ISO 844:2026

This document specifies methods for determining the compressive strength, the corresponding compressive strain, the compressive stress at 10 % nominal compressive strain, and the compressive modulus of rigid cellular plastics.
Two procedures are specified. Procedure A and Procedure B.
Procedure A utilizes the compression plate displacement for the nominal property determination. It is used to determine:

compressive strength and the corresponding nominal compressive strain;
compressive stress at 10 % nominal compressive strain;
nominal compressive modulus.

Procedure B uses an extensometer and determines the conventional properties. It is used to determine:

compressive strength and the corresponding compressive strain;
compressive modulus.