JPS5852940B2 - Concrete ofcum - Google Patents

Description

[Detailed description of the invention] The present invention relates to conservation structures containing concrete.

Safes or vaults that use concrete, insulation or fillers in their wall constructions are well known.

Prior art patents for such security devices using fillers include U.S. Patent Nos. Re 15429;
No.; 1443087; 2134861 and 2492
No. 422 is included.

Many problems are associated with conventional concrete structures and methods of making them.

For example, prior art concrete structures typically
It has a thick outer metal wall and a relatively lightweight inner wall between which a required mass of concrete is poured and allowed to harden.

Concrete is a mixture of binding paste and aggregate.

The paste is mainly composed of cement and water.

Excess water is required to make the concrete mass pourable or workable.

Water in excess of the amount needed to complete chemical irrigation or hardening reactions is called "convenient water" or "natural water".

This free water typically remains in variable quantities within the cement structure, creating many problems specific to the manufacture and use of conservation cement structures.

First, such free water tends to corrode the walls of the safe.

Additionally, it has been reported that free water often causes perspiration that is harmful to the contents of the safe.

Also, the presence of free water is usually accompanied by an undesirable loss in concrete strength.

Furthermore, during the cement hardening process, free water oozes out from inside the concrete and appears on the surface of the concrete.

Exudate water must be removed during fabrication, impeding efficiency.

In addition, concrete can be used without destroying the structure of the safe.
It is almost impossible to determine the exact percentage of free water in the mass.

As free water remains in the concrete mass for many years, shrinkage typically occurs and the concrete mass cracks.

Thus, a passageway through the weakened concrete mass can be opened for safecracking.

Furthermore, shrinkage also occurs during the curing process of conventional or standard concrete composites, which causes the cement to shrink and separate from the interior wall or casing of the vault structure.

Such shrinkage prevents the formation of a mold-close composite and facilitates the insertion of various safe-cracking means.

In addition to this, one of the major drawbacks associated with known concrete safe liners or walls is that they are not sufficiently resistant to attack by acetylene torches or high temperature devices.

Known concrete masses have a tendency to split, collapse, or burst when exposed to an acetylene torch.

Such splitting or disintegration of the concrete by the torch makes the concrete easier to penetrate after zero with a hammer, drill or other tool.

Even if not penetrated by a torch, known concrete structures are unsatisfactory in their protection against safe breaking.

In short, improvements are required. The present invention relates to a new conservation concrete structure that has many advantages.

Safes or vaults made in accordance with the principles of the present invention have excellent resistance to attack by torches, tools, or other devices often used by safe breakers.

The present invention also provides a unique method of making a conservation concrete body or composite that overcomes many of the drawbacks associated with the prior art.

The present invention relates in one of its aspects to a novel conservation concrete composite which has been found to be particularly suitable for use in forming safe liners or wall structures.

The composite according to the invention is obtained from a moldable mixture of granular refractory aggregate, reinforcing filaments, expanded cement and water.

The expandable cement preferably has shrinkage compensating and self-stressing properties.

Such moldable aqueous mixtures are prepared to provide a slump or consistency that allows them to be worked with and to allow free flow during fabrication of security doors and walls in accordance with the present invention.

Furthermore, the present invention is based, in part, on the recognition that free water in known concrete safe bodies can cause collapse, splitting, or bursting of concrete exposed to the high temperatures of an acetylene torch.

However, with the adoption of the conservation concrete composite and structure of the present invention, torch splitting, collapse, and bursting have been eliminated.

The present invention uses expansive cement as a hydraulic binder for conservation concrete masses.

The expanding cement used in the present invention preferably has shrinkage compensating properties as well as self-stressing properties.

Some concrete composites with heat-resistant or fire-resistant aggregates, reinforcing filaments, shrinkage-compensating expanding cement and water can be processed suitable for use in the production of strong concrete bodies and composite concrete bodies for conservation structures. It has been empirically demonstrated that the scales are formulated to the required consistency to make a mixture of.

In contrast, when prior art concrete composites are formulated with comparable processable slump, the cement structures formed thereby are weak and overflowing; It has the disadvantages already mentioned in the description.

In contrast, even though the moldable mixture of the present invention has a high slump due to the presence of large amounts of water, the integrity concrete composite undergoes a chemical reaction in which the water enters the matrix. Becomes chemically bonded or exists in a form that does not cause splitting, collapse, or rupture of the hardened concrete mass.

The correct reason or theory for such results is not completely understood.

