Barrier for absorbing live fire ammunition and uses thereof

Abstract

This disclosure is directed to an improved ballistic concrete barrier and methods of using the barrier for training with weapons using live ammunition or grenades or other fragmentation devices.

Description

In one embodiment, the water is about 0.48 part by mass (466 pounds of water/972 pounds of cement=0.479 part by mass water). The act of obtaining includes creating the grout or obtaining the grout from some third party.

Step 2008—Add a chemical air entrainment additive (DaraFill® Dry, W. R. Grace & Co.).

Step 2012—Following the addition of the additive, mix the grout for five minutes. Mixing may be achieved by rotating the drum on a cement mixer truck.

Step 2016—Add Calcium Phosphate, Aluminum Hydroxide, and fiber. One suitable fiber is Grace Fibers™. Mix for an additional ten minutes.

Step 2020—Check density such as by weighing using a ¼ cubic foot testing pot. Target weight is 22.7 pounds (approximately 91 pounds per cubic foot) as the actual target is 91 pounds per cubic foot±3 pounds per cubic foot.

Step 2024—Continue to mix if needed to reduce density to desired range. Additional mixing lowers the density. Continue to mix, checking frequently, until target density is achieved. The target wet density material when poured into components is 1458 kg/m³ (91-pounds per cubic foot+3 pounds per cubic foot).

Step 2028—Pour ballistic concrete material into molds. As with traditional SACON® type ballistic concrete, vibration such as may be used with standard structural concrete is to be avoided to minimize destruction of air bubbles.

Changes in Order and Additives.

Note that the step of adding the calcium phosphate and aluminum hydroxide could be done at the same time as adding the chemical air entrainment additive.

Note further, that as the calcium phosphate and aluminum hydroxide are added to reduce lead-leaching from ballistic concrete blocks which have absorbed ammunition with lead components; these chemicals are not central to the ballistic properties of the ballistic concrete. Thus, in applications where the need to reduce lead-leaching is not important (whether because of local rules, post use disposal plans, or a movement to ammunition with minimal or no lead), one can make ballistic concrete in accordance with the teachings of the present disclosure without addition of calcium phosphate or aluminum hydroxide.

The fiber may be added at the same time as the chemical air entrainment additive (and possibly the calcium phosphate and aluminum hydroxide) as this process does not require achieving a pre-fiber density before adding the fiber. When the process is modified so that there is not a need to add material after five minutes of mixing, simply mix for fifteen minutes before checking density. Additional mixing may be required to reduce density.

After filling the molds, the material may be optionally tapped down with a rod to eliminate voids around embedments in the casting forms. Not all components will be poured into molds with embedments. Molds without embedments may not need a rod to eliminate any voids, but a form with an embedment such as a window cutout may need a treatment with a rod to eliminate voids.

Less Restrictions on Pouring.

Unlike traditional SACON® type ballistic material with fragile foam bubbles, ballistic material made in accordance with the teachings of the present disclosure is not limited to a 2 foot maximum drop during pouring or a 2 foot maximum depth of a pour. Thus, unlike traditional SACON® type ballistic material, ballistic material made in accordance with the teachings of the present disclosure may be poured into wall panels oriented in their final vertical orientation. Optionally, ballistic material made in accordance with the teachings of the present disclosure may be poured into molds with pour heights well in excess of 2 feet tall. Pours of greater than 3 feet in height are obtainable. Pours of greater than 6 feet in height are obtainable. Pours of greater than eight feet in height from bottom to top of mold are obtainable. Pour structures of full height walls of eight feet or more may be done.

Quicker Turn-Around on Use of Mold Components.

While traditionally, SACON® ballistic concrete components have been left in the molds for fourteen days with the sides only removed after three days, an alternative process viable with the improved ballistic concrete is to remove the sides of the forms within 24 hours and remove the bottom of the form after at least three days.

Those of skill in the art will recognize that the ability to remove the mold components significantly faster results in an overall throughput of molded panels of more than 300% for a given investment in molds. Thus, less money needs to be tied up in molds, transportation and storage of molds. T

The component is wrapped in plastic to assure adequate hydration during curing. One of skill in the art will recognize that the timing of these steps may be adjusted based on weather conditions, particularly temperature but also factoring humidity. The components are allowed to harden and dry and are ready for use and/or testing after 28 days.

One of skill in the art will recognize that the fibers enhance the strength and resilience of the components and ability of the molded components to withstand a bullet entry without spalling. Spalls are flakes of material that are broken off a larger solid body such as the result of projectile impact, weathering, or other causes. It is desired that the molded components retain their structural integrity with the exception of the trail formed by the bullet entry. Thus while the fibers are important, one of skill in the art can identify and substitute other fibers that are suitable for the task, see e.g., paragraph defining term fiber in definitions section above. The choice of fibers will impact the overall density of the wet material as the weight of the fibers impact the density calculation.

