Structural Epoxy Products

I have a question for those who are experienced in structural epoxy's application and properties.


I don't mean polyester resin products such as JB Weld, those are not real epoxies. I mean true structural epoxies from companies such as Abraton, The Rot Doctor, System 3 etc...


I have personally used these products to perform structural repairs of interior or exterior wood products and have good results with them, but still I would like to get a better idea when to use what products.


My understanding is that epoxy is epoxy is epoxy, yet there are products out there for repairing wood, repairing steel, repairing concrete, and repairing fiberglass. Different epoxy products. From asking the manufacturers directly I was told that yes there are different epoxy products for different materials, but it is essentially the same part A and part B that you mix, the only difference is the ratio of mixing. Different ratios of mixing results in different expansion and contract properties of the cured epoxy, which may approximate the expansion and contraction of the material being joined or repaired. In other words, they could have sold to the consumers a bucket of part A and a bucket of part B, and give instructions that for wood, mix it using this ratio, for fiberglass, mix it using this ratio and for steel use that ratio etc...but for simplicity sake, they produced different products, one for each material, and they prepared the products so that it's always 1:1 mixing. That's my understanding anyways.


Is my understanding correct? If not please set me straight.


Now I am in a situation that I need to repair and join dissimilar materials. For example between steel and concrete, or between steel and galvanized steel etc...and I was wondering what type of epoxy is appropriate for these applications.


I started looking at the spectrum of products and I noticed many newer epoxy products. For example, they have "steel filled epoxy" and "aluminum epoxy". So my question is, what would a "steel filled epoxy" do? Is a steel filled epoxy stronger/better than a regular epoxy designed for repairing steel? If so, why? I don't think a sawdust filled wood epoxy is stronger than a regular wood repairing epoxy, is it?


Some example products:


https://www.systemthree.com/products/silvertip-metlweld-metal-bonding-epoxy


https://www.abatron.com/product/metalfix-p-5/


https://www.abatron.com/product/ferrobond-p-5/


https://www.abatron.com/product/bronzeweld/


https://www.abatron.com/product/ss-bond-p/