Nevertheless, the advantages of the invention have been demonstrated.

It also provides other unique benefits. For example, known standard integrity concrete, as previously discussed, shrinks as it dries, and this shrinkage causes concrete cracking even in the presence of reinforcing steel.

However, the composite of the present invention eliminates such stress cracking and also allows moldable components to be poured into the steel casing of the safe without separating the steel casing from the walls.

Not only does the elimination of seepage water facilitate the fabrication technique of the conservation structures of the invention, but even if high slump is used, the mixed water is clearly consumed at a very high rate during the initial irrigation process. be done.

Furthermore, excess mixing water does not adversely affect the concrete being produced.

In another aspect, the present invention provides a maintenance concrete having self-stressing reinforcing filaments.

It has been found that self-stressing concrete can produce security structures with significant compressive strength and resistance to attack by safe-cracking means.

For example, the integrity concrete is virtually impenetrable by hammer or mass attack.

It is believed that self-stressing concrete and fibers work together in the cement matrix of the present invention to achieve the above results.

Processable slump can also be achieved by placing reinforcing fibers in the cement paste and aggregate mixture.

Granular refractory or refractory aggregate is one of the essential components of the conservation concrete composite of the present invention.

This aggregate provides several important properties including impact resistance, hardness to prevent crushing, and abrasion resistance.

Furthermore, the aggregate should preferably also lend itself to recycling.

The currently recommended granular heat-resistant aggregate is silica sand. An example is standard 20-30 Ottawa sand (ASTM C-190),
This Ottawa sand has American sieve analysis values of approximately 15% or less remaining on a 20-mesh sieve and approximately 5% or less passing through a 30-mesh sieve. A substantially pure 5i02 having the characteristics required to provide strength and working in a manner consistent with the principles of the present invention is used.

Needless to say, fine-form silica sand can also be used.

The term "silica sand" applies to sand consisting almost exclusively of grains of the mineral quartz (S i 02 ).

Typically, such sand contains more than 95% 8102;
Their composition contains more than 99% Si02.

One of the important reasons for using silica sand as an aggregate in the preferred embodiment of the present invention is its substantially non-hygroscopic nature.

It is recommended that aggregates with non-hygroscopic properties be selected to reduce the possibility that free water will become trapped or included in the aggregate and therefore the internal structure of the cement.

As previously detailed, trapped moisture within the concrete, ie within the internal aggregate structure, can lead to its disintegration when the concrete is exposed to torch temperatures.

Silica sand does not absorb moisture from the concrete mix and
It has been found that it does not provide moisture, thus preventing moisture capture.

It goes without saying that other aggregates may also perform the function described above.

Accordingly, other sands may be used alone or with other non-hygroscopic aggregates such as granite, ferrosilica, quartz, etc.

Additionally, although the silica sand is a fine-grained aggregate, other coarse-grained materials may be used alone or in conjunction with the fine-grained materials without departing from the scope of the invention.

The fine aggregate used here is (1) 9.5 mw (
aggregate that passes through a No. 4 (4,76 mm) sieve, passes almost completely through a No. 4 (4,76 mm) sieve, and is primarily retained on a No. 200 (74 μ) sieve;
, 76) sieve and is primarily retained on the No. 200 (74μ) sieve.

By coarse aggregate is meant the aggregate that is primarily retained on the No. 4 (4,76ii) sieve or the portion of the aggregate that is retained on the No. 4 (4,76) sieve.

Reinforcing filaments suitable for use in accordance with the present invention are of a type that provides flexural and tensile strength to the conservation concrete mass.

Furthermore, as previously mentioned, the reinforcing filaments used with the expanded hydraulic binder are exceptionally strong and approximately 562 mm
~703kg/cTL (8000~11000psi
) Make concrete self-stressing to create a secure structure with a compressive strength of pedestal.

It is recommended to use metal filaments as reinforcing elements in conservation concrete masses.

This is because they provide sufficient internal stress to create compressive strength, flexibility and tensile strength of the concrete mass.

Furthermore, it has been discovered that the use of such metal filaments in the concrete mass tends to damage the tip of the torch against the action of an acetylene torch.

The recommended type of metal reinforcing filament is U.S. Patent No. 3429.
No. 094 describes this in detail.

The specifications of these patents relating to fine steel wire suitable for use in accordance with the principles of the present invention are incorporated herein by reference.

