Fibre concrete & / or reinforcing?

[Danllan]

I've an extension to the cowyard to do, not a big area so a 6 metre load should do it; I want to be able to drive over it, but nothing bigger than a 90hp or a small digger. I was brought up laying 6" with reinforcing rebar mesh as standard for anything that needed to last and take a bit of weight on it, and that is what I have always done and so far so good, but...

A couple of days ago I was with a chap down the road, and I noticed his new pad. It will take some hefty traffic over it and I asked about the spec', and was told it was a fibre mix without any steel reinforcing in it. I forgot to ask the thickness, but I estimate it to be at least 6".

So my question to those who know about these sort of things, which I don't beyond the basics, is this: is this stuff, on a good base, going to be up to the job I want? Thanks in advance.

 

[vantage]

We were the same, mesh everything until we were persuaded to do our drive with fibres. I think the advice would be check what fibre your concrete supplier uses as my experience is that there is a lot of variance. Our new drive should not have had any unplanned cracks, but we had 5 in about 150 m, I was not a happy bunny, all cracks are straight across therefore contraction, fibre did not do the job required.

 

[som farmer]

there is concrete 3 inches thick in our yard, it takes silage trailors, fully loaded lorries, it was laid in 1956, some concrete laid in 1965 at 4 inches is cracking up, concrete laid in 1972 at 6 inches, will have to be replaced soon. A 12 foot wide 'drive' through the last lot of concrete, was laid at 6 inches, with metal reinforcing, for the milk tanker to reverse up, (1966) has had to be patched. For any new concrete we specify fibres, its not a lot more, and its laid at 6 inches. So, I deduce, its down to who mixes it, who lays it, and how suitable the ground prep. Fibres haven't been about long enough to know how good they are.
But I know same 'spec' concrete differs from supplier to supplier.
I also found some concrete, that should have been layed at 12 inches, with metal mesh, to hold silage panels, was 6 inches, and no metal ! I was quite pleased, as we had to dig through it !

 

[quattro]

We just use 6in with fibres in,for grain stores where lorry’s are in and out the base is probably the most important bit to get right

 

[Steevo]

Fibres aren't worth messing with in my opinion.

Solid subbase is the most important factor. Get that wrong and you're failed from the start.
Plastic sheet under the area to be laid to keep the moisture in.
Mesh reinforcing (min 8mm) sheets laid within 50mm of top or bottom of concrete
Min 6" thickness laid and correctly finished - vibrating screed of some sort is a must.
Leave it min 4 weeks to cure full before any load at all is placed on it

 

[Gus]

Busy yard, lots of trucks. Top picture is fibre, bottom pic is steel. All laid in the same year or thereabouts. I know there are lots of variables but this was done by big construction firms so should have been a high quality job.

 

[Exfarmer]

The sub base is more important than anything

 

[S J H]

Fibres are not a replacement for mesh, @RWG Contracts will tell you more.

 

[Doing it for the kids]

We don’t feck about and lay 8 inch with both mesh and fibre. Cost is not a vast amount more per m2

Modern concrete is nothing like the old days. Trying to break up some of the 3 inch stuff laid before the war here is extremely hard work! I doubt my grandkids will have the same problems, all though I hope they do ??

 

[som farmer]

the worst we have to get through, is 4in modern, easy, 3 in very hard, weird insulation, another 3 in layer, and then into flagstones laid on edge ! The insulation bit was for pigs, you can still smell them when you disturb it, even though the pigs haven't been there for 30 years. Obviously there has been a farm here for 100's of years, as we very often hit old building foundations, big holes are easy, post holes are a bast##d.
Read some where that they had discovered why roman concrete was so strong, they put volcanic ash in it !

 

[Danllan]

Thanks gents, more or less you've confirmed my own thoughts. I think I'll stick with the standard mix C40 and mesh.

With reference to some comments made about the old stuff... around here it's called 'black Narberth', and it is almost unbelievably hard, just a few inches of it on a decent base is as good as eight or nine inches of the current stuff. I don't know if this is because it is a better mix, or because it has had longer to cure, or a combination of the two.

No matter, at the order request of Mrs Danllan I had to take the top 'edge' off an old ground beam made of the stuff, to help soften the effect of it in the garden of a letting cottage. It was a ridiculously hard job even using a neighbour's breaker drill. The stuff is every bit as hard and tough as silicified sandstone.?

 

[Northeastfarmer]

Concrete should be made with whinstone chippings....nothing is as good
Modern concrete is not a patch on the old stuff

 

[Banana Bar]

Make sure you ask for structural fibre. I laid 10 loads 6 yrs ago that had fibre ( not structural) in it that is now cracking. Laid another 8-10 loads in November with structural fibres and reinforcing, I’m certain that won’t crack.

 

[Forever Fendt]

poly fibres at about 3 or£4 per meter are to hel

Fibres aren't worth messing with in my opinion.

Solid subbase is the most important factor. Get that wrong and you're failed from the start.
Plastic sheet under the area to be laid to keep the moisture in.
Mesh reinforcing (min 8mm) sheets laid within 50mm of top or bottom of concrete
Min 6" thickness laid and correctly finished - vibrating screed of some sort is a must.
Leave it min 4 weeks to cure full before any load at all is placed on it
[/QUOTE. This 100%

 

[Forever Fendt]

Fibres aren't worth messing with in my opinion.

Solid subbase is the most important factor. Get that wrong and you're failed from the start.
Plastic sheet under the area to be laid to keep the moisture in.
Mesh reinforcing (min 8mm) sheets laid within 50mm of top or bottom of concrete
Min 6" thickness laid and correctly finished - vibrating screed of some sort is a must.
Leave it min 4 weeks to cure full before any load at all is placed on it

This 100%

 

[Dry Rot]

British Ready-mixed Concrete Association (BRMCA) part of the Mineral Products Association (MPA)

British Ready-mixed Concrete Association (BRMCA) is the association of member companies dedicated to representing the interests of British ready-mix concrete producers. Part of the Mineral Products Association (MPA)

www.brmca.org.uk

 

[quattro]

Make sure you ask for structural fibre. I laid 10 loads 6 yrs ago that had fibre ( not structural) in it that is now cracking. Laid another 8-10 loads in November with structural fibres and reinforcing, I’m certain that won’t crack.

That reminded me ther was two different types of fibres one was for commercial type floors yards

 

[TripleSix]

It's a lot easier to put mesh in whilst laying it than afterwards....

 

[Danllan]

It's a lot easier to put mesh in whilst laying it than afterwards....

Wise words...

 

[sheepmatilda]

You don't see bridges made from fibre concrete!