CA1085786A - Cartridge for grouting an anchor element in a hole of a support structure - Google Patents
Cartridge for grouting an anchor element in a hole of a support structureInfo
- Publication number
- CA1085786A CA1085786A CA304,914A CA304914A CA1085786A CA 1085786 A CA1085786 A CA 1085786A CA 304914 A CA304914 A CA 304914A CA 1085786 A CA1085786 A CA 1085786A
- Authority
- CA
- Canada
- Prior art keywords
- cartridge
- anchor element
- microcapsules
- hole
- water
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000004568 cement Substances 0.000 claims abstract description 44
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 32
- 239000003094 microcapsule Substances 0.000 claims abstract description 31
- 239000000203 mixture Substances 0.000 claims abstract description 10
- 239000011440 grout Substances 0.000 claims abstract description 5
- 239000000843 powder Substances 0.000 claims description 16
- 229910052602 gypsum Inorganic materials 0.000 claims description 7
- 239000010440 gypsum Substances 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 7
- 239000000126 substance Substances 0.000 claims description 4
- 230000009969 flowable effect Effects 0.000 claims description 2
- 239000008241 heterogeneous mixture Substances 0.000 claims description 2
- 239000011396 hydraulic cement Substances 0.000 claims description 2
- 239000007864 aqueous solution Substances 0.000 claims 1
- 239000007788 liquid Substances 0.000 claims 1
- 239000007787 solid Substances 0.000 abstract description 5
- 229920003023 plastic Polymers 0.000 abstract description 2
- 239000004033 plastic Substances 0.000 abstract description 2
- 239000011257 shell material Substances 0.000 description 10
- 239000002775 capsule Substances 0.000 description 7
- 238000003780 insertion Methods 0.000 description 6
- 230000037431 insertion Effects 0.000 description 6
- 239000004567 concrete Substances 0.000 description 5
- 239000000945 filler Substances 0.000 description 4
- 229920005989 resin Polymers 0.000 description 4
- 239000011347 resin Substances 0.000 description 4
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 description 3
- 229910052939 potassium sulfate Inorganic materials 0.000 description 3
- 235000011151 potassium sulphates Nutrition 0.000 description 3
- 239000011435 rock Substances 0.000 description 3
- 239000004698 Polyethylene Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000002788 crimping Methods 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- -1 polyethylene Polymers 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 230000003014 reinforcing effect Effects 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 229920003345 Elvax® Polymers 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- IQYKECCCHDLEPX-UHFFFAOYSA-N chloro hypochlorite;magnesium Chemical compound [Mg].ClOCl IQYKECCCHDLEPX-UHFFFAOYSA-N 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000011507 gypsum plaster Substances 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- CENHPXAQKISCGD-UHFFFAOYSA-N trioxathietane 4,4-dioxide Chemical compound O=S1(=O)OOO1 CENHPXAQKISCGD-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D20/00—Setting anchoring-bolts
- E21D20/02—Setting anchoring-bolts with provisions for grouting
- E21D20/021—Grouting with inorganic components, e.g. cement
- E21D20/023—Cartridges; Grouting charges
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/06—Inhibiting the setting, e.g. mortars of the deferred action type containing water in breakable containers ; Inhibiting the action of active ingredients
- C04B40/0666—Chemical plugs based on hydraulic hardening materials
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B13/00—Dowels or other devices fastened in walls or the like by inserting them in holes made therein for that purpose
- F16B13/14—Non-metallic plugs or sleeves; Use of liquid, loose solid or kneadable material therefor
- F16B13/141—Fixing plugs in holes by the use of settable material
- F16B13/143—Fixing plugs in holes by the use of settable material using frangible cartridges or capsules containing the setting components
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Mining & Mineral Resources (AREA)
- Structural Engineering (AREA)
- Inorganic Chemistry (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Joining Of Building Structures In Genera (AREA)
- Dowels (AREA)
Abstract
TITLE: CARTRIDGE FOR GROUTING AN ANCHOR ELEMENT
IN A HOLE OF A SUPPORT STRUCTURE
Abstract of the Disclosure A grouting cartridge is described for placing in a hole of a support structure. The cartridge is capable of rapidly forming a solid grout about an anchor element where the anchor element is thrust into the hole. The cartridge comprises a frangible outer tubular casing fabricated of plastic or the like and containing a uniform mixture of a water-hardenable cement and a multitude of frangible microcapsules which hold droplets of water. One or more of these cartridges is placed in the borehole, and the anchor element in a one-step operation is inserted therein, and preferably rotated, to pierce the casing and rupture the microcapsules to uniformly wet the cement to form a cement paste. The cement paste under the pressure of the anchor element flows into intimate contact with the hole wall of the support structure and into intimate contact with the surfaces of the anchor element. The cement paste rapidly solidifies forming a solid grout between the support structure and the anchor element to affix the anchor element securely to the support structure.
