Sharp + Building For 'Raised' Brickwork

[EViS]

There is a concrete slab in our garden which is very up/down. We want to turn this into a shed base with some parallel lines of bricks acting as bearers (one brick high). We also have a pile of bricks and sharp sand from a previous project.

In order to create flat lines of brickwork (bearers) on the dodgy slab base, some of the bricks will need to sit on around 60mm of mortar (where the slab low spots are).

Would it be wiser for us to purchase some building sand and create a 50:50 mix of sharp:building sand for the mortar? Or will using 100% building sand be a better bet in this instance. Our thinking is that the mix of sharp will be stronger for the thick mortar which will be necessary in the slab low spots.

 

[simonjay]

There is a concrete slab in our garden which is very up/down. We want to turn this into a shed base with some parallel lines of bricks acting as bearers (one brick high). We also have a pile of bricks and sharp sand from a previous project.

In order to create flat lines of brickwork (bearers) on the dodgy slab base, some of the bricks will need to sit on around 60mm of mortar (where the slab low spots are).

Would it be wiser for us to purchase some building sand and create a 50:50 mix of sharp:building sand for the mortar? Or will using 100% building sand be a better bet in this instance. Our thinking is that the mix of sharp will be stronger for the thick mortar which will be necessary in the slab low spots.

Sharp sand will be stronger (think screed) but harder to work, but you're only bunging down a few bricks ! Use normal mortar mix in the vertical joints.
For 60mm depth I'd probably put mostly sharp sand and even bung in a few handfuls of pea gravel and a bit more cement along with the sharp sand if you are worried. Then you will have concrete !
Also, one row of bricks will not be very stable - two courses would be better.

However, I'd be more concerned about the slab base. As long as its stable should be ok though.

Simon.

 

[EViS]

The slab base looks rock solid, just uneven. So is buying in some building sand to add to the mix a pointless task in your opinion?

Also, why would two courses be more stable than one? Especially with a sharp sand only mix which doesn't adhere very well to bricks?