Concrete Technology

A: The correct choice explains progressive expansion and gel exudation long after hardening. Plastic shrinkage explains early shallow cracking but doesn't produce gel or ongoing expansion. Delayed ettringite needs high early temperatures and shows uniform expansion without gel bleed. Sulfate attack tracks exposure zones and softening, not random map cracking across the deck.

A: The correct choice targets chloride diffusion control, which is the governing mechanism in XD exposure. Higher strength helps structurally but doesn't address corrosion kinetics. Carbonation governs XC classes, not chloride-laden conditions. Supplier variability is handled by conformity rules, not exposure class limits.

A: The correct choice decodes standard reinforcement shorthand used on GA drawings. Steel area per width would be noted as As, not bar size. Dowel length is dimensioned explicitly, not embedded in spacing notation. Vertical spacing between layers is called out separately with section details.

A: The correct choice uses free water available for hydration divided by cement mass. Including absorbed water overstates effective water because it doesn't contribute to paste. Subtracting all aggregate moisture double-counts absorption already corrected. Total batch water ignores field moisture corrections used in control.