Concrete strength relationships: arrange the following strengths in decreasing order (highest to lowest): (1) Cube compressive strength, (2) Cylinder compressive strength, (3) Split-tensile strength, (4) Modulus of rupture (flexural tensile strength).

Introduction / Context:
Concrete exhibits different strengths depending on the test method and stress state. Understanding the typical hierarchy of strengths helps engineers interpret specifications and convert between test results when necessary.

Given Data / Assumptions:

• (1) Cube compressive strength is usually measured on 150 mm cubes.
• (2) Cylinder compressive strength is typically lower than cube strength for the same concrete due to aspect ratio and friction effects.
• (3) Split-tensile strength estimates the indirect tensile capacity.
• (4) Modulus of rupture represents flexural tensile strength and is generally higher than split-tensile strength.

Concept / Approach:
Typical relationships for normal-strength concrete are: f_c,cube ≈ 1.25 * f_c,cyl (approximate), modulus of rupture f_r ≈ 0.7 * √f_ck (MPa), and split-tensile strength f_t ≈ 0.56 * √f_ck. Thus, compressive strengths are much higher than tensile strengths, and among tensile measures, flexural (modulus of rupture) exceeds split-tension.

Step-by-Step Solution:
Order compressive strengths: cube (1) > cylinder (2).Compare tensile measures: modulus of rupture (4) > split tensile (3).Combine: 1 > 2 > 4 > 3.

Verification / Alternative check:
Code guidance and empirical correlations (e.g., IS/ACI) consistently show cylinder strength lower than cube, and flexural strength higher than split-tensile for the same concrete.

Why Other Options Are Wrong:

• Any sequence placing tensile strengths above compressive strengths is unrealistic.
• Sequences with split-tensile above modulus of rupture contradict standard correlations.

Common Pitfalls:
Assuming cube and cylinder strengths are equal; confusing direct tensile with flexural tensile capacity.

Final Answer:
1, 2, 4, 3