Problem with paving - Need advice please

[dayrider]

Hi all thank you for letting me post this add
My problem is I bought 180 cream paving slab from band q and we stated laying then strait away we laid about 60 and the lad who was laying them finished for the day later when I took a closer look at the job I noticed some off the pavers where a different shade it looked as if I ran out of cream pavers and added nearest shade next day I decided to take all the pavers up they came up very easy and I am left with a grit sand and cement base running out from back wall so I went to b and with 2 off differs slabs and they are going to replace them I told them I can only use a small bed to relay them as I can nearing my 150mm to dp they gave my 5 bags of rapid set concrete free of charges and subject I do a 5 point dap on slabs I have just layed 2 using this method to see if they hold down I will check tomorrow will this method be ok as I don’t want to brake up base as is was very thick for the fall away from house

[TheRockConcreting]

they gave my 5 bags of rapid set concrete free of charges

There are many things wrong with what you've done and be told to do, someone will explain i'm sure, but what i will say is don't use the 5 bags of rapid set, trade them in for normal.

[dayrider]

Just checked the 2 laid slabs they seem to have stuck solid to the concrete and I have a fall on the concrete base but on the first attempt using grit sand and cement on a full bed the paving just lifted up easily after 4 days down and the slabs had not stuck to the mix no cement left on paving my concern now is how long I will have before the cement becomes unusable and can I adds something to increase its working time

[r896neo]

Dabs of any kind are a fail. Paving should be laid on a full bed of mortar. I just lifted a patio today that is being completely relaid at great expense as it couldn't be repointed because it was laid on tiny dabs.

When you say your bedding is very thick what do you mean? 50mm is about the maximum you'd want from a grit sand mortar, any more and you should really use a fine concrete.

Trying to re use the base is very much not recommended but if you really must try then tile cement would be a better bet than normal cement.

Falls should be incorperated into the sub base not the bedding layer. For example over a 5m length you need a minimum fall of around 75mm. This should be set in the hardcore sub base or if your not using a sub base (bad idea) then the area should be dug out to these falls.

Simply starting with a 25mm bed and increasing it to a 100mm to get your falls will give you problems in the long term and be a waste of mortar and time.

[r896neo]

So what have you got? A full concrete base?

Was the mix quite dry? if so then they will not bond to it that well but that is not necessarily a problem?

Rapid set cement is useless for paving it goes off far too fast.

[dayrider]

I think this cement is kind of tile cement as you mix to the same way just using water it was 17 pound a bag the guy who laid the paving did do 25 to 100mm to get the fall I was doing the mixing why can’t the fall be in the bedding mix

[dayrider]

Thinking of just doing small mixes in a tub didn’t like the fact that the slabs just lifted don’t rely want to take it back as I travel 20 miles to get it

[r896neo]

Firstly its a waste of time and money but secondly you can't have the fall in the bedding as it will affect the long term stability of the paving. It is absolutely essential when using a sand base to have a consistant thickness but it is also worth considering with a mortar base too.

I'm sure tony or another expert can tell you the science behind it.

As long as there was enough cement in it it will probably be ok on a patio but its not the right way to do it and highlights a few worries about the competence of the bloke who laid it.