Portland Cement - how to mix????

[Al]

Hi.

I have half a bag of Portland cement that my builders left.

I need to put a swing in the garden and I'm supposed to bury part of the legs legs in cement.

Do I just mix the cement with water or do I need to add some sand? There are no instructions on the bag!

Thanks,

Al.

[Nigel Mercier ®]

No, you need to bury the legs in concrete.

You need some all-in aggregate (or ballast). This is a mix of stones from 20mm down to coarse sand. You should mix it 4 parts of ballast to 1 part cement. You can probably use it dry, tip it in the holes around the legs, then add a bit of water to set it.

[Toby]

The ratio is not too critical, but for this kind of application I'd go for six parts ballast to one of cement. Mix it dry, then add small amounts of water. Also as it is going straight into the ground aim for a damp mix rather than sloppy. The curing is a chemical reaction not one of evaporation.

Using this ratio conveniently uses three bags of ballast.

Ballast? It's sand, grit, small stone aggregate etc all mixed in one. To make concrete you really need cement, sand and some aggregate.

Toby.

[Rick Hughes]

You want concrete not a mortar mix - use something like a 1:2:4 mix .... i.e. 1 part cement, 2 parts sand, 4 parts chippings.

Mix dry first, then heap up and make a depression in middle, add some water, and mix ... you should keep water low - just enough to make all parts of the mix join together, the test is if you can squeeze it in your hand and it will form a ball without falling apart, then it's about right - if water squeezes out - it's too wet (add a bit of cement & sand to dry out)

(Or if you chop up and down with a shovel it will keep the shapes made without slumping back.)

Pack into the hole - ram down with an offcut of wood and then later in the day water in with a watering can. - job done.

If you use a wet mix it will be difficult to keep post upright, and there is no need for loads of water.

But for a swing none of the above is critical.

Rick