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RS 425: 2026
Calcined and non-calcined pozzolanic ash — Specification

Abstract

This Rwanda Standard specifies requirements for pozzolanic ash, whether calcined or non-calcined, intended for use in the manufacture of cement and in the production of concrete and mortar.
The pozzolanic ash covered by this Standard is derived from naturally occurring siliceous or aluminous materials, including but not limited to volcanic materials, clays, shales, and other mineral sources, which have been processed by crushing, grinding, and, where applicable, calcination to achieve pozzolanic reactivity.
This Standard is applicable to pozzolanic ash used as:
? a constituent in factory-produced blended cements; and
? a supplementary cementitious material added directly during the production of concrete or mortar, where appropriate quality control measures are in place.
The requirements of this Standard are based on performance-oriented criteria, including physical, chemical, and mechanical properties relevant to durability, strength development, and compatibility with cement.
This Standard does not cover coal-derived fly ash produced from the combustion of coal, and therefore coal fly ash classifications such as Class F and Class C are covered in ASTM C618.

General Information

Code	Classification	Theme	Pages	Publisher	Availability
RS 425: 2026	STANDARDS OF RWANDA ORIGIN	Civil engineering	13	Second Edition Jul 2026	Available