Lime concrete – slump and strength benchmarks for field identification Which of the following statements are correct for typical lime concrete used in traditional works?

Difficulty: Easy

Slump is about 50 to 75 mm
Flexural strength at 90 days is about 0.2 N/mm^2
Compressive strength at 90 days is about 1.5 N/mm^2
Compressive strength at 26 days is about 1.2 N/mm^2
All of the above

Correct Answer: All of the above

Explanation:

Introduction / Context:
Lime concrete (lime as the primary binder with aggregates) precedes modern Portland cement concrete and is still referenced for heritage works, bedding, and specific environmental contexts. Its workability and strength development differ markedly from OPC mixes. This question checks recognition of typical slump and low-strength benchmarks for lime-based concretes in traditional practice and exam standards.

Given Data / Assumptions:

Lime is the main binder (fat or hydraulic lime), sometimes blended with pozzolana.
Values are indicative of traditional field ranges, not strict code minima.
Strength develops slowly; 90-day values are typically quoted for lime systems.

Concept / Approach:

Lime binders react and gain strength far more slowly than OPC. Slump values around 50–75 mm indicate moderately workable mixes suitable for placement without segregation. Flexural and compressive strengths are an order of magnitude lower than comparable OPC concretes, with late-age strength (90 days) still quite modest.

Step-by-Step Solution:

1) Workability: slump ≈ 50–75 mm is consistent with plastic, placeable lime concrete.2) Flexural strength: ~0.2 N/mm^2 at 90 days reflects low tensile capacity.3) Compressive strength: ~1.2 N/mm^2 at ~26–28 days rising to ~1.5 N/mm^2 at 90 days aligns with slow-pozzolanic and carbonation-driven gains.4) Hence all listed statements are accurate for typical lime concrete benchmarks.

Verification / Alternative check:

Conservation literature and traditional materials handbooks document low early strengths for lime systems and the need for extended curing and carbonation periods, matching the indicative numbers provided.

Why Other Options Are Wrong:

Because each individual statement is consistent with traditional values, the combined option correctly states “All of the above.”

Common Pitfalls:

Expecting OPC-like strengths or rapid setting; ignoring the role of moisture and CO2 exposure in strength gain; misreading “26 days” as a typo for 28—values are indicative and align with the trend.

Final Answer:

All of the above

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Lime concrete – slump and strength benchmarks for field identification Which of the following statements are correct for typical lime concrete used in traditional works?

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