Mixing building sand with type 1

[TrevorL]

I have a bulk bag of building sand, which I think may have a high clay content. It makes terrible mortar, so I was initially going to use it for blinding on top of type 1 for my garage concrete slab. I’ve since found out that sharp sand should be used for this and have some on order.
Do you think it would be alright to mix it in with the type 1? It would be a ratio of 8 bags of type 1 to 1 of building sand. I was thinking about laying it on the ground under the type 1. (5.52m x 4.84m)

Also, LLL recommended using Flexcell for an expansion joint. This may be a silly question, but would you place it on the outside or inside of the membrane?

Thanks

[118-1187271617]

Hello trevor

the flexcell strips...what normally happens is you put the roadform (or timber shutter) up after laying the polythene so the forms are struck, you have a nice slab edge with just a couple (!?) of inches of polythene showing at the bottom. Do the pour, strike the shutter then slap a bit of adhesive to the side where the shutter was, put the bitufibre or flexcell on and there you go...

Tony the Boss is probly better qualified than I (Grammar) to advise on the type1 & sand mix

hope it helps

[Tony McC]

You can use the building sand as a blinding or mix it in with the Type 1 - it really won't make much difference omce it's buried beneath the garage slab.

[seanandruby]

"the flexcell strips...what normally happens is you put the roadform (or timber shutter) up after laying the polythene so the forms are struck, you have a nice slab edge with just a couple (!?) of inches of polythene showing at the bottom. Do the pour, strike the shutter then slap a bit of adhesive to the side where the shutter was, put the bitufibre or flexcell on and there you go"...

...Am i missing something here, why would you put an expansion joint outside a finished slab? surely it should go around the inside where it abuts the walls? if it is for the next slab, then the polythene should have a 300 ml overlap, and maybe dowel bars? sorry if this sounds pedantic. ???

[TrevorL]

Thanks you all for your help.
Yes, the slab will be laid within the walls. I have just finished laying the type 1 and sand blinding, today.
I will be laying the slab in two parts.
From what I have read, the slab needs to have a slope towards the garage door. So I will fix a sloping batten to the top of brickwork on one side and have a sloping shuttering board halfway across the slab. I just didn't know if the Flexcell should go inside or outside the DPM?
My guess is inside.
It's like most things, once you do them once or see them done, everything slots into place.
Laying this slab will be a big turning point in the building project for me, I've wasted so much time trying to keep it all dry.

[seanandruby]

just lay the poleythene to the walls. use the flexi board fixed to the walls on a gradient for your levels, no need for a wooden batten unless you need a grout check for a construction joint, which you dont. good luck.

[TrevorL]

Thanks for that Sean
How would you normally fix the flexi board to the wall? Is it ok for the fixings to puncture the membrane?
Each half of the slab will be 2.76m x 4.84m and averaging 150mm thick - would you bother with steel reinforcing for that size?
I will be up at the builders merchants first thing tomorrow to see what this flexi board is like.

[lutonlagerlout]

you could always add nylon fibres to the mix trevor
builders merchants will have them
regards LLL

[118-1187271617]

sorry trevor...i got the shitey end of the stick as per usual...what I described was for bays, not a garage...should have read what you were after m8.
the flexi board...if you use the white foam stuff you have to be careful, cos i think that has its own adhesive...others just eat through it.

sean sounds like he knows more about joints than me...mine usually end up soggy with lots of little burns on my shirt...
:;):

[TrevorL]

Well, I’ve now laid my slab. I stuck the Fillcrete to the side of the DPM with grab adhesive.
I decided to use battens in the end because I didn’t think the Fillcrete would hold its edge when I tamped the concrete.
I got Mixa-mate in for the concrete. Went for a belt & braces approach regarding reinforcing, and used steel mesh and fibres.
I’m a happy man!
Thanks again for all your help
All the best
Trevor

[lutonlagerlout]

nice one trevor!
how did you get on with mixamate?
we used to use them but the drivers were always trying to mug us off on the quantities,so we stopped
LLL

[TrevorL]

Mixamate were ok, I would use them again. Maybe I was lucky with the driver/operator!
I needed approx 2 metres for each half of the slab and I didn't know if premix companies worked in tenths of a metre! so Mixamate seemed the best option. The worst scenario would have been if I had ordered exactly 2m from Readymix and found the slab was 5mm too low!
I will post some pictures soon, it's starting to look good now.
This is the bit I have been looking forward to, building up the walls from the DPC level using my "Brickie" contraption. If I'm not happy with my speed or quality of work though, I will get a real bricky in to do the work.
I am using the Dartmoor Heathers you recommended. Like you said, they are a much better brick than the LBC Heather.

[lutonlagerlout]

readymix do quantities from .6m3 upwards in increments of .2m3
look forward to seeing the piccies
if you are jointing the bricks you need a marshaltown 82 jointing iron,and use the widest end
cheers LLL