How is Globulite Manufactured?

maybe the same way pearls are made

Sounds like a case of which came first, the chicken or the egg (how do you know if you can do it if you don't know how it is done!). Do you at least know what Globulite is used for, the size of the spheres, wall thickness, etc (this may help)?

globulite - (geology) A small, isotropic, globular of spherulelike crystallite; usually dark in color and found in glassy extrusive rocks.

Perhaps they are working on a process for doing what a volcano does to create globulite. Is it valuable?

Maybe is good as a filtering media or good for releasing chemicals stored inside the spheres, or good for insulation, or as concrete filler... How big they may be? This may reveal is final aplication... Good luck in your new job... Regards Luis

The balls range from 15 to 5000 mm. Of course, only the small ones are used in walls. The bigger are used for structural purposes.

I think there are several ideas you can use to generate hollow spaces inside casting bodies. 1. lost wax casting method 2. air injection in molded semi-liquid concrete. 3. centrifugation in 2 axes (plus air injection) 4. mercury injection with magnetic field containment. (drained after cure) 5. sprayed or concrete over a shell of the hollow. 6. half shell molding, with after cure mating. I am curious to know more about the product.

In spanish this product is called "globulita" It is used to reduce the weight of concrete walls by spreading the hollow balls over the iron mesh and then adding the wet cement. I suspect it is made by 2-axis centrifugation, but not sure. Other, simpler way, would be to spread the cement over a thin ball of something else. For the same purpose I bet it would be great to use cement mixed with rice husk or other agricultural waste. The balls wouldn't be hollow, but would be light anyway.

Nowhere in this article is the word globulite mentioned, but there is a distinct possibility that globulite may be the key ingredient.

BUILDING MATERIALS: Concrete Cast in a New Light

By Tony Kaye

Aerated wall panels promise cheaper, faster building and better insulation than conventional precast concrete.

http://www.solve.csiro.au/1105/article11.htm

No, it isn't made with globulite. I have a friend working on a very similar product and I am pretty sure the key ingredient is foam. It seems like a movement here in Uruguay. Hey, more work for ME's!

Yeah, I don't know what the secret ingredient is. The article and the company's web page didn't elaborate. Probably didn't want to be copied.

Here's another foam like concrete that I have been watching develope commercially for some time.

Builders in the U.S. can now use an innovative concrete material that Europeans adopted decades ago. Autoclaved Aerated Concrete (AAC) is a precast, manufactured building stone made of all-natural raw materials. It is an economical, environmentally friendly, cellular, lightweight, structural material that provides thermal and acoustic insulation as well as fire and termite resistance. AAC is available in a variety of forms, ranging from wall and roof panels to blocks and lintels. Although it has been a popular building material in Europe for over 50 years, AAC has only been introduced to the U.S. in the past few years.

http://www.toolbase.org/TechInventory/techDetails. aspx?ContentDetailID=690

Chrisg288 certainly enumerated all the ways a hollow sphere can be made but did not give any comments on how they might apply in this case.

Using his list, let's take a look:

1. lost wax casting method : This would require manufacturing (or buying) wax balls, suspending them in the mold on thin cores, then melting and draining the wax back out after the concrete is poured and hardens. Quite a complex task and probably not cost effective in this application.

2. air injection in molded semi-liquid concrete: If the air injection is to form a hollow center I don't believe this would create a very uniform wall thickness, which would be very important in determining the strength of the spheres and therefore, the strength of the wall they were used in. If the air injection is to form "foamed" concrete, then you have a very different product.

3. centrifugation in 2 axes (plus air injection): If by centrifugation he means turning at a very high speed, this is not necessary. Nor would air injection be necessary. Two-axis low speed turning, "slush casting" would do the job. See description below.

4. mercury injection with magnetic field containment. (drained after cure): OH, PLEASE! For a low-tech, commercial product like this? Don't be ridiculous!

5. sprayed or concrete over a shell of the hollow. Now, this one might have some merit, however now you have introduced another material, plastic, ceramic, metal, whatever, which might be costly and might not be wanted in the final product.

6. half shell molding, with after cure mating. Of all the possible suggestions he made this one has the most merit. Many large hollow concrete casting are made this way, including, I believe, hollow concrete sewer fabrications like man-holes, culverts, etc. However, the joint where the two halves are connected may not be as strong as the rest of the structure. Also, this would be a multiple step process, requiring a lot of handling.

I believe the most cost effective method to produce hollow concrete spheres would be a low speed, multi-axis form of "slush casting". In metal-casting, "slush casting" is a process where a mold is filled with the metal. As the metal comes in contact with the mold, it instantanteously solidifies at the surface as it gives up heat to the other material. As the metal cools, this solid becomes thicker. When the desired wall thickness is acheive, the molds are inverted and the remaining molten centers are poured back out through the gate, leaving a hollow casting.

In this case with concrete, the required volume which will give the desired wall thickness can be calculated, added to the mold (which may be gated or simply a gate-less "clam-shell") and then the spherical molds are gently rolled around a constantly changing axis (or bi-axial motion may also be used). As what happens in a cement mixer that is not cleaned frequently enough, the concrete "cakes" up on the walls of the mold. When sufficient time has passed that all of the concrete should have set up, the rolling action may stop. This time should be adjusted if analysis shows that the concrete "slumps" because it did not set up fully. When nearly or fully cured (depending on handling techniques) the mold halves are opened and the spheres removed and transferred to storage to fully cure or await transportation.

A similar process is used in hollow molding of large plastic objects, notably children's toys, playground equipment, floats, etc. where plastic resing powders are dumped into a clamshell mold which revolves while inside an oven, causing layers of powder to melt and cling to the mold. The motion distributes the powders evenly throughout the mold.

I am not a concrete expert, so if you see any flaws in my idea, please comment.

I am a bit confused... Does he want a hollow substance or a hollow product?

If it is a substance it will be mixed into the concrete. A product will be placed on a grid and then concrete will be casted over it.

I have no ideas on how to make a hollow substance, but here is my idea for a hollow concrete product (used to cast concrete over)

The "ball" must not be too big (concrete slabs thickness minus 1/3 of the measurement feels right for the diameter of the ball) The ball can be two interlocking halves or just glued together with a urethane adhesive after cured. The inside space can be a sphere, but on the outside it can be rough, creating more surface area for the poured concrete to bind better, creating extra strength. The end product must look something like uniform rocks of a size that is easely handled and wall thickness that is thin enough to make it light-weight yet thick enough to be moulded without breaking when released from the mould or collapsing when concrete is poured over it..