Gravel loose in concrete

[someofthegear]

Couldn't see this already covered in the forum, apologies if it is but hope you can help. Yesterday we laid a concrete base for a shed over a DPM, a bit of 1" polystyrene sheet (bit broken up) and a few lengths of rebar welded into a rough grid. The proportions (1:2:4) were probably a bit variable (not done much of this), as was the water content.
The site is awkward so had to pour in one corner and rake it out. We got pretty much to the 4" depth aimed for, but near the far edges, the gravel shows through and the rest of the mix seems to drained off in the raking or run off from being too wet. Had a look today and some of the gravel is still loose.
It's day two so should I render it or use a slurry now while still wet or wait for it to dry and then do it?
Also, should I use a render with SBR or an epoxy repair mix or something else?
Any advice appreciated. Breaking up and redoing isn't an option as getting the material onsite for mixing was extremely difficult and expensive...
Should add, we tamped it down and covered with a tarpaulin but no float or trowel or misting yet.

 

[ree]

What do your 1:2:4 proportions mean?

Was the DPM one sheet or off-cuts?
Were the off-cuts of plastic left loose or folded into welted seams?

Did you raise shutters at the edge of the slab?

Re-bar or similar was not needed.

How did you mix it?

Probably best to leave it as long as possible to dry out, and then screed it.

Build a rough frame and cover to shed rainwater.

 

[someofthegear]

Thanks for the reply ree

1x cement : 2x sharp sand : 4x 20mm gravel

The DPM was one piece, corners were just folded. 4" timber shuttering all-round which we jacked up a little to maintain the 4" depth over the the polystyrene which was quick broken up after some strong winds.

Rebar was because it's 6' from a sharp drop off (just in case). We mixed in a hired 4/3 mixer but the site was awkward and between the dark, our inexperience and tripping over things, the mix probably wasn't as consistent as it should have been. I should have said, we added a chloride free frost proofer because of the weather (equivalent of 2.5l/50kg cement).

 

[tony1851]

It's early days yet. Just be patient and leave it a few more days - it will end up better than you think. If you do need to do any repairs or tidying-up, it won't be a problem if it's hardened off.

Why put 1" bits of polystyrene under it?

 

[ree]

The mix proportions are fine for a slab.

Concrete is merciless - there's nothing for you to do now but wait for drying out. Unless you want to start cracking out and patching in?

If you ever pour concrete again, hand mixed or delivered, inside or outside: get all tools and materials to hand, including a fresh water supply, and lights for interior work.
Set everything up down to the last detail including wheelbarrow runways. Then go home.

Mix or have it delivered first thing in the morning, thereby giving yourself all daylight to work the stuff.

Delivered concrete is virtually always the way to go.

 

[someofthegear]

Thanks guys. The polystyrene started off as 8'x4' sheets to give some insulation below the slab but the recent high winds turned it into a bit of a jigsaw puzzle.

Good advice re getting everything ready the day before, we didn't organise the weekend too well

If it isn't worth trying to do anything while still wet, I'll wait and see with fingers crossed that we haven't created a very expensive gravel pit...