FOAMING AGENT AND METHOD FOR FOAMING AND STABILIZING FOAMS FOR CONSTRUCTION MATERIALS CONTAINING AIR PORES

Abstract

A foaming agent for foaming a binder glue or a binding material slurry for producing air pore containing building materials, particularly filling, lightweight construction and insulating materials, consists of the following: a) 0.1 to 65.0 wt. % ionic, preferably anionic, foam-forming surfactant; b) 0.05 to 9.0 wt. %, preferably 1.0 to 7.0 wt. %, particularly preferably 2.0 to 6.0 wt. %, of at least one compound ELF-RG which is solid at room temperature, selected from the group consisting of ethoxylated long-chain fatty alcohols, ethoxylated natural resins, ethoxylated artificial resins and ethoxylated glycols; c) 0 to 9.0 wt. % fatty alcohol having a chain length of C10 to C18, preferably of C12 to C16; d) 0.1 to 60.0 wt. % of solvent selected from the group of vicinal diols having from 1 to 6 carbon atoms, diethylene glycol, triethylene glycol and diethylene glycol ethers; e) 0 to 20 wt. % of organic additives; f) 0 to 20 wt. % of pH regulators; g) from 0 to 99.75 wt. % of water,
wherein the mixture yields a total of 100 wt. %.

Claims

1. Use of at least one ethoxylated compound ELF-RG which is solid at room temperature, selected from the group consisting of ethoxylated long-chain fatty alcohols, ethoxylated natural resins, ethoxylated artificial resins and ethoxylated glycols, for stabilizing a foam made of a foaming agent for building materials on the basis of ionic foaming surfactants for the production of air pore containing construction materials, in particular filling, lightweight and insulating materials.

2. Use according to claim 1, characterized in that the content of the ELF-RG in the foaming agent not yet combined with a building material component is at least 0.05 wt. %.

3. Use according to claim 1, characterized in that the at least one compound ELF-RG is employed in combination with at least one fatty alcohol.

4. Foaming agent for foaming a binder glue or a binding material slurry for the production of air pore containing construction materials, in particular filling, lightweight and insulating materials, which agent consists of the following: a) 0.1 to 65.0 wt. %, preferably 4.0 to 25.0 wt. %, particularly preferably 12.0 to 17.0 wt %, ionic, preferably anionic, foam-forming surfactant; b) 0.05 to 9.0 wt. %, preferably 1.0 to 7.0 wt. %, particularly preferably 2.0 to 6.0 wt. %, of at least one compound ELF-RG which is solid at room temperature, selected from the group consisting of ethoxylated long-chain fatty alcohols, ethoxylated natural resins, ethoxylated artificial resins and ethoxylated glycols; c) 0 to 9.0 wt. %, preferably 0.1 to 7.0 wt. %, particularly preferably 2.0 to 6.0 wt. % fatty alcohol having a chain length of C10 to C18, preferably of C12 to C16; d) 0.1 to 60.0 wt. %, preferably from 10.0 to 55.0 wt. %, particularly preferably from 15 to 50.0 wt. % of solvent selected from the group of vicinal diols having from 1 to 6 carbon atoms, diethylene glycol, triethylene glycol and diethylene glycol ethers; e) 0 to 20 wt. % of organic additives; f) 0 to 20 wt. % of pH regulators; g) 0 to 99.75 wt. %, preferably 20.0 to 85.0 wt. %, particularly preferably 15.0 to 75.0 wt. %, of water, wherein the mixture yields a total of 100 wt. %.

5. Foaming agent according to claim 4, characterized in that components a) to d) are present in the following ratios: a) surfactant to b) ELF-RG: 1:1 to 12:1, preferably 3:1; d) solvent to b) ELF-RG: 2:1 to 16:1, preferably 9:1; c) fatty alcohol to b) ELF-RG: 1:4 to 5:1, preferably 1:1; a) surfactant to c) fatty alcohol: 1:1 to 12:1, preferably 3:1; a) surfactant to d) solvent: 5:1 to 1:12, preferably 1:3; c) fatty alcohol to d) solvent: 2:1 to 1:16, preferably 1:9.