IN A HOLE OF A SUPPORT STRUCTURE
Abstract of the Disclosure A grouting cartridge is described for placing in a hole of a support structure. The cartridge is capable of rapidly forming a solid grout about an anchor element where the anchor element is thrust into the hole. The cartridge comprises a frangible outer tubular casing fabricated of plastic or the like and containing a uniform mixture of a water-hardenable cement and a multitude of frangible microcapsules which hold droplets of water. One or more of these cartridges is placed in the borehole, and the anchor element in a one-step operation is inserted therein, and preferably rotated, to pierce the casing and rupture the microcapsules to uniformly wet the cement to form a cement paste. The cement paste under the pressure of the anchor element flows into intimate contact with the hole wall of the support structure and into intimate contact with the surfaces of the anchor element. The cement paste rapidly solidifies forming a solid grout between the support structure and the anchor element to affix the anchor element securely to the support structure.
Description
la857B6 The present invention relates to the art of installing anchor elements and the like in boreholes and a grouting cartridge for use in such installations.
Anchor elements such as rock bolts are common features of mines and the use of hardening resins in securing the anchor elements in boreholes is well known. Early practice involved the pre-mixing of the various reactive components of the resin, pumping the mixture into the borehole and thereafter inserting the bolt in the borehole. Subsequently, a number of techniques have been developed wherein dual compartment resin packages are used, the compartments of the packages separately storing reactive components of the resin. In use, a package (or packages) is inserted into the borehole and then ruptured by the bolt as the latter is inserted into the borehole and rotated. In this way, the reactive components are mixed in situ to form a solid gel and thereby bond the bolt into position.
Although attempts have been made to use a fast-setting cement in fixing anchor elements, these cements form pastes which hydrate so rapidly that the ability of the paste to flow is lost. Gne attempt involves an elongated capsule containing water surrounded by an enclosure containing cement. When the water capsule is broken the water has a tendency to flow out the inlet of the hole and not to uniformly mix with the cement. ~nse-quently the cement is not uniformly wetted. Either the cement is too dry or too wet.
Advantages of the invention will be apparent from the detailed description of a preferred embodiment found hereinbelow.
A preferred embodiment of this invention is shown in the accompanying drawing, in which:
Fig. 1 is an isometric view of the grouting cartridge which is the subject of the present invention;
Fig. 2 is a longitudinal sectional view of a borehole showing a cartridge mounted therein;
Fig. 3 is a view similar to Fig. 2 except showing an anchor bolt being inserted into the borehole penetrating the cartridge;
~085786 Fig~ 4 is a view similar to Fig. 3 except showing the anchor bolt fully mounted in the borehole with solid grout securing the anchor bolt therein.
As described hereinabove, the invention concerns a grouting cartridge 10 for use in fixing an anchor element 11 such as rock bolt or the like in borehole 12. Cartridge 10 is preferably tubular-shaped containing powdered cement 15 and microcapsules 16 of water so packaged to ease hand-ling and placement of quick-set cement mortarinto the drilled hole for re-taining the anchor element.
Referring to the drawings, the water-cement package or cartridge 10 of the invention is illustrated and, as stated, preferably comprises an elongated outer casing or wrapper in the form of a thin frangible film tube, denoted 14. The casing 14 extends between enclosed ends 19 and 20.
