Patent ID: 12240786

EXAMPLES

A number of sample specimens were first prepared in accordance with the present invention in order to investigate the extent to which different mix ratios and starting materials affect the compressive strength and density of the material obtained. In addition, other properties such as the color of the obtained material and the27A-MAS-NMR spectra were investigated for some of the samples.

For density determination, the volume and weight of a rectangular sample body were determined and the density was calculated as weight/volume.

The compressive strength of the specimens was measured using a Zwick/Roell Z250 universal testing machine. For this purpose, the compressive forces (in N) were recorded graphically over the deformation distance. The maximum pressure reached was related to the surface area (mm) of the probe.

For the recording of the NMR spectra Al-MAS-NMR spectroscopy could be performed with the following measurement parameters: 4 mm MAS BB/1 H probe in a Bruker AVANCE III 400 WB (magnetic field 9.4 T; rotational frequency 9 kHz) with a frequency of 104.3 MHz for27Al, a single pulse excitation (1 μs pulse length; round trip delay 0.5 s), and a 1 M aqueous solution of AlCl3*6H2O as an external standard (0 ppm). In the figures showing NMR spectra, the chemical shift in ppm relative to external standard is plotted on the x-axis and the signal strength in arbitrary units is plotted on the y-axis.

The following materials were used for examples 1 to 9:Betolin K35: potassium water glass, s=2.6; Wallner GmbH, aqueous solution with 35%. solids contentBetol K5020T: potassium water glass, s=1.49; Wallner GmbH, aqueous solution with 48% solids contentProtectosil® WS808: water glass with propyl radical, s=0.4; Evonik; 55% solids contentSecar®71: calcium aluminate (Al2O3>68.5%, CaO>31.0%), Kerneos Inc.Almatis® CA-14: Calcium aluminate (Al2O3=71%, CaO=28%), Almatis GmbH, Frank furtNa48/50: sodium silicate, s=2.6, Wallner GmbH, aqueous solution with 44.5% solids contentNa50/52DS: sodium silicate, s=1.54, Wallner GmbH, aqueous solution with 48% solids contentNa38/40: sodium silicate, s=3.4, Wallner GmbH, aqueous solution with 35.8% solids contentQuartz flour: 1205-SIKRON quartz SF800
Compressive Strength and Density

First, the compressive strength and density of material samples were investigated using various examples 1-4.

Example 1

100 g K35, 100 g K5020T, 36 g WS808, 50 g KOH, 64 g water) were mixed with 600 g Secar® 71 and 60 g quartz flour. The mixture could be stirred for five minutes and was solid after 20 min. The density of the cured material was 2.13 g/cm, the compressive strength 179 N/mm2.

Example 2

100 g K35, 100 g K5020T, 36 g WS808, 50 g KOH, 64 g water) were mixed with 600 g Almatis® CA-14 and 60 g quartz flour. The mixture could be stirred for five minutes and was solid after 20 min. The density and compressive strength of the cured material were comparable to those of Example 1.

Example 3

80 g Na 48/50, 20 g Na50/52DS, 21 g NaOH, 29 g water were mixed with 350 g Secar® 71 and 4.3 g KH2PO4. The density of the cured material was 2.11 g/cm, the compressive strength 132 N/mm2.

Example 4

80 g Na 48/50, 20 g Na50/52DS, 21 g NaOH, 29 g water were mixed with 350 g Almatis® CA-14 and 4.3 g KH2PO4. The density and compressive strength of the cured material were comparable to those of Example 3.

It was therefore found that the compressive strength can be significantly higher than those obtained with concrete on the application date.

Spectra of the Material−1

Solids according to the invention were then prepared using a series of material mixtures with different ratios of water glass to calcium aluminate and examined spectroscopically. For this purpose, the following waterglass-water mixtures were used in Examples 5-7:WG1: 9.92 g NaOH dissolved in 20 g water mixed with 100.2 g Na38/40.WG2: 19.98 g NaOH, dissolved in 10 g water, mixed with 100.6 g Na38/40Almatis CA-14 was used as the calcium aluminate.