Benefits of the Improved Bullet Absorbing Components

To date, the improved bullet absorbing components have consistently performed well in ballistic testing. Anecdotal evidence suggests significantly higher failure rates for traditional SACON® ballistic concrete than with the improved production process. These failure rates may be due to a lack of consistency of the product using traditional SACON® ballistic concrete. The improved production process produces a very consistent material with an extremely low (much less than 1%) failure rate of the penetration test listed above.

Other benefits for the improved ballistic concrete are the predictable and uniform results in ballistic performance when the mix falls within the target density range. By uniform results, it is meant that penetration tests on different parts of a panel made with the improved ballistic panel will all pass the penetration test.

The process is sufficiently predictable that when a sample falls outside of the target range for density after the prescribed mixing period, this aberrant result is a strong indicator that the sand used in the mix is out of specifications, perhaps because of inclusion of clay or another contaminant.

Modification for Slower Projectiles

Those of skill in the art, recognize that the muzzle velocities for different types of ammunition differs a considerable amount. For example, within pistols, the muzzle velocity of a 9 mm handgun is significantly higher than the muzzle velocity of a 45 caliber pistol. The muzzle velocity for a given type of ammunition will actually depend on part on the length of the barrel of the gun.

In order to design a ballistic barrier for a lower velocity projectile than used in the standard penetration test described above, the ballistic barrier must be made easier to penetrate so that the back end of the projectile penetrates more than one inch into the ballistic barrier. Increasing the amount of chemical air entrainment additive and or increasing the mix time to downwardly adjust the density target for the ballistic material will enable the ballistic panel to be tuned for use with a particular lower velocity projectile. Density of the ballistic concrete may be dropped by simply mixing longer without changing the amount of air entrainment additive. May need to augment with additional air entrainment additive for a severe change in density.

Modifications for Other Bullet Depth Ranges.

One of skill in the art could modify the teachings of the present disclosure to tune the ballistic concrete to capture a bullet from a prescribed round, firearm, and firing distance within a depth range that is different from the 1 to 5 inch range referenced above. Thus, a ballistic concrete component could be tuned to capture bullets in a depth range of 2 to 6 inches of depth as measured to the part of the bullet closest to the entry point, or 0.5 inches to 3 inches of depth as measure to the part of the bullet closest to the entry point.

It is to be understood that, while the teachings of the disclosure have been described in conjunction with the detailed description, thereof, the foregoing description is intended to illustrate and not limit the scope of the claimed invention. Other aspects, advantages, and modifications of the teachings of the disclosure are within the scope of the claims set forth below. All publications, patents, and patent applications cited in this specification are herein incorporated by reference as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.

One of skill in the art will recognize that some of the alternative implementations set forth above are not universally mutually exclusive and that in some cases additional implementations can be created that employ aspects of two or more of the variations described above. The legal limitations of the scope of the claimed invention are set forth in the claims that follow and extend to cover their legal equivalents. Those unfamiliar with the legal tests for equivalency should consult a person registered to practice before the patent authority which granted this patent such as the United States Patent and Trademark Office or its counterpart.

Claims

1. A method for creating a bullet absorbing structural component made from ballistic concrete, the method comprising:

forming the bullet absorbing structural component by combining multiple components in a mixer, comprising:

(i) about 1 part by mass Portland cement;

(ii) about 0.5 to 1.5 part by mass fine aggregate;

(iii) about 0.48 part by mass water;

(iii iv) about 0.005 to 0.15 part by mass fiber;

(iv v) about 0.005 to 0.05 part by mass calcium phosphate;

(v vi) about 0.005 to 0.05 part by mass aluminum hydroxide; and

(vi vii) about 0.0005 between 0.001 to about 0.05 part by mass air entrainment additive;

such that the bullet absorbing structural component is capable of stopping a live-fire test of an m855 round with a bullet fired from an m16a2 rifle at a distance of 82-ft with a penetration depth of between 1 and 5 inches as measured to a back of the bullet from a point of bullet entry on the bullet absorbing structural component; and

wherein the bullet absorbing structural components are made with a maximum pour drop of the ballistic concrete exceeding 2 feet.

2. The method of claim 1, wherein the bullet absorbing structural component comprises:

(i) about 0.8 to 1.2 part by mass, fine aggregate;

(ii) about 0.008 to 0.012 part by mass, fiber;

(iii) about 0.008 to 0.012 part by mass, calcium phosphate; and

(iv) about 0.008 to 0.012 part by mass, aluminum hydroxide; and

(v) about 0.0008 to 0.002 part by mass, air entrainment additive.

3. The method of claim 2, wherein the bullet absorbing structural component comprises:

(i) about 0.9 to 1.1 part by mass, fine aggregate;

(ii) about 0.009 to 0.011 part by mass, fiber;

(iii) about 0.009 to 0.011 part by mass, calcium phosphate; and

(iv) about 0.009 to 0.011 part by mass, aluminum hydroxide; and

(v) about 0.0009 to 0.0015 part by mass, air entrainment additive.

