Gypsum-based building material

Abstract

To provide an alternative fire-resistant building material in which fire resistance can be incorporated preferably at low cost and which does not affect known handling of the building material.SOLUTION: A building material comprising an inorganic binder-source of reactive silicon-source of reactive calcium.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to building materials with improved fire resistance. [Background technology]

[0002] Various types of building materials that are not consumed in a fire, such as gypsum or cementitious materials in general, often begin to crack in the event of a fire, due in part to the shrinkage of the matrix material typically associated with volume loss due to the transformation of gypsum to anhydrite and the sintering process involved in the minerals.

[0003] Such cracks during a fire accelerate the ingress of heat into the material and further destruction. Heat and smoke can penetrate into adjacent rooms through the cracks. For example, when a wall construction collapses, flames penetrate into adjacent rooms.

[0004] Depending on the type of material, loss of mechanical stability can be a relevant risk to the stability of the building and the safety of the inhabitants. Summary of the Invention [Problem to be solved by the invention]

[0005] Although there are numerous materials with improved fire resistance, there remains a need for alternative materials that can incorporate fire resistance, preferably at low cost, and that do not affect the known handling of building materials.

[0006] It is an object of the present invention to provide such an alternative fire resistant building material. [Means for solving the problem]

[0007] This problem is solved by a building material that includes an inorganic binder, a reactive silicon source, and a reactive calcium source.

[0008] Preferred inorganic binders are cementitious materials or calcium sulfate based materials.

[0009] Preferred cementitious materials are cement or concrete. Preferred calcium sulfate materials are calcium sulfate dihydrate, stucco, α- and / or β-calcium sulfate hemihydrate, or calcium sulfate anhydrite.

[0010] The reactive silicon source is a material capable of generating reactive silicon dioxide in the event of a fire. Suitable materials are amorphous silicon dioxide, in particular pyrogenic silicon dioxide (fumed silica) or microsilica (silica fume), or mixtures thereof.

[0011] The reactive calcium source is a material that can produce reactive calcium oxide in the event of a fire. Suitable materials are calcium oxide, calcium hydroxide, calcium carbonate, and mixtures thereof.

[0012] The amount of reactive silicon source is preferably in the range of 0.5 to 20% by weight of the amount of inorganic binder in the building material.

[0013] A preferred amount of the reactive silicon source is 2 to 15 wt % or 3 to 10 wt %.

[0014] The amount of the reactive calcium source is preferably 0.5 to 40% by weight based on the amount of the inorganic binder in the building material.

[0015] A preferred amount of the reactive calcium source is 2 to 30% by weight or 3 to 20% by weight.

[0016] As an example, if the building product contains 100 kg of inorganic binder, the amount of reactive silicon source may be 0.5 to 20 kg.

[0017] When the amount of inorganic binder is 100 kg, the amount of reactive calcium source can be 0.5-40 kg.

[0018] By way of example, the material may include 100 kg of an inorganic binder, 10 kg of a reactive silicon source, and 20 kg of a reactive calcium source.

[0019] It is also possible to calculate the amount of reactive calcium source and reactive silicon source based on the total weight of the material.

[0020] Based on the total weight of the building material, suitable amounts range from 0.5 to 30% by weight for the reactive calcium source and from 0.5 to 18% by weight for the reactive silicon source.

[0021] Suitable particle size of the reactive silicon source when measured as D50vol is 0.01 to 400 μm, preferably 0.01 to 200 μm, or 0.01 to 50 μm, or 0.01 to 5 μm.

[0022] Suitable particle sizes of the reactive calcium source are 0.1 to 800 μm, preferably 0.1 to 200 μm, or 0.1 to 50 μm, or 0.1 to 10 μm, measured as D50vol.

[0023] "D50vol" represents the particle size at which 50% by volume of the particles are larger than the respective value and 50% by volume of the particles are smaller than the respective value. Such values ​​can be measured according to (for example, measurement by laser particle size analysis using a Mastersizer 2000, solvent: isopropanol).

[0024] The amount of reactive calcium source relative to the amount of reactive silicon source is 2.5:1 to 1:1 by weight.

[0025] In suitable embodiments, the building product may be a building board, plaster, putty, joint compound, screed, fill, or filler.

[0026] When used in the form of a board, the board may be gypsum fiberboard, plasterboard with or without fiber reinforcement, and liner, cement board, or matting of paper liners or fibers as building blocks.

[0027] According to the present invention, the building product is capable of forming wollastonite when heated above 600°C.

