Understanding Concrete Strength Properties

Concrete exhibits significantly different strengths under compression and tension. It is known for its high compressive strength but relatively low tensile strength.

Tensile Strength vs. Compressive Strength Ratio

The question asks for the approximate fraction representing the ratio of concrete's ultimate tensile strength to its ultimate compressive strength. This ratio is a critical parameter in structural design.

• Compressive Strength: Concrete can withstand large compressive forces.
• Tensile Strength: Concrete cracks easily under tension due to its brittle nature and low tensile capacity.

Determining the Approximate Fraction

Standard engineering practice and material science data indicate that the tensile strength of concrete is typically a small fraction of its compressive strength. Common values found in literature suggest this fraction is approximately 10%.

Let $f_t$ be the ultimate tensile strength and $f'_c$ be the ultimate compressive strength. The ratio is $\frac{f_t}{f'_c}$.

Comparing the options provided:

• Option 1: $\frac{1}{2} = 0.5$ (50%)
• Option 2: $\frac{1}{4} = 0.25$ (25%)
• Option 3: $\frac{1}{20} = 0.05$ (5%)
• Option 4: $\frac{1}{10} = 0.10$ (10%)

The fraction $\frac{1}{10}$ corresponds to 10%, which aligns well with the generally accepted range (often between 8% and 15%) for the tensile strength relative to compressive strength in concrete.

Conclusion on Tensile Strength Fraction

Based on typical material properties, the ultimate tensile strength of concrete is approximately $\frac{1}{10}$ of its ultimate compressive strength.