Outside floor tiles - Grouting advice

[NOTTNICK]

Our builder laid fabulous black 1200 x 600 tiles around our house and also on a large patio.
He used Fast Point brush in grout and it looked great for a while.

Unfortunately, the grout is all falling out and we have never been able to powerwash by any means as the grout comes out too.

I notice that the depth of the 12mm gap between the tiles is sometimes only about 5mm, so I can see why perhaps this is happening.
I'd obviously like to fix it.
I can see 2 possible solutions and I am really hoping that the first will work (my reason for posting).

1. I am thinking of powerwashing the old grout out. I now this will be fairly easy. I could then use different grout.
Would this work? Is there enough depth for grout to hold? What grout is recommended? Will it bond with the tile cement?

Otherwise:
2. I use a carefully aligned track saw with a diamond blade and cut out the fixing cement to a greater depth and replace the grout (again what would be best)?
This sounds like a lot of work as I have about 75 square metres of tiles and I hope to avoid this.

Or is there another way?

On a separate note - I see he has not put in anything to deal with expansion and the black tiles do get hot! I have had one crack so I guess this must be why. I am guessing I need to consider this if I can replace the grout.

Any advice here would be really appreciated.
Thanks

 

[Tile Fix Direct]

Are your 1200x600 tiles 20mm thick porcelain?

 

[NOTTNICK]

No, they are concrete - approx 10.5mm thick. Conproj G Grey Lp 1200x1200mm - http://www.europeanheritage.co.uk/products/tiles/concrete-effect/conproj-g-grey-lp-1200x1200mm/

 

[J Sid]

Is there movement in the tiles?
And how long has it been down?

Have you spoken the company that fixed them as this should be your port of call

 

[NOTTNICK]

No, the tiles are all solid.
Down for just over 3 years.
I want to look at solutions first so I am informed. If it is fixable by option 1 or similar I may just do it myself.

 

[J Sid]

If the tiles are solid then I'd clean old grout out. Try to do it by hand if you can, I'd use a angle grinder myself as a power washer will force water under them and it will need to be dry before re grouting. I'd use bal wide joint or ardex FL floor grout.
Really needs doing before winter as a cold/freezing will start doing damage and slabs will soon become un bonded

 

[Boggs]

They are porcelain according to the link you have supplied.

 

[J Sid]

They are porcelain according to the link you have supplied.

Well spotted 👍
Sadly, I would be surprised if they are still fixed.
You really need to get someone round, a good tiler not ground worker to check them before you regrout them

 

[Dave]

The joint filler used could well have not consolidated sufficiently in a narrow joint and
a reason for grout breaking away could be freeze/thaw from a couple winters.
Rake it all out and use a grout suitable for the joint width and not one of those brush in joint filling products, Tile grout would be more suitable for porcelain and harsh weather.

 

[NOTTNICK]

Thanks for all this. I shall replace the grout soon with some more appropriate product.

I still think that the tiles are concrete though and not porcelain.

The text on the page I got through a quick internet search says
Concrete Project is the full-thickness porcelain stoneware from ImolaCeramica made for modern architecture and design covering solutions. The concrete is turned into a tile with a clear contemporary mood
So there seems to be a mismatch. I think the company copied just that line from the Italian Imola Ceramica website. Here it says:

Concrete project.
The concrete is turned into a tile with a clear contemporary mood, designed to inspire and surround exterior surfaces, but also ventilated facades and high-traffic public spaces. Its minimalist style features in flooring that is highly modular in different sizes depending on requirements and the desired visual effect.