[0028] Wollastonite is a fire-retardant material that forms interlocking crystals that stabilize the mechanical properties of building materials and inhibit cracking. Because the reaction to wollastonite is energy-consuming, an in-situ reaction has the advantage of increasing the time window during which the temperature of the building product can be kept below 100°C.

[0029] The building material of the present invention may further comprise auxiliary reagents used in the production of the building material. Suitable auxiliary reagents are retarders, accelerators, hydrophobic agents, liquefiers, strengthening agents (e.g., sodium trimetaphosphate, starch), substances that liberate water of crystallization when heated (such as aluminum trihydrate), or thickeners.

[0030] The building materials of the present invention may contain fibers to improve their mechanical properties. Suitable fibers are glass fibers, mineral fibers, carbon fibers, polymer fibers, cellulose fibers, and mixtures thereof.

[0031] A further embodiment of the present invention is a method of making a building product comprising combining at least an inorganic binder, a reactive silicon source, and a reactive calcium source.

[0032] In a preferred embodiment, the method further comprises the step of forming a building board in accordance with the state of the art.

[0033] A further embodiment of the present invention is the use of a mixture of a reactive silicon source and a reactive calcium source to form wollastonite in a building product in situ when the building product is exposed to fire. [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 1 is a diagram of the shrinkage of samples with different compositions upon heat input (embodiments according to the present invention). [Figure 2] FIG. 1 is a diagram of the shrinkage of samples with different compositions upon heat input (comparative example). DETAILED DESCRIPTION OF THE INVENTION

[0035] The present invention is further illustrated by the following non-limiting examples.

[0036] Example 1 Gypsum prisms measuring 120 mm x 40 mm x 20 mm for shrinkage measurements and 160 mm x 40 mm x 20 mm for stability measurements were prepared from slurries containing the following materials: Calcium sulfate: stucco (mainly calcium sulfate hemihydrate in the beta form), Iphofen Reactive silicon source: 50% suspension of microsilica (SiO2) in water, EMSAC500, ELKEM, d50vol: 0.15μm, specific surface area by Blaine method: 15-30m 2 / g Reactive calcium source: limestone powder (CaCO3), Kalkstein-Fuller KSF60 / 3, Fels-Werke, d50vol: 8.4μm, specific surface area by Blaine method: 0.54m 2 / g Fiber: Glass fiber, DuraCore® M300, Johns Manville

[0037] [Table 1]

[0038] The shrinkage measurements were performed in a muffle furnace, where the samples were heated and their change in length was continuously recorded. The measurement method and required equipment are described in detail in WO 2017 / 000972(A1). Briefly, the sample was movably mounted in a horizontal orientation on a sample holder. One end of the sample abutted against a counterbearing. At the opposite end of the sample, a detector rod applied pressure to the sample, ensuring that the sample always abutted against the counterbearing. The detector rod measured the movement of the end of the sample under pressure. This measurement, related to the original sample length before heating, resulted in the percent change in length shown in Figures 1 and 2.

[0039] The change in length of the specimen is measured as it passes through a standard temperature / time curve according to EN 1363-1. Comparative specimen 7, which does not contain any wollastonite or its extracts and contains only glass fibers, expands in the first 20 minutes, as do all the other specimens (see Figure 1). During this time period, the specimen is heated and the crystalline water contained within the gypsum slowly becomes gaseous. As a result, the specimen body expands. When the water vapor begins to outgas, the specimen body begins to shrink. After about 40 minutes, all the crystalline water evaporates and the specimen begins to sinter. After 2 hours, the comparative specimen body has lost more than 11% of its original length.

[0040] This shrinkage is substantial and poses serious problems when the material is used in tightly fastened drywall construction, such as plasterboard. Plasterboard is typically fastened to metal studs via numerous screws. A shrinkage of 11% in the length or width of the board, i.e., a few centimeters in the case of plasterboard, causes the calcium sulfate material, already embrittled by volume loss, to break and / or splinter from its fasteners and fall at least partially into the room.

[0041] In contrast, Sample 1 exhibits only approximately 4% length shrinkage. XRD Rietveld analysis reveals that this sample contains 6% wollastonite by weight, formed from 8% microsilica suspension and 8% limestone by weight during heating. Furthermore, the low shrinkage period following the expansion period is delayed by approximately 10 minutes. The slow shrinkage continues until 50 minutes after initiation, then decreases to moderate shrinkage. The decrease in shrinkage between approximately 50 and 60 minutes is associated with the end of outgassing of water of crystallization. At this point, the calcium sulfate material begins to sinter. The sintering process, if not addressed, leads to further significant volume loss in the calcium sulfate material.

