I need to mix 100 litres of good quality concrete. Using 20mm (or thereabouts) ballast, What weight (Kg) of cement is needed for a 3:1 mix?
TIA
cement quantity for concrete
Nov 17, 2005
6 Replies
Don't forget the fine aggregate - you need to fill those gaps.
At I:3 mix by volume you'd need 25L cement and 75L ballast Cement weighs approx 1600kg/m³ = 1.6kg/L so you'd need 40kg = just over 1½ bags.
I:3 is a *really* strong mix though. 1:6 is good quality, so one 25kg bag of cement would be perfect.
About 15 good shovels. Why are you going 3:1 with concrete, though?
He's using ballast.
Various online calculators:
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The message from "jim_in_sussex" contains these words:
Concrete is usually specified in terms of volume and with 3 constituents
- gravel, sharp sand and cement - and 3:2:1 is a very strong mix.
According to my ancient source of information a cubic yard of 3:2:1 concrete requires 0.748/0.499/0.299 cu yards of each constituent or
0.794/0.601/0.271 tons. Oh yes and 30.9 gallons of water (which presumably assumes that the aggregate is perfectly dry, an impossibility in my experience).Join the Discussion
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