TWO-COMPONENT MORTAR MASS AND USE THEREOF

Abstract

A two-component mortar mass includes a resin component (A), which contains as curable constituent at least one radically curable resin, and a curing component (B) which contains a curing agent for the radically curable resin of the resin component (A), wherein the curing component (A) and/or the curing component (B) contain(s) as further constituent at least one inorganic additive. The inorganic additive contains a transition aluminum oxide having an average particle size d50 of at least 7.0 m and a pore diameter of 4.0 nm to 30.0 nm.

Claims

1: A two-component mortar compound, comprising: a resin component (A), which, as the curable ingredient, contains at least a free-radical-curing resin, and a hardener component (B), which contains a hardening agent for the free-radical-curing resin of the resin component (A), wherein the resin component (A) and/or the hardener component (B) contains at least one inorganic additive as a further ingredient, wherein the inorganic additive comprises a transition alumina having a mean particle size d50 of at least 7.0 m and a pore diameter of 4 nm to 30 nm.

2: The two-component mortar compound according to claim 1, wherein the inorganic additive comprises at least the transition alumina as well as one or more further substances, which are selected from the group consisting of inorganic fillers, hydraulically binding or polycondensable inorganic compounds, modifiers and mixtures thereof.

3: The two-component mortar compound according to claim 1, wherein the inorganic additive comprises a filler.

4: The two-component mortar compound according to claim 1, wherein the inorganic additive comprises a hydraulically binding or polycondensable inorganic compound.

5: The two-component mortar compound according to claim 1, wherein the inorganic additive further comprises an inorganic modifier.

6: The two-component mortar compound according to claim 1, wherein the transition alumina is present in the mortar compound in a proportion of 0.5 to 10 percent by volume.

7: The two-component mortar compound according to claim 1, wherein the mean particle size d50 of the transition alumina is at least 12.0 m.

8: The two-component mortar compound according to claim 1, wherein the polymerization shrinkage of the mortar compound is less than 3.1%.

9: The two-component mortar compound according to claim 1, wherein the transition alumina has a mean particle size d50 of up to 120 m.

10: The two-component mortar compound according to claim 1, wherein the transition alumina has a pore diameter in a range of 4.5 nm to 20 nm.

11: The two-component mortar compound according to claim 1, wherein inorganic additives, including the transition alumina, are present in the mortar compound in a proportion of 50 to 80 percent by weight relative to the total weight of the compound.

12: The two-component mortar compound according to claim 1, wherein the free-radical-curing resin comprises a urethane (meth)acrylate resin and/or a (meth)acrylate-modified epoxy resin.

13: The two-component mortar compound according to claim 1, wherein the resin component (A), comprises at least one polymerization inhibitor selected from the group consisting of phenolic compounds, and optionally, a non-phenolic compound selected from the group consisting of stable free radicals, phenothiazines and mixture thereof.

14: The mortar compound according to claim 13, wherein the polymerization inhibitor comprises a phenolic compound, which is able to bind to the transition alumina.

15: The two-component mortar compound according to claim 1, wherein the hardener component (B) is anhydrous.

16: The two-component mortar compound according to claim 1, wherein the resin component (A) comprises: a free-radical-curing resin in a proportion of 5 to 45 wt %; a reactive diluent in a proportion of 0 to 25 wt %; an accelerator in a proportion of 0 to 3 wt %; a polymerization inhibitor in a proportion of 0 to 5 wt %; and at least one inorganic additive in a proportion of 50 to 80 wt %; wherein the sum of all proportions adds up to 100 percent by weight, and wherein the inorganic additive comprises at least one transition alumina having a mean particle size d50 of at least 7 m and a pore diameter of 4 nm to 30 nm.

17: The two-component mortar compound according to claim 1, wherein the mortar compound obtainable by mixing the resin component (A) and the hardener component (B) comprises: a free-radical-curing resin in a proportion of 5 to 50 wt %; a reactive diluent in a proportion of 0 to 25 wt %; an organic peroxide in a proportion of 0.5 to 5 wt %; a polymerization accelerator in a proportion of 0 to 0.5 wt %; at least one transition alumina in a proportion of 2 to 20 percent by weight; further inorganic additives in a proportion of 10 to 78 wt %; and water in a proportion of 0 to 10 wt %; wherein the sum of all proportions of the compound adds up to 100 percent by weight.