Tube 14 contains a hetrogeneous mixture of a continuous phase, hydraulically setting dry cement powder indicated by the numeral 15, and a discontinuous phase of a multitude of individual microcapsules 16 uniformly dispersed and suspended in the cement powder continuous phase 15. Crimping sleeves or clamps 21 may be used at both ends 19 and 20 to enclose these ends and main-tain the contents substantially air and moisture free.
The microcapsules 16 of water and cement powder 15 are the principal ingredients of the filler for the cartridge. Chemicals for accelerating hardening may be added in amounts generally not exceeding 3 percent of the weight of the cement. The cement must be a type that will harden (inundated), and which is technically known as ~y~raulic cement.
Suitable types of hydraulic cement include portland, pozzolan, gypsum plaster magnesium oxychloride, and magnesium oxysulfate. The cement is generally used neat, or undiluted with sand or other filler, to form a stronger, faster hardening material.
The microcapsules 16 are spherical in shape and comprise an outer shell of insoluble frangible material surrounding and containing a small globule or droplet of water. The microcapsules can be made in varying sizes ranging from 400 to 5000 microns in diameter. Preferably the lass7s6 microcapsules have a diameter hetween InOO and 1700 microns. When combined with cement, the microca~sules serve to store the water separate from the cement until the microcapsules are broken.
To form a package or cartridge 10, the cement powder 15, micro-capsules 16 and accelerating chemical are blended in proper proportion into a heterogeneous dry mixture with the microcapsules 16 uniformly dispersed and suspended in the cement powder 15, which is then encased in tubular wrapper 14 of thin film, closed at each end with a binding or clamp, such as indicated at 21. The length of the cartridge is not fixed, but should not exceed the depth of the hole in which the rod or bolt is to be anchored;
nor should the cartridge be so long as to be inconvenient to handle. The cartridge diameter must be sized to permit ready insertion into the pre-drilled hole in rock, concrete, or other substance.
As discussed above, before installing the anchor element, one or more cartridges 10 is inserted into the hole. Then an anchor element 11 such as a steel bolt is forcibly inserted into the hole, generally by rotation as illustrated in Figs. 2-4. The anchor element 11 can be threaded, but usually comprises a deformed concrete reinforcing bar, commonly referred to as a "rebar".
The pressure and rotation of the anchor element during insertion ruptures and penetrates the cartridge, shreds the wrapper or casing, and progressively breaks the microcapsules ahead of the anchor element, thereby uniformly releasing the contained water to form a uniform paste between the ends of the cartridge. The water and cement form a flowable paste 24 which under the pressure of the anchor element fills the annular space between the wall of the hole and anchor element to intimately contact the hole wall and the anchor element. The paste 24 fills voids in the borehole wall structure.
Rotation of the anchor element also aids in the agitation and migration of the paste flow. The progressive formation of the paste ahead of the anchor element permits the anchor element to be inserted with a rather uniform pressure.
The ensuing chemical reaction of hydration causes hardening of 1~85786 the l-aste 24 to form a solid grout 26 to hold the anchor element 11 securely in the borehole 12.
Considering the invention in more detail, the microcapsules 16 of water are preferably formed by surrounding small droplets of water with a fluid shell material which is then hardened after capsule formation.
Generally, the water represents about two-thirds and the shell represents about one-third of the total weight of the microcapsules. This relation-ship varies with the diameter of the microcapsules.
It is necessary that the shells of the microcapsules be suffi-ciently strong to contain the water without leakage under normal handling and storing conditions. However, the shell of the microcapsule must be sufficiently frangible to be easily ruptured by the application of external pressure engendered by the insertion of the anchor element so as to form a paste formed ahead of the anchor element. The shell should be sufficiently frangible to be crushed between one's fingers. Preferably the shell should be crushable by the application of 10 to 600 grams force as measured by a Hunter Force Gauge, ~Iodel L-500M.
The wrapper or casing 14 serves to confine the mixture in a tubular shape and can be of thin plastic fil~, paper, or similar material.
