Cement Paste and Concrete – Fundamental statements about hydration and performance Which of the following statements correctly describe what happens as water–cement paste hardens and how cement contributes to concrete behavior?

Difficulty: Easy

Correct Answer: All of the above

Explanation:


Introduction / Context:
Cement is the primary binder in conventional concrete. When mixed with water, a complex set of chemical reactions occurs, turning a plastic mixture into a hardened stone-like material. Understanding these fundamentals is necessary for proper mix design, placing, and curing practices that lead to durable structures.


Given Data / Assumptions:

  • Ordinary Portland cement as the principal binder.
  • Normal curing and proper water content for hydration.
  • Aggregates are inert fillers contributing volume and skeleton, but not binding capacity.


Concept / Approach:

Hydration of cement produces compounds (for example, calcium silicate hydrates) that form the binding matrix. This matrix envelops and adheres to aggregate particles, creating a composite material. Proper paste quality, aggregate characteristics, and curing govern the resulting strength, durability, and watertightness. Poor curing or wrong proportions increase porosity and permeability, undermining performance.


Step-by-Step Solution:

Option A: Correct—hydration is the cause of setting and hardening; without water, hydration halts.Option B: Correct—the paste binds aggregate into a coherent mass; the interfacial transition zone quality is crucial.Option C: Correct—adequate binder content, low w/c ratio, and curing yield strong, durable, and relatively watertight concrete.Therefore, “All of the above” is the accurate selection.


Verification / Alternative check:

Laboratory tests (compressive strength, permeability) consistently correlate improved curing and optimized w/c ratio with superior performance metrics, confirming these statements.


Why Other Options Are Wrong:

“None” contradicts basic cement chemistry; any single statement would be incomplete by itself in representing the full picture.


Common Pitfalls:

Assuming cement content alone determines quality; ignoring the decisive role of w/c ratio and curing; poor consolidation leading to honeycombing and leakage.


Final Answer:

All of the above

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