6. Foaming agent according to claim 4, characterized in that it is diluted to up to 30 times of its volume with water before foaming.

7. Foaming agent according to claim 4, characterized in that it is in pasty or powdery solid state obtainable by freeze-drying or evaporation in vacuo.

8. Method for producing a liquid air pore containing building material, in particular a filling, lightweight construction or insulating material, from a foamed binder glue or from a foamed binding material slurry consisting of binder glue and aggregates and additives, wherein the binder glue consists of mixing water and binder, comprising the following steps: preparing the binder glue by mixing binding agent and mixing water and where applicable preparing the binding material slurry by mixing the binder glue with aggregates and additives, characterized in that the foaming agent according to claim 4, optionally with additional water, is added unfoamed to the dry binding agent, the mixing water, the binder glue or the binding material slurry, and that the binder glue or the binding material slurry is foamed in the mixer by the mixing process to yield the foamed binder glue or the foamed binding material slurry.

9. Method according to claim 8, further comprising the step of curing the binding material slurry to obtain the solid air pore containing building product.

10. Method according to claim 9, further comprising the step of shaping the solid air pore containing building product, particularly by cutting, sawing or milling.

11. Method for producing an air pore containing building material or construction product, in particular a filling, building or insulating element, comprising the following steps: mixing of binding agent, mixing water, possibly aggregates and additives and a foaming agent according claim 4, filling the resulting mixture into a mold and obtaining the porous building product by curing the mixture in the mold in an autoclave under at least one of the following conditions: increased pressure, increased relative humidity and elevated temperature.

12. Method according to claim 11, further comprising the step of shaping the solid air pore containing building product, particularly by cutting, sawing or milling.

13. Liquid air pore containing building material, particularly filling, building or insulating material, obtainable by the method of claim 8.

14. Solid air pore containing building material, particularly filling, building or insulating material, obtainable by the method of claim 9.

Description

DESCRIPTION OF THE DRAWINGS

[0119] In the drawing:

[0120] FIG. 1 shows the schematic sequence of the production of a lightweight building material on the construction site or in industrial production;

[0121] FIG. 2 shows the schematic sequence of the production of lightweight construction material in a somewhat modified process;

[0122] FIG. 3 shows the schematic sequence of the production of lightweight construction material using a dried foaming agent.

[0123] FIG. 1 shows a first process sequence for producing a foamed binding material slurry from which (pore) lightweight construction products result or are produced after drying. The required starting materials are fed from the storage tanks 1, 2 and 3 to a standard mixer 4. A variety of mixer types can be used. However, the mixing intensity should be variably adjustable so that the desired density (the desired pore volume) is achieved when the foaming agent is added to the mixer in unfoamed form.

[0124] The binder is placed in the container 1 in dry form. It may include aggregates. This mixture of solids is conveyed into the mixer 4 via a line a. Alternatively, binders and aggregates may be held in separate storage and dispensing containers which would be connected to the mixer via separate lines (not shown). Parallel to this, the mixing water from container 2 is conveyed into the mixer 4 via a line b.

[0125] Foam is introduced into foam generator 3 and conveyed into the mixer 4 via a line c. In mixer 4, a foamed binding material slurry is produced, which is conveyed to the building site on a construction site or into a mold for curing by means of a pump 5 via a line d. Alternatively, the foam can be passed directly into the binding material slurry via a line e. For this purpose, the foam from line e is injected into the glue stream of the unfoamed binder glue or the unfoamed binding material slurry.

[0126] The transfer lines d, d and g may be flexible hoses with which the foamed slurry is conveyed to a building site. Uses of the slurry as insulation material in intermediate walls, as a plaster, as floor corrective compound or screed are possible.

