in an integrated system with other materials.

14. The method according to claim 12, wherein the step of curing takes place under pressure and at elevated temperature in an autoclave.

15. The method according to claim 8, further comprising the steps of forming a formed or freely poured lightweight-construction and insulating material from the the binder paste foam or the foamed building material slurry; and performing one or more of cutting, sawing, or milling of the formed or freely poured lightweight-construction and insulating material to produce porous lightweight construction products.

16. Porous lightweight construction products, made by the process of: producing a pory lightweight-construction and insulating material by means of a binder paste foam or a foamed building material slurry, comprising the steps of foaming a foaming agent comprising a foam-forming ionic surfactant component; at least one fatty alcohol; and at least one polycarboxylate ether for stabilization in an aqueous-organic solvent, wherein the aqueous-organic solvent is selected from the group of alkyl glycols, alkylene glycols up to C6 alkyl, diglycols and diglycol ethers, and also, optionally, up to a maximum of 20 wt % of the mixture, of further ingredients, and optionally with additional water, to produce a resulting foam; and combining the resulting foam with mixing water for a binder, with a binder paste composed of binder and mixing water and also, optionally, additives, or with a building material slurry composed of the binder paste and aggregates, to produce the binder paste foam or the foamed building material slurry; forming a formed or freely poured lightweight-construction and insulating material from the the binder paste foam or the foamed building material slurry; and performing one or more of cutting, sawing, or milling of the formed or freely poured lightweight-construction and insulating material to produce porous lightweight construction products.

Description

DESCRIPTION OF FIGURES

[0078] In the drawing:

[0079] FIG. 1 shows the diagrammatic process of production of lightweight building material on the building site or in industrial manufacture;

[0080] FIG. 2 shows the diagrammatic process of production of lightweight building material in a slightly altered method regime;

[0081] FIG. 3 shows the schematic process of production of lightweight building material using a dried foaming agent.

DESCRIPTION

[0082] The invention is illustrated below using formula examples and method examples. These examples are intended to serve solely for more effective illustration of the invention, and not to restrict it in its general aspects.

FORMULA EXAMPLES=FOAMING AGENT

Example Foaming Agent 1

[0083] 18.0 wt % anionic surfactant, sodium C14-16 olefinsulfonate

[0084] 2.0 wt % fatty alcohol, C12-C14 mix 50:50

[0085] 18.0 wt % butyldiglycol (diethylene glycol monobutyl ether)

[0086] 6.0 wt % Melflux PCE 239 L/35% N.D. (BASF)

[0087] 56.0 wt % water

[0088] 100% total solution

Example Foaming Agent 2

[0089] 12 wt % anionic surfactant, sodium C14-16 olefinsulfonate

[0090] 15.0 wt % sulfuric ester salt

[0091] 2.0 wt % fatty alcohol, C10-C12 mix 25:75

[0092] 18.0 wt % hexylene glycol

[0093] 6 wt % MELFLUX PCE 1493 L/40% (BASF)

[0094] 47.0 wt % water

[0095] 100% total solution

Example Foaming Agent 3 (Concentrate)

[0096] 40.0 wt % anionic surfactant, sodium C14-16 olefinsulfonate

[0097] 3.0 wt % fatty alcohol, C12-C14 mix 50:50

[0098] 34.0 wt % butyldiglycol

[0099] 8.0 wt % PCE, MELFLUX PCE 239 L/35% (BASF)

[0100] 15.0 wt % water

[0101] 100% total concentrate, dilutable with 2-22 1 of water per liter of concentrate

[0102] Foams from these foaming agents are mixed with various binder pastes or binder slurries to form foamed building material slurries.

[0103] A building material paste is produced conventionally.

[0104] The compositions identified in Examples 1 or 2, among others, may be selected, for example. The precise solids composition and the water content are guided by the end use of the foamed slurry being produced. Accordingly, the nature and amount of the selected aggregates and composition of the binder mix are selected. Depending on the desired density, various amounts of the foaming agent are used per kilo of slurry, according to the formula examples for the foaming agents.

Example Mixture 1 Gypsum Paste

[0105] 40 wt % (of the binder weight) mixing water, the desired amount of alpha hemihydrate, 2% of retardant

Example Mixture 2 Cement Paste

[0106] 50 wt % (of the binder) mixing water, the desired amount of CEM I 42.5 Portland cement, 2.0 wt % melamine sulfonate plasticizer

Examples Applications

[0107] APPLICATION 1: Production of a gypsum board for interior insulation. Required wet density=450 kg/m.sup.3, binder used: gypsum, alpha-hemihydrate incl. retardant, aggregates: none.