More specifically, the steel wire is preferably substantially straight, and its length is arbitrarily selected between about 1.27 cm (-z inch) and about 3.81 cIrL (100 inches). Re,
Its diameter is maximally 7.62 inches (0.3 inches), preferably about 0.1524 mm (0.006 inches) to about 1.587 inches.
5 mm (0,0625 inches).

the steel wire has a length-to-diameter ratio of about 40 to about 120;
Preferably, the steel wire has a weight of about 1,898,289 kg/cI? L
~2,249,824kg/i (27,000,000
psi to 32,000,000 psi).

These steel wires are slightly crimped to improve their bonding effect in the concrete mass.

Of course, other metal filaments can also be used as reinforcing filament elements in conservation concrete.

Also, the filament may be round, flat, or otherwise shaped.

Various types of metal and metal alloy filaments may alternatively be used, including, for example, boron, carbon, steel, copper alloys, and the like.

Additionally, such metal filaments can be painted to resist corrosion.

As already mentioned, the formable mixture of refractory aggregate, steel filaments and expanded hydraulic binder allows the inclusion of an amount of water that allows the concrete composite to be mixed and processed according to manufacturing techniques. It has been found.

The expanded cement component cooperates with the other essential components of the moldable composite to obtain the advantageous concrete according to the invention.

Such expansive cements are well known.

A comprehensive report on such expansive cements is available in Expandable Cement Concrete, Publication 5P-38, 1973.
(National Diet Library catalog card number 73-77948)
Published by American Concrete Institute Committee 223 under the title .

Particularly suitable shrinkage-compensating expansion binders are known as mold cements as classified by the American Concrete Institute (ACI) Committee on Nomenclature 116 (Publication 5p19, Library of Congress Catalog Card No. 6730).
095).

Commercially available products suitable for use in the present invention include Chemcomb (
It is sold under the product name Chem Comp.

This shrinkage compensating expansion binder or cement is described in detail in US Pat. Nos. 3,155,526 and 3,251,701.

Such discussion in these patents is incorporated herein by reference.

Basically, such an expanding binder contains a conventional Portland cement component and an expanding component.

The swelling component of the Chemkelp is mainly stable calcium sulfoaluminate (CaO)4(M2O3)3SO3.
The calcium sulfoaluminate is in the form of a ternary compound or extractable associative lime (Cab) and extractable associative anhydrous calcium sulfate (Ca 804 ).
said extractable lime AST in the form of a complex compound with
MC C114-58, said associative anhydrous calcium sulfate was determined by the method of Forsen, modified by Manabe, entitled ``Determination of Calcium Sulfoaluminate in Cement Pastes by 6 Tracer Techniques''. Published in January 1960, Journal A, C, I, Vol. 31, No. 7.

Further details regarding these compositions can be found in U.S. Pat.
It is described in the 1st column, lines 19 to 55, and the 3rd column, lines 26 to 9 of the specification of No. 51701.

Accordingly, a particularly recommended shrinkage-compensating expanding hydraulic cement based on the principles of the present invention contains a major amount of Portland cement and a minor amount of expanding cement, the expanding cement comprising at least a portion of Portland cement. There is sufficient quantity to compensate for shrinkage and to impart swelling properties when the swelling component is hydrated.

- So generally, expansive concrete is usually divided into two types: shrinkage-compensating and self-stressing.

According to the definition of the American Concrete Institute (ACI), shrinkage-compensated concrete is an expansive cement in which compressive stress, which substantially offsets the tensile stress generated in concrete by drying, is generated by suppressing its expansion.

Self-stressing concrete refers to expansive cement concrete that, when its expansion is inhibited, generates a compressive stress sufficient to strongly compress the concrete after drying shrinkage (and creep) occurs.

The compressive stress induced in concrete by shrinkage-compensating cement is about 2-7 kg/c/1 (25-100 psi), while the compressive stress by self-stressing cement is about 7-70 ky/crlL (100-1,000 psi). ps
i).

The expanding cement consists of a major portion (approximately 90-70%) of Portland cement and a small remaining portion of expanding components for shrinkage compensation and self-stressing properties.

The American Concrete Institute defines three types of shrinkage compensating cement: type, S type, and M-X (or M) type.

These three types of shrinkage compensating cements are each characterized by having a different alumina banded compound.

In other words, type K is C, A3S. MX type is CA+C1□A7
(calcium aluminate cement)) and S type each have C3A.

Sulfates exist as gypsum, hemihydrate, anhydrous gypsum, and partly as C4A5S in die-type cements.