For example, 1-1/2 mill thick (0.0015) inch) polyethylene tubing can be used in making cartridges 0.95 inches in diameter and 12 inches long.
Cartridges may be of any length that can be reasonably handled, provided that, as noted previously, they are shorter than the depth of the hole. As discussed, the wrapper tube is crimped, clamped or tied off on one end, filled to the desired length, and then closed off at the other end by crimping, clamping or tying. The cartridge wrapper 14 must be strong enough to contain the mixture and to withstand reasonable handling. On the other hand, the wrapper or casing 14 must be weak, or frangible enough to be punctured and shredded by insertion of the bolt. The diameter of the cartridge must be slightly smaller than the hole to allow clearance for insertion. The actual amount of clearance depends on the minimum diameter of the hole, which, in turn, is often determined by the smoothness or 1~85786 roug}mess of the hole surface. Cartridge diameters generally should be small enough to be inserted into the hole without difficulty, but large enough to provide some drag or friction, especially in upwardly directed holes, so as to provide self-retention.
For a particular formula, the proportions of cement, micro-capsules, and additives are usually determined by laboratory tests using water in place of water capsules. After the formula is determined, the amount by weight of water capsules can be calculated, using the actual water content as provided by the manufacturer's specifications. In the calculation, the shell material is treated as inert filler, similarly to sand in a cement paste when making mortar.
The general operable range is to mix 1 part water with 2.5-4.0 parts by weight of cement powder. This range varies with the type and manu-facture of the cement powder. Particularly good results have been achieved by using one part water to three parts alpha gypsum cement powder. It is preferable to use "neat" cement without substantial filler or inert material.
When using microcapsules having diameters between 1000 and 1700 microns, applicant has found that a mixture of about 50-55 grams of microcapsules with each 100 grams of alpha gypsum cement powder has produced good results.
In a specific example, a formula of alpha gypsum cement with 1-1/2 percent potassium sulfate accelerator and 32 percent water added by using water capsules, consisted of the following proportions by weight:
Component (and calculation) Grams Percent Alpha gypsum cement 100.0 66.7 Potassium sulfate 1.5 1.0 Water capsules:
Water 67% Water required (32% x 101.5 gms)32.5 32.3 Shell 33% Inert shell (32.5 gms x 33/67)16.0 150.00 100.00 1~85786 After the desired proportions o~ cement, microcapsules, and adclitives, if any, are detcrmined, the correct quantities are weighed and then blended into a heterogeneous mixture with the microcapsules essentially unifonmly dispersed in the cement powder continuous phase. Blending is done in any suitable device that is gentle in action and will not prematurely crush the microcapsules.
Considering an exemplary test installation, twelve inches of a 30-inch long, No. 6 (3/4-inch) deformed concrete reinforcing bar (rebar) were anchored into a l-l/16-inch diameter by 12-inch deep hole in concrete.
The following materials and specifications were utilized:
Cartridge: 0.95 inches in diameter, 11 inches long Filling material:
Alpha gypsum cement (U.S. Gypsum Corp., 100 gms. 66.0%
Airtrol 11) Potassium sulfate 1.5 gms. 1.0%
Microcapsules:
Theoretical water: 64.7%
Size: 1000 - 1700 microns (0.039 - 0.067 inches) Shell: 60% Sunoco Wax 4412 25% Piccolyte S-115 15% Elvax 210 50 gms. 33.0%
100. 0%
Wrapper: 1-1/2-inch, lay flat tubing of 0.0015-inch (1-1/2-mils) thick polyethylene. Forms a round tube 0.35 inches diameter.
End crimpers for cartridge: 2 model 410 NAED wire crimp sleeves The cartridge was placed in a 1-1/16-inch-diameter by 12-inch-deep hole. The upper end of the rebar was machined smooth so that it would fit in a l/2-inch Jacobs chuck mounted on a handheld electric drill.
