The ASTM C151 standard, which covers the autoclave expansion of hydraulic cement, requires specific moulds to prepare test specimens. These moulds are designed to create mortar prisms used in measuring expansion, which is a key indicator of cement soundness.
Key Mould Specifications for ASTM C151:
- Dimensions: The standard mould is a two-gang prism mould that produces specimens measuring 25 x 25 x 285 mm (1 x 1 x ¼ inches).
- Effective Gauge Length: The prism has an effective gauge length of 250 mm (10 inches).
- Material: Usually constructed from high-quality steel or stainless steel to ensure durability and prevent warping under repeated use.
- Components: The mould assembly consists of the base plate, side plates, and dividers, along with specialized gage studs (inserts) that are screwed into the ends of the mould.
- ASTM Compliance: The mould must conform to ASTM C490, which covers the specifications for apparatus used in length change measurements.
These moulds are essential for producing consistent samples that are tested in an autoclave machine, following the procedure outlined in ASTM C151.
