Epoxy granite (Mineral casting, Polymer concrete)---Particle size distribution

Hi all,

In previous threads, all of us discuss every sector in one thread including of epoxy resin, particle size distribution, design, mix, process etc. It feel confusion.

I suggest that seperate all sectors by thread, we discuss it one by one. Expert of each sector can direct us easliy.

In general, manufacturers decide particle size distribution by Fuller curve (maximum compact), particles interference. No matter Fuller curve or particles interference, they never consider stability of particles structure, I think it will result in creepage. Currently, someone decide particle size distribution by fractal theory, the stability of particles has been considered, a good effect is presented.


I hope what I said accounts for a modest spur to induce you to come forward with valuable contributions



Regards


Steven

Firstly, we should consider fillers substance. In general, manufacturers use granite, quartz, diabase etc. Manufacturers select what particles they use according to how convenience material collected. Manufacturers usually collect the material nearby their plant.

Currently, most of Europe and US manufacturers take river sand as aggregates.

The pricture as below.

Attachment 175390

there's angles of basalt for prevening creepage.

Attachment 175414

Firstly, Nie Hao Steven and Howard.

Your suggestion to split the discussion into specialised groups can have real benefits.
Returning to topic:-

My personal thoughts are that irrespective of the actual material selected, it should be crushed material and not tumbled. Crushed material such as the basalt shown in the photograph, has the additional benefit of all those sharp edges locking themselves to each other, thus contributing to the mechanical strength of the component; with the epoxy just being required to hold them in their relative positions.

Nicely smoothed (tumbled) pebbles can only supply mass and volume. By the nature of their shapes or form, they cannot contribute at all to the mechanical strength of the component of which they form a part,

Russell Dunn
TangGu
P.R. China

Studer is the first manufacturer who made mineral casting in mass production. At the first, Studer took crushed granite as fillers, with particle size distribution by Fuller curve.


Granite is harder than river sand. However, the flowability of crushed granite is not good, which result in many air bubbles in mineral casting, compressive strength will subsequently be decreased. What's more, the cost of crushed granite is more expensive than river sand. Nowadays, manufacturers in Europe and US take river sand as fillers

Crushed granite

Attachment 175464

I have access to bars of granite. ranging from 1/4" x 1 1/4" to 5" x 1 1/4". Some as much as 3 feet long. So far I've read a lot and all I can find is builders using small aggregates, but I'm thinking or scoring the sides of these strips and using whole bars of granite. I would only use one bar to a section, somewhat as a center filler section with a smaller aggregate EG around it to build the final shape. I want be trying to glue the bars together. Has anyone tried anything like this or know of a reason it shouldn't be used. This will be my first EG project.

David Hair

Hi David and Group,
I do not think I would want to attempt to glue the bars together but rather would try to place them in the centre of cross sections individually to use as reinforcement bars much the same as steel is used in concrete construction.
Russell Dunn
Ferlach,
Austria

That's what I was thinking also. I think I'm going to cut 2 groves on each slick side with a cross grove about every 1 1/2". If I pick the right bar and cut to size I think I can save about 1/2 the EG. Do you think the bars would make the finished product stronger or weaker due to so much slick finish on the bars.

David Hair
georgia, USA