Example 5

A concrete substitute was prepared from 40 g Almatis® CA-14 and 19.4 g WG1; the mixture was solid and gray in color after 32 min. The density was determined to 2.21 g/cm and the compressive strength to 101.3 N/mm2. (Sample Bl)

Example 6

A concrete substitute was prepared from 40 g Almatis® CA-14 and 9.48 g WG1; the mixture was solid after 3-4 min and of white color. (Sample CI)

Example 7

A concrete substitute was prepared from 40 g Almatis® CA-14 and 28.86 g WG2; the mixture was solid after 20 min and of gray color. The density was determined to be 1.97 g/m. (Per be Dl). The27Al MAS-NMR spectra from examples 5-7 are shown inFIGS.2-4.FIG.1(Pro be A) shows in comparison the27A-MAS-NMR spectrum of Almatis® CA-14. This 27A1 MAS NMR spectrum shown inFIG.1was measured with a 4 mm MAS BB/′H probe in a Bruker AVANCE III 400 WB (magnetic field 9. 4 T; rotational frequency 9 kHz) with a frequency of 104.3 MHz for Al, a single pulse excitation (1 ps pulse length; round trip delay 0.5 s), and a 1 M aqueous solution of AlCl3*6H2O as external standard (0 ppm).

Reference has already been made in the introduction to literature on the interpretation of Al spectra. Taking into account the references cited above, the signals in the range from 0 to 100 ppm in FIG. can be assigned as followsAl(VI) at 11.77 ppmAl(V) at 47.19 ppmAl(IV) at 77.68 ppm (main peak)

It should be mentioned that by using a different instrument and/or slightly different measurement conditions the exact appearance of the spectrum could differ somewhat fromFIG.1; however, even then the three characteristic peaks mentioned would be recognizable in the range 0-100 ppm (with AlCl3*6H2O as 0 ppm standard).

The main peak at about 78 ppm is characteristic of calcium aluminate and is not found, for example, in the spectrum of tobermorite or in the spectrum of Roman concrete (seeFIG.11from “Unlocking the secrets of Al-tobermorite in Roman seawater concrete” by Marie D. Jackson, Sejung R. Chae, Sean R. Mulcahy, Cagla Meral, Rae Taylor, Penghui Fi, Abdul-Hamid Emwas, Juhyuk Moon, Seyoon Yoon, Gabriele Vola, Hans-Rudolf Wenk, and Paulo J. M. Monteiro, Cement and Concrete Research, Volume 36, Issue 1, January 2006, Pages 18-29).

FIGS.2-4show that these three signals of the calcium aluminate with approximately the same chemical shifts in ppm can also be seen in the spectra of the material according to the invention, but with different intensities. A characteristic feature of the material according to the invention, as shown in the spectra ofFIGS.2to4, is that in addition to these signals of the starting material calcium aluminate, a new signal appears between the signal assigned to Al(IV) and the signal assigned to Al(V), even if this signal may not be seen as a separate peak due to superposition, but as a shoulder of the Al(IV) signal on the side of the higher field. The additional signal or the added shoulder in the Al spectrum is currently explained by the fact that in the material-forming reaction new bonds are formed from Al(IV) via oxygen to Si centers by the substitution of already existing Al(IV) centers; in view of this understanding, it is considered significant for the reaction presented that energy-rich Al(IV)—O—Al(IV) bonds are replaced (substituted) by lower-energy Al(IV)—O—Si bonds. This makes the reaction exothermic in the aggregate, and so it can proceed at room temperature.

The material according to the invention can thus be described as having the three peaks of calcium aluminate in an Al-MAS-NMR spectrum in the range 0-100 ppm (using AICI3-6H2O as an external standard) and additionally a signal between the main peak and the peak nearest to the higher field, which signal can be present as a shoulder. The formation of new bonds naturally changes the relative peak heights compared to those in the spectrum of calcium aluminate.

The kinetics of the solid-state formation reaction were then investigated using IR spectra, showing the change over time in the IR absorption spectrum of a mixture of water glass and calcium aluminate activated with NaOH in accordance with the invention. To show this change, several spectra recorded during the course of the reaction are superimposed in the figures. The spectra recorded later have the stronger bands.

