Concrete mix for ground anchor

What would be the best concrete mix (stone/sand/cement) for mounting a ground anchor onto? This is to make a block under a metal Asgard shed to bolt an anchor onto, rather than a concreted-in anchor.

I’m wondering if I should even add stones, maybe just use 3 to 1, sand to cement. I have quite a bit of sand available, even then some stones would help bulk it out.

Standard strong concrete mix. Aggregate will add strength. 1:2 ½:3 ½ (cement : sand : aggregate)

Concrete without aggregate is just mortar.

I understand aggregate will increase compressive strength, but will it do anything to make the bolts of the anchor resist pulling out? Maybe it would reduce the chance of cracking when drilled?

As suggested above, I’d make concrete not mortar. I’m no expert but I have drilled and cut into a lot.

You could get some threaded rod and bend it to the right dimensions then sink it into the concrete. Then there’s no drilling.

Why not post-crete? It’s literally made to stick things into that you don’t want to move

@jamiemcf The shed base is metal so will have drill through. Planning on using a removable anchor from Pragmasis so I can move the shed

Why not post-crete?

I have seen this recommended but I’m not sure about drilling it without cracking, or how well it will hold fixings.

Also I have a load of concreting sand, stones and a mixer for another project

C32/40
CEM I
4-20mm crushed limestone
0-2mm Trent Valley sand
MCC 340
W/C 0.55
S2
Or failing that, a bucket load of 1:3:6 by volume, and be done with it. Job’s a good ‘un

I have seen this recommended but I’m not sure about drilling it without cracking, or how well it will hold fixings.

do you need to drill it? Can’t you just set your anchor in to it?

@dmorts, a double doofer.

I have one. My garage base is a standard concrete mix and he expansion boltsnd it’s bar tight.

A standard concrete mix will see you right.

I’m wondering why you dont just set the anchor un before it sets too?

We used a large cardboard tube for out, filled it, the added the anchor held up by a broom until it set.

Too late to edit, but I think I’d need a digger to lift ours if moving it is on the cards

Buy a precast padstone. Use your own concrete mix to set the padstone into a bigger hole. Drill padstone to take a 12mm ss eyebolt. Chemfix eyebolt into padstone.
You then know the eyebolt fixing is in something structural, designed and manufactured for strength. The aggregate mix you set that in will add heft and secure the padstone.
Its the battery angle grinder that you need to able to defeat.
The only way to do this is some sort of spinning bar imside a tube of gas pipe.

I’m on the mechanical fixing is a weird choice.

https://www.oxfordproducts.com/motorcycle/brands/oxford/security/anchors/terraforce_ground_anchor/

something like that with a stick through it to suspend it over the hole while you pour in the concrete, place some extra bars in across the studs as you fill up if you want it to never come out.

1 shovel of cement, 2 shovels of sand, 4 shovels of gravel will give you about 30 newton. Don’t add too much water and it’ll be plenty strong enough.

I don’t think you need to worry about anchor pull out strength and drilling, the issue will be the block pulling out of the ground if someone uses a bar to lever it up. I would just use postcrete and make the hole wider at the bottom

As others say, i’d just use postcrete and set it in before it sets, it’ll be done in 5 minutes, is easy to mix properly and due to the quick setting, you don’t have to faff around too much with holding it in place.

Would put it into a container as well, like a plastic bucket or the likes to get a desired shape for the location.

The trick is to use as litlle water as possible, but the concrete still needs to be workable, so add a plasticiser to your mixing water (washing up liquid will work if you don’t have the proper stuff).

Lawman

, do you even know what you you’ve posted or have you just copied and posted some random nonsense?? Do you know what C32/40 means or what w/c is for example???

a double doofer

Exactly that

Sounds like standard concrete will do overall.

The base of the shed is metal sheet, therefore I can’t concrete anything in to use. The plan is to create the block underneath then drill through the shed base to mount the anchor. This will also secure the shed down.

Or, finish the concrete below ground level, install the anchor and make a hole in the floor of the shed, this will make it much harder to attack the anchor itself with any tools.

washing up liquid will work

It may help workability, but it’ll weaken the concrete. Proper plasticiser is dirt cheap, no idea why this a thing people do.