Powered by the electric drill motor, the rebar was drilled down through the cartridge to the 12-inch depth in 5 seconds. The motor was removed, and a hollow center hydraulic jack placed over the rebar to rest on the concrete surface. A collet was placed above the jack to grip the rebar. This arrangement allowed the jack to push up on the rebar for pull on the anchored portion. After an elapsed time of 4 minutes from beginning of bolt insertion, the jack was activated until the bolt began pulling from the hole. A pressure gauge, calibrated to show the pull force, read 9,000 1~8~
pounds at failure.
Although tlle invention has heen described relative to exemplary embodiments theretQ,it will be unde~stood that variations and modifications can be effected in these embodiments without departing from the scope and spirit of the invention.
Anchor elements such as rock bolts are common features of mines and the use of hardening resins in securing the anchor elements in boreholes is well known. Early practice involved the pre-mixing of the various reactive components of the resin, pumping the mixture into the borehole and thereafter inserting the bolt in the borehole. Subsequently, a number of techniques have been developed wherein dual compartment resin packages are used, the compartments of the packages separately storing reactive components of the resin. In use, a package (or packages) is inserted into the borehole and then ruptured by the bolt as the latter is inserted into the borehole and rotated. In this way, the reactive components are mixed in situ to form a solid gel and thereby bond the bolt into position.
Although attempts have been made to use a fast-setting cement in fixing anchor elements, these cements form pastes which hydrate so rapidly that the ability of the paste to flow is lost. Gne attempt involves an elongated capsule containing water surrounded by an enclosure containing cement. When the water capsule is broken the water has a tendency to flow out the inlet of the hole and not to uniformly mix with the cement. ~nse-quently the cement is not uniformly wetted. Either the cement is too dry or too wet.
Advantages of the invention will be apparent from the detailed description of a preferred embodiment found hereinbelow.
A preferred embodiment of this invention is shown in the accompanying drawing, in which:
Fig. 1 is an isometric view of the grouting cartridge which is the subject of the present invention;
Fig. 2 is a longitudinal sectional view of a borehole showing a cartridge mounted therein;
Fig. 3 is a view similar to Fig. 2 except showing an anchor bolt being inserted into the borehole penetrating the cartridge;
~085786 Fig~ 4 is a view similar to Fig. 3 except showing the anchor bolt fully mounted in the borehole with solid grout securing the anchor bolt therein.
As described hereinabove, the invention concerns a grouting cartridge 10 for use in fixing an anchor element 11 such as rock bolt or the like in borehole 12. Cartridge 10 is preferably tubular-shaped containing powdered cement 15 and microcapsules 16 of water so packaged to ease hand-ling and placement of quick-set cement mortarinto the drilled hole for re-taining the anchor element.
Referring to the drawings, the water-cement package or cartridge 10 of the invention is illustrated and, as stated, preferably comprises an elongated outer casing or wrapper in the form of a thin frangible film tube, denoted 14. The casing 14 extends between enclosed ends 19 and 20.
Tube 14 contains a hetrogeneous mixture of a continuous phase, hydraulically setting dry cement powder indicated by the numeral 15, and a discontinuous phase of a multitude of individual microcapsules 16 uniformly dispersed and suspended in the cement powder continuous phase 15. Crimping sleeves or clamps 21 may be used at both ends 19 and 20 to enclose these ends and main-tain the contents substantially air and moisture free.
The microcapsules 16 of water and cement powder 15 are the principal ingredients of the filler for the cartridge. Chemicals for accelerating hardening may be added in amounts generally not exceeding 3 percent of the weight of the cement. The cement must be a type that will harden (inundated), and which is technically known as ~y~raulic cement.
Suitable types of hydraulic cement include portland, pozzolan, gypsum plaster magnesium oxychloride, and magnesium oxysulfate. The cement is generally used neat, or undiluted with sand or other filler, to form a stronger, faster hardening material.
The microcapsules 16 are spherical in shape and comprise an outer shell of insoluble frangible material surrounding and containing a small globule or droplet of water. The microcapsules can be made in varying sizes ranging from 400 to 5000 microns in diameter. Preferably the lass7s6 microcapsules have a diameter hetween InOO and 1700 microns. When combined with cement, the microca~sules serve to store the water separate from the cement until the microcapsules are broken.
