Strength of brick masonry in 1:6 cement mortar — typical value For brick masonry constructed with a 1:6 cement mortar mix, what is the typical compressive strength taken for design/estimation purposes (in tonnes/m²)?

Introduction / Context:
Masonry strength depends on brick quality, mortar type, workmanship, and curing. For estimation and preliminary design checks, standard practice often adopts indicative compressive strengths based on mortar proportion. A 1:6 cement mortar is a common general-purpose mix for brickwork above plinth level.

Given Data / Assumptions:

• Ordinary burnt clay bricks of standard quality.
• Mortar proportion 1:6 (cement:sand by volume).
• Average workmanship and curing under normal conditions.

Concept / Approach:
Empirical tables from building construction practice provide indicative strengths. Richer mortars typically yield higher masonry strength, but the rate of increase diminishes due to unit–mortar interaction and failure modes. For 1:6 mortar, a representative safe compressive strength value often used is about 20 tonnes/m² for preliminary checks (with final design guided by relevant codes and tests).

Step-by-Step Solution:

Verification / Alternative check:
Cube or prism tests for masonry and code-based characteristic values corroborate lower strengths for lean mortars relative to 1:4 or 1:3 mixes.

Why Other Options Are Wrong:

• 40–75 tonnes/m²: These values are more consistent with richer mortars and/or high-quality units; they overstate capacity for 1:6 mortar.

Common Pitfalls:
Assuming mortar strength equals masonry strength; ignoring workmanship and brick unit variability.

Final Answer:
20 tonnes/m2