Use of Le Chatelier apparatus in cement testing The Le Chatelier method is primarily used to determine which property of cement?

Introduction / Context:
Soundness is the ability of cement to retain its volume after setting without delayed expansion. Unsoundness may arise from excessive free lime or magnesia, causing cracking and disintegration. The Le Chatelier test detects such potentially harmful expansion under accelerated conditions.

Given Data / Assumptions:

• Ordinary Portland cement; potential unsoundness due to free CaO/MgO.
• Le Chatelier apparatus measures expansion of a cement paste specimen.
• Controlled heating protocol is followed.

Concept / Approach:
In the Le Chatelier test, a split brass mould confining a cement paste is submerged in water and subjected to a specified heating regime. The separation of indicator points after treatment indicates expansion. Limits are set to ensure acceptable soundness. This procedure does not measure hardness, compressive strength, or broad durability; it specifically targets volumetric stability related to latent expansion constituents.

Step-by-Step Solution:

Verification / Alternative check:
Autoclave expansion is another method to evaluate soundness; results are correlated but use different conditioning (steam under pressure) to reveal potential expansion due to magnesia or other compounds.

Why Other Options Are Wrong:

• (b) Hardness is not a cement test parameter.
• (c) Strength tests use mortar cubes or prisms, not Le Chatelier.
• (d) Durability is a broad in-service concept, not a single lab test via this apparatus.

Common Pitfalls:
Poor paste preparation; incorrect heating rate; misreading the scale; confusing Le Chatelier limits with autoclave expansion criteria.

Final Answer:
Soundness of cement (undesirable expansion)