FIG.5ashows the change of the IR spectra in transmission between 650 and 2000 cm 1,FIG.5bshows the absorption between 650 and 1200 cm−1. Absorptions above 1300 cm 1 are caused by water. The transformation of a Si—O—Si bond into an Al—O—Si bond accompanying a shift from 995 to 920-960 cm−1as dominating the bond is well seen inFIGS.5aand5b. Accordingly, the IR spectrum of the solid material according to the invention shows a characteristic band around 960-910 cm−1. It should be mentioned that conventional geopolymers vibrate at somewhat higher wave numbers between 960-1000 cm−1. It should also be mentioned that in the IR spectrum two characteristic shifts of the water bands to about 1390 cm−1and to a signal between 2800 and 3000 cm−1can also be observed, compare alsoFIG.5.

Aggregates of Different Grain Size

It was then investigated how aggregates of different grain size affect density and compressive strength.

Example 8A and B

102 g Na38/40, 10 g NaOH, 50 g water and 925 g coarse crushed stone were mixed with 165 g Secar® 71 (A) and 165 g Almatis® CA14 (B), respectively. Density: 2.27 g/cm3(A), compressive strength: 40.9 N/mm (A); density and compressive strength for (B) were comparable.

Example 9A and B

102 g Na38/40, 10 g NaOH, 18 g water were mixed with 325 g desert sand (120 pm particle size) and 180 g Secar® 71 (A) or 180 g Almatis® CA14 (B). Density: 2.01 g/cm3(A), compressive strength: 37.5 N/mm (A), flexural strength: 7.8 N/mm (A); density, compressive strength and flexural strength of (B) were comparable.

Carbon Dioxide Emissions

It was then computationally determined, for various specimens practically manufactured according to the invention, the reduction in CO2emissions that can be obtained in the manufacture of the material according to the invention compared to concrete.

The CO2emissions released during the production of concrete cannot be pushed below a fixed limit value, since about 2/3 of the CO2emissions released during the production of concrete are due to the conversion of the CaCO3to CaO. If the emission is calculated as 0.75 tons of CO2for each ton of cement produced, or 0.354 tons of CO2for one m of concrete of compressive strength 40 N/mm, the CO2emissions can be compared with those released when using the mixture according to the invention, provided that it is assumed that water glass, NaOH and, to a limited extent, calcium aluminate are also produced by using solar power generated without emissions.

The values given in the example formulations for the reduction of CO2 emissions now refer, on the one hand, to the CO2emissions from the production of currently available concrete of the specified quality and, on the other hand, to the CO2emissions from water glass, NaOH and calcium aluminate assuming exclusive use (100%) of solar electricity in the production of the required starting materials.

Example 10

6.4 g NaOH+86 g water glass Na38/40 with 36 g calcium aluminate (and 330 g construction sand) is solid after 90 min (final hardness: 41 N/mm2). The Si/AG ratio is 1/1. (Proportionate CO2 emissions, based on concrete: 20%).

Example 11

14 g NaOH+86 g water glass Na38/40 with 50 g calcium aluminate (and 370 g construction sand) is solid after 180 min (final hardness: 30 N/mm2). The Si/Al−ratio is about 3/4 (5.7/8). (Proportionate CO2emissions, based on concrete: 24%)

Example 12

14 g NaOH+86 g water glass Na38/40 with 50 g water and 35 g calcium aluminate (and 680 g construction sand) is solid after 24 h (final hardness: 11 N/mm2). The Si/Al-ratio is 1/1. (Proportion of CO2emissions, based on concrete: 11%).

Example 13 (Maximum Value from FIG.6)

30 g NaOH+32 g water glass Na38/40 and 68 g water glass Na48/50 with 70 g water and 370 g calcium aluminate (and 31 g quartz flour) is solid after 12 min (final hardness: 155 N/mm2). The Si/Al-ratio is 1/8 (proportional C02 emissions, based on concrete: 100%).

In the last example in particular, it should be noted that a very high final strength was achieved and that quartz powder, i.e., a very fine aggregate, was incorporated, which typically leads to a considerable mixing energy requirement for high-performance concrete, which was not taken into account comprehensively and correctly in the lump-sum considerations. This means that considerable amounts of CO2can be saved overall.

Lipophilization

It was then investigated by using different functionalizing silanes how the material can be functionalized.

For this purpose, water glass, sodium hydroxide and calcium aluminate and the required amounts of water were brought into contact together with the different functionalized silanes during the preparation of the solids, and the solids obtained were then subjected to a search.

