Auger post holes through concrete?

[Diggerdave]

I have to put a cattle race up in a barn with concrete floor. Quite a few 6 inch galv gate posts etc.. to sink in a couple of foot or so. I have a 3 ton and 5 ton digger and I have heard that a digger mounted auger with rock teeth will bore through concrete. It's a 6inch slab with no mesh. Just wondered if anyone had experience of doing this?, before I go and hire one. Just thought it would be easier and neater than cutting and pecking out the holes. Thanks, Dave.

 

[doobin]

I don’t think it would be any easier. I did a similar job recently and cutting/breaking out was a piece of cake.

For accurate placement you don’t need much more of a square than the post itself and that barely took any breaking.

However if it was talking dozens then I’d be tempted to try your way, especially with round posts. I’d use a big sds to centre mark if working on your own.

Use fast set cement dust mixed into a fairly wet mix and you can get them to go off held in ten minutes or so. Length of rebar to poke it all about as you won’t have much room to play. Much easier to mix up in a gauged mix with a drill basket mixer and some decent buckets- a cement mixer is more hassle than it’s worth for such small amounts especially when using fast set.

For holding them plumb, square posts are easier obviously but for your job I’d make up a circular plate with bolts to grip the post and just wedge that against the floor so the post is plumb and correct height. Fast set cement ( I only use master Crete as it’s consistent) is a godsend on these jobs.

Fill them all to a few inches of the top and then last job use some sbr (around 250ml per kg cement) in the mix to float them all off- that’ll ensure that it’s bonded to the surrounding concrete well and will take a knock without cracking. I like to use steel measuring jugs which hold around a kilo of cement to dole out the mix into the buckets. Easy to do a very accurate 6:2 mix.

I did this row in a day on my own, all around 18” deep which is plenty when properly keyed to the concrete.

 

[Giles]

Big core drill same size as auger or bit bigger, core remove plugs then auger away. Fastest cheapest way can get firm who’ll do it for you for like £500-600 a day if you’ve not got a big stand mounted core drill etc

Next option is cut and break out then make good

The rock augers are ok if you hit a rock etc or in shale etc but expecting them to progress through concrete slab you’ll be disappointed or be spending a day on each hole

 

[Steve]

I have bored through concrete with an auger with out any problems other than as doobin has said you need a centre mark with a kango to stop it wandering off.

 

[Diggerdave]

Thanks for the replies. About 15 holes to do. Good tip on using SDS for centre mark if we do go auger route. I'll give it some more thought. Some good help there doobin

 

[Smiffy]

I don’t think it would be any easier. I did a similar job recently and cutting/breaking out was a piece of cake.

For accurate placement you don’t need much more of a square than the post itself and that barely took any breaking.

However if it was talking dozens then I’d be tempted to try your way, especially with round posts. I’d use a big sds to centre mark if working on your own.

Use fast set cement dust mixed into a fairly wet mix and you can get them to go off held in ten minutes or so. Length of rebar to poke it all about as you won’t have much room to play. Much easier to mix up in a gauged mix with a drill basket mixer and some decent buckets- a cement mixer is more hassle than it’s worth for such small amounts especially when using fast set.

For holding them plumb, square posts are easier obviously but for your job I’d make up a circular plate with bolts to grip the post and just wedge that against the floor so the post is plumb and correct height. Fast set cement ( I only use master Crete as it’s consistent) is a godsend on these jobs.

Fill them all to a few inches of the top and then last job use some sbr (around 250ml per kg cement) in the mix to float them all off- that’ll ensure that it’s bonded to the surrounding concrete well and will take a knock without cracking. I like to use steel measuring jugs which hold around a kilo of cement to dole out the mix into the buckets. Easy to do a very accurate 6:2 mix.

I did this row in a day on my own, all around 18” deep which is plenty when properly keyed to the concrete.

View attachment 52146View attachment 52147View attachment 52148

That seems a lot of hassle compared to bags of post mix

 

[Steve]

That seems a lot of hassle compared to bags of post mix

Post mix is carp though.

 

[doobin]

That seems a lot of hassle compared to bags of post mix

You want the job done or you want the job done right? Post mix will give you a dry joint that will crack out first time someone taps it with a loader bucket.

It’s no hassle, like I say, I did all those posts on my own in one day

 

[Giles]

Depends what the concrete is as well if it’s serious c35 8” slab etc you’ll be there for a while with auger etc pecker be quicker.

We spent 3-4 years putting pits into factory floor , floor saw square then pecker it out.

 

[Smiffy]

You want the job done or you want the job done right? Post mix will give you a dry joint that will crack out first time someone taps it with a loader bucket.

It’s no hassle, like I say, I did all those posts on my own in one day

Depends on the post mix you use. Civils suppliers stock some stuff for seating stuff in the road that makes blue circle rapid set look carp. They do some two part stuff aswell.

 

[Diggerdave]

Yes it is c35 between 6 and 8 inches, shuttering is 7 inch. That's why I asked the question, I don't want to look a twat if an auger is going be really slow.

 

[DaveDCB]

Go on then.. who’s idea what it to put the posts in after the slab?

 

[Steve]

Go on then.. who’s idea what it to put the posts in after the slab?

Probably the concrete gang . I don’t imagine they fancied laying that slab around 15 posts.

 

[DaveDCB]

True!
When we have done sheds with calf pens in we use socketed posts, makes the shed multifunctional then as you can strip all the posts out

 

[V8Druid]

True!
When we have done sheds with calf pens in we use socketed posts, makes the shed multifunctional then as you can strip all the posts out

yep .. have made hundreds of post sockets over the years for this sort of thing, often with drop in caps .. round and square (which were often easier - form up two channels and weld together, toe to toe)

 

[Diggerdave]

I poured the slab. , as Steve said, didn't want to work around all the posts, and has 6inch fall across length of shed, would take a bit of getting right. Race is 2nd hand also, and wasn't broken out when I started pour.

 

[Steve]

I have no doubt you would be able to auger the holes, but if I was doing the job I would cut out squares exactly as doobin said & I wouldn’t use postcrete especially on the round hanging posts as when it shrinks it will allow the post to turn in the hole & cutting squares eliminates the risk of the whole concrete core turning in the hole.