Patio Grouting Problem

starbelgrade

I've laid a patio out the back without any problems, until I grouted the slabs.

I mixed a dry sand : cement mix at a ratio of 4:1, filled the gaps between the slabs, pressing the mix in good & hard with a length of timber & then watered the patio to consolidate the grout.

However, the grout hasn't set at all & is very crumbly - you can even scrape it out with your finger.

I'm at a loss as to what I've done wrong. Could it be the sand type? The guy in Brooks recommeded plastering sand... or am I missing something else?

Any help / suggestions would be appreciated, but I've a feeling that I'll be scraping it out & doing it all again, which I'm not looking forward to doing.

Overheal

http://www.groutgetter.com/problems_solved/patio_grout.shtml

you shouldnt really use sand and cement. you really ought to be using actual grout, like Spectralock (epoxy grout; v.good; not cheap), or a sanded grout. I'd go with Sanded Grout, which you then mix with water. 1 bag should do you approximately 100sf, but ask when you buy.

Plastering Sand? we may be getting lost in translation here but they are hopefully talking about this stuff: http://www.laticrete.com/architects/products/grouts/cementitious_grouts/productid/50.aspx

But given Irish climate and the tendency for Hot and Cold, you want to allow for tile expansion and contraction. An epoxy will flex with the slabs. http://www.laticrete.com/architects/products/grouts/stain_resistant/productid/47.aspx this stuff is very easy to work with and virtually impossible to mix incorrectly

starbelgrade

Cheers for that Overheal - unfortunately the advise I was given was to do it as I did. Looks like I've a busy day ahead of me at the weekend!

JohnButler

I use rompox all the time and have never had any problems. You should check it out.