Concreting Farmyard

I'm

I've had a search around but can't see any threads on this topic - perhaps my search skills are limited - any pointers to other threads or thoughts would be gratefully received

I'm planning to concrete a 3.5k sqft farmyard in the next couple of months, I've some experience in foundations and footpaths, but nothing requiring this volume. We are aiming for 5 inches of 35n20 - approx 8 lorry loads.

It doesn't have to be a perfect job and I'm aware of the importance of preparation, but I was hoping some of you folks might give me some advice help me avoid major pitfalls. Getting in a contractor to undertake the work would be my preference, but moneywise it just isn't an option.

In terms of clearing and leveling - is there a piece of equipment beyond a straight edge and spirit level that I should be using ? What is the story with expansion joints ? How do you work out where to place them and how to you actually do them during the pour ?

Again, all advice welcome

Quazzie

Here are some links that might help. I'm suer there will be others along with more technical information in a while.

Link 1 Figure 9 is probably how ya should plan to layout your yard, Dimensions will be down the to overall area to be concreted

Link 2 Just some handy useful information that might help.

I'm

Cheers Quazzie, excellent links - many thanks

De_man

hi, you could also have a look at www.pavingexpert.com

zamur

Hi,

As you said, you're aware of the importance of preparation - preparation is key for a job like this!

Make sure that the ground which the slab is to be laid is well compacted. Are your using steel mesh? For a farmyard slab, which will probably have heavy traffic it would be advisable put in some. Depending on the loading, either A393 or A252 mesh (British Standard Codes) would be fine.
As it is such a large area, you will probably need a system of drainage, i.e. gullies. If you don’t propose to use these, you will have to fall the slab towards a permeable area or ditch etc. It would be best to set the falls up before pouring the concrete.
A string line, spirit level, measuring tape and straight edge would be fine, but for such a large area I would suggest using a spinning laser. You can hire these from your local hire shop. They are easy to use and really worth getting. I would also advise using a spinning laser when pouring the concrete for getting the levels and falls correct.
Again because it is such a large area, you need to divide it up into bays, you said you think approx 8 trucks, then try and have 8 areas. As you haven’t poured such a slab before it may be best to pour one bay a day. Another benefit of bays is that you will have screeds that will also act as levelling points.
For finishing the concrete I would suggest hiring a Fresno Trowel (see info and video here http://www.concretenetwork.com/concrete/concrete_tools/trowels.htm ). These trowels are really great for levelling large slabs, and they also come with brush attachments for finishing the concrete surface.
For expansion, you can use flexcell board or saw cuts – depending on how particular you are and the dimensions of each bay.
Hope that is some way helpful!

Bitten & Hisses

I did lots of this type of work 2 years ago, albeit using a contractor. Preparation is key, as already stated. Excavate down to a solid base, then use something like a 2" clean limestone and compact it well. You'll probably need a little grit or 804 to blind it and then compact it again. If the ground beneath you is of good enough quality, tracking it in with a 13-tonne digger should be ok.
Ensure you have provisions for capturing surface water and that you have sufficient falls to these points. If you get this wrong, your yard will accumulate $hite for the rest of its days. If you're going to pour the slab in a few stages, it will be fairly straightforward to pour sections with different falls in different stages, if you catch my drift.

I'm

Thanks zamur and Bitten & Hisses, great advice, had given me alot to think about. It seems obvious now that you've said it, but I hadn't really considered splitting in the pour up over a couple of days. Also, I'd never thought to try and hire the spinning level. Thanks again !

cjpm

I wouldn't bother worrying too much about expansion joints on a farmyard slab, the amount of expansion is pretty small as the slab is in contact with the relatively cool ground always.

The easiest approach is to set it out in manageable bays and do each on different days. Each bay should be 3.5 to 4.5m wide max as when the concrete contracts (as it sets) the max gap between slabs will be 1.2mm which is almost nothing! However for a silage slab, this gap should be cut with a con-saw (while green, its easier to cut) and the cut washed and filled with flexible sealent.

If you could arrange the pouring of the bays so that you leave the middle ones till the following week, you then can screed from the edges of the completed bays which will all have the corect levels etc. Makes life a lot easier.

Contraction is a problem in concrete as it sets. A 30m long slab could potentially have a 12mm crack (if it cracked in one place) or a series of smaller cracks (more probable).

The bays should be saw cut every 3.5-4.5m (NB. while it's green!!) then contraction cracks will not occur and the saw cuts can be easily sealed, if sealing for a silage slab is requred. However, if it's only a simple farmyard slab anyway, and you don't really care about a few small cracks as it will always be covered in sh*te, then small unsightly cracks aren't an issue to worry about


N.B. don't pour on a roasting hot day, or in frost either
N.B. FOLLOW CURING PROCEEDURE - There is no point paying for good concrete if your don't cure correctly, it's vital to get the longest life possible for the concrete.