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IS 5218:1969 is the Indian Standard (BIS) for method of test for toughness of natural building stones. 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
! 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.
EN 14158:2004CEN (European Committee for Standardization), Europe
MediumCurrent
Natural stone test methods - Determination of rupture energy
Both standards measure the impact resistance of natural stone, but EN 14158 uses a pendulum impact method (Charpy test).
BS 812-112:1990BSI (British Standards Institution), UK
LowCurrent
Testing aggregates. Method for determination of aggregate impact value (AIV)
Defines a falling weight impact test conceptually similar to IS 5218, but is intended for aggregates, not dimension stone.
ASTM C170 / C170M - 21ASTM International, USA
LowCurrent
Standard Test Method for Compressive Strength of Dimension Stone
Both assess mechanical properties, but ASTM C170 measures static compressive strength, not dynamic impact toughness.
Key Differences
≠The IS 5218 test uses a vertical falling weight apparatus with an incrementally increasing drop height, whereas the closest European equivalent, EN 14158, uses a pendulum impact tester (Charpy principle) which applies a single blow.
≠IS 5218 reports the result as a 'Toughness Index', which is the height in cm of the blow causing failure. EN 14158 reports the result as 'Rupture Energy' in Joules (J).
≠The test specimen for IS 5218 is a small cylinder (25 mm diameter x 25 mm height), while EN 14158 requires a larger, notched prismatic specimen (e.g., 70mm x 70mm x thickness).
≠The loading in IS 5218 is a series of impacts of increasing energy until failure, whereas EN 14158 uses a single impact with sufficient energy to cause fracture in one blow.
Key Similarities
≈The fundamental objective of both IS 5218 and EN 14158 is to quantify the ability of a natural stone to absorb energy and resist fracture under a sudden, dynamic load (impact).
≈Both Indian and European standards require the test specimens to be conditioned by drying in a ventilated oven to a constant mass before testing to ensure results are not affected by moisture content.
≈The end point of the test in both IS 5218 and EN 14158 is the clear fracture or breaking of the stone specimen.
Parameter Comparison
Parameter
IS Value
International
Source
Test Specimen Geometry
Cylinder, 25 mm diameter x 25 mm height
Notched prism, 70 mm x 70 mm x thickness
EN 14158:2004
Test Apparatus Principle
Falling weight on a plunger
Pendulum impact tester (Charpy type)
EN 14158:2004
Loading Method
Multiple blows with incrementally increasing drop height (1cm, 2cm, 3cm...)
Single blow from a predetermined height
EN 14158:2004
Result Unit
Toughness Index (height in cm of failure blow)
Rupture Energy (Joules)
EN 14158:2004
Specimen Conditioning Temperature
105 ± 5 °C
70 ± 5 °C
EN 14158:2004 (referencing EN 12372)
Impacting Hammer Mass
2 kg
13.5 - 14.0 kg
BS 812-112:1990
Number of Blows
Variable, until failure
Fixed at 15 blows
BS 812-112:1990
⚠ Verify details from original standards before use
Key Values6
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)
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.