Strongest concrete mix recipe

[Jillilfixit]

Hello all,

I hope someone can help.

Basically, I am making a semi-portable anchor point to lock some bikes to. I am going to fill a large container up with concrete and sink a heavy duty ground anchor in to it. It is also going to be reinforced with with wire or something.

The problem is, I am unsure at what mix I should use in order for it to be very resilient against hammer attacks; it need to be very strong. I have done some reading on it already and many have said that the ready mixes from B&Q etc are not very strong so I want to make my own mix.


Can someone tell me the best recipe for my needs.

 

[noseall]

Semi-portable?

Defeats the objective somewhat.

Anyhoo, 4 parts granite chippings, 2 parts sharp sand and 1.5 parts cement.

Add enough water to make it workable but not overly sloppy.

Wire reinforcement would be good.

Vibrate the mold once the mix is in place to rid the concrete of air.

Keepthe mold away from sulight or sources of heat and lay a damp sack on the exposed bit. Let it cure for as long as you can.

 

[Norcon]

If its semi portable thieves might still be able to shift it.
Also any chains you secure the bikes with are easily cut with cordless Dremel tools and angle grinders.

Our church was having the oil stole for the boiler so they built up the door of the oil storage building with an 18" wall and poured a new solid concrete roof with a concrete recess for a half ton man hole concrete lid to fit snugly into.
Only access is through the roof now and only a forklift will lift it off with screw in anchors needed.

The thieves were back and had the top edges all broken trying to lift it off with pry bars trying to get to the oil.
Maybe next time they'll bring a forklift.

 

[Jillilfixit]

Thanks for the info. Yeah, when I say "semi-portable" I mean VERY heavy but movable. Landlord wont allow me to dig a hole in his garden and fill it with concrete; understandable really.

I am going to get a heavy duty anchor and a 16 or 19mm chain. Just need a good concrete mix so the anchor cant be picked out.

I will also use wire.

 

[Norcon]

Any chain you have can be easily cut and severed.
You could have a solid block of steel weighing several ton which is virtually impregnable with titanic sized anchor chains welded to it.

The thieves will just cut the chains.

Though of course with the high value of scrap iron these days they will certainly try to load up the steel block.

Thieves broke into a scrap yard near my home a few weeks back.
They took a wall down using a kango while the owner slept in his bed nearby.
Stole the copper and left the kango behind them.

 

[Jillilfixit]

Not sure why people are so pessimistic when it comes to security; would it be better to leave my bike unlocked with a post-it note saying "please take me"; I will at least save money buying a lock in the first place.

Of course I know it is not 100% theft proof.

How about some useful info regarding the OP; much more helpful.

 

[Norcon]

I would make a pre cast concrete block with a slot in it that the wheel drives into and then becomes partly concealed inside the slot.

Then a heavy bar slots through the wheel (again concealed in the concrete) and is secured by a mortise type lock with a skeleton key.

The thief now has to look at the easiest part to cut and sever. (unless he can pick the lock)
That will probably be the wheel or some part of the bike frame structure.

There's probably something like it on google.

 

[Jillilfixit]

That is a good idea. I have apick proof lock that wil be used with a bold cutter proof chain. Not sure how I will make a mould for the wheels though. I was thinking of this as an anchor;

http://www.google.co.uk/products/ca...=X&ei=HdrwT8i6FaGr0QXQj5WQDg&ved=0CJoBEPMCMAk

 

[HERTS P&D]

What about this:

http://www.ebay.co.uk/itm/PORTABLE-...ycle_Parts&hash=item415168babe#ht_3129wt_1065

It screws into the ground, no damage to front garden.

Andy

 

[ConcreteDrBill]

Try this!
=http://www.lafarge.co.uk/CementDatasheet/RTU High Strength.pdf 40N/mm2 should be strong enough

 

[joe-90]

Not sure why people are so pessimistic when it comes to security; would it be better to leave my bike unlocked with a post-it note saying "please take me"; I will at least save money buying a lock in the first place.

Of course I know it is not 100% theft proof.

How about some useful info regarding the OP; much more helpful.

Do you demand free advice from your solicitor? Thort not.

 

[Jillilfixit]

Do you demand free advice from your solicitor? Thort not.

I'm hardly demanding advice and comparing gaining advice from a solicitor and from an online public open forum is ridiculous.

Try this!
=http://www.lafarge.co.uk/CementDatasheet/RTU High Strength.pdf 40N/mm2 should be strong enough

That is perfect! I have searching for that kind of pre-mix but I could only find quick setting mixes that did not mention strength, some people mentioned that the quick setting ones were not very strong.

Thank you.

 

[joe-90]

No it's not - it's time from a professional person - or don't you think tradespeople are worthy of that title? You must be some kind of snob.

Oh and you still don't seem to realise that the chain is the weak link.

Using a cheapo bike is your best defence.

 

[Jillilfixit]

No it's not - it's time from a professional person - or don't you think tradespeople are worthy of that title? You must be some kind of snob.

I never said that or think that. You are comparing gaining advice from a public open forum and a solicitor. I'm sure there are people here with just an interest in DIY which do not mind sharing their knowledge with people like me who are researching a DIY project; this is what a forum is about. If I have interrupted you on a job and you don't have time to answer my question then don't.

Oh and you still don't seem to realise that the chain is the weak link.

Yes I do realise that. I am only making this set up 42" hand bolt cropper proof which is achievable with the chain and lock I have.

Using a cheapo bike is your best defence.

...

 

[Burnerman]

Cast your ground anchor into a round 25 oil drum or similar, using the reinforcement and concrete recommendations given. We hope no one will try to lift that - especially if its in an enclosed garden!
Motorbike security chains are the best going - as are indeed the locks - so when its lock up time, try to suspend the lock itself in mid air, not on the ground so it can't be easily tortured. Also thread the chain through the frame, not the wheel.
Unfortunately our worst enemy is the portable battery angle grinder - but at least it makes a noise!
Can you incorporate a PIR security lamp, and maybe an anti tamper alarm too?
John