[0127] FIG. 2 shows a modified method. Here, a previously, e.g. in a ready-mix concrete plant, generated binder or a binding material slurry is added in container 1 directly from the transport mixer, or the slurry is fed to the pump 5 via line d. Alternatively, the foam can be added to the transport mixer via line c, the transport mixer fulfilling the function of mixer 4 and replacing it. The two components binder glue and foam are mixed in mixer 4 or in the transport mixer, and a foamed binding material slurry is formed as in the method of FIG. 1. From the mixer 4 (via path d) or from the transport mixer (via path d), the foamed binding material slurry is transported by means of pump 5 to the building site 6 or into a mold. Aggregates may have been previously added from a separate container directly into the mixer 4 or the transport mixer.

[0128] FIG. 3 shows an example of a process procedure in which a powdery, dry foaming agent is used. Again, a mix of solids, i.e. binder and if necessary aggregates, is provided in container 1. Container 2 contains mixing water. Container 7 now contains the dry, for example freeze-dried, foaming agent which is added to the binder in container 1 via line c and/or to the mixing water in container 2. The powdery foaming agent is fed to mixer 4 via the flow of material, or it is directly added to the mixer 4 (in this case schematically path a, b, f). In the mixer 4, a binder glue foam or a foamed binding material slurry is produced, which is transported to building site 6 by means of pump 5 via the line d or into a mold as already described with respect to the preceding figures.

Quality Tests

[0129] Foamed binding material slurries have to meet pre-defined requirements. These requirements are derived from the desired construction product. The selected composition of the binding material slurry is often a trade secret, and the number of possible combinations and the different concentrations of individual components does not permit a generally valid quality test for foamed binding material slurry. However, a number of general tests have been established which demonstrate the quality of the improved stability of the foaming agent of the binding material slurries claimed by this invention. Of course, a stable foam is not a guarantee for a good construction product by itself. The chosen binder mixture, the additives added and the applied manufacturing and drying process play too large a role for achieving a defined quality. However, no air pore containing building product is possible without a functioning foaming agent. Especially for on-site applications, where critical parameters are constantly changing, robust and reliable foam stability of the used foam is required. In an industrial manufacturing process, the parameter deviations are lower. Material, temperatures, processes are internally standardized. But even here, the pore-forming agent has to withstand the process and offer a robustness that still achieves a satisfactory result in case of parameter deviations.

[0130] The tests described below are general in nature and applicable in most cases. Often, only a combination of the described tests can help prove the suitability or non-suitability of a pore-forming agent.

[0131] The desired binding material slurry is produced for a quality test series. In the following example we tested the following mixtures:

[0132] AA gypsum paste of alpha hemihydrate, here SOdanit of CASEA GmbH and tap water.

[0133] BA cement paste of Portland cement, here CEM I 42,5 R of Holcim Deutschland and tap water.

[0134] Both mixtures are mixed with a foam that is foamed of a foaming agent according to example mixture 3 in a 2-pump foam generator of the company Finke from Detmold.

[0135] Basically, the addition of the foam at any time before setting of the building material glue is possible, but should be carried out as soon as possible following glue production. The glue must remain in uncured state to allow mixing with the foam.

[0136] In principle, the foamed binding material slurry can be produced in different compositions and different densities.

Test 1: Pump Stability

[0137] The glue or the slurry can be conveyed with all pump types currently available on the market; for foamed slurries, hose and screw pumps are suitable. The variety of available pumping principles and the variable foam adding points require a practical test of whether the desired result can be achieved with the selected pump.

[0138] It is irrelevant whether the pumps convey materials produced in batch process or whether the material is continuously produced.

[0139] It is irrelevant whether the lightweight gypsum is prepared in advance, in the pump or directly behind the pump in the delivery hose/pipe or in the low-maintenance or maintenance-free swirl/mixer element. However, it should be noted that piston pumps can destroy the pores of foamed slurry.

Test Procedure:

[0140] The density of the foamed slurry is measured before and after pumping. The pumping test is passed if the density measured after pumping corresponds to the density measured before the pumping process or to the predefined target density.

Test 2: Stability while Moving and Pouring

[0141] Foamed slurries based on any mixtures of solids must pass from the mixing point to the drying point. The pumping process is described in Test 1. In addition, the material may have to be poured off, i.e. moved again at the building site. This movement is simulated in the test.

