Which property of concrete makes it most advantageous for construction of bridges?
Correct Answer: C. High compressive strength
📚 Detailed Explanation: High Compressive Strength Makes Concrete Ideal for Bridges
Why C (High compressive strength) is correct: Bridges are primarily compression structures — arches, piers, abutments, and beam webs all carry compressive loads. Concrete’s high compressive strength (typically 20–80 MPa for structural grades) makes it the ideal material. Combined with reinforcing steel to handle tension, reinforced concrete bridges achieve excellent structural performance, durability, and longevity.
Properties of Concrete Relevant to Bridge Construction
| Property | Bridge Relevance | Is it an Advantage? |
|---|---|---|
| A. Low thermal conductivity | Reduces temperature extremes in deck slab — secondary benefit | Minor advantage, not the primary reason for bridge use |
| B. Low durability | Would be a serious limitation — bridges must last 50–100 years | ✗ NOT a property — concrete actually has HIGH durability |
| C. High compressive strength | Piers, arches, abutments, deck soffits — all carry compressive loads; concrete excels here | ✓ PRIMARY advantage — the main structural reason |
| D. Low tensile strength | Concrete tensile strength ≈ fck/10 — a weakness, managed by reinforcement or prestress | ✗ This is a limitation, not an advantage |
Why Concrete is Used in Bridge Construction
| Feature | Benefit for Bridges |
|---|---|
| High compressive strength (20–80 MPa) | Carries gravity loads, traffic loads, and wind loads in compression efficiently |
| High durability | Resists weathering, frost, carbonation, chloride attack over 100-year design life |
| Mouldability / form flexibility | Cast into complex arch, pier, and box-girder shapes |
| Excellent with steel (RCC / PSC) | Steel handles tension; concrete handles compression — ideal composite |
| Low maintenance | Concrete bridges need far less maintenance than steel bridges in corrosive environments |
- Concrete is used in bridge construction primarily for its high compressive strength.
- Bridges are compression-dominant structures; concrete piers, abutments, and arches rely on this property.
- Combined with steel reinforcement or prestress, concrete handles both compression and tension effectively.