Initial setting time ends when the Vicat needle stops at:

5 +/- 0.5 mm from the bottom of the mould

Final setting is when:

The needle makes an impression but the annular attachment does not

OPC setting time limits are:

Initial at least 30 min, final at most 600 min

Initial at most 30 min, final at least 600 min

2071 Chaitra · 1 mark

Define initial and final setting time

Short answer

Initial setting time is when cement paste begins to lose plasticity; Vicat 1 mm needle stops 5±0.5 mm from mould bottom. For OPC, it must be at least 30 min. Final setting time is when paste hardens fully; needle with collar makes an impression but collar fails to. OPC limit is 600 min max.

Define initial and final setting time of cement.

Initial setting time: the time from adding water to cement until the paste begins to lose plasticity, that is, when the Vicat needle (1 mm square) stops 5 ± 0.5 mm from the bottom of the mould. For OPC it must be at least 30 minutes.
Final setting time: the time from adding water until the paste has completely lost plasticity and become hard enough to resist a definite pressure, that is, when the needle with annular attachment makes an impression but the attachment fails to. For OPC it must not exceed 600 minutes (10 hours).

✓ Answer checked by Claude Opus 5.5 (high effort)

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