[0108] To produce one cubic meter of foamed gypsum slurry, achieving the desired density after curing in the ambient air in the drying container, 450 kg of gypsum paste are needed. According to Example 1, 450 kg of gypsum paste contain 321 kg of gypsum and 129 liters of water. Gypsum has a density of 1.7. 321 kg of gypsum therefore have a volume of 189 liters. Together with the water, the resulting volume is 318 liters. The volume of 682 liters remaining as the balance to one cubic meter are made up with the foam from example foaming agent 1, and mixed with the paste to give one cubic meter of foamed gypsum slurry.

[0109] APPLICATION 1a: Production of a lightweight concrete panel for exterior insulation. Required wet density=350 kg/m.sup.3, binder paste used as per example mixture 2.

[0110] To produce one cubic meter of foamed slurry, achieving the desired density after curing in the ambient air in the drying container, 350 kg of cement paste are needed. According to example mixture 1, 350 kg of cement paste contain 233 kg of cement and 117 liters of water. Cement has a density of 3.1. 233 kg of cement therefore have a volume of 75 liters. Together with the water, the resulting volume is 192 liters. The volume of 808 liters remaining as the balance to one cubic meter are made up with foam from example foaming agent 1, and mixed with the paste to give one cubic meter of foamed slurry.

[0111] APPLICATION 2: Production of a leveling compound for liquid incorporation on the building site beneath the screed. Desired density=600 kg/m.sup.3, desired strength 1.5 N/mm.sup.2, binder used: gypsum, natural anhydrite, aggregates: 20 wt % of gravel ground to low particle size, initiator potassium sulfate 2.0 wt % of the binder.

[0112] To produce a foamed gypsum slurry which cures in the ambient air at the construction point, 480 kg of anhydrite with a density of 2.2 and a volume of 218 l are required. The aggregates possess a density of 2.7 and hence a volume of 45 liters, and so 737 liters of foam are needed for one cubic meter of leveling compound. 2 liters of concentrate as per example foaming agent 3 are introduced into the mixing water, and the overall mixture is mixed in an intensive mixer to give the foamed slurry.

[0113] APPLICATION 3: Production of a bearing layer in road construction, which when used allows all of the layers and elements beneath the covering asphalt layer to be done away with.

[0114] Desired density. 850 kg/m.sup.3, desired compressive strength: 3.5 N/mm.sup.2, binder used: Portland cement, CEM I 42.5 N.

[0115] To produce a foamed concrete slurry which cures at the construction point, 565 kg of cement with a density of 3.1 and a volume of 182 liters are required. Together with the volume of the mixing water, of 283 l, this makes a volume of 465 liters, which is mixed with the slurry together with 535 liters of foam, produced from example foaming agent 2, and gives the desired material.

[0116] APPLICATION 4: production of a lightweight gypsum plaster for the interior region of an outside wall, whose air pores equip the material with a heat insulation value. In calculating the U value of a wall construction, this value can be counted in and so help to reduce the overall wall construction. Additionally, the lightweight gypsum plaster is easier to process than the standard plaster, on account of its low weight, and the coverage of the raw material used is increased considerably.

[0117] Desired density=750 kg/m.sup.3, binder used: gypsum, alpha-hemihydrate, (customary DIY store or building material supplier) bagged product 25 kg, aggregates: none.

[0118] To produce a lightweight gypsum from foamed gypsum slurry, which attains the desired density after curing in the ambient air in the drying container, 25 kg of gypsum (bagged product) are mixed with 10 liters of water to form gypsum paste. Gypsum has a density of 1.7, giving a volume of 15 liters for 25 kg of gypsum. Together with the water, the resulting volume is 25 liters.

[0119] Alternative 1: The paste is mixed with 25.5 liters of foam as per example foaming agent 1 to form a foamed slurry, the foam being produced beforehand in a standard foam generator, FINKE for example, and then incorporated by mixing.

[0120] Alterative 2: The foaming agent concentrate in dried or pasty form is added to the solid or to the mixing water, and the mixture is foamed in an intensive mixer. This is done by adding 1.0 g of powder (produced from example pore former 3) to 25 kg of gypsum.

