Le Chatelier Mould is a precision-engineered expansion mould designed in accordance with the Le Chatelier method for evaluating the soundness (volume stability) of hydraulic cement. The mould features a two-piece (split-ring) construction, allowing controlled placement of the specimen and reliable monitoring of dimensional changes during thermal conditioning. The high-quality brass alloy body, with a smoothly machined internal surface and rigid bridge connections limiting deformation, ensures reproducible measurement conditions. It is resistant to oxidation and chemical effects. The ring geometry, with a nominal 30 mm internal diameter and 30 mm height, accommodates the standard specimen volume.