There is little doubt that the formation of ettringite, based on the reaction 6C+A+3S+32H-+C3A.3C8-H32, is the source of expansion energy.

The abbreviation symbol indicating the oxide is Ca0=C2S■0□=
S, Al203=A, Fe203=F, 5O3-8° and H20=H.

In fact, none of the aforementioned oxides occurs as a reactant, except in part for water.

The expression of reactants as oxides in general reactions is governed by the phase law.

The practical use of expansive cements is based on control of the kinetic energy and extent of the ettringite formation reaction.

Ettringite begins to form as soon as water comes into contact with cement particles.

Type K cement is recommended in this invention.

This is because the swelling agent of anhydrous calcium sulfate evenly controls ettringite formation in the cement composite.

It is theorized that the ettringite precipitate is forced into the cavities of the cement paste and acts to reduce permeability and hygroscopicity.

The formation of said compound is accompanied by a significant increase in quantity and is the basic structure of expansive cement.

These cements consist essentially of Portland cement containing about 10-30% expansive component.

The expansion element contains enough Cab as required to form the desired amount of ettringite.

S03. and Al2O2, the ratio is usually determined by the producer.

Ettringite begins to form as soon as water is added to the cement during mixing and continues to form during the white curing period until the SO3 or Al2O2 is used up.

The main part of t-IJ rock formation needs to be done after the cement has gained sufficient strength.

Otherwise, the expansion would only deform the still plastic concrete and would not create the desired compressive stresses in the restrained concrete.

Two types of water use reactions take place in expanded cement.

The formation of calcium silicate, a hydrate that provides strength, and the formation of ettringite, a compound that causes swelling requiring additional water of hydration.

The results of the present invention are considered surprising.

This is because the colloidal properties of t-IJite are believed to have a tendency to retain large amounts of water.

It has been recognized that such water is undesirable in conventional cements.

Also, in accordance with the present invention, it has been discovered that water causes splitting and disintegration.

It is therefore quite surprising that the preservation concrete structures according to the invention do not split, collapse or burst despite the tendency of ettringite.

Therefore, large amounts of water can be added to the moldable mixture, which facilitates processing and fabrication of the security safe structure of the present invention.

Slumps on the order of about 13.97 to 16.51 crIL (5.5 to 6.5 inches) may be used.

These values of slump are far in excess of the slump allowed in conventional Portland cement, but do not weaken the concrete structure in the hardened state.

Hydrable expanding cement absorbs excess water in the mixture by reacting with the excess water to form hydrated connective tissue.

Unlike ordinary cements traditionally used in conservation structures, which require excessive amounts of water, which can remain in the concrete and have the disadvantageous effects described above, this is necessary due to its expansive component. This additional water is used up or trapped during the curing process.

Additionally, the use of an expanded cement binder as described above provides approximately 633 to 773 9/cIIL (9,000 to 11
Compressive strengths on the order of ,000 psi) are obtained in security structures according to the present invention, and such compressive strengths constitute a virtually impenetrable barrier to safe-cracking hammers and impact tools.

As the conservation concrete hardens, the expanding cement binder adheres to the steel filaments and at the same time the volume of the concrete expands due to the expansion reaction.

Since concrete is fixed to steel filaments,
The expansion causes the steel filament to be stretched, thus
Concrete is compacted.

Although the concrete is pre-stressed, the magnitude of the pre-stress is significantly smaller than that of the original stress.

The expansion reaction is complete within the first few days of concrete curing.

Then, when the concrete is exposed to dry conditions,
The concrete shrinks exactly like standard Portland cement concrete.

However, unlike standard Portland cement concrete, shrinkage merely releases a small amount of precompression and does not build up tensile stresses.

The proportions of the various components in the preservation concrete composite of the invention can be chosen appropriately.

However, the following wide tolerance ranges, expressed in parts by weight, are preferred.

Sand: about 120-190 parts Expanded cement: about 80-175 parts Steel filament: about 40-65 parts Water: about 30-75 parts The above ingredients are mixed in a barrel-shaped mixer with a paddle in the examples below. used.

The dried ingredients are sequentially fed to the mixer as the mixer operates.

After these ingredients are mixed for several minutes, 20% water is added in stages.

In this case, the mixer is operated for several minutes between each addition stage.

After all ingredients have been fed, the mixer is run for a few more minutes.

At this point, the slump is caused by ASTM technology (ASTM
C143-39).

