Morning,Cindy.I'll try to answer this post and the one before.
First,silica fume can be purchased in Burnaby.Try Universal Concrete Products,Target or Pacific on Boundary.For MK,try Univar in Richmond.A 55 lb bag was 41 dollars
For a non-slumping mix,you're right.The two pozzolans here make it possible.I've worked on a ball,doing the whole surface in one go,and the mix won't fall off!!
I use what I call "Mymud".Equal parts Portland and pottery silica sand(about 130 mesh);add 8% by weight of cement either SF or MK.I use only admix,no water,and fibres.I've used different fibres,and like Harbourite best.I get them from Pacific on Boundary.I use my mix in conjunction with detail mesh to get a lightweight product,like masks,balls,septic covers.
A word of caution,though.This mix sets very quickly.In doing a 26 inch ball,The first part of the application is virtually dry when I complete the coverage,an hour or so!
Good luck in your project.
Cheers from here

add lime

Thanks guys , I appreciate the advise,
Cindy

Good luck Cindy. I can't wait to see pics.
Debbie

David-Quantify and qualify.How much lime and why.Saying "add lime"is simply too vague a reference.

Rick
I can't really say because I use S type cement with lime already added. Try a bag, it cheap.
I'm no expert on lime but it does make sticky non slumping concrete. I was adding my own lime but gave up a while back because the stuff is too caustic and I like to make final touches with my bare fingers.
Lime is what makes stucco stick and not slump but it also weakens the concrete.
But now almost all my work is with cryogenic perlite and regular Portland so I'm not really up on other recipes any more.
I have finally moved from experimenting with recipes to actually turning out product I like.

All I can say is try a bit of lime and see if it does what you want.:)

BTW Rick I owe you thanks.
I never heard of Cryogenic Perlite until you posted about it and now I couldn't imagine doing what I do without it.
I bought TEN bags. Now that is a lot of Perlite but I'm finding it's actually cheaper to use than sand.
Now I use enough sand to give my product durability and if I need strength I do a strong sand liner inside my work. And because I use integrated color even if the softer Perlite gets chipped or scraped it can be repaired with a few strokes from a brass brush. The scrapes and chips just add character.

I actually bought 50 brass brushes at the dollar store 2 for a dollar so I can include them when I sell a piece.

Now I just need a few easy to make pieces that will actually earn a dollar.:)