When it comes to concrete or the use of cement on singletrack I always find most answers know very little about the stuff but then again I know nothing about postcrete and probably will never buy it
4-2-1 as said above will give you strong enough general mix but as for 0-2 mm sand never gets anywhere near concrete as it should be aggregate,Sharp sand, cement and clean water
Other additives can be added for strength, workability, set times etc but never dusty fine sand

it’ll weaken the concrete.

How will it do that then?? Any references??

Fairy liquid is used as an air entrainer, not a plasticiser. Keep it simple, use a 1:2:4. Job jobbed.

@natrix

It applies to mortar, so I guess also concrete

https://www.designingbuildings.co.uk/wiki/Plasticiser#:~:text=information%20see%3A%20Plasticisation.-,Washing%2Dup%20liquid,foam%20if%20used%20in%20excess.

EDIT: Everyday is a school day, seems for concrete it might actually strengthen it! As @jacksdad says it’s acting as an air entrainer not plasticiser. The tiny bubbles can reduce the tendency to crack when set.

Have a read of what it says in dmorts link

Numerous types of plasticisers are available commercially to enhance workability. They typically work by …. providing air entrainment to assist workability.

Entraining small air bubbles plasticizes the mix. Washing up liquid can be used in a DIY setting as a plasticizer.

If you used washing up liquid in a truck mixer or large commercial mixer and mixed the concrete for a long time it could produce too many bubbles, but for a DIY job it enhances workability and therefore reduces the amount of water needed.

most answers know very little about the stuff

I’d agree there.

about 30 newton

Wasn’t Newton some sort of scientist??

@natrix so for both concrete and mortar controlled introduction of bubbles seems the key point? Too big and numerous they will add weakness. Also I seem some mention elsewhere of the salts in washing up liquid affecting mortar in the long term.

I will avoid washing up liquid for now. The cement I have has “enhanced workability” properties.

Concrete is totally different from mortar when it comes to plasticiser or breaking the surface tension in water, you can’t work no matter how skilled you are with mortar without either plasticiser or lime
I buy proper stuff and only if stuck would use fairy liquid, plasticiser used to be made and sold by proctor and gamble that tells you more or less what it is

I would think P&G would be using their expertise on bubbles and foam to make plasticiser, rather than just rebranding or tweeking washing up liquid. They make a huge variety of chemicals.

The bubbles in washing up liquid have little to do with cleaning. Dishwasher tabs and liquid don’t foam.

I found out myself what you said about workability. I tried to make mortar once without plasticiser. Completely unusable! I now buy dry premix instead as I never need that much.

Cracking where you put the anchors can be avoided by making sure the anchors are at least their own length away from the edge of the concrete. You could also put some reinforcement in the concrete – it doesn’t have to be proper reinforcing bars, any kind of steel bar, preferable bent at the ends, will do. Doesn’t matter if it’s rusty, but make sure it’s at least 7cm from the surface of the concrete – the alkalinity of the concrete will prevent it rusting further.

Defo not postcrete it’s the worst of the worst made to just about keep a post upright and set quickly

OP, I did pretty much this for my Asgard shed at our old place, 4:2:1 mix for the concrete. I cast a full sized base about 5inches thick to site the (4 bike) store onto, but I set 2 allthread bars into the base before it set. The threaded bars were set 3 inches deep into the concrete with a plate washer on the bottom with some nuts holding in place, set to the pitch of my ground anchor.

I then built the store over these studs, with the holes drilled through the base where they poked through, drop the ground anchor on then 2 nuts on the top of each one done up bstard tight and then split the thread so they couldn’t be undone.

I had to get the grinder in to cut the thing free when we moved, then cut the protruding studs flush with the concrete to make it tidy.

A lot of overthinking going on here.

Just dig a big hole, line it with old bricks/slabs and then pour concrete into it (a couple of mixer loads say) until you’re at ground/shed level. Then drill into it with a longest bolts you’ve got.

A lot of overthinking going on here.

Agreed. All it needs is a lump of anything hard and heavy to weigh down the chain. It’s not the channel tunnel!