Appareil Gillmore

Gillmore apparatus is designed to determine the initial and final setting times of hydraulic cement with repeatable accuracy, using a precision needle-and-carrier mechanism. It consists of two stainless-steel needles of different masses, a balanced support frame, glass plates, and a high-stability steel base. The test principle is based on evaluating the penetration or surface marking response of fresh cement paste when contacted by needles of standardized dimensions and weights. Two needles are used: one for initial set and one for final set. The initial-set needle typically has a 2.12 mm tip diameter and a mass of 113.4 g. It is periodically applied to the cement paste, and the initial setting time is recorded once the needle no longer leaves a visible mark on the surface. The final-set needle has a 1.06 mm tip diameter and a total mass of 453.6 g. Final setting time is reached when this heavier needle also fails to leave an impression on the specimen surface.