[0042] Without wishing to be bound by theory, the inventors believe that wollastonite extract We hypothesize that the addition of α-hydroxybenzoates results in the in situ formation of wollastonite during heating of the sample body. The reaction to wollastonite is endothermic, thus consuming energy that would otherwise be used to evaporate the water of crystallization. As the water of crystallization evaporates and wollastonite forms, the body cools. This results in an extended period (the first 50-60 minutes) during which the sample body first expands and then only slowly contracts, remaining close to its original volume. This is a critical period, since it is within this time range that people can be easily evacuated from a burning building. The structure remains intact and the temperature does not rise uncontrollably. Therefore, the longer this period, the greater the chance of saving lives.

[0043] Once formed, wollastonite has another positive effect on shrinkage, reducing the shrinkage that occurs with the onset of the sintering process. Our current understanding is that wollastonite is unaffected, or only slightly affected, by the sintering process, likely providing a rigid scaffold that prevents sintering of the gypsum surface and reduces overall sample shrinkage. All samples containing wollastonite extracts shrink less than 4%, compared to Comparative Sample 7, which shrinks by approximately 11%. Thus, shrinkage is reduced by approximately one-third.

[0044] The lowest shrinkage value was achieved with Sample 6, which contained the highest amount of wollastonite precursor material (8 wt. % microsilica and 16 wt. % limestone flour) and an additional 0.3% fiber. Shrinkage was indeed slight (0.2%).

[0045] Samples 1 and 4 have the same composition. Sample 4 further contains glass fibers, which is the only difference from Sample 1. The same is true for Samples 2 and 5, as well as 3 and 6. The samples containing glass fibers, i.e., Samples 4, 5, and 6, further reduced shrinkage by about 1% compared to the reference sample without glass fibers. Thus, the presence of glass fibers further reduced shrinkage.

[0046] The fracture resistance and sagging resistance of the samples according to Table 1 were measured in a muffle furnace heated to 930 °C. The samples were positioned on two supports, with their length ends resting on the supports, and the supports were placed at a distance of 11 cm from each other. The samples remained in the furnace for 60 minutes, provided they had not previously broken. If the sample broke, the measurement was stopped.

[0047] Table 2 shows the results of the measurements. The wollastonite content listed was determined after testing the specimens via XRD Rietveld analysis. The column "Failure" lists the measurement time that elapsed before failure occurred. If failure did not occur within 60 minutes of the total measurement, the result is listed as ">60." The column "Maximum Sag" contains the sag value due to heat treatment, i.e., the sag after heat treatment (if any) subtracted from the sag before heat treatment.

[0048] [Table 2]

[0049] Two replicates of each sample were investigated, Test 1 and Test 2. One of the replicates of Comparative Sample 7 broke; the other showed 17 mm of sagging. Sample 1, which contained the smallest amount of wollastonite precursor material of all the samples according to the present invention, did not break but sagged 2 and 4 mm, respectively. All other samples sagged only slightly, i.e., 2 mm, and most were less than 1 mm. Thus, the formation of wollastonite enhances sagging stability under heat.

[0050] Example 2 material Calcium sulfate: stucco, Iphofen Reactive silicon source: 50% suspension of microsilica (SiO2) in water, EMSAC500, ELKEM Glass powder, MWT Mineralwerk Thuringen Reactive calcium sources: limestone powder (CaCO3), Kalkstein-Fuller KSF60 / 3, Fels-Werke, Quicklime (CaO), max. 15% >90μm according to DIN4188 Fiberglass: Fiberglass, M300, Johns Manville Wollastonite: Tremine 939-010, Quarzwerke Gruppe Liquefying agent: Viscocrete G2, Sika

[0051] [Table 3]

[0052] The stated length measurements, as well as sag and breakage measurements, were performed as described in Example 1.

[0053] The samples listed in Table 3 are comparative examples, except for Sample 11, which contains quicklime (CaO) as the reactive calcium source and microsilica as the reactive silicon source. Sample 11 has the lowest shrinkage (about 1.3%) after heating of all the samples tested in Table 3 (see Figure 2).

[0054] Next, samples 10, 9, and 8 performed best, exhibiting shrinkage in the 2% to 3% range after heating. These samples were produced by adding only a reactive silicon source, without adding a reactive calcium source. The silicon content increased from sample 8 to sample 10. The relatively low shrinkage is believed to be the result of calcium carbonate impurities in the stucco used. Natural gypsum is typically not a pure material and contains impurities to varying degrees. Limestone is an abundant impurity in gypsum because it precipitates from highly saline water just before gypsum precipitation occurs when the water's salinity load increases due to evaporation. Therefore, the low shrinkage of samples 8, 9, and 10 is presumed to be due to the formation of wollastonite from the added microsilica and impurity calcium carbonate. Because samples 9 and 10 only differ slightly in terms of shrinkage after heating, it is further presumed that the calcium carbonate impurity has almost completely reacted with the wollastonite.