18: A method for chemical fastening of a structural part which is present in a mineral substrate, comprising: contacting said structural part with the two-component mortar compound according to claim 1, wherein said structural part is a threaded anchor rod, a rebar, a threaded sleeve or a screw in a drilled hole.

19: The two-component mortar compound according to claim 3, wherein the filler is selected from the group consisting of quartz, glass, corundum, porcelain, stoneware, heavy spar, light spar, gypsum, talc and/or chalk as well as mixtures thereof.

Description

[0099] Further advantages of the invention will become obvious from the following description of preferred embodiments with reference to the attached drawings. In the drawings:

[0100] FIG. 1 shows a diagram illustrating the polymerization shrinkage as a function of the mean particle size of the transition aluminas;

[0101] FIG. 2 shows a diagram illustrating the bond strength, determined in a steel-sleeve test, of mortar compounds as a function of the undercut depth of the steel sleeve.

INVESTIGATION OF THE ALUMINAS USED

Crystal Phase

[0102] The crystal phase of the aluminas used was determined by X-ray diffraction. The X-rays were generated with a Cu X-ray tube. The structure model needed for qualitative and quantitative analysis of the crystal phases was taken from the PDF file (Powder Diffraction File) and the ICSD file (Inorganic Crystal Structure Database).

Particle Size

[0103] The particle-size analysis was carried out with the LS 13320 instrument of Beckman Coulter, using laser diffractometry. The detectable particle-size range of the measuring instrument used was 0.017 m to 2000 m. For the measurements, the samples were slurried with demineralized water and treated ultrasonically for 30 seconds. Part of the suspension was then introduced into the measuring cell of the instrument. The d5, d50 and d95 values were determined on the basis of the volume distribution. The d50 value used for the evaluation represents the median of a distribution. This means that 50 vol % of the particles in the sample are smaller than the particle size corresponding to the d50 value.

Specific Surface and Pore Analysis

[0104] The BET specific surface and the pore sizes of the investigated samples were determined with the NOVAtouch LX4 instrument of the Quantachrome Co. Nitrogen was used as the measuring gas for determination of the sorption isotherms. The pore-size distribution was determined according to the method of Barret, Joyner and Halenda (BJH method). According to this, the pore-size distribution of the samples can be calculated from the desorption branch of the isotherms. The most frequent pore diameter of the desorption branch of the sample was defined as the characteristic value of the distribution. Thus pore diameter is understood to be the most frequent pore diameter of the sample.

Investigations of the Mortar Compound

Polymerization Shrinkage

[0105] The shrinkage behavior of the mortar compounds is determined by measurement of the linear thickness change of a mortar bed by means of a laser beam during curing. To perform the measurement, 2.5 g of mortar compound mixed for 10 seconds at 1000 rpm in a Speedmixer is applied with a spatula onto a steel plate, which is bounded on the left and right by spacers having a height of 2.5 mm. A steel plate having a thickness of 0.5 mm is placed as a reflector on the mortar. Using a further steel plate, the mortar together with the reflector plate is pressed flat to a height of 2.5 mm. The thickness of the mortar bed is therefore exactly 2 mm. For the measurement, the upper steel plate is removed again and the thickness change of the mortar bed during and after curing is determined by reflection of a laser beam on the reflector plate. At least 5 measurements are made and a mean value is calculated. The polymerization shrinkage indicates the percentage change of thickness of the cured mortar bed relative to the thickness of the mortar bed prior to curing.

[0106] The values determined for the polymerization shrinkage are evaluated relative to the reduction of shrinkage achieved in comparison with a mortar compound without transition aluminas and are subdivided into the following groups

[0107] Very pronounced: Polymerization shrinkage <1.0%

[0108] Pronounced: Polymerization shrinkage 1.0% to 2.3%

[0109] Slight: Polymerization shrinkage 2.3% to 3.1%

[0110] No: Polymerization shrinkage >3.1%

Polymerization Kinetics

[0111] To determine the enthalpy and rate of the polymerization reaction, DSC measurements were made with Mettler-Toledo measuring instruments. For the DSC measurements, approximately 100 mg mortar compound was introduced into a corundum crucible and the polymerization reaction was followed isothermally at 21 C. A corundum crucible was likewise used as reference crucible. Due to the exothermic reaction, a distinct peak, from which the enthalpy per gram of mortar compound used was determined, was visible in the DSC curve. In addition, the rate of the reaction was determined on the basis of the slope of the conversion curve of the reaction at the inflection point.