It was found that the lipophilic compound octyl triethoxysilane lipophilizes the entire batch when added to the binder in a range of 0.5-3%. This makes not only the surface water repellent, but the whole stone. It is therefore possible to grind or drill without the stone losing its water-repellent properties in the corresponding areas.

Even when the water glasses Rhodarsil R51T (tripotassium methylsilane triolate, a methyl siliconate) or Protektosil WS 808 (tripotassium propylsilane triolate, a propyl silicate) were added between a few % and 100% as a water glass substitute, a continuous lipophilization of the stones was achieved.

Silicon Nanoparticles as Si Tetrahedral Source

It was then investigated whether the material according to the invention could also be produced without water glass.

In order to show that a material according to the invention can also be produced without water glass, SiO2nanoparticles (here: Köstrosol 1540) were recombined with calcium aluminate instead of water glass. In this case, 10 g of Köstrosol mixed with 3 g of NaOH and 20 g of calcium aluminate solidified within 3 min. SiO2nanoparticles can thus readily act as a Si tetrahedral source.

Mixtures for Rapid Curing

Various mixtures were used to investigate how the curing time can be shortened.100 g K42 (Betolin K42 from Woellner), 20 g KOH, 50 g water with 55 g water and 420 g calcium aluminate. The mixture is solid after 90 sec, with a compressive strength of 123 N/mm2.100 g K35 (Betolin K35 from Woellner), 20 g KOH, 50 g water with 55 g water and 425 g calcium aluminate, solid after 8 min, with a compressive strength of 169 N/mm2.Si/Al ratio 0.33: 100 g Na38/40 (Betol 38/40 from Woellner), 10 g NaOH, 10 g water, 250 g calcium aluminate, 125 g desert sand, solid after 12 min, with a compressive strength of 162 N/mm2.

It should be emphasized that compounds with such rapid curing are already very suitable for 3D printing.

Aggregates

Various additives were added to formulations as described in Examples 1-13 in order to check whether a good material bond was obtained.

In this way, it could be confirmed that a good material bond of the compounds with the following aggregates is obtained: is obtained: Alumina, quartz flour, blue quartz flour, titanium dioxide, metakaolin, polyfill, Ceratec, Granoflour tubular gray, Granoflour yellow, concrete recycling material, fine rubber granules, coal, barium sulfate, concrete gravel, red clay gravel, mica, talc, fireclay, corundum, microsicilica, poraver in various grain sizes, namely 0.06-0.125; 0.25-0.5; 0.5-1.0; 1,0-2.0; liaver in various grains, namely 0.25-0.5; 0.5-1.0; 1,0-2.0; 2,0-4.0; wood chips; Gutex wood fiber; wood chips, expanded clay; Aeroballs; Aeropor 180; Aeroballs 0.5-0,7, Nabalox, Alfa Tab 0-0.5045; Alfa Tab 0-0.6; wollastonite Tremin 263-100, Lumiten 3108, and various types of sand, namely ultrafine sand, recycled sand 0-2 mm; desert sand from China, Dubai, Oman, Jordan and Tunisia, quartz sand from Krauchenwies in the Swabian Alb and unsifted sand from a Portuguese sand beach. Stable solids could be produced with all these materials, and these solids are sufficiently abrasion resistant for applications to be anticipated without further ado.

It was examined whether the various aggregates interfere with each other or whether the material according to the invention can be used to produce a good bond. To this end, layers of material with one aggregate were cured in a mold and then further layers of material with different aggregates were cured on top to determine whether a stable material bond was produced. Thus, a first “sandwich” was created with material layers containing desert sand, aluminum hydroxide and brick recycling material, as well as another “sandwich” whose material layers included liaver, wood or concrete gravel as aggregates. These material layers proved to be stable, i.e., no separation failure occurred at the layer boundaries.

As far as mineral aggregates are concerned, it was then investigated whether segregation occurs before curing when using aggregates with very different grain sizes. For this purpose, a formulation was used which had a long curing time of more than 60 minutes for the material according to the invention. Such a mixture was mixed with mineral aggregates of different grain size, poured into a column mold and placed with the mold on a vibrating table to investigate whether prolonged vibrating could provoke segregation. It was found that no segregation occurred despite the prolonged shaking.

