Initial Setting Time of Cement

Using paste mixed at standard consistency, the Vicat apparatus is fitted with a 1 mm needle and lowered onto the paste at regular intervals. Initial setting time is reached when the needle fails to penetrate to within 5 mm of the bottom of the mould.

IS 269 requires a minimum initial setting time (typically 30 minutes for OPC) so there is enough working time to transport, place and compact concrete or mortar before the cement starts to stiffen.