Finishing, Curing, and Protection
Core concepts
Understand the finishing sequence: screeding, bull floating, waiting for bleed water to dissipate, then troweling or brooming. Know that finishing bleed water back into the surface weakens it (dusting, scaling). Curing maintains moisture and temperature for hydration; methods include moist curing, curing compounds, and plastic sheeting. Know curing duration depends on cement type, temperature, and exposure-longer for colder weather and blended cements. Protect fresh concrete from early freezing, rapid drying, and thermal shock.
Traps
Questions test timing: troweling too early traps bleed water and weakens the surface; troweling too late is difficult and may crack. A frequent trap is confusing curing with finishing-curing starts after finishing and lasts days, not minutes. Watch for curing compound selection (must be compatible with later coatings) and the rule that curing compounds are not a substitute for adequate moist curing where water is available. Cold-weather protection is about preventing freezing, not just slowing set.
Worked example / rule of thumb
If bleed water is still visible, delay troweling; do not sprinkle cement on the surface to dry it. Rule of thumb: begin moist curing as soon as finishing permits and keep it continuous for the specified period; protect from freezing until the concrete reaches adequate strength.