What is the standard specimen size for the toughness test?

A cylinder of 25 mm diameter and 25 mm height (Clause 4.1).

How is the Toughness Index calculated?

It is the number of blows at which the specimen fails. The first blow is from a 1 cm height, the second from 2 cm, and so on, until failure (Clause 6.1).

What is the weight of the hammer used in the test?

The test uses a hammer weighing 20 N (approximately 2 kg) as specified in Clause 3.1.

What constitutes 'failure' of the specimen?

Failure is the point at which the test specimen breaks into two or more pieces.

IS 5218

: 1969

Method of Test for Toughness of Natural Building Stones

CurrentSpecializedTesting MethodMaterials Science · Stones

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This standard outlines the method for determining the toughness of natural building stones using the Page's Impact Test. It specifies the apparatus, specimen preparation, and testing procedure wherein a cylindrical stone specimen is subjected to increasing impact energy until failure. The result is expressed as a Toughness Index, which indicates the stone's resistance to impact.

Method of Test for Toughness of Natural Building Stones

Quick Reference Values

Specimen diameter25 mm

Specimen height25 mm

Test hammer weight20 N

Initial drop height1 cm

Incremental increase in drop height per blow1 cm

Minimum number of specimens to be tested3

Key Formulas

Toughness Index = n (where 'n' is the number of blows at which the specimen fails)

Practical Notes

The test is highly sensitive to specimen geometry; ensure the specimen faces are perfectly flat, parallel, and perpendicular to the cylindrical axis.

A higher Toughness Index indicates greater resistance to impact. Stones with an index below 9 are considered poor, 9-13 fair, and above 13 good.

This test helps in selecting appropriate stones for applications like flooring, steps, and pavements where they are subjected to impact loads.