[0055] Sample 12 was tested to demonstrate that it matters whether wollastonite is formed in situ in the event of a fire or whether preformed wollastonite is used as an additive. 5% by weight of preformed wollastonite was added to Sample 12. After heating, Sample 12 exhibits approximately 6% shrinkage. The amount of wollastonite added to Sample 12 is equal to the amount of wollastonite found to form in Sample 8. However, Sample 8 exhibits only about half the shrinkage (2.8%) of Sample 12.

[0056] In Sample 14, glass powder was used as a silicon source together with limestone powder. The silicon and calcium source contents were relatively high. Nevertheless, the shrinkage after heating was more than 7%. Therefore, it is not enough to provide any pulverized silicon source, but it must be a reactive source, i.e., an amorphous silicon source, which is really effective in terms of shrinkage due to heat exposure. I concluded that there was no.

[0057] Sample 13 contains neither reactive silicon nor a reactive calcium source and exhibits shrinkage after heating of about 11%.

[0058] [Table 4]

[0059] Table 4 lists the results of the breakage and sag measurements for the specimens constructed as shown in Table 3. 3. Comparative specimens 12-14 either broke or showed high sag values ​​after temperature application (see Table 4). 4. Also, both replicates of specimen 8 broke. Surprisingly, for specimen 9, one specimen broke and one specimen showed a sag value of less than 1 mm.

[0060] Sample 11, an embodiment of the present invention, exhibited very low sag values ​​of less than 1 mm after 60 minutes of heating.

Claims

1. - inorganic binder - reactive silicon source - a reactive calcium source.

2. 2. The building material according to claim 1, wherein the inorganic binder comprises a cementitious material, in particular cement, concrete, or calcium sulfate, the calcium sulfate being selected from calcium sulfate dihydrate, stucco, α- and / or β-calcium sulfate hemihydrate, calcium sulfate anhydrite.

3. 3. A building material according to claim 1 or 2, wherein the reactive silicon source is amorphous silicon dioxide, in particular pyrogenic silicon dioxide or microsilica, or a mixture thereof.

4. (i) the particle size D50vol of the reactive silicon source is 0.01 to 400 μm, preferably 0.01 to 200 μm, or 0.01 to 50 μm, or 0.01 to 5 μm; or (ii) the particle size D50vol of the reactive calcium source is between 0.1 and 800 μm, preferably between 0.1 and 200 μm, or between 0.1 and 50 μm, or between 0.1 and 10 μm; or (iii) A building material according to any one of claims 1 to 3 which is a combination of both.

5. 5. The building material according to claim 1, wherein the amount of reactive silicon source is 0.5 to 20% by weight, preferably 2 to 15% by weight, particularly preferably 3 to 10% by weight, based on the amount of inorganic binder in the building material.

6. 6. A building material according to any one of claims 1 to 5, wherein the reactive calcium source is selected from calcium oxide, calcium hydroxide, calcium carbonate, and mixtures thereof.

7. 7. The building material according to claim 1, wherein the amount of reactive calcium source is 0.5 to 40% by weight, preferably 2 to 30% by weight, particularly preferably 3 to 20% by weight, based on the amount of inorganic binder in the building material.

8. 8. A building material according to any one of claims 1 to 7, wherein the amount of said reactive calcium source relative to the amount of said reactive silicon source is from 2.5:1 to 1:

1.

9. The building material of any one of claims 1 to 8, wherein the gypsum building product is a building board, a plaster, a putty, a joint compound, a screed, a filler, or a filler.

10. 10. The building material of claim 9, wherein the building board is a gypsum fiber board, a plasterboard, a cement board, or a building block.

11. 11. The gypsum-based building material of any one of claims 1 to 10, wherein the building product is capable of forming wollastonite upon heating above 600°C.

12. 12. A building material according to any one of claims 1 to 11, comprising an adjuvant selected from retarders, accelerators, hydrophobic agents, liquefiers, strengtheners, substances that liberate water of crystallization when heated (ATH), or thickeners.

13. at least - inorganic binder - reactive silicon source - a reactive calcium source.

14. The method of claim 13 further comprising forming a board.

15. 1. Use of a mixture of a reactive silicon source and a reactive calcium source to form wollastonite in a building product in situ when said building product is exposed to fire.

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