Bond Strength

[0112] For determination of the bond strength achieved with two-component mortar compounds, the mixed mortar is introduced into a steel sleeve having defined geometry and defined fill height of the mortar (bonding depth). Then, using a centering aid, an anchor rod is placed centrally in the steel sleeve filled with mortar. After curing of the mortar at room temperature and for at least 12 hours, the sample is screwed by means of a threaded adapter into a tension testing machine (type: Zwick Roell Z050, 50 kN). The sample is tested to failure with tensile force at defined speed. The corresponding force-displacement dependence is recorded continuously. Respectively five individual measurements are made and the mean value of the maximum force at failure is calculated.

[0113] The measurements were performed using anchor rods having M8 thread as well as steel sleeves having the following geometry:

[0114] Undercut depth: 0.35+/0.02 mm

[0115] Undercut width: 3 mm

[0116] Bonding depth: 36 mm

[0117] Inside diameter 14 mm

[0118] The bond strength determined from these measurements is defined at the ratio of maximum force at failure to sheared area of the anchor rod used (M8 anchor rod: 904.3 mm.sup.2).

EXEMPLARY EMBODIMENTS

[0119] The invention will be described hereinafter on the basis of preferred exemplary embodiments, but these are in no way to be understood as limitative.

Two-Component Mortar Compound Based on a Urethane Methacrylate Resin

Example 1 (Comparison)

[0120] The resin component (A) of a two-component mortar compound is first prepared by homogenizing, to a pasty mass free of air bubbles, in the dissolver under vacuum, 34.5 g of an acrylate resin mixture with 44.2 g of a quartz sand, 18.5 g of an aluminate cement and 2.8 g of a hydrophobic fumed silica as thixotropic agent. The composition of the acrylate resin mixture is indicated in the following Table 1. The resin component (A) obtained in this way is introduced into a cartridge.

TABLE-US-00001 TABLE 1 Composition of the acrylate resin mixture Percent by mass Urethane methacrylate and reactive diluent 97.31 Accelerator 2.30 Pyrocatechol 0.27 4-tert-Butylpyrocatechol 0.09 Tempol 0.03

[0121] An aqueous benzoyl peroxide suspension having a solids content of 35 percent by weight, containing 64 wt % filler in the form of quartz flour, 1 wt % of fumed silica and 35 wt % of benzoyl peroxide, is used as hardener component (B) of the two-component mortar compound. Thus the proportion of benzoyl peroxide in the hardener component (B) is 12.25 wt % and the water proportion is 22.75 wt % relative to the weight of the hardener component (B). The hardener component (B) is filled into a second cartridge.

[0122] For application as a chemical mortar compound for fastening of structural parts, the resin component (A) and the hardener component (B) are squeezed out of the cartridges and passed through a static mixer or mixed in a dissolver, whereby the reaction of these components begins, with curing of the reactive resin and optionally hardening of the cement. The reacting compound is injected into the drilled hole, whereupon the structural part to be fastened is introduced and adjusted.

[0123] The weight ratio of the resin component (A) to the hardener component (B) is 4.8:1, wherein the ratio of urethane methacrylate together with reactive diluent to benzoyl peroxide is adjusted to 13.5:1. This ratio of free-radical-curing components to hardening agent is the same is all exemplary embodiments.

[0124] The mortar compound according to Example 1 has a polymerization shrinkage of approximately 3.4%.

Examples 2 to 14

[0125] In the same way as indicated in Example 1, mortar compounds were produced in which respectively 5 percent by volume of the aluminate cement was replaced by an alumina. Thus the volume of the resin compound remained constant. The calculations of the formulation were based on an alumina density of 4 g/cm.sup.3. All aluminas used are commercial products.

