Concrete Mix for entrance gate pillar

[marblerun]

Hi all,

This one is getting the better of me.

I'm building a new pillar, about 5.5 ft above ground with 27 inch diameter. It will be taking iron gates.

I'm looking to find the right concrete mix to use, that will be the right strength, be durable but also that will have a smooth finish.

The attached link suggests 1:2:4 (cement, sand, aggregate) http://www.ecocem.ie/architectural,finish.htm Elsewhere I've seen M25, M40 and Type S mentioned...........

The mix will be poured into circular formwork which I have, as well as the braces to support.

Any thoughts on above mix?

Regards and thanks,

MR

 

[jeds]

I wouldn't worry too much about strength - almost any of the standard mixes will be strong enough. But if you are looking for an architectural finish on the placed concrete it won't easy. The mould will have to be very carefully prepared, the mix must be exactly right and must be placed and vibrated with scientific precision. A 5 ft deep mould will also put extreme pressure on the bottom of the mould so will need to be something like heavy gauge steel. My advice is speak with your concrete supplier. You might find they don't supply architectural mixes in small quantities. Otherwise you might have to accept that you will have to make good the finish surface and possibly overpaint.

 

[maltaron]

To achieve a smooth finish you will need smooth formwork, oiled with form oil. And as suggested will have to be filled and compacted with a poker vibrator in no more than 400mm layers. I will also advise that the bottom of a 5ft form will be under immense pressure, I would suggest filling the first half, stick in 2 or 3 rebars and leave 3 or 4 hours for initial set, then pour in a little grout and finish the job.

 

[marblerun]

Thanks for the replies. The mould I am using is one of these - I have a 6ft length. It has a fair face liner which doesnt need any oil. http://www.industrialpackaging.ie/documents/ConstructionGuideBrochure_000.pdf Also, I have 3 steel braces which should keep it from deforming. Also, I should have said that there is an existing square pillar (20 inches wide) - the round mould will fit around/against this. This should reduce the pressure considerably. The difficult part will be to get the concrete into the 3 inch space at the sides and work a vibrator also.

Do you think that the 1:2:4 mix will be ok for a smooth finish and also be weather reistant? I am planning to hire a mixer and do it myself.

 

[maltaron]

By my calculation a 27" diameter tube will not fit over a 20" square pillar.

 

[marblerun]

Your mathematics are correct. However, the actual shape will look like this:

//www.diynot.com/network/marblerun/albums/

 

[marblerun]

One other question for you all. Thanks!!

This is my calculation for a Water cement ratio of 0.45. Result is 2/3 a bucket of water to 1 bucket of cement (and say 5 buckets of aggregate).

Is my water calculation correct?


Cement 50kg

Water Cement Ratio 0.45

Water 22.5kg

Water 22.5 litres

Cement Density 1.5 Kg/Litre

Cement Volume 33.3 litres

Buckets of cement 1.0

Buckets of Water 0.675 (22.5/33.3)


Thanks,

MR

 

[pred]

Me personally would phone ready mix, tell them what it was for and have them deliver how much is it?? 1cubic meter?? the mixer will probably cost £25 to hire then you got to pick it up then clean it out befor you take it back, also how many builders were aware, if a mixer go's walkabout, guess who is liable.

 

[marblerun]

I will need the mixer for a week. to pour the foundation, kicker and then the column itself. Delivery to site wouldn't really work. Need to do it in my own time also.

Any advice on the water?

Thanks,

MR

 

[noseall]

Are you using reinforcing steel in the pillar?

Are you casting the gate hooks into the pilar?

 

[marblerun]

Yes, reinforcing the steel.

No gate hooks, will let the gate firm do this later. Bolts plus epoxy I expect.