Concrete Constituents Calculation

Something like this?

Maybe you can get something out of this simple information regarding concrete mix. Here in our place this is the porportion I often use, for mixture ratio of 1:2:4, the corresponding quantities are; 8.20 bgs of cement per cu.m of concrete, 0.44 cu.m of fine aggregate (sand) per cu.m of concrete, 0.88 cu.m of coarse aggregate (gravel) per cu.m of concrete, Maybe you could actually determine the right quantity if you try experimenting starting with this information I gave.

you need gravel of varied sizes as well as sand of varied sizes. Any tech library will have some comments about this. The ready mix companies have made studies in this so they have the maximum amount filled by rock of assorted sizes with a small amount of cement to hydrate into the remaining gaps in the structure.

So they buy and grade their sand and gravel and use a certain amount of each part plus the cement to get the best results.

If you make contact with them they can prepare a special mix. Often a ready mix is cheaper, unless you have sand/gravel on the property and can grade it.

http://www.nrmca.org/

Guest, i use 88Lbs (around 40kgs) per bg of Portland Cement for that particular mix, with regards to wastage try this simple method. Translate the volume of the fine and coarse aggregates into no of sacks. Okay to redefine the foregoing statement this is what you will gonna do. First make a wooden box measuring to 1.00m x 1.00m x 0.44m high (bottom surface of the box has to be levelled), pour in the Fine Aggregates up to the brim of the said box, level the top surface of the said material, get empty sacks of cement then transfer the quantity measured by that box to the empty sacks, at this point you can determine the equivalent no of bags per 0.44 cu.m of the said material. Do the same procedure for the Coarse Aggregates, by the way this method is only good for small batches using a 1bagger concrete mixer, it is easier to transmit aggregates manually using sacks rather than the usual method ( I just dont know how they pour the aggregates into the mixer bucket in you place). Other factors to minimize waste is the surface of the stock pile area, a concrete pave stock area has a great chance of 99% matls recovery rather than piled up directly into the ground surface. Considering this information, as what I have said, try experimenting to come up with the desired results.

Thanks Pice for your reply. You can close to what I really wanted. However, you did not say what size of the cement bag, assumptions on wastage and other related mix matters

It all depends on the job, if you are on a large contract pour then you would want the best strengths using the least amount of cement, so you would set your ratios accordingly, this is how the big boys minmise costs. fillers and additives are also an important issue, using slag or PFA stretches the cement and still gives standard strengths.

Your ratio is set down to the strength required of the job in hand.