What is the maximum allowed water absorption for broken brick aggregates?

The maximum water absorption should not exceed 25% by mass.

Can I use broken bricks with mortar attached to them?

The broken brick aggregates should be clean and free from adhered mortar, dirt, and other deleterious materials.

Can under-burnt bricks be used as aggregates?

No, the standard explicitly states that the broken bricks must be well-burnt and free from under-burnt clay.

IS 3068

: 1986

broken brick (burnt clay) coarse aggregates for use in lime concrete

CurrentRareSpecificationMaterials Science · Building Limes and Gypsum Products

Download PDF BIS Portal Google

This standard specifies the requirements for coarse aggregates derived from broken burnt clay bricks (brick bats) intended for use in lime concrete. It covers physical properties, grading limits, water absorption restrictions, and limits on deleterious materials to ensure the durability of lime-based foundation and terracing concrete.

broken brick (burnt clay) coarse aggregates for use in lime concrete

Quick Reference Values

Maximum Water Absorption25% by mass after 24 hours of soaking

Fines passing 4.75 mm IS SieveMaximum 10% by weight

Standard nominal maximum size40 mm

Practical Notes

Brick aggregates are highly porous; they must be thoroughly pre-soaked in water before mixing to prevent them from absorbing mixing water from the lime concrete, which would hinder the chemical setting process.

Under-burnt or over-burnt (vitrified) bricks should be strictly rejected as they compromise the strength and weather resistance of the lime concrete mix.

Though rarely used in modern reinforced concrete, this standard is vital for heritage building conservation, restoration work, and traditional roof terracing (e.g., Madras terrace).