[0121] FIG. 1 shows a first procedure for the production of a foamed building material slurry, from which, after drying, lightweight building material products (e.g. lightweight gypsum products) come about or are produced. The starting materials needed are supplied from reservoir vessels 1, 2 and 3 to a standard mixer 4. A wide variety of different types of mixer can be used. However, the mixing intensity ought to be variably adjustable, so that the desired density (the desired pore volume) is achieved in the slurry, according to the foaming agent variant used and solids mix used.

[0122] The binder is charged dry to the container 1. It may contain aggregates. This solids mix is conveyed via a line a into the mixer 4. Alternatively, binder and aggregates can be held in two separate reservoir and delivery vessels, both of which would be connected via separate lines to the mixer (not shown here). In parallel with this, the mixing water from container 2 is conveyed via a line b into the mixer 4.

[0123] Foaming agent is charged to container 3 and conveyed via a line c into the mixer 4. Alternatively, the foaming agent (pore former, PB) can be produced with a foam generator and conveyed directly into mixer 4. In the mixer 4, a binder paste foam is generated, which is passed via a feed d into a pump 5, and passed further via a hose g to a construction point 6 on a building site, or into a mold. Alternatively, the foam produced using the foam generator can be passed directly by a line e into the binder paste or, where aggregates are present, into the building material slurry. For this purpose, the foam from line e is injected under pressure into the paste jet of the unfoamed binder paste or of the unfoamed building material slurry.

[0124] This admixing by injection into the paste jet is preferred in the case of continuous production operation. The foamed slurry can be used to fill molds in which the slurry sets, which is not implemented in detail in this diagrammatic representation.

[0125] The transfer line g may be a flexible hose, with which the foamed slurry is introduced at a construction site. Possible uses of the slurry are as insulating material in partition walls, as plaster, as floor leveling compound or as screed.

[0126] FIG. 2 shows a modified method. In this case, in container 1, a binder paste generated beforehand is charged directly, or the paste is supplied directly from the transport mixer via line d to the mixer 4, in which the foamed slurry is generated. Alternatively, the foam may be conveyed via line c to the transport mixer, with the transport mixer fulfilling the function of mixer 4 and replacing it. The two binder paste and foam components are mixed in the mixer 4 or in the transport mixer, and a binder paste foam is formed which remains stable under the mixing conditions, as in the method of FIG. 1. From the mixer 4 (via path d) or from the transport mixer (via path d), the completed binder paste foam is brought by means of the pump 5 through hose g to the construction point 6 or into a mold. Aggregates may have been added beforehand, from a separate container, directly into the mixer 4 or the transport mixer. The foamed building material slurry is brought like a paste via the line d, pump 5 and line/hose g to the construction point 6, or discharged directly from the transport mixer at the construction point.

[0127] FIG. 3 shows an example of a method regime using a pulverulent, dry foaming agent. Again, a solids mix, i.e. binder and optionally aggregates, is charged to container 1. Mixing water is in container 2. Container 7 then contains the dry foaming agent, freeze-dried for example, which is added via line c to the binder in container 1 and/or to the mixing water in container 2. Via the flow of material, the pulverulent foaming agent is supplied to the mixer 4 or is added directly to the mixer 4 (here, diagrammatically, path f). In the mixer 4, a binder paste foam or a foamed building material slurry is produced, which, as already described for the preceding figures, is transported via lines d and g by means of pump 5 to the construction point 6 or into a mould.

[0128] Tests

[0129] To produce a gypsum paste, an alpha-hemihydrate (Sdanit) or an anhydrite (Raddipur +) from Sudharzer Gipswerke and mains water are used. From a mixture according to formula example 2, a foam was produced using a two-pump foam generator (from Finke, Detmold).

[0130] In principle the foam can be added at any time before the gypsum paste stiffens, but the addition ought to take place as close as possible to the production of the paste. The paste must remain in the uncured state, in order to allow it to be mixed with the foam.

[0131] In principle, lightweight gypsum can be produced in a variety of densities. For these tests, the density classes selected were 450 kg/m.sup.3 and 850 kg/m.sup.3.

[0132] Tests: 1. Pumping

[0133] The paste or the slurry can be conveyed with any of the pumps presently available on the market; for foamed slurries, peristaltic pumps and screw pumps are suitable. The multiplicity of pump designs available and the variable points of foam addition require practical testing of the pump selected to determine whether it is able to achieve the desired outcome.

