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From: glhurst@onr.com (Gerald L. Hurst)
Newsgroups: alt.engr.explosives
Subject: Re: BIG BLU-82 Question
Date: 11 Mar 1997 22:10:52 GMT

In article <19970311180001.NAA04731@ladder01.news.aol.com>,
tomhun8054@aol.com (TomHun8054) says:

>The experts out there will laugh at this one, but is the explosive
>"slurry" inside the BLU-82 the most effective explosive for that device? 
>What I mean is, wouldn't something like C4 or something give bigger bang
>for the buck, or is that stuff too expensive, etc?  I know this is another
>stupid newbie question, and I'm sure there's a simple answer, but if you
>could indulge me, I'd appreciate it.

Slurries are very inexpensive compared with conventional military
explosives and much easier to load into large casings.  C-4 is a 
specialty plastic explosive which has only moderate explosive 
properties as military HE goes because it contains inert plasticizers
to make it pliable for demolition use.  Packing 10,000 pounds of the
material in a bomb casing would be a chore. 

More conventional HE for blast is usually cast into the casing.  This
process is also very laborious and has the big problem of shrinkage
which results in multiple voids in the casting (riser).

With slurry, filling a bomb is merely a matter of pouring the material
into the casing.

It is true that slurry has a fair amount of water in it, but this
water can be turned into a reactant by the addition of lots of 
aluminum.  Aluminum is, of course, also used in other high blast
compositions for essentially the same reason -- to increase the 
energy by, in effect, reacting with product water.

A final advantage of slurry is that it can be stored in non-explosive
component form and turned into field-manufactured explosive as it is
needed.  Commercially, most commercial slurry is manufactured in 
local mini plants which could be put in a trailer if necessary.

When the big bombs were first being developed, we constructed a
mini-plant in a semi, drove it from Seattle to Fort Walton Beach,
Florida (Eglin AF base) and used it to manufacture and load several 
prototype bombs using napalm bomb casings.  The explosive was 
Astrolite A-1-5, a rather expensive, quite powerful and relatively
dangerous non-aqueous aluminized slurry.

During this same period, Mel Cook, the acknowledged father of water-
based slurries, was walking around with a copy of his book, "The
Science of High Explosives." under his arm. Cook was our competitor 
in the development of the big bombs for helicopter landing zone 
clearance in Viet Nam. Cook got the job despite our efforts and 
rightly so.  His water-based materials were ideal for the intended 
use, especially based on cost and safety.

In those days, water-based materials were new and their future was 
uncertain.  Today, they have captured the lion's share of the 
commercial market and made dynamite a nearly extinct species.

Jerry (Ico)

From: ahahma@polaris.utu.fi (Arno Hahma)
Newsgroups: rec.pyrotechnics
Subject: Re: elimination of large rocks
Message-ID: <1991Jun24.195710.9283@polaris.utu.fi>
Date: 24 Jun 91 19:57:10 GMT

In article <1991Jun20.195839.12033@ohsu.edu> kozowski@ohsu.edu (Eric Kozowski) writes:

>>Please explain what water gel is.

>by DuPont (they don't make dynamite anymore) as a replacement for
>dynamite.  I will post a followup with more detail.

Water-gels or slurries are a group of explosives based on aqueous solutions
of oxidizers and/or fuels. There are as many types of slurries as there are
manufacturers, so a general description is not easy to give. Three basic types
could be distinguished, according to the method of sensitization: metallized
slurries, slurries based on emulsions/occluded gas and slurries based on other
explosives, such as TNT, ethylene glycol di- and mononitrates, RDX, HMX, PETN,
etc.

Common to all of them is, that the most of the oxygen comes from an inorganic
(usually, but not necessarily) salt dissolved in water. The fuel can be
a metal powder, oil (as an emulsion) or another explosive or even an organic
subtance dissolved in water. Essential for all slurries is a gelatinizing
agent. The consistency varies from pourable to stone hard solid, this is
adjusted with the gelatin (usually polyvinyl alcohol, guar gum, dextran gums,
urea-formaldehyde resins).

The advantage of a slurry is its safety and great versatility. A slurry will
not explode, if it is not sensitized in some of the above ways. The sensitizer
can be added at the blasting site, so the slurry will be completely safe until
pumped down to the borehole. On the other hand, the composition can be made
cap sensitive, if it is to be used like dynamite. Moreover, a slurry
composition is a good way to use surplus material. Just mix a soup of
any water-soluble oxidizer, some waste explosive (like TNT from disarmed
ammo) and water + gelatinizing agent.

ArNO
    2

 
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