Laying a section of concrete in the backyard

[12oz]

I have an area of land in my garden that I wish to concrete. The area is approx 3metres x 3metres. Please tell me what steps I would need to take to build a concrete platform. The challenge is that I am a weight lifter and require this area to perform olympic lifts. This often involves dropping weights from overhead. Please advise a method that can be used to prevent the concrete from cracking over time.

[landie]

You wont need steps unless it's very high. Sorry couldn't resist that one LOL :-)

Serious mode now, you would need a foundation of crushed stone or aggregate about six inches deep for drainage (well compacted) and a four to six inch thickness of concrete (4 inch thickness would use approx one cubic metre of concrete). Ensure that the concrete is laid quickly and vibrated well to expel air from the mix.

[sddsddean]

Agree with the aggregate subbase. Before you lay the concrete, cover the area with a sheet of polythene. This will stop moisture leeching out of the concrete while it goes off. Assuming you are going to order the concrete from a mini mix company, you want "28 Newton AEA with fibre reinforcing". 28 Newton is the strength, AEA is air entraining agent (essential to stop cracking if the concrete is outdoors) and the fibre reinforcing saves you having to worry about any. Its made up of 2" long steel or fibreglass fibres (I did my conservatory floor with it). If you mix it yourself, you will have to get some reinforcing mesh (A142 will do) and some AEA that you can add to your mix. Easiest way is to put all the concrete in, then 'press' the mesh in before trowelling off. The concrete in both cases should be vibrated, but not excessively so, otherwise you will be undoing the job of the AEA. Good Luck!!

Just done a quick bit of working out. For a 150mm thick slab, you will need 1.35m^3 of concrete; thats almost 3 tonnes!! Get a mini mix!!

[zmudge]

(1) What is the maximum weight of each weght ?

(2) Presumably they are in pairs. How far apart is each weight ?

(3) What is the maximum height you will be dropping them ?

(4) Will they always drop roughly in the same place on the slab ? If so, please describe. Or can they drop anywhere right up to each edge ?

[flaming]

Glad I don't live next door!

[12oz]

Thanks for all your contributions. In response to a previous question. The weights can be anywhere from 120Kg-200Kg. The weights are rubber plated olympic weights.When the bar is loaded up to, lets says 170KG. ( consisting of 20Kg x4, 15kg x2 + 20kg olympic bar). The weights are approximately 5and a half feet apart from each other. The weights will be dropped from a height of about 7 foot.

As for the noise point that is a consideration as well. After all this work has been done I intend to put down rubber tiles, like the type seen in parks. I am hoping that the rubber tiles and rubber plates will cause minimum noise, whilst still being solid under foot.

Any advise is appreciated..erm make that most advise is appreciated. Thanks

[12oz]

Also the weights will tend to be dropped in the same place. Ideally I would like for the weights to be able to be dropped anywhere on the platform but the likelyhood is that it will be the same place.

PS- Yeah it is true I do not envy the neighbours, but hey I gotta whole lotta training to do and times a runnin out ;)

[zmudge]

Obviously it is going to get quite a pounding. I suggest therefore that you use railway sleepers as permanent formwork with rods tied to a layer of mesh reinforcement in the concrete. The concrete should then have 1" marine ply stuck down to receive your rubber tiles. I have prepared a rough sketch of what I have in mind which can be seen here. I've not done this before on AnswerBank so hope it works !! When you have had a look shall be pleased to explain further/modify as necessary.

[zmudge]

The link has come out rather large so that you have to scroll both horizontally and vertically to see it all. I hope you can understand it.

[12oz]

Zmudge thank you for the diagram it is excellent. Do you know how much of these materials would be needed. I want to do as much of the work myself. How much of this can be a diy jobbie. Purchasing tools is not a problem.