Pile selection — which is a comprehensive advantage of using a concrete pile instead of a timber pile?

Introduction / Context:
Pile foundations transfer loads to deeper soils/rock or mobilize skin friction when near-surface soils are weak. Material choice (timber, steel, reinforced or prestressed concrete) affects durability, capacity, and constructability. This question contrasts concrete and timber piles in terms of practical advantages.

Given Data / Assumptions:

• Concrete pile refers to cast-in-situ or precast (reinforced or prestressed) concrete.
• Timber piles are susceptible to biological decay and insect attack above permanent groundwater level.
• Design must consider capacity, durability, and installation limits.

Concept / Approach:

Concrete piles offer superior durability in aggressive environments (with proper cover and mix), are not vulnerable to termites, and can be made longer or spliced to reach deep strata. They can deliver higher capacities via larger cross-sections and prestressing/reinforcement. Timber often needs cut-offs below water to remain permanently submerged to avoid decay, while concrete has no such requirement when properly detailed.

Step-by-Step Solution:

Verification / Alternative check (if short method exists):

Field practice and specifications commonly restrict timber piles where durability cannot be ensured; concrete piles are widely used for bridges, offshore, and urban foundations.

Why Other Options Are Wrong:

Each single advantage (A–D) is true but partial; only “All of the above” captures the comprehensive set.

Common Pitfalls (misconceptions, mistakes):

Overlooking sulphate attack and chloride ingress for concrete (needs proper mix/cover); assuming timber is always inferior (it can be economical in fresh-water conditions when kept permanently submerged).

Final Answer:

All of the above