[0126] The polymerization shrinkage was determined for the mortar compounds obtained by mixing the resin component (A) and the hardener component (B). For some mortar compounds, the gel time was shortened so much by the addition of the transition aluminas that no shrinkage measurement was possible. In these cases, the gel time was prolonged by addition of a larger proportion of polymerization inhibitors.

[0127] The crystal phase and the source of supply of the aluminas used as well as the reduction of shrinkage using the mortar compounds produced with the aluminas are presented in the following Table 2.

TABLE-US-00002 TABLE 2 Aluminas Crystal Shrinkage Example Alumina phase Supplier reduction 2 Al.sub.2O.sub.3-KNO / iolitec pronounced nanomaterials 3 Al.sub.2O.sub.3-INO / iolitec slight nanomaterials 4 Al.sub.2O.sub.3 activated / Sigma Aldrich very neutral pronounced 5** Al.sub.2O.sub.3-fumed*** / Cabot no 6** Al.sub.2O.sub.3-calcined Sigma Aldrich slight 7** Al.sub.2O.sub.3-fused Sigma Aldrich no 8** Al.sub.2O.sub.3-Chempur Chempur no 9 Al.sub.2O.sub.3--iolitec * iolitec slight nanomaterials 10 Al.sub.2O.sub.3-SCCa 5/150 * Sasol very pronounced 11 Al.sub.2O.sub.3-SCCa 5/90 * Sasol very pronounced 12 Al.sub.2O.sub.3-SCFa 140 /* Sasol pronounced 13 Al.sub.2O.sub.3-SBa 90 /* Sasol pronounced 14 Al.sub.2O.sub.3-TH 100/90 /* Sasol slight *Crystal phase according to manufacturer's statements **Comparison examples ***Only 2.3 percent by volume

[0128] When alumina Al.sub.2O.sub.3 fumed was used, it was only possible, due to the intensive thickening effect, to introduce approximately 2.3 percent by volume into the mortar compound.

[0129] From the examples of Table 2, it may be inferred that the polymerization shrinkage is significantly influenced by the type of alumina used. All aluminas having a polymerization-shrinkage-reducing effect are transition aluminas. The aluminas can be subdivided into four groups in terms of shrinkage reduction. The first group consists of three transition aluminas (Al.sub.2O.sub.3 activated neutral, Al.sub.2O.sub.3-SCCa 5/150 and Al.sub.2O.sub.3-SCCa 5/90), which significantly reduce the polymerization shrinkage to less than 1%. The next group contains three transition aluminas (Al.sub.2O.sub.3-KNO, Al.sub.2O.sub.3-SCFa 140 und Al.sub.2O.sub.3-SBa 90), which reduce the shrinkage to approximately 1.3% to 1.6%. This is followed by four aluminas having a polymerization shrinkage of approximately 2.3 to 2.7%. The aluminas of the fourth group have no influence on the polymerization shrinkage compared with the compound according to Example 1.

[0130] The exemplary embodiments show further that the reduction of the polymerization shrinkage is also influenced by the particle size of the alumina. The particle-size distribution of the transition aluminas used in indicated in Table 3.

TABLE-US-00003 TABLE 3 Particle size distribution Shrinkage Example Alumina reduction d5 [m] d50 [m] d95 [m] d5/d95 2 Al.sub.2O.sub.3KNO pronounced 4.5 0.0 34.3 0.1 93.2 0.33 0.05 0.00 3 Al.sub.2O.sub.3INO slight 2.4 0.sup. 20.3 1.8 78.1 7.6 0.03 0.00 4 Al.sub.2O.sub.3 activated very 48.3 1.0 102.5 0.5 158.8 0.7 0.30 0.00 neutral pronounced 5** Al.sub.2O.sub.3-fumed*** no 0.1 0.0 0.16 0.0 0.43 0.1 0.26 0.07 6** Al.sub.2O.sub.3-calcined slight 16.7 2.0 73.5 2.3 130.5 1.6 0.13 0.01 7** Al.sub.2O.sub.3-fused no 13.9 0.0 31.0 0.1 68.5 0.3 0.20 0.00 8** Al.sub.2O.sub.3-Chempur no 0.3 0.0 2.6 0.8 28.7 11.3 0.01 0.00 9 Al.sub.2O.sub.3--iolitec slight 0.5 0.5 14.8 8.3 56.1 20.4 0.01 0.01 10 Al.sub.2O.sub.3SCCa very 10.6 1.8 66.8 1.3 114.3 1.0 0.09 0.02 5/150 pronounced 11 Al.sub.2O.sub.3SCCa 5/90 very 34.7 13.7 76.5 6.1 134.7 3.4 0.25 0.10 pronounced 12 Al.sub.2O.sub.3SCFa 140 pronounced 2.9 0.1 30.6 1.5 99.3 5.4 0.03 0.00 13 Al.sub.2O.sub.3SBa 90 pronounced 3.3 0.4 29.5 3.3 84.9 3.4 0.04 0.00 14 Al.sub.2O.sub.3TH 100/90 slight 3.5 0.1 33.5 0.1 93.6 0.5 0.04 0.00 **Comparison examples

