Engineering Materials·MCQ explained

The final operation of finishing concrete floors is known as:

Try it first: pick an option, then read the explanation.

Correct answer: C. Troweling

Detailed Explanation: Troweling — The Final Floor Finishing Operation

Why C (Troweling) is correct: Concrete floor finishing follows a defined three-step sequence. Troweling is always the last step — it produces the final hard, smooth, dense surface by working the steel trowel over the floated surface once surface bleed water has evaporated.

Concrete Floor Finishing Sequence

StepOperationToolPurposeTiming
1ScreedingStraight-edge / Screed boardStrikes off excess concrete; sets surface levelImmediately after placement
2FloatingWood or bull floatRemoves screed marks; embeds aggregate; closes surfaceAfter initial set begins; surface firm but workable
3Troweling (Final)Steel trowelCreates hard, dense, smooth surface; compresses cement pasteAfter floating; once bleed water evaporates

Troweling in Detail

AspectDetail
ToolFlat steel trowel (hand trowel or power trowel for large areas)
TechniqueFirm pressure in circular or figure-8 motion; multiple passes
TimingMust be done before concrete becomes too hard to work; not too early (bleed water must evaporate first)
ResultHard, dense, dust-free, smooth surface resistant to wear
  • Sequence: Screeding → Floating → Troweling (final).
  • Never trowel while bleed water is still on the surface — it weakens the surface layer (laitance).
  • Multiple troweling passes increase density and hardness of the surface.