Producing impermeable (low-permeability) concrete — key quality measures Which of the following measures are necessary to produce concrete with low permeability and good watertightness?

Introduction / Context:
Permeability governs durability, corrosion risk, and leakage in liquid-retaining structures. Low-permeability concrete results from controlled water–cement ratio and disciplined construction practices throughout mixing, placing, compaction, and curing.

Given Data / Assumptions:

• Normal structural concretes without intentional air entrainment (unless specified).
• Objective: minimize connected capillary pores and voids.
• Quality aggregates and proper grading available.

Concept / Approach:

Permeability decreases when the paste is continuous and dense, voids are minimized, and hydration proceeds sufficiently. Each listed measure directly contributes: thorough mixing for uniformity, proper compaction to remove entrapped air, adequate curing to allow hydration products to refine pores, and suitable aggregates to reduce internal porosity and paste demand.

Step-by-Step Solution:

Verification / Alternative check:

Permeability tests (e.g., water penetration depth) show significant improvement with these practices versus poorly mixed/compacted/uncured concretes.

Why Other Options Are Wrong:

• They are not wrong individually; the comprehensive, correct choice is to implement all.

Common Pitfalls:

• Focusing only on admixtures while neglecting compaction and curing.

Final Answer:

All of the above.