What is the standard specimen size for testing compressive strength of stone?

Specimens should be cubes of 50 mm side or cylinders of 50 mm diameter and 50 mm height (Clause 2.1).

What loading rate should be applied during the test?

The load should be applied continuously at a rate of 14 N/mm² (140 kg/cm²) per minute until failure (Clause 5.1).

How long should the stones be soaked for saturated condition testing?

Specimens should be immersed in water at 20°C to 30°C for 72 hours (Clause 3.1.2).

How are dry condition specimens prepared?

They must be dried in an oven at 105 ± 5°C for 24 hours and cooled in a desiccator before testing (Clause 3.1.1).

IS 1121 Part 3

: 1974

Methods of Test for Determination of Strength Properties of Natural Building Stones - Part 3: Water Absorption

CurrentSpecializedTesting MethodMaterials Science · Flooring and Paving

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IS 1121 Part 3 covers the standard testing method for determining the tensile strength (typically via indirect/split cylinder method) of natural building stones. It is utilized by materials engineers to verify stone quality, load-bearing capability, and suitability for masonry or structural applications.

Specifies the method for determining the water absorption of natural building stones, an indicator of porosity and durability.

Quick Reference Values

specimen dimensions50 mm cubes or cylinders 50 mm diameter x 50 mm height

loading rate14 N/mm² per minute

dry conditioning temp105 ± 5°C

dry conditioning time24 hours

water immersion time72 hours at 20 to 30°C

bearing surface tolerance0.025 mm

Key Formulas

C = W / A — Compressive Strength (where W is crushing load in N, A is area of bearing surface in mm²)

Practical Notes

Stones are highly anisotropic; ensure you test and report strengths both parallel and perpendicular to the bedding planes or rift.

The bearing surfaces of the specimens must be strictly flat and parallel to ensure uniform stress distribution; capping with plaster of Paris may be required if perfectly smooth surfaces cannot be achieved.

Moisture severely affects the strength of natural stone; tests are typically conducted in both completely dry and saturated conditions.