[0131] In FIG. 1, the mean particle size of the transition aluminas is plotted against the polymerization shrinkage. From this diagram, it can be seen that a pronounced reduction of polymerization shrinkage occurs starting from a mean particle size of approximately 25 m, while a slight reduction of shrinkage can be achieved starting from a mean particle size of approximately 14 m.

[0132] -Aluminas do not exhibit any pronounced shrinkage reduction even at a larger mean particle size. A mortar compound produced according to Example 4 using the transition alumina Al.sub.2O.sub.3 activated neutral, which was ground for approximately 15 minutes in a ball mill, still exhibits only a slight shrinkage reduction of 3% at a mean particle size d50 of 7.1 m. For a grinding time of only 5 minutes and a resulting mean particle size of approximately 12.0 m for the Al.sub.2O.sub.3 activated neutral, an improvement of the shrinkage reduction to approximately 2.6% was observed. An Al.sub.2O activated neutral obtained by shortening the grinding time to 3 minutes and having a mean particle diameter of approximately 20 m yields mortar compounds having a polymerization shrinkage of approximately 1.8%. These measurements likewise show that the polymerization shrinkage of the mortar compounds is decisively influenced by the particle size of the transition alumina used.

[0133] From BET measurement of the transition aluminas, no relationship between the specific surface (BET) and the polymerization shrinkage can be discerned. However, the pore diameter of 27.0 nm determined for the transition alumina TH100/90 suggests that the polymerization shrinkage of the mortar compound will increase if the the pores in the transition alumina used are too large. A preferred pore diameter of the transition aluminas therefore lies in a range of approximately 5 to 15 nm.

[0134] The use of porous silica gels in mortar compounds according to Example 1 having a mean particle size d50 of 11 to 130 m and pore diameters in a range of 3 to 15 nm, in a proportion of 5 percent by volume, surprisingly does not lead to any reduction of the polymerization shrinkage.

Examples 15 to 19

[0135] In the same way as indicated in Example 1, mortar compounds were produced in which different proportions by volume of the aluminate cement in the resin component (A) were replaced by corresponding proportion of the transition alumina Al.sub.2O.sub.3-KNO. Thus the volume of the resin compound remained constant. The polymerization shrinkage was determined for the mortar compounds obtained by mixing the resin component (A) with the hardener component (B) in the Speedmixer. The results obtained are presented in the following Table 4.

TABLE-US-00004 TABLE 4 Proportion by volume Al2O3-KNO Polymerization shrinkage Example [%] [%] 15 0.5 3.1 16 1 2.4 17 3 1.7 18 5 1.3 19 8 1.5

[0136] The results presented in Table 4 show that a pronounced reduction of the polymerization shrinkage takes place starting from a proportion of approximately 1 percent by volume of the transition alumina in the mortar compound. At higher proportions by volume, starting from approximately 10%, it was then possible to process the investigated compound only with difficulty.

[0137] From DSC measurements on the mortar compound according to Example 16, it is evident that neither the reaction enthalpy nor the rate of curing is influenced by the addition of the transition aluminas. Merely a shortening of the gel time can be observed, and it can be compensated for by addition of further polymerization inhibitors. The pH of the transition alumina used likewise has no influence on the shrinkage reduction.