Slump is approximately 13.97 cIfL ~ 16.51 crrL
(5.5 to 6.5 inches), the moldable mixture of the various components is placed in place with sufficient vibration to ensure injection into the cavity of the safe, such as doors, walls, etc. flowed into.

The above objects and other objects of the present invention will be more clearly understood by referring to the drawings and the examples shown below.

Referring to the accompanying drawings, in FIG. 1 a door 3 is attached to the opening of a safe 4 by suitable means, not shown.

The front face 5 of the door 3 is made of 12 gauge stainless steel and the rear face 6 is constructed with exposed conservation concrete 7.

Although the internal components of the door 3 are not shown in the cross-section shown in FIG. 2, the moldable aqueous mixture is constituted by said internal components to obtain a mold-compatible composite concrete mass. It should be understood that the vibrations have a slump that allows the vibrations to easily fill voids and gaps.

The facade 5 made of stainless steel, after being bent into the appropriate shape, forms a container or cavity for the preservation concrete.

The remaining walls of the safe 4 are not shown in detail, but they may also be formed by the preservation concrete composite of the invention or in composite form with a steel casing or other supporting material.

It goes without saying that the illustrated safe 4 is merely for detailed illustration of the present invention, and it is understood that other security structures may be constructed to obtain the results provided by the present invention. will be done.

Using the general mixing procedure previously described, silica sand, K-type expanded cement (Chemcomb, supra), approximately 0.4ii (0.01
After a length of approximately 19 inches (7 inches) of steel fiber and water are mixed, with or without the addition of other materials, sufficient to ensure packing into the mold cavity. It is given a strong vibration and is poured into the right place.

The metal door 3 shown in Figure 1 defines a cavity.

Table 1 shows the types and amounts of various materials used in the experimental examples.

Quantities of materials are expressed in kg (lbs) and in the experimental examples, expanded metal, granite chips, reinforcing rods, and glass fibers were used.

Latex binders and glass fibers were used to increase impact resistance.

The concrete of each example was cured at ambient temperature and no signs of water leaching were observed.

After time, the compressive strength of each example was measured 7 days, 14 days, and 28 days after finishing pouring.

As shown in Table 2, after 28 days, the compressive strength of all concrete composites (except for the concrete composite 6 containing glass fiber and latex binder) is approximately 422 kg/
-~647ky/ff1 (6,000~9.200ps
It was between i).

Experimental example 6 is approximately 142 kg/i (2,000 psi)
It had the following compressive strength.

Table 2 therefore mainly shows 562-703 kg/
It has been shown that compressive strengths on the order of cIIL (8,000 to 10,000 psi) can be obtained with the conservation concrete composites of the present invention using steel fibers.

The amounts of glass fiber and latex of the sixth example do not provide such high compressive strength, and therefore such particular mixture is not recommended where high compressive strength is desired.

Next, the concrete samples according to Experimental Examples 1 to 8 were treated with acetylene at a temperature of approximately 1871°G (3400'F).
Tested using a torch.

Additionally, diamond core drill and hammer tests were conducted.

Table 3 shows the results of these tests along with the values in the flame removal column.

The number is the amount of material removed from the specimen using an acetylene torch in milliliters (1 rll) per minute.

The diamond core drill weighs 22.68 kg (501
bs ) is used under constant weight, and its diameter is 5.08c
It was 1 rL (2 inches).

The numbers listed in the drill test column are expressed in depth per minute in centimeters (inches).

The hammer test was conducted using a 7 2.576 (1601bs) hammer equipped with a 2.54 (1 inch) rough chisel at 1.22 m.
The specimen was dropped from a height of (41 Jle) to the same location five times, and the numerical value shown is the penetration depth measured after the test in centimeters (inches).

As shown in Table 3, preservation concrete composites according to the present invention exhibited excellent torch resistance within the range of about 511 Ll/min to about 311 rLl/min.

In comparison, known conservation concrete IJ-to mixes using conventional Portland cement binders and aggregates do not withstand such acetylene torches to the same extent.

On the contrary, known integrity concrete has a tendency to split, disintegrate, and be dislodged explosively, thereby facilitating penetration into the concrete.

For example, an acetylene torch under the same conditions will act approximately 3 to 8 times faster than standard Portland cement.

Table 3 also shows that although the flame removal in Experiment No. 6 is on a relatively small scale, the diamond core drill removes a larger amount of material from the concrete specimen when no steel fiber is used. It shows that it promotes.