Test Procedure:

[0142] The foamed slurry is filled into a container and poured therefrom from a pre-defined height into a second container, possibly the material is stirred at this point or otherwise mechanically moved to simulate the actual production process. Before and after pouring, the density is measured. If a foaming agent according to the invention is used, the density remains unchanged. When pouring foamed binding material slurries according to the invention, drop heights of more than 3 m are possible.

Test 3: Standing Stability

[0143] Depending on the selected composition, the foamed binding material slurry can withstand installation heights of more than 150 cm applied in a single operation. The material remains stable with respect to volume with homogeneously distributed air pores.

Test Procedure:

[0144] Foamed slurry is filled into a container in which the material can dry. After the filling process, the upper filling limit is marked. After drying, the upper edge of the building material must still be at the marked location. If material has sagged during drying, it has lost volume. Pores have dissolved, the contained air has escaped, the material collapses, the density cannot be maintained. The foam is unstable.

Remarks on the Stabilities Determined in Test 1-3:

[0145] Any gypsum-based or cement-based slurry can be foamed if the mixture is not mixed with any additives that neutralize the pore-forming agent or otherwise deprive it of its character (defoamer). In principle, however, volume stability can only be achieved if there is a sufficient amount of suitable binder in the binding material slurry. The best pore-forming agent cannot durably stabilize a mixture that cannot develop sufficient stability from the binder mixture used in the drying process.

[0146] An empirical value is that the binder content in the slurry should be at least 12.5% of the total solids mass.

Test 4: Homogeneity of Air Pore Distribution

[0147] In dried building material it may be necessary to determine whether the air pores retain their size and distribution in space in the drying process or whether inhomogeneities have formed. For this purpose, a predefined number of identically dimensioned specimens is cut out of a sufficiently dimensioned body of different layers. With these bodies, the average size of the air pores is determined under a microscope or by means of CRT. Thereafter, the specimens are weighed. Identical densities mean homogeneous distribution of the pores in the system. Inhomogeneities are formed when pores separate from the structure of the foamed binding material slurry and lenses with a higher proportion of pore-forming agent and lenses with a higher proportion of slurry form. The slurry settles mostly on the ground and the pores move upwards. Depending on the application, this development may be an exclusion criterion that makes the foamed binding material slurry unsuitable for the intended use. Test 4 offers a simple means to detect inhomogeneities even without CRT.

General Remarks Regarding Comparison Tests:

[0148] The tests can be carried out individually or in their entirety as suggested and, of course, be further supplemented. If a test procedure is defined and alternative foams are used for the comparison in the test procedure, it is found that foams of foaming agents produced according to the invention are superior to alternative foams in that predefined target values are achieved better in individual or all tests.

Comparison of Foaming Agents:

[0149] For the comparison of a foaming agent according to the invention with an alternative foaming agent, a foaming agent S according to example formulation 3 is compared with a foaming agent S-, where S- also corresponds to example recipe 3, but no ELF-RG is added to the S-. The slurry used in this comparison corresponds to that described in Reference Mix I. The mixture according to Table 1A is brought to the desired density Table 1 B by mixing in prefoamed pore-forming agent. The foamed binding material slurry thus obtained is subjected to Tests 1 to 3. The mixer used was a standard Eirich mixer. The foam was produced with a foam generator of the company Finke. After the preparation, the foam was mixed under the slurry in the standard mixer. The pump used was a hose pump. The filling container is a wooden container made in-house.

[0150] Table A shows the test result.

TABLE-US-00001 TABLE A Prepara- Prepara- Density Installation Installation tion tion after height (cm) height (cm) density volume pump test Beginning of End of Name (kg/m3) (I) (kg/m3) standing test standing test S 800 500 800 80 80 S 800 500 1,600 80 47

[0151] It is found that the foaming agent S passes both the pumping test and the standing test without limitation. Volume and thus density remain the same. When pumping, the density does not decrease. In the standing test, the initial filling level is still present after setting the slurry, i.e. the material has not lost any volume.

