concrete mixing

[novicediy]

With regard to 6 to 1 mix Does it mean one part by volume of cement to one part of ballast by volume to 4 parts of sand by volume. mixing together ?? So If I buy one bag of cement I will need to buy one bag of ballast and 4 bags of sand. Any advice will be very much appreciated.

[pedderwo]

I always use washed sand and chippings mixed, I think they are 50/50. So I suppose your mix would really be 3 Washed Sand 3 Chippings and 1 cement. So for every bag of cement 3 of each of the others.

[Toureman]

6 to 1 means 6 to 1

Just use 1 cupful of cement to 6 cupfuls of ballast.

OR 1 spade full of cement to 6 spade fulls of sand.

As long as you keep the ratios the same it does not matter what the amount is that you mix.

[Hermit]

I wouldn't lose too much sleep over it. 1:6 is fairly weak, some applications are as low as 1:4; its the amount of water you add that is more crucial. Too much water will result in very weak concrete as what is unused in the cement reaction just takes up space and when it finally drains/evaporates that's empty space. Apparently its only about 1/2 to 2/3 of the water you add that is really needed to set the concrete, the rest is to make it workable so jsut watch for that.

[Paul35]

Usually the proportions of all three components (cement:sand:ballast [ which I think is coarse aggregate in American usage]) must be mentioned to describe a concrete mix. The most common for building purposes is 1:2:4, 1 being cement, 2 sand and 4 aggregate, and which yields a cylinder strength of at least 3000 psi.

If no other information is available 1 to 6 concrete can be taken to be 1:2:4. Remember, sand is a must in any concrete mix.