Waterproofing a dry mix concrete - Have you tried any products?

[samantha urbanstone]

Hi this is my first post, Ive got a bit of a problem with waterproofing my dry mix,I make garden ornaments, Ive just started doing water features, Im finding a wet mix impossible to demold due to the vacuum, and the dry mix is no good as water just steams through the walls (no good for a resevoir) Ive tried painting on a pond sealer but Ive heard you can get powdered stuff to add to the mix! can anyone help?

[dig dug dan]

I may be clutching at straws, but dont you have a bung in the mould that you pull out when set to allow air in thus stop the vacuum?

[samantha urbanstone]

No, you imagine I would, the money Ive spent on these moulds!! the mould makers said that dry mix is the only way, though I have tested it out myself. I can release the vacuum with other moulds with various methods I have used, but this one is deep, it is like a bucket within a bucket! thanks anyway

[Tony McC]

Not too sure - there's at least a couple of professional "mould technologists" prowling these forums, so I'll see if one of them can help.

[samantha urbanstone]

thanks Tony, Ive used the links on this site and found a company called Kryton they make a powder called K.I.M that forms crystals that expand to fill gaps when in contact with water, it is used for underwater building (bridges and the like) I am yet to get a quote! but I am hopeful this will solve my prob!

[simeonronacrete]

Samantha

You could try adding some Ronafix Ronafix Data Sheet to the gauging water. Instead of using water on its own, mix Ronafix with water, 1:1, and add enough of that to your cement/sand/aggregate to give the workability that works for you.

Be aware that it will 1) make the mortar more sticky and 2) make it slightly darker. You can lighten the colour by swapping some of the Portland cement for white portland cement.

By the way you're not the "lovely Samantha" form Radio 4's I'm Sorry I Haven't Got A Clue are you?

Hope this helps.

Regards

[samantha urbanstone]

thanks Simeon I think this stuff might be worth a try, just a couple of questions,

I use very little water especially if the sand is damp, will it mix in evenly enough? and

I am only using a dry mix cause I cant demould the wet mix, will the stickyness you mention give me the same demoulding problem?

I dont know the Samantha you are referring to as I am at least 20 years away from tuning into radio 4!! but Im sure the lovely ladies and radio 4 couldnt give a monkeys about concrete!

thank you again

Samantha

[simeonronacrete]

Samantha - Because Ronafix plasticises it should improve worakbility, and should help, not hinder, the mobility if the mortar.

Can't guarantee that Ronafix won't make mortar too sticky. But if you've got that much of a problem perhaps it's worth a try.

As it happens there is a Radio 4 Forum called "Ladies under 40's Concrete Fanciers Forum". They meet weekly to take rubbings of concrete, read stories to new and old structures and several marriages have occurred as a result. Yes, even I was surprised.

Happy Sunday

Simeon

[samantha urbanstone]

thanks I will order some monday, Ive just has a look at the ronacrete site, (nice looking site) Im no sure what 'takinging concrete rubbings' involves but I am intrigued! I stand corrected!

I will contact you monday to find out where I buy, thanks again

Samantha

[samantha urbanstone]

Sorted!! My ideal solution was to demould a wet mix then the sump would match the rest of my water feature, so I put a square of bubble wrap over the part of the mould that corresponds to the bottom of the sump and held it in place with cling film so concrete wouldn’t seep under it, I wouldn’t have mentioned it if it hadn’t of worked but it does, it demoulded like a dream! Then just peel off the cling film which is only on the inside anyway.

OH and if anyone else out there is as naïve as me, he was winding me up over the ladies under 40 concrete forum, I actually looked for it!! He’s a bad bad man!! Thanks for your suggestions anyway guys. Samantha

[mouldmaker]

Did I get here too late?

Did I hear someone call out "Is there a mould technologist in the house?"

Send me a message or an email if you're still stuck.

Mike