To form a package or cartridge 10, the cement powder 15, micro-capsules 16 and accelerating chemical are blended in proper proportion into a heterogeneous dry mixture with the microcapsules 16 uniformly dispersed and suspended in the cement powder 15, which is then encased in tubular wrapper 14 of thin film, closed at each end with a binding or clamp, such as indicated at 21. The length of the cartridge is not fixed, but should not exceed the depth of the hole in which the rod or bolt is to be anchored;
nor should the cartridge be so long as to be inconvenient to handle. The cartridge diameter must be sized to permit ready insertion into the pre-drilled hole in rock, concrete, or other substance.
As discussed above, before installing the anchor element, one or more cartridges 10 is inserted into the hole. Then an anchor element 11 such as a steel bolt is forcibly inserted into the hole, generally by rotation as illustrated in Figs. 2-4. The anchor element 11 can be threaded, but usually comprises a deformed concrete reinforcing bar, commonly referred to as a "rebar".
The pressure and rotation of the anchor element during insertion ruptures and penetrates the cartridge, shreds the wrapper or casing, and progressively breaks the microcapsules ahead of the anchor element, thereby uniformly releasing the contained water to form a uniform paste between the ends of the cartridge. The water and cement form a flowable paste 24 which under the pressure of the anchor element fills the annular space between the wall of the hole and anchor element to intimately contact the hole wall and the anchor element. The paste 24 fills voids in the borehole wall structure.
Rotation of the anchor element also aids in the agitation and migration of the paste flow. The progressive formation of the paste ahead of the anchor element permits the anchor element to be inserted with a rather uniform pressure.
The ensuing chemical reaction of hydration causes hardening of 1~85786 the l-aste 24 to form a solid grout 26 to hold the anchor element 11 securely in the borehole 12.
Considering the invention in more detail, the microcapsules 16 of water are preferably formed by surrounding small droplets of water with a fluid shell material which is then hardened after capsule formation.
Generally, the water represents about two-thirds and the shell represents about one-third of the total weight of the microcapsules. This relation-ship varies with the diameter of the microcapsules.
It is necessary that the shells of the microcapsules be suffi-ciently strong to contain the water without leakage under normal handling and storing conditions. However, the shell of the microcapsule must be sufficiently frangible to be easily ruptured by the application of external pressure engendered by the insertion of the anchor element so as to form a paste formed ahead of the anchor element. The shell should be sufficiently frangible to be crushed between one's fingers. Preferably the shell should be crushable by the application of 10 to 600 grams force as measured by a Hunter Force Gauge, ~Iodel L-500M.
The wrapper or casing 14 serves to confine the mixture in a tubular shape and can be of thin plastic fil~, paper, or similar material.
For example, 1-1/2 mill thick (0.0015) inch) polyethylene tubing can be used in making cartridges 0.95 inches in diameter and 12 inches long.
Cartridges may be of any length that can be reasonably handled, provided that, as noted previously, they are shorter than the depth of the hole. As discussed, the wrapper tube is crimped, clamped or tied off on one end, filled to the desired length, and then closed off at the other end by crimping, clamping or tying. The cartridge wrapper 14 must be strong enough to contain the mixture and to withstand reasonable handling. On the other hand, the wrapper or casing 14 must be weak, or frangible enough to be punctured and shredded by insertion of the bolt. The diameter of the cartridge must be slightly smaller than the hole to allow clearance for insertion. The actual amount of clearance depends on the minimum diameter of the hole, which, in turn, is often determined by the smoothness or 1~85786 roug}mess of the hole surface. Cartridge diameters generally should be small enough to be inserted into the hole without difficulty, but large enough to provide some drag or friction, especially in upwardly directed holes, so as to provide self-retention.
For a particular formula, the proportions of cement, micro-capsules, and additives are usually determined by laboratory tests using water in place of water capsules. After the formula is determined, the amount by weight of water capsules can be calculated, using the actual water content as provided by the manufacturer's specifications. In the calculation, the shell material is treated as inert filler, similarly to sand in a cement paste when making mortar.