Moreover, as far as wood as an aggregate is concerned, wood chips of different wood types were combined with one and the same material mixture resulting in the material according to the invention to form a wood chipboard. In this way, stable chipboard could be produced without the need for heating under pressure. The material mixture yielding the material according to the invention was thus used as a binder. Wood chips from both hardwood and softwood species were used for various samples in order to check whether one and the same material according to the invention is in principle suitable for bonding different wood chips together, which was confirmed. No differences were found when using the same binder for different types of wood.

In order to test the fire resistance, particle boards produced with the material of the invention were then flamed with a Bunsen burner. For this purpose, a water glass mixture of 102 g K35, 10 g H2O, 12 g KOH was prepared and 74 g of this mixture was mixed with 100 g calcium aluminate and 60 g wood fiber as well as 9.4 g R51T and cured in board form. It was found that after a flame treatment time, at which conventionally produced wood particle boards were already in flames, no damage was observed on the wood particle boards produced with the material according to the invention.

Maximum Compressive Strengths

It was then investigated how, for given starting materials, the compressive strength can be influenced by varying the Si/Al−ratio.

After initially establishing that particularly high compressive strengths are obtained when the Si/Al ratio is particularly small, whereas only lower compressive strengths can be obtained when the Si/Al becomes larger, i.e., less aluminum is used in relation to the silicon, the compressive strength was investigated for particularly low Si/Al ratios. By varying the mixing ratios of a material-forming compound according to the invention, it was possible to plot the compressive strength curve inFIG.6. This shows that, if the Si/Al ratio is too low, the compressive strength decreases as before, so that the use of the expensive calcium aluminate in excess does not result in any advantages in terms of mechanical stability.
Spectra of the Material—II

The effect of varying the Si/Al−ratio on the27A-MAS NMR was then investigated. For this purpose, samples of the material according to the invention were again prepared with different mixing ratios of a material-forming mixture according to the invention in such a way that samples with the desired Si/Al−ratio were obtained.

Table 1 lists the amounts of NaOH, water glass Na38/40 and calcium aluminate used to produce the samples with the desired Si/Al−ratios. Furthermore, except for waiting times and compressive strength after five and 21 days, respectively, data for these specimens are tabulated in Table 1:

TABLE 1Data of different mix designs with curing times and compressivestrengths, measured after 5 and 21 days, respectively.Si/AlNaOHNa38/40Ca-aluminateCuring timeN/mm20.12514.2 g86 g286 g5 min57 (5 days)0.15620.0 g100 g + 10 g H2O268 g17 min77 (21 days)0.23110.0 g100 g + 10 g H2O180 g20 min60 (21 days)0.37514.2 g86 g96 g100 min75 (5 days)0.62514.2 g86 g58 g140 min32 (5 days)0.8759.1 g91 g44 g50 min47 (5 days)

The27Al-MAS NMR spectra recorded on these samples are shown inFIGS.7-10. Note the slightly different scaling of the X-axis in some cases.

These spectra show that the new binder or the novel solid-state material can not only be identified per se by27A-MAS-NMR, but furthermore that further relevant information can be obtained from the spectrum. Important conclusions can be drawn from the strengths of the signals at the respective peaks or from the area values of the signals by comparing the strengths or area values of different signals.

Thus, the ratio of the area value of the signal at 65 ppm, i.e., the actual bond signal from the —O—Si—O—Al—O bonds, to the area value of the signal at 78 ppm, i.e., the signal from the —O—Al—O— bonds, runs from 0—if only —O—Al—O bonds are present in the calcium aluminate—to over 10. The value in the upper signal ratio range close to 10 is limited by the detectability of the signal at 78 ppm, because for Si/Al ratios close to 1 the signal at 78 ppm will be very small and possibly even close to zero, because the calcium aluminate will react off almost completely at this Si/Al ratio. However, NMR instruments today are generally very good. It is therefore possible with today's NMR instruments to set a noise ratio of 3s (sigma) as the detection limit for the 78 ppm signal, and despite this sharp criterion for clear detectability of the 78 ppm signal in a material according to the invention even if, even if it was generated with a ratio of Si/Al almost equal to 1, at which practically all calcium aluminate should have been reacted, still unreacted calcium aluminate should be found in an amount sufficient for spectral recognition, for example in insufficiently mixed regions.

