Anchoring Arrangement and Use of an Anchor Rod

Abstract

The invention relates to an anchoring arrangement (1) having an anchor rod (2) which is anchored with mortar (3) in a bore (4) in an anchoring substrate (5) (concrete). The anchoring arrangement (1) is crack-resistant when the following conditions are fulfilled:

Description

The invention will be described in greater detail below with reference to an embodiment shown in the drawings. The single FIGURE shows an axial section through an anchoring arrangement according to the invention.

The anchoring arrangement 1 according to the invention shown in the drawing has an anchor rod 2 which is anchored with mortar 3 in a bore 4 in an anchoring substrate 5. A threaded rod is used as anchor rod 2. The anchoring substrate 5 consists, for example, of concrete. The mortar 3 is preferably a two-component synthetic resin mortar, but it is possible to use other synthetic resin mortars or other mortars that fulfil the conditions of the invention, especially a sufficiently high bond stress.

A plastics sleeve 6 is placed on the anchor rod 2, the plastics sleeve having two functions: during introduction of the anchor rod 2 into the bore 4, the plastics sleeve 6 mounted on the anchor rod 2 is pressed into the mouth of the bore 4 and holds the anchor rod 2 centrally in the bore 4. The plastics sleeve 6 thus forms a centring element for the anchor rod 2. In addition, the plastics sleeve 6 forms a setting depth marker. It is placed on the anchor rod 2 at a predetermined position and is seated on the anchoring substrate 5 with a flange 7 at the mouth of the bore 4 and thereby defines the setting depth of the anchor rod 2. The plastics sleeve 6 can have an outlet opening (not shown) for excess mortar 3.

A cutter element 8 is placed or screwed onto the forward end of the anchor rod 2 located in the bore 4. The cutter element 8 has a cutter 9 extending transversely or obliquely relative to the bore 4 or alternatively has a point. The cutter 9 can in principle be formed on the forward end of the anchor rod 2. It serves for destroying a mortar cartridge and for intermixing and distributing the mortar components contained in the mortar cartridge in the bore 4. Such mortar cartridges, which usually consist of glass and contain two or more mortar components separately from one another, are known per se and need not be described here. The mortar 3 can also be introduced into the bore 3 in some other way, for example injected using an applicator gun. In that case the cutter element 8 is not required.

According to the invention, the mortar 3 has a bond stress of at least 6 N/mm², the bond stress being the breaking load, that is to say the tensile force exerted on the anchor rod 2 at which the mortar 3 breaks, per unit surface area of the bond. Further conditions of the anchoring arrangement 1 according to the invention are that the diameter of the bore divided by the diameter of the anchor rod multiplied by the bond stress is at least 14, preferably from 17 to 20. The ratio of the diameter of the anchor rod to the diameter of the bore is at least 0.4 and a maximum of 0.85, preferably a maximum of 0.7. Tests (see below) have shown that the anchoring arrangement 1 according to the invention is crack-resistant when the conditions indicated are observed. The anchoring arrangement 1 is regarded as being crack-resistant when its breaking load in a cracked anchoring substrate 5 is at least 80% of the breaking load in an uncracked anchoring substrate 5, the anchoring substrate 5 being concrete. The crack is a parallel crack which passes through the bore 4 in an axial plane and has a width of 0.5 millimetre. The bore 4 becomes wider transversely with respect to the crack by the width of the crack.

Tests with an anchor rod 2 of diameter M12 at an anchoring depth of 95 millimetres and a 0.5 millimetre wide parallel crack yield the values listed in the table below:

• Anchor rod: threaded rod M12
• Anchoring depth: 95 mm
• Mortar: fischer FIS EM 390 S
• 0.5 mm parallel crack

	Breaking	Bond stress	Bore Ø/anchor rod Ø ×	Anchor rod
Bore Ø	load	(bore Ø)	bond stress	Ø/bore Ø	Remarks
14	36.0 kN	8.6 N/mm2	10.1 N/mm2	0.86	not crack-
					resistant
16	64.0 kN	13.4 N/mm2	17.9 N/mm2	0.75	crack-resistant
18	71.0 kN	13.2 N/mm2	19.8 N/mm2	0.67	crack-resistant
20	66.0 kN	11.1 N/mm2	18.4 N/mm2	0.60	crack-resistant
22	71.5 kN	10.9 N/mm2	20.0 N/mm2	0.55	crack-resistant
18	48.0 kN	8.9 N/mm2	13.4 N/mm2	0.67	blown out 2x
					not crack-
					resistant

The table shows that larger diameters of bore tend to result in crack resistance in accordance with the above criteria. Cleaning the bore also has a crucial effect on the anchoring, as shown by the last line of the table where the bore had been blown out twice using a manual blow-out device. In the other tests, the bore had been better cleaned with compressed air and/or by brushing out and thus the breaking load was considerably increased.

Claims

1-7. (canceled)

8. An anchoring arrangement, comprising an anchor rod which is to be anchored with a mortar in a bore in a cracked anchoring substrate, said anchor rod has an anchoring region configured as a region provided with an element selected from the group consisting of a standard thread, a knurling and a surface-shaping of a reinforcing bar, said anchoring region of said anchor rod having a smallest outer diameter and a largest outer diameter with a ratio of the smallest outer diameter to the largest outer diameter being from 0.8 to 1, wherein following conditions are fulfilled:

9. The anchoring arrangement as defined in claim 8 wherein the ratio of the smallest outer diameter to the largest outer diameter in the anchoring region of the anchor rod is from 0.85 to 0.95.

10. An anchoring arrangement as defined in claim 8, wherein a following condition is fulfilled:

11. An anchoring arrangement as defined in claim 8, wherein the bond stress is ≧10 N/mm2

12. An anchoring arrangement as defined in claim 8, wherein said anchor rod is configured as a rod having a surface-shaping.

13. An anchoring arrangement as defined in claim 8, wherein said anchor rod is configured as a threaded rod.

14. An anchoring arrangement as defined in claim 8; and further comprising a centering element which centers said anchor rod in the bore.

15. An anchoring arrangement as defined in claim 8, wherein said anchor rod has a cutter.

16. A method of using an anchor rod in a cracked anchoring substrate with a mortar, comprising the steps of providing in the anchor rod an anchoring region configured as a region having an element selected from the group consisting of a standard thread, a knurl, and a surface-shaping of a reinforcing bar; selecting a ratio of a smallest to a largest outer diameter in said anchoring region of said anchor rod to be from 0.8 to 1; and selecting a bond stress greater than 5.6 N/mm2.

17. A method as defined in claim 16, wherein said selecting the ratio includes selecting the ratio of the smallest to the largest outer diameter in the anchoring region of the anchor rod to be from 0.85 to 0.95.

18. A method as defined in claim 16; and further comprising selecting the bond stress greater than 10 N/mm2.