Examples 20 to 24

[0138] Mortar compounds having different polymerization inhibitors were produced in the same way as indicated in Example 1. The composition of the resin component (A) of the respective produced mortar compounds is indicated in the following Table 5. The proportion of Al.sub.2O.sub.3 activated neutral in Examples 21 to 24 corresponds to 1 percent by volume of the mortar compound.

[0139] In Table 5,

[0140] Tempol: means 4-hydroxy-2,2-6,6-tetramethylpiperidine-1-oxyl

[0141] BHT means tert.-butylhydroxytoluene

[0142] BK: means pyrocatechol

[0143] tBBK: means 4-tert-butylpyrocatechol

TABLE-US-00005 TABLE 5 Composition of the resin component (A) Example 20 Example Example Example Example (comparison) 21 22 23 24 Component [wt %] [wt %] [wt %] [wt %] [wt %] Urethane methacrylate 33.6 33.5 33.5 33.5 33.5 resin and reactive diluent Accelerator 0.8 0.8 0.79 0.79 0.79 Quartz flour 44.2 44.2 44.2 44.2 44.2 Aluminate cement 18.4 16.6 16.6 16.7 16.7 Fumed silica 2.8 2.5 2.5 2.5 2.5 Al.sub.2O.sub.3 activated neutral 0 2.2 2.2 2.2 2.2 Tempol 0.2 0.2 0.01 0.01 0.01 BHT 0.2 BK 0.1 tBBK 0.1 Total 100 100 100 100 100 Shrinkage reduction no slight no pronounced pronounced

[0144] The examples show that mortar compounds containing sterically unhindered phenols such as pyrocatechol or tBBK achieve a very pronounced shrinkage reduction. Similar results were obtained with other dihydric phenols, such as hydroquinone, 3,4-dihydroxybenzaldehyde, 3,5-di-tert.-butylpyrocatechol and 4-methylpyrocatechol. In the absence of phenolic polymerization inhibitors and/or during use of sterically hindered phenols such as BHT, however, no substantial shrinkage reduction was measured. This result can be attributed to the observation that phenolic polymerization inhibitors, especially such having two and more hydroxyl groups, have a strong interaction with transition aluminas, thus suggesting covalent binding of the phenolic hydroxyl groups to the surface of the aluminas. In contrast, sterically hindered phenols such as BHT are unable to bind to the transition alumina.

Example 25

[0145] For production of a two-component mortar compound containing anhydrous hardener component, the resin component (A) was first prepared with the composition indicated in the following Table 6. The mixture was homogenized to a pasty mass free of air bubbles under vacuum in the dissolver. The resin component (A) obtained in this way was introduced into a cartridge.

TABLE-US-00006 TABLE 6 Resin component (A) Proportions in compound [wt %] Methacrylate resin and reactive diluent 34.5 4-tert-Butylpyrocatechol 0.035 Quartz sand 44.2 High-alumina cement 16.55 Fumed silica 1 0.9 Fumed silica 2 1.6 Al.sub.2O.sub.3-activated neutral 2.22

[0146] An anhydrous benzoyl peroxide mixture commercially available under the trade name Perkadox and phlegmatized by inert fillers was used as hardener component (B). Dibenzoyl peroxide in a proportion of 19 to 22 percent by weight and fillers in a proportion of 78 to 81 percent by weight were contained in this hardener component. The hardener component (B) was filled into a second cartridge.

[0147] Then the resin component (A) and the hardener component (B) were mixed in the Speedmixer and the polymerization shrinkage was determined. The weight ratio of the free-radical-curing component (methacrylate resin together with reactive diluent) to the hardening agent in the hardener component (B) was 13.5:1.

[0148] The mortar compound according to Example 25 has a polymerization shrinkage of 1.6%. This proves that water in the hardener component (B) is not needed for shrinkage reduction and that, when an anhydrous hardener component is used, small quantities of transition aluminas are already sufficient to achieve a pronounced shrinkage reduction.

Example 26

[0149] For production of a two-component mortar compound containing transition alumina introduced into the water-containing hardener component (B), the resin component (A) indicated in Example 1 was mixed in the Speedmixer with the hardener component (B) indicated in the following Table 7, and the polymerization shrinkage was measured. The quantity of transition alumina introduced into the mortar compound corresponds to 1 percent by volume.