With this in mind, the peak areas for the three signals to be attributed to the calcium aluminate and for the additional signal were determined. If the peak area of the individual signals is normalized to the total area in the spectrum, values are obtained as listed in Table 2. Per se, the considered signals of the calcium aluminate at the values 78 ppm, 47.2 ppm and 11 ppm together with the additional signal should account for 100% of the total area; however, the peak area values deviate from this somewhat in some cases, which can be attributed to effects such as noise, inaccuracies in the calculation due to the superposition of curves, etc. Nevertheless, it is clear that the signal component of the signal around 65 ppm increases significantly with the Si/Al ratio. It should be noted that the signal at 47.2 ppm, which can be attributed to a five-coordinate aluminum, plays no role in the reaction.

TABLE 2Peak area values in percent of each of the27Al signalsSignal atSi/Al78 ppm65 ppm47.2 ppm11 ppm65 ppm/78 ppm080.8%0.0%6.7%12.5%00.12540.1%17.6%3.1%39.2%0.40.15625.1%30.6%3.1%34.5%1.20.23121.6%38.8%3.1%36.5%1.80.3757.40%49.5%3.1%40.0%6.70.6257.58%56.2%3.1%33.1%7.40.87511.7%62.0%3.1%23.2%5.3

In a corresponding manner, the peak heights of the individual signals in the Al-MAS NMR can be determined instead of the area values. The corresponding, relative signal heights are listed in Tab. 3, again using relative normalization. Again, the signal at 47.2 ppm, which can be assigned to a fivefold coordinated aluminum, plays no role in the reaction.

TABLE 3Peak height values (in percent) of the individual27Al signalsSignal atSi/Al78 ppm65 ppm47.2 ppm11 ppm65 ppm/78 ppm080.8%0.0%6.7%12.5%00.12540.0%12.5%3.5%44.0%0.310.15633.9%25.5%3.5%37.1%0.750.23140.6%19.8%3.5%36.1%0.490.37515.5%26.8%3.5%54.2%1.70.62516.8%40.4%3.5%39.3%2.40.87535.3%38.6%3.5%22.6%1.1
Exemplary Compositions at Range Limits

Mixtures were then defined against the background of the experiments which lead to the formation of material with very large or very small Si/Al ratios; for comparison, a reaction mixture was also defined which gives a material with intermediate Si/Al ratios. These mixtures are intended to indicate only exemplary reaction mixtures for the range limits, without being self-limiting. As an example, the reaction mixtures of Table 4 are suggested. As far as a mixture to obtain a material just below the Si/Al ratio of 12:12 is concerned, the calcium aluminate content will then be slightly lowered and the water glass content slightly increased.

TABLE 4Limits of the range of the test resultsSi/Al ratio1:128:1212:12Calcium aluminate70.2%35.0%26.3%Water glass (solid)5.10%19.9%22.0%NaOH (solid)2.34%9.10%4.70%Water22.4%36.0%47.0%

The inert content can be up to 80%. The above weight-percentage ratios thus drop to a maximum of 1/5 of the above values when related to the weight of a building element provided with aggregates. The proportion of calcium aluminate in the total massecuite required for the production of building elements of a given mass thus does not fall below the value of 5.26%, even for such a high inert material content.

With regard to KOH and potassium silicate, the values for caustic soda and water glass are at most a factor of 56/40=1.4 above those of sodium hydroxide solution and sodium silicate. The inert material content can be increased up to 80%. The percentage ratios listed above thus drop to a maximum of 1/5 of the above values. Thus, the calcium aluminate content of no mixture falls below the value of 5.26%.

Thus, described above, among others, but not exclusively, was a mixture containing Si, Al, Ca, O and at least one of Na and K, which in the27A-MAS-NMR spectrum exhibits in addition to the27A-MAS-NMR spectrum of calcium aluminate a signal with a chemical shift which lies between that of the main peak of calcium aluminate and that peak of calcium aluminate which is closest to the main peak in the higher field. The solid can be used, among other things, as a construction material with aggregates, as a coating, as an adhesive for bonding second construction elements, for sanitary ceramic elements, for high-temperature applications, for repairing existing structures, especially for underwater repair, for the construction and/or repair of structures, especially when high compressive strengths are required or chemically aggressive conditions occur. It can be produced by contacting water glass, sodium and/or potassium hydroxide, calcium aluminate, one or more aggregates and, if necessary, additionally water, in particular seawater, even at temperatures below 0° C. without heating.