The general operable range is to mix 1 part water with 2.5-4.0 parts by weight of cement powder. This range varies with the type and manu-facture of the cement powder. Particularly good results have been achieved by using one part water to three parts alpha gypsum cement powder. It is preferable to use "neat" cement without substantial filler or inert material.
When using microcapsules having diameters between 1000 and 1700 microns, applicant has found that a mixture of about 50-55 grams of microcapsules with each 100 grams of alpha gypsum cement powder has produced good results.
In a specific example, a formula of alpha gypsum cement with 1-1/2 percent potassium sulfate accelerator and 32 percent water added by using water capsules, consisted of the following proportions by weight:
Component (and calculation) Grams Percent Alpha gypsum cement 100.0 66.7 Potassium sulfate 1.5 1.0 Water capsules:
Water 67% Water required (32% x 101.5 gms)32.5 32.3 Shell 33% Inert shell (32.5 gms x 33/67)16.0 150.00 100.00 1~85786 After the desired proportions o~ cement, microcapsules, and adclitives, if any, are detcrmined, the correct quantities are weighed and then blended into a heterogeneous mixture with the microcapsules essentially unifonmly dispersed in the cement powder continuous phase. Blending is done in any suitable device that is gentle in action and will not prematurely crush the microcapsules.
Considering an exemplary test installation, twelve inches of a 30-inch long, No. 6 (3/4-inch) deformed concrete reinforcing bar (rebar) were anchored into a l-l/16-inch diameter by 12-inch deep hole in concrete.
The following materials and specifications were utilized:
Cartridge: 0.95 inches in diameter, 11 inches long Filling material:
Alpha gypsum cement (U.S. Gypsum Corp., 100 gms. 66.0%
Airtrol 11) Potassium sulfate 1.5 gms. 1.0%
Microcapsules:
Theoretical water: 64.7%
Size: 1000 - 1700 microns (0.039 - 0.067 inches) Shell: 60% Sunoco Wax 4412 25% Piccolyte S-115 15% Elvax 210 50 gms. 33.0%
100. 0%
Wrapper: 1-1/2-inch, lay flat tubing of 0.0015-inch (1-1/2-mils) thick polyethylene. Forms a round tube 0.35 inches diameter.
End crimpers for cartridge: 2 model 410 NAED wire crimp sleeves The cartridge was placed in a 1-1/16-inch-diameter by 12-inch-deep hole. The upper end of the rebar was machined smooth so that it would fit in a l/2-inch Jacobs chuck mounted on a handheld electric drill.
Powered by the electric drill motor, the rebar was drilled down through the cartridge to the 12-inch depth in 5 seconds. The motor was removed, and a hollow center hydraulic jack placed over the rebar to rest on the concrete surface. A collet was placed above the jack to grip the rebar. This arrangement allowed the jack to push up on the rebar for pull on the anchored portion. After an elapsed time of 4 minutes from beginning of bolt insertion, the jack was activated until the bolt began pulling from the hole. A pressure gauge, calibrated to show the pull force, read 9,000 1~8~
pounds at failure.
Although tlle invention has heen described relative to exemplary embodiments theretQ,it will be unde~stood that variations and modifications can be effected in these embodiments without departing from the scope and spirit of the invention.
Claims (6)
1. A cartridge for grouting an anchor element in an elongated hole of a support structure, characterized by:
an elongated tubular casing fabricated of a frangible material having a diameter between enclosed ends sufficient to enable the cartridge to be introduced into the hole;
a heterogeneous mixture of a continuous phase of dry hydraulic cement powder and a discontinuous phase of a multitude of water-containing microcapsules essentially uniformly dispersed in the continuous phase that fills the interior of the tubular casing between the enclosed ends;
wherein the microcapsules have diameters in a range of 400 to 5000 microns; and wherein the microcapsules have frangible shells enclosing drop-lets of liquid water that are pressure sensitive and are capable of being progressively ruptured by the force of an anchor element being thrust into the cartridge when the cartridge is positioned in the hole to thereby dispense the water substantially uniformly throughout the interior of the casing and the cement powder to enable the water and cement powder to thoroughly interact to form a flowable cement paste in intimate contact with the hole wall and the anchor element, which when solidified forms a uniform grout about the anchor element to secure the anchor element to the support structure.