TABLE-US-00007 TABLE 7 Hardener component (B) Proportions in compound [wt %] Dibenzoyl peroxide 12.25 Water 22.75 Fillers 53 Fumed silica 1 Al.sub.2O.sub.3-activated neutral 11

[0150] The mortar compound according to Example 26 does not exhibit any reduction of the polymerization shrinkage compared with Comparison Example 1. Without intending to adhere to a theory, it may be assumed that the transition alumina in the hardener component (B) is deactivated by the contact with water lasting for a longer time period and/or that an interaction with the phenolic polymerization inhibitors is prevented.

Example 27

Determination of the Bond Strength

[0151] The bond strengths obtained using the mortar compounds having resin compositions according to Examples 1 as well as 16 to 18 are compiled in the following Table 8:

TABLE-US-00008 TABLE 8 Bond strength of the mortar compounds Polymerization shrinkage Bond strength [%] [N/mm.sup.2] Example 1 3.4 23.6 Example 16 2.4 25.0 Example 17 1.8 29.9 Example 18 1.3 31.8

[0152] As can be seen from the results presented in Table 8, the inventive two component mortar compound does not exhibit any deterioration, compared with the compound according to Comparison Example 1, of the load ratings for the adhesion of anchor rods in the steel-sleeve test.

[0153] The measurements described hereinabove were repeated with modified steel sleeves, wherein the undercut depth of the steel sleeves were varied between 25 m and 350 m for an undercut width of 3 mm.

[0154] FIG. 2 illustrates the dependence of the bond strength on the undercut width of the anchor rods for the reference compound according to Example 1 and the two-component mortar compounds according to Examples 16, 17 and 18. It will be seen that the mortar compound according to Example 18by virtue of the smaller shrinkage for all tested undercut depthsyields a substantially constant bond strength, whereas the reference compound according to Example 1, which has a smoother surface with smaller undercut depth, fails more easily and has adequate pull-out strength only for rough surfaces with undercut depths starting from 200 m. At the same time, it can be shown that the performance of the bonded anchor is better the smaller the polymerization shrinkage of the mortar compound is. The dependence of the bond strength achieved with the mortar compounds on the undercut depth of the steel sleeves is much stronger for mortar compounds having high polymerization shrinkage than for mortar compounds having low polymerization shrinkage.

Example 28

Load Ratings of Mortar Compounds in Oversized Drilled Holes

[0155] For determination of the load ratings achieved with two-component mortar compounds, high-strength M12 or M24 threaded anchor rods are used in the form of dowels held by the respective two-component mortar compound in a drilled hole having a specified diameter and a drilled-hole depth of 72 mm. The mortar compounds according to Example 1 having a polymerization shrinkage of 3.4% and according to Example 17 having a polymerization shrinkage of 1.8% were used for this test. The drilled holes were drilled wet using a diamond drill and cleaned using compressed air (6 bar), brushed and then blown out again with compressed air.

[0156] After a curing time of 24 hours at room temperature, the mean failure load is measured by pulling the threaded anchor rod out centrally against closely positioned bracing means, and the mean failure load of three anchors is determined.

[0157] The tests were repeated on oversized drilled holes having a diameter of 1.5 times that of the respected threaded anchor rods under otherwise identical conditions.

[0158] The values determined in this way for the mean failure load are presented in the following Table 9.

TABLE-US-00009 TABLE 9 Load ratings Threaded rod Drilled hole diameter diameter Failure load Change Mortar compound [mm] [mm] [N/mm.sup.2] [%] Example 1 12 14 23.8 Example 1 12 18 17.6 26.4% Example 17 12 14 25.0 Example 17 12 18 22.3 10.8% Example 1 24 28 12.4 Example 1 24 35 8.4 32.2% Example 17 24 28 22.2 Example 17 24 35 25.6 +13.5%

[0159] Compared with the mortar compound according to Example 1, it is not only the mean failure load in drilled holes drilled under wet conditions that can be significantly improved by the addition of transition alumina to the resin component (A). It can also be shown that the mean failure load decreases less rapidly in oversized drilled holes and that the inventive compounds are therefore more stable relative to external influences.