[0152] Foaming agent S- in comparison shows significant weaknesses. In the pump test, a significant part of the volume is lost. During the standing test, the construction height is reduced by more than 40% from 80 cm to 47 cm. A failure of the pore-forming agent S- is evident. For the standing tests, material with pore-forming agent S- was prepared once more, as the material from the pumping test had already failed. Since it is possible that a material fails during the pumping test but passes the standing test, the standing test was performed with a second mixture.

[0153] In this comparison of S and S-, the pore-forming agent is optimally stabilized by the use of ELF-RG according to the invention.

Reference Mixtures

I: Lightweight Concrete Production by Supplying a Foam to the Previously Prepared Cement Paste

[0154] The following applies to the mixtures according to Table 1 below. All mixtures using the example of cement:

1Mixture A (reference mixture), unfoamed
2Mixture B, lightweight concrete, density 0.8 kg/liter or 800 kg/m.sup.3
3Mixture C, lightweight concrete, density 0.4 kg/liter or 400 kg/m.sup.3

TABLE-US-00002 TABLE 1 Total of which of which of which Density volume foam cement water Name (kg/m3) (I) (I) (I) (I) A 1,800 1,000 0 400 600 B 800 1,000 560 180 260 C 400 1,000 775 90 135

[0155] The following quantities are required to produce one cubic meter of foamed lightweight concrete:

Cement, Here CEM 1 42.5, Required, Column of which Cement:
A: 1,200 kg of cement
B: 540 kg of cement
C: 270 kg of cement
Water, Here Tap Water, Column of which Water:
A: 600 kg of water
B: 260 kg of water
C: 135 kg water
Foam, Here Prepared from Reference Mixture 1, Column of which Foam:
A0 liter of foam
B 560 liters of foam
C 775 liters of foam

[0156] From 60% to 100% of the specified quantities of water can be used without damaging the lightweight concrete structure. Lower or higher water levels are possible but are not recommended due to possible negative effects such as increased toughness, too fast or incomplete setting etc.

[0157] The reference mixtures can be prepared with all conceivable solid mixtures and foam densities. In calculation of foam volume and amounts of pore-forming agents derived therefrom, the different density of the solid mix is to be observed.

II. Light Gypsum Production by Supplying the Unfoamed Foaming Agent for Mixed Water in Gypsum Paste Production

[0158] For the production of 5.0 liters of gypsum glue, an alpha-hemihydrate of CASEA GmbH and tap water is used. The gypsum glue is prepared in a 7 liter mixer. An undiluted pore-forming agent according to example foaming agent 1 is added to the mixing water. The pores are created in the glue mixing process.

[0159] The following applies to the mixtures according to Table 2 below. All mixtures using the example of plaster:

1Mixture X (reference mixture), unfoamed
2Mixture Y, light gypsum, density 0.7 kg/liter or 700 kg/m.sup.3
3Mixture Z, light gypsum, density 0.5 kg/liter or 500 kg/m.sup.3

TABLE-US-00003 TABLE 2 Total of which of which of which Density volume foam gypsum water Name (kg/m3) (I) (I) (I) (I) X 1,600 5.0 0 5.5 2.75 Y 700 5.0 2.9 2.3 1.15 Z 500 5.0 3.5 1.8 0.63

[0160] The following quantities are required:

Gypsum, Here Alpha-Hemihydrate of CASEA GmbH, Column Thereof Gypsum:

[0161] X: 1,200 kg of gypsum
Y: 540 kg of gypsum
Z: 270 kg of gypsum
Water, Here Tap Water, Column of which Water:
X: 2.75 kg of water
Y: 1.1 kg of water
Z: 0.63 kg of water
Foam, Here Produced from Reference Mixture 1, Column of which Foam:
X 0 liter of foam
Y 2.9 liters of foam
Z 3.5 liters of foam

Undiluted Foaming Agent According to Example Foaming Agent 3 is Required as Follows:

[0162] a. 0.00 liters [0163] b. 0.02 liters [0164] c. 0.03 liters