an elongated tubular casing fabricated of a frangible material having a diameter between enclosed ends sufficient to enable the cartridge to be introduced into the hole;
a heterogeneous mixture of a continuous phase of dry hydraulic cement powder and a discontinuous phase of a multitude of water-containing microcapsules essentially uniformly dispersed in the continuous phase that fills the interior of the tubular casing between the enclosed ends;
wherein the microcapsules have diameters in a range of 400 to 5000 microns; and wherein the microcapsules have frangible shells enclosing drop-lets of liquid water that are pressure sensitive and are capable of being progressively ruptured by the force of an anchor element being thrust into the cartridge when the cartridge is positioned in the hole to thereby dispense the water substantially uniformly throughout the interior of the casing and the cement powder to enable the water and cement powder to thoroughly interact to form a flowable cement paste in intimate contact with the hole wall and the anchor element, which when solidified forms a uniform grout about the anchor element to secure the anchor element to the support structure.
2. The grouting cartridge as defined in claim 1 characterized by the microcapsules having diameters in a range of 1000 to 1700 microns.
3. The grouting cartridge as defined in claim 1 characterized by the mixture being blended having 1 part water to 2.5 - 4.0 parts of cement powder by weight.
4. The grouting cartridge as defined in claim 1 characterized by the mixture being blended having one part water to three parts gypsum cement powder by weight.
5. The grouting cartridge as defined in claim 1 characterized by the microcapsule shells being sufficiently frangible to be ruptured en masse upon the application of a pressure of between 10 and 600 grams force.
6. The grouting cartridge as defined in claim 1 characterized by the microcapsules containing an aqueous solution having a chemical accelera-tor for accelerating the hardening of the cement powder when the micro-capsules are ruptured.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US80988377A | 1977-06-24 | 1977-06-24 | |
| US809,883 | 1977-06-24 | ||
| US05/853,700 US4096944A (en) | 1977-06-24 | 1977-11-21 | Cartridge for grouting an anchor element in a hole of a support structure |
| US853,700 | 1977-11-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1085786A true CA1085786A (en) | 1980-09-16 |
Family
ID=27123276
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA304,914A Expired CA1085786A (en) | 1977-06-24 | 1978-06-06 | Cartridge for grouting an anchor element in a hole of a support structure |
Country Status (4)
| Country | Link |
|---|---|
| AU (1) | AU515904B2 (en) |
| CA (1) | CA1085786A (en) |
| GB (1) | GB2000842B (en) |
| SE (1) | SE7807096L (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4516884A (en) * | 1983-09-01 | 1985-05-14 | United States Steel Corporation | Grouting composition cartridge |
| EP3692246A4 (en) * | 2017-10-02 | 2021-06-30 | Besab AB | A sealing device, a package and a method for sealing a rock bolt |
| CN107676103B (en) * | 2017-10-30 | 2019-12-31 | 中国人民解放军陆军工程大学 | Construction method for extra-large-span cave depot grid arch support |
| CN113310872B (en) * | 2021-05-25 | 2022-11-18 | 北京中煤矿山工程有限公司 | Elastic wave assisted cement grouting water stopping model test device |
-
1978
- 1978-06-06 CA CA304,914A patent/CA1085786A/en not_active Expired
- 1978-06-21 GB GB7827462A patent/GB2000842B/en not_active Expired
- 1978-06-21 AU AU37345/78A patent/AU515904B2/en not_active Expired
- 1978-06-21 SE SE7807096A patent/SE7807096L/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| GB2000842A (en) | 1979-01-17 |
| SE7807096L (en) | 1978-12-25 |
| AU515904B2 (en) | 1981-05-07 |
| GB2000842B (en) | 1982-03-31 |
| AU3734578A (en) | 1980-01-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |