Concrete Volume & Mix

Because it was searched for in IS 456, IS 10067, ACI 211.1 and the PCA manual and appears in none of them. It is not needed here: IS 10067 Table 2 already publishes quantities per cubic metre of finished concrete. At a cement bulk density of 1440 kg/m³ the cement quantities of that table imply a factor of 1.36 to 1.44, so using 1.54 over-orders cement by roughly 7 to 14%.

IS 10067 Table 2 is written for shingle, and its note requires the constants to be increased by 5% for leaner and 7% for richer mixes when crushed aggregate is used. The standard does not draw the line, so the tool takes 1:1:2, 1:1½:3 and 1:2:4 as rich (+7%) and 1:3:6 and 1:4:8 as lean (+5%), and applies the increase to cement, sand and aggregate alike. Crushed stone is the default; natural gravel uses the table as printed.

As water ÷ w/cm. Water is 205 kg/m³ from PCA Table 9-5 (19 mm aggregate, 75–100 mm slump, non-air-entrained). The w/cm is interpolated in PCA Table 9-3 at the required average strength, not at f′c: with no test record f′cr = f′c + 8.5 MPa, which gives about 418, 471 and 523 kg/m³ for f′c 25, 30 and 35 MPa. Table 9-3 ends at 45 MPa, so 40 MPa and above are not offered. Sand and aggregate are not published for a design mix and are left blank.

The ribbed slab is one-way with ribs along its length: the gross slab less the whole blocks that fit across the width between an edge rib on each side, with any leftover strip taken as solid concrete; the tool reports the ribs, blocks and strip. The stair is the waist slab on its slope length plus a triangle per step, and a slope length more than 5% away from steps × √(riser² + tread²) is flagged.

That mapping is trade convention, not code. IS 456:2000 Table 9 proportions nominal mix concrete BY MASS (total dry aggregate per 50 kg of cement) not by the volumetric ratios everyone quotes, and cl. 9.3 limits nominal mixes to M20 and below. The grade shown beside each mix here is labelled as the convention it is, and choosing 1:1:2 raises a warning.

Durability, not strength. SBC 304 Tables 4.3.1 and 4.4.2 set a minimum cementitious content, a maximum w/cm and a minimum grade against sulfate and chloride exposure: 350 kg/m³ at w/cm 0.45 for severe sulfate, 370 kg/m³ at 0.40 for very severe chloride, and w/cm ≤ 0.35 in sabkha. Those often govern over a strength-based mix, and this tool does not check them.

No, and the tool says so where they appear. Cement, sand, aggregate, ready-mix, rebar and pumping rates were carried over from the previous build of this site; they are not owner-approved and carry no review date. Enter your own supplier's rate. A site-batched cost is not given for a design mix, because its sand and aggregate quantities are not published.