Concreting-ballast or SEPERATE pebbles & sand?

[mart]

I have the option to order separate 1 tonne bags of sand & pebbles to make up the standard 321 mix, or order 1 tonne bags of ballast (sand & pebbles already mixed). I’m not aware of there being any real difference/advantage either way, unless there is a difference in cost . If it is a standard mix it will be ok. However, it did occur to me that the sand in these 1 tonne bags of ballast could separate out somewhat and fall to the bottom.

Considering that the bags are in the builders yard for a while, and are then transported to me several miles on a lorry, how realistic are my concerns?

 

[James325]

I'd use ballast. Why add another mixing stage... Sounds like more work to me.

 

[rtbcomp]

I'd use ballast too - it'll be slightly wet so the sand wouldn't filter out to the bottom.

 

[mart]

There will not actually be another mixing stage or extra work. I fill a large bucket 5 times irrespective of which bag I fill it from, and put it in to my mixer. That would be 3 pebbles & 2 sand. Or, 5 ballast.

 

[mike os]

how much you got to mix? and how critical is the mix... ie rebar etc?

 

[outofthefire]

If its just for a garage base or similar it wont matter if it was for something more important i'd buy them separate just for piece of mind that you know the mix is going to be consistent.

 

[cumbriasteve]

If the bags are left to the elements the sand does wash down a bit and you end up with a stony top surface, if you order seperate you can choose your gravel. pebbles. stones whetever you want to call them.
I used 10mm for my garage floor and it was so much easier to spread and tamp down than a ready mixed ballst

 

[migwig]

Use ballast. I'm a landscape gardener and would never bother with seperate aggergates unless the finish was critical. And I've never experienced separation in a builder's bag, just the odd fag-end on top.

 

[mart]

Mike: I have a large area to mix in total, but as I am working on my own I am shuttering off in sections Just done a section about 5MT X 1MT. I want to be able to stand cars on it without cracking. No rebar etc.

Outofthefire: In essence yes, garage base plus standing area for vehicles at the side of the garage.

CumbiaSteve: Although I acknowledge what RTBcomp said about the damp sand sticking to the pebbles (and I agree in the short term use), it is very likely in my situation that the bags will be exposed to the elements-possibly for a considerable time. I think I will order 3 one tonne bags of pebbles & 2 one tonne bags of sand.

Although there has been differing views on this, every comment has been welcomed and was helpful in it’s own way. It has helped me to decide, and that’s what the forum is about. Thanks everyone.

 

[pidgeon chit welder]

My local builders merchant has recently quotes me exactly the same price for sand , 19 mm stone and all in concrete mix.
Shovelling stones in harder work than shovelling all in one mix .
The bags usually contain around 0 .78 of a tonne the mix ratio is set at the filling plant so you get finings sand and stone in the correct proportions .
I've had seven dumpy bags full of all in one stood in my front garden since the 11 april 2010 .
The landscapers started to use it to lay my paths ( I'm now disabled ) on the 14 March 2011 there is no separation of sand and stone as it lets rainwater filter through rather than wash things out .
none of the bags had deied out either it was a nice damp shovelling job .

The problem of stones at the top has not happened as the mix was slightly wet and was well tamped down .
The stones fall the finings and fat rises to give a good smooth hard surface...I don't think I can see any stones in the finished top but there will be some showing in a few years as the finings wear down to the real concrete bed

Have you thought of asking what a small mix company would charge for doing the job.

Where I used to live I found out that even with a decent small business discount I could not buy the all in one and cement powder as cheap as this small company could suppy the 5 cubic metres .
I had 5 cubic metres of stuff ready mixed off the back of a lorry mounted one cubic yard diesel engined mixer for my garage base and few months later a conservatory foundation 14 mtr by 600 mm deep by 400 wide & the 150 mm conservatory base a few weeks later.

They specialised in conservatory foundations and garage bases

They did it so quick it was all down in just over an hour with three labourers ( my pals ) doing the barrowing for some 40 mtrs from the back of the mix lorry.

Because they mix on site to requirements there was no excess to waste or humping bags of dust.

I found them & several others such companies in yellow pages then got a few quotes once I'd calculated how much I'd be needing.
That afternoon we had a big friends family BBQ after the lads had tamped down the garage base in a big monolith slab 6 inch thick no rebar and slipped a hessian framed cover over things to stop it drying out too soon .

I used a light spray hose on the hessian , just enough to keep it damp till late at night & started early the next morning through to tea time to slow the drying out as it was mid summer and hot .



One last thing make sure you actually see any bag of ballast to make sure it is what you are after.
I discovered that around the country mixed ballast means several differing things ..
Here in South Wales they delivered 10 dumpy bags of crushed limestone 20 mm right down to the dust ..it made a crap path and was very hard to work