4. The method of claim 1, wherein the fiber is a polyolefin fiber.

5. The method of claim 4, wherein the polyolefin fiber is a fibrillated fiber.

6. The method of claim 1, wherein the air entrainment additive is DaraFill® Dry.

7. The method of claim 1, wherein a mixture comprising the Portland cement, the fine aggregate, the fiber; the calcium phosphate; the aluminum hydroxide; and the air entrainment additive is mixed until the mixture has a wet density within a range of 88 to 94 pounds per cubic foot.

8. The method of claim 1, wherein the bullet absorbing structural component has air bubbles resulting from the air entrainment additive that are less than about 0.04 inches (1 mm) in diameter.

9. The method of claim 1, wherein the bullet absorbing structural component has air bubbles resulting from the air entrainment additive that are greater than 0.0004 inches (10 μm) in diameter.

10. The method of claim 1, wherein the bullet absorbing component has air bubbles resulting from the air entrainment additive that are less than about 0.04 inches (1 mm) in diameter and greater than 0.0004 inches (10 μm) in diameter.

11. The method of claim 1, wherein the bullet absorbing structural components are made on site at a training facility that will use the bullet absorbing structural component to capture live fire ammunition used at the training facility.

12. The method of claim 1 wherein the bullet absorbing structural components are made with a maximum pour drop of the ballistic concrete exceeds 2 feet.

13. The method of claim 1 wherein the bullet absorbing structural components are made with a maximum pour drop of the ballistic concrete exceeds exceeding 6 feet.

14. The method of claim 1 wherein the bullet absorbing structural components are poured with a maximum depth of more than 2 feet while in a mold.

15. The method of claim 1 wherein the bullet absorbing structural components are poured with a maximum depth of more than 3 feet while in a mold.

16. The method of claim 1 wherein the bullet absorbing structural components are poured with a maximum depth of more than 6 feet while in a mold.

17. The method of claim 1 wherein an upright wall panel is poured in place for a wall with a height of more than 6 feet measured from a bottom of the mold.

18. A method for creating a bullet absorbing structural component made from ballistic concrete by combining multiple components in a mixer, the method comprising:

obtaining a grout of Portland cement, fine aggregate and water in a mixer;

adding chemical air entrainment additive;

adding fiber to the grout;

forming the bullet absorbing structural component by mixing until the wet density of the grout falls within a desired density range for use in a bullet absorbing structural component for use with weapon using a particular round with a bullet fired from a particular distance so that a back edge of a bullet from a round fired perpendicularly towards a cured bullet absorbing structural component is within a range of 1 inches to 5 inches as measured from a point of bullet entry on the bullet absorbing structural component; and

wherein the ballistic concrete is poured into a mold such that a maximum height of the poured ballistic concrete exceeds 2 feet.

19. The method of claim 18 wherein the round is an m855 round with a bullet fired from an m16a2 rifle at a distance of 82-ft.

20. The method of claim 18 wherein mixing continues until the wet density is within a range of 88 to 94 pounds per cubic foot.

21. The method of claim 18 wherein the grout is mixed for several minutes after the addition of the chemical entrainment additive before the addition of the fiber.

22. The method of claim 18 wherein additives are added to the grout to reduce lead leaching from a bullet absorbing structural component which is used to absorb bullets containing lead.

23. The method of claim 22 wherein the additives are calcium phosphate and aluminum hydroxide.

24. The method of claim 18 wherein the ballistic concrete is poured into a mold such that a maximum height of the poured ballistic concrete exceeds 2 feet.

25. The method of claim 18 wherein the ballistic concrete is poured into a mold such that a maximum height of the poured ballistic concrete exceeds 3 feet.

26. The method of claim 18 wherein the ballistic concrete is poured into a mold such that a maximum height of the poured ballistic concrete exceeds 6 feet.

27. The method of claim 18 wherein ballistic concrete is poured into a mold having removable side walls and the side walls are removed from the mold within 24 hours of completing a pour into the mold.

28. The method of claim 18 wherein bullet absorbing structural component is made from ballistic concrete poured into a mold and the bullet absorbing structural component is removed from all portions of the mold within three days of completing the pour into the mold.

29. The method of claim 18 wherein the ballistic concrete is made without an addition of a wet foam comprising water, a foaming agent, and a foam stabilizing agent.

30. A method for creating a bullet absorbing structural component made from ballistic concrete by combining multiple components in a mixer, the method comprising:

obtaining a grout of cement, fine aggregate and water in a mixer;

adding chemical air entrainment additive;

adding fiber to the grout;

forming the bullet absorbing structural component by mixing until the wet density of the grout falls within a desired density range for use in a bullet absorbing structural component for use with weapon using a particular round with a bullet fired from a particular distance so that a back edge of a bullet from a round fired perpendicularly towards a cured bullet absorbing structural component is within a range of 1 inches to 5 inches as measured from a point of bullet entry on the bullet absorbing structural component; and

31. The method of claim 30 wherein bullet absorbing structural component is made from ballistic concrete poured into a mold and the bullet absorbing structural component is removed from all portions of the mold within three days of completing the pour into the mold.