Further, the concrete of the sixth experimental example without steel fibers had inferior results in the Behammer test compared to the concretes of the other experimental examples that did have the steel fibers.

Therefore, in order to realize all of the advantages of the principles of the present invention, a concrete structure should have refractory aggregate, expanded cement, and reinforcing filaments, preferably metal reinforcing filaments.

When steel or other metal filaments are used, K
The mold-expanded cement allows shrinkage compensation and self-stressing of the concrete mass to be achieved, thus resulting in highly advantageous compressive strengths.

Such shrinkage compensation also provides a mold-close composite of cement and steel casing or other support material.

To demonstrate the recommended selection of non-hygroscopic refractory aggregates in the concrete of the present invention, several concrete test specimens were prepared utilizing two different types of sand to create mixtures similar to Examples 1 to 8 above. prepared by using.

In the first set of samples, the sand was the aforementioned Ottawa-type silica sand, and in the second set of samples, river sand or natural sand was used.

The sample is approximately 30.48crfLX 30.48crrLX
It was 15.24 cIrL (thickness) (12 inches x 12 inches x 6 inches).

Next, an acetylene torch test was performed.

The specimens containing river sand showed a tendency to split and disintegrate, but this tendency was less severe compared to known standard concrete.

In contrast, no splitting or disintegration was observed in the specimens containing silica sand.

Therefore, non-hygroscopic silica sand is particularly important to completely prevent splitting or disintegration.

It has been determined that the moisture contained in the Jll sand causes delamination or flaking of the specimens.

This was concluded after a second sample containing river sand was dried for three days at 65°6°G (150'F) prior to torch testing.

In this case, the sample did not burst and almost no flaking occurred.

Therefore, the residual moisture becomes trapped in the hygroscopic porous river sand particles in the concrete structure and has a tendency to cause flaking and collapse of the concrete mass upon exposure to high temperatures.

Therefore, in accordance with the most preferred principles of the invention, non-hygroscopic aggregates are used to completely prevent concrete collapse.

In view of the above description and experimental examples, it will be understood that modifications of the invention may be made without departing from its spirit and scope.

[Brief explanation of the drawing]

FIG. 1 is a front view of a safe embodying the invention; FIG. 2 is a longitudinal sectional view of the safe world filled with a conservation concrete composite according to the invention. In the drawings, 3 indicates the "door"; 4 indicates the "safe"; 5 indicates the "front"; 6 indicates the "rear"; near indicates the "preservation concrete".

Claims (1)

[Scope of Claims] 1. about 120 to 190 parts of silica sand aggregate, and about 40 to 65 parts of silica sand aggregate;
about 80 to 175 parts of an expanding cement comprising a torch tip of a part and a metal fiber for reinforcing hardened concrete, and Portland cement and an expanding component, said expanding component being hydrated as it hardens. and providing a mixture capable of being milled and shaped with expanding cement in an amount at least sufficient to compensate for shrinkage of the Portland cement and to impart expansive and self-stressing properties to the Portland cement. For safes or safe structures comprising self-stressing hardened concrete made from a moldable homogeneous mixture having about 30 to 75 parts of water, said mixture having about 13.5 parts of water. 97-16.
having a slump on the order of 51 crfL (5.5 to 6.5 inches) and in which the hardened concrete is resistant to torch and attack by hammers, chisels, drills and cutting instruments without flaking, splitting or bursting; including a resistance of
A safe or vault structure characterized in that it provides improved resistance to attack by safe-cracking means. Silica sand aggregate having a sieve analysis value of about 15% or less remaining on a 220 mesh sieve and about 5% or less passing on a 30 mesh sieve, and about 1.27 to 3.81 crft (1/2
2 to 1 inch) The length of the stand and maximum approximately 7.62 mm (0,
A safe or vault door having a hardened concrete body made from a moldable aqueous mixture comprising torch-tipped and hardened concrete reinforcing copper fibers having a diameter of 3 inches and a K-type expanded cement component; As a wall, the ratio of the amounts of the various components is about 120 to 190 parts of sand and about 4 parts.
0 to 65 parts of metal fiber, about 80 to 175 parts of mold expanding cement, and about 30 to 75 parts of water, and the mixture of the ingredients is about 13.97 to 16.51 c1rL (
Torch resistance and resistance to attack by hammers, chisels, drills and cutting instruments, with a slump of the order of 5.5 to 6.5 inches and in which the hardened concrete does not flake, split or burst; A safe or vault door or wall characterized in that it provides improved resistance to heat and instrument attack.