How is the target mean strength for a mix design calculated?

It's calculated as: f_target = fck + 1.65 * s, where 'fck' is the characteristic strength and 's' is the standard deviation obtained from site data or assumed from Table 1 (Clause 3.2).

How is the initial water content estimated?

The initial water content is estimated from Table 2 based on the nominal maximum size of aggregate and the required workability (e.g., slump range).

Is this code still in use?

No, IS 10262:1982 has been withdrawn. It was first replaced by IS 10262:2009 and subsequently by the current version, IS 10262:2019. New designs must use the latest version.

IS 10262

: 1982

Concrete Mix Proportioning - Guidelines

SupersededEssentialGuidelinesBIMMaterials Science · Admixtures and Chemical Products for Concrete

Superseded by IS 10262:2009

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This standard provides guidelines for designing concrete mixes based on specified strength, durability, and workability requirements. It outlines a step-by-step procedure starting from calculating target strength to determining the proportions of cement, water, and aggregates, concluding with trial mixes to validate the design.

Provided guidelines for the proportioning of concrete mixes, including considerations for using admixtures.

Quick Reference Values

Target mean strength statistical factor1.65

Assumed standard deviation for M20 concrete (Table 1)4.0 N/mm²

Estimated water content for 20mm aggregate (25-50mm slump)186 kg/m³

Approximate entrapped air for 20mm nominal max size aggregate2.0 %

Volume of coarse aggregate for 20mm aggregate in Zone II0.62 per unit vol of total aggregate

Key Formulas

f_target = fck + 1.65 * s — Target mean compressive strength

Practical Notes

This 1982 version is obsolete and has been superseded by IS 10262:2019. The new version is more comprehensive, including provisions for mineral and chemical admixtures and high-strength concrete.

The accuracy of the mix design heavily depends on the precise determination of material properties like aggregate specific gravity, water absorption, and grading. These must be tested before starting the design process.

The values in the tables (e.g., water content) are initial estimates. Trial mixes are mandatory to fine-tune the proportions to achieve the required workability and strength in real-world conditions.