Coarse Aggregate Blend (20 / 10 / 40 mm)
IS 10262:2019 sets the total coarse aggregate proportion, but it does not fix how that total should be split between individual stone sizes. This page explains how single-sized fractions are combined to meet IS 383 grading, and gives a common starting blend. Open the calculator with a blend already filled in.
Why the split is a separate step
IS 10262:2019 establishes the total coarse aggregate proportion. It does not fix a universal 20/10 mm split. The total coarse aggregate must be made up of the available single-sized fractions — for example 20 mm and 10 mm, and 40 mm where used — combined so that the combined grading meets the requirements of IS 383. A commonly used starting blend for 20 mm nominal maximum size is about 60% of 20 mm and 40% of 10 mm, but the actual approved blend depends on the grading of the specific aggregates being used. All fractions in the blend must total 100%.
Worked example
Take a total coarse aggregate content of 1140 kg/m³. At a 60/40 blend: 20 mm = 684 kg/m³, 10 mm = 456 kg/m³. Change the blend to 55/45 and the masses shift accordingly — 20 mm = 627 kg/m³, 10 mm = 513 kg/m³. The calculator validates that the fractions you enter add up to 100%.
Questions this page answers
Is the 60/40 split required by IS 10262?
No — it is a common benchmark starting point. The actual requirement is that the combined grading of the blended fractions meets IS 383.
Can I use 40 mm aggregate?
Yes, the calculator supports a 40/20/10 mm blend where a three-size combination is being used.