What is the typical relationship between compressive strength and modulus of elasticity in concrete?

• A. Higher compressive strength generally corresponds to higher modulus of elasticity; both depend on mix and aggregate.
• B. No relationship.
• C. Higher compressive strength means lower modulus.
• D. Modulus depends only on temperature.

Answer: (A)

In concrete, compressive strength and modulus of elasticity tend to rise together because both reflect the same underlying microstructure: a dense, well-cured cement paste bonded to a stiff aggregate with minimal porosity and a strong interfacial transition zone. When the paste is high-quality and the aggregate is well-graded and properly bonded, the material resists crushing more and also deforms less under load, leading to higher strength and greater stiffness. The relationship isn’t exact, though—different mixes can show deviations due to variations in aggregate stiffness, curing conditions, and microcracking. But the common trend is that stronger concrete is usually also stiffer, whereas the idea that there’s no relationship, that modulus depends only on temperature, or that stronger concrete is less stiff, doesn’t fit observed behavior.