Cutting curved stones for kidney shaped patio?

[diyonly]

Hi Ian,

Thanks for your quick reply. I'll take it out, but whereas mine is easy to take out, his pointing is solid and because the colour isn't matching, I want to do all the pointing in one go, so the mix matches.

So my question is do I go over his pointing or do I have to take his out too? & if so, how if it's already solid?

He put spots, so surely they won't spread perfectly? Also I was simply the following:

http://www.pavingexpert.com/jointing05.htm
http://www.pavingexpert.com/layflag1.htm

 

[Ian H]

I wouldn't go over it, it will end up crumbling too. You could cut his out with your grinder by running the blade down each edge and popping out the leftovers. Or you could try and match his mix.

Spot bedding like in your link isn't the best but you can put down a full bed of wet mixed with raised bits/spots that will fully fill the void once you knock the slabs down.

 

[diyonly]

Ian, your a star! The grinder idea is great. I doubt it if I'll be able to match it.

 

[diyonly]

Sorry to trouble you again. I did what you said and took out all the pointing using a grinder. I then did a dry cement/sand/dye colour mix and brushed it in. After that I dampened the brushed-in mortar and went over it with a pointing trowel. It seemed to have done the job. However I've checked it this morning and still dry powder. What am I doing wrong? What do I need to do?

 

[r896neo]

Forget all this dry nonsense, dry mixes dont work. Yes they are easy to put in but they never harden properly. mortars and concretes harden because the cement when hydrated with water begins the chemical reaction, dry mixes are crap because so little of the cement gets hydrated properly as water cant get to it.

You can either point it wet with a pointing gun or use a semi dry mix that is ironed in firmly with a trowel. I would recommend the semi dry mix. It should be dry enough that when you squeeze a handful water doesnt come out but wet enough that it holds together after squeezing. You have to get down on your hands and knees and squeeze it in with a trowel and jointing iron. Use 4:1 plastering sand:cement.

To make a good semi dry mortar you start with your water and then say 1/3 of your sand in the mixer, then add about 90% of the cement and have it all relatively wet so the cement gets properly hydrated. Then use the rest of your sand and cement to gradually dry the mix up and end up with your semi dry mix. If you try to mix semi dry by adding the water at the end it doesnt mix properly.

If you make it too wet then throw it out onto a piece of wooden board and spread it out thinly, this will dry it quickly. A wet mix that is left to dry up a bit is far far superior in strength than a mix that was started off too dry and never really hydrated properly.

If you really want a brush in product then buy a decent one part polymeric compound like marshalls weatherpoint, gtfk vdw, joint it or easyjoint.

 

[diyonly]

Thank you very much. I can brush out the dry mortar, but what shall I do with the current partial pointing that's already hardened? It took me a whole day just to grind out a small patch of pointing and just hope I don't have to repeat that again.

Also what about the dye colour I've used? If I use it in the semi-dry mix, won't it stain the stone?

 

[r896neo]

If you put it in as a Dr mix its going to be pretty easy to rake out. Hammer a nail into a bit of wood and have it protruding by 25mm then use that to rake out joints to 25mm depth.

The dye will not stain if the pointing is dry enough. Test a small inconspicuous area first until you get the consistency right.

 

[diyonly]

The nail/wood idea is brilliant, thanks.

I know you said that the dye won't stain if dry, but you've said that I do a semi dry mix, so surely that would stain it, wouldn't it?