[0134] It is immaterial whether the pumps convey material produced in a batch process, or whether the material is produced continuously.

[0135] It is immaterial whether the lightweight gypsum is produced beforehand, in the pump, or immediately downstream of the pump in the conveying hose/pipe, or is produced in a low-maintenance or no-maintenance fluidizer/mixer element. It should be borne in mind, however, that piston pumps may destroy the pores of foamed slurries.

[0136] Tests: 2. Volume Stability

[0137] The porosified or foamed solids/water mixture (paste) can be pumped to more than 75 meters and withstands construction heights (liquid pouring) of more than 100 cm. At the same time, the material remains stable in volume, with no alteration in homogeneously distributed air pores. 99% of the air pores have a uniform size 2 mm. Larger pores occur only if, during dispensing, pumping or application, the movement of the paste allows air inclusions (overpouring, sloshing, etc.). These larger pores have no adverse effect on the overall pore structure if their proportion of the volume is below 2%.

[0138] Tests: 3. Aggregates/Content of Aggregates

[0139] Experiments have shown that any gypsum-based or cement-based paste can be porosified if the paste is not admixed with any chemistry which neutralizes the pore former or otherwise robs it of its capacity. The minimum binder content ought not to fall below 12.5% of the overall solids mass.

[0140] It should be borne in mind that for foamed building material slurries, the average compressive strengths and tensile strengths are generally lower than for unfoamed gypsum mixtures.

[0141] Reference Mixtures

[0142] The mixtures in the table below are subject to the following remarks. All of the mixtures use gypsum as example:

[0143] amixture No. 1 (reference mixture), without porosification

[0144] bmixture No. 2, lightweight gypsum, density 850 kg/m.sup.3

[0145] cmixture No. 3, lightweight gypsum, density 500 kg/m.sup.3 40

TABLE-US-00001 TABLE 1 Per mixture Gypsum Water Gypsum Water Foam Density Volume Foaming agent example 1 initial mass initial mass No. KG KG Liters (wetness per m.sup.3) (liters per mixture) (liters per mixture) (KG per m.sup.3) (KG per m.sup.3) 1 55.9 29.6 0.0 1712.1 50.0 0 1119 593 2 28.0 14.8 25.5 848.0 50.5 0.04 554 294 3 16.5 8.7 35.8 499.5 50.5 0.05 326 173

[0146] Producing one cubic meter of lightweight gypsum requires the following quantities of gypsum (here alpha-hemihydrate):

TABLE-US-00002 a - 1119 kg gypsum b - 554 kg gypsum c - 326 kg gypsum

[0147] Producing one cubic meter of lightweight gypsum requires the following quantities of water (here mains water):

TABLE-US-00003 d - 29.8 kg water e - 14.8 kg water f - 8.7 kg water

[0148] From 50% to 125% of the indicated quantities of water can be used without detriment to the lightweight gypsum structure. Lower or higher quantities of water are possible, but are not advisable, owing to the occurrence of adverse contraction effects (more water than 125%) and possibly excessive toughness and excessively rapid curing for the desired operation (less than 50% water).

[0149] Producing one cubic meter of lightweight gypsum requires arithmetically the following quantities of pore formers (if a Finke foam generator is used):

TABLE-US-00004 a - 0.00 liter b - 0.75 liter c - 1.00 liter

[0150] The reference mixtures can be carried out with all conceivable solids mixtures. In the calculation of foam volume and required quantities of pore formers, the different density of the solid should be taken into account.

[0151] II. Lightweight Gypsum Production by Supplying the Foaming Agent to the Mixing Water During Gypsum Paste Production

[0152] The gypsum paste is produced using an alpha-hemihydrate from Sdharzer Gipswerke and mains water. The gypsum paste is prepared in a 150 1 mixer from EMT. A foam of undiluted foaming agent according to example foaming agent 1 is added to the mixing water.

[0153] Producing one cubic meter of lightweight gypsum requires arithmetically the following quantities of foaming agent:

TABLE-US-00005 a - 0.00 liter b - 0.20 liter c - 0.35 liter

[0154] Comparative tests: when foaming agents without PCE were produced, in contrast, there was no operational reliability. The foams from the foaming agents collapsed within seconds to minutes, could not be pumped at sufficiently constant volume, and showed no volume stability even on curing.