AASHTO M 295:2021 Standard Specification for Coal Fly Ash and Raw or Calcined Naturall P ozzolan for Use in Concrete.
This specification covers coal fly ash and raw or calcined natural pozzolan for use in concrete where cementitious or pozzolanic action, or both, is desired or where other properties normally attributed to finely divided coal fly ash and raw or calcined natural pozzolans may be desired or where both objectives are to be achieved.
Note 1—Finely divided materials may tend to reduce the entrained air content of concrete. hence, if a fly ash or natural pozzolan is added to any concrete for which entrainment of air is specified, provision should be made to ensure that the specified air content is maintained by air content tests and by use of additional air-entraining admixture or use of an air-entraining admixture in combination with air-entraining hydraulic cement.
The values stated in SI units are to be regarded as the standard.
A A SHTO Standard:
• R 80, Determining the Reactivity of Concrete Aggregates and Selecting Appropriate Measures for Preventing Deleterious Expansion in New Concrete Construction
2.2. ASTM Standards:
• C 125, Standard Terminology Relating to Concrete and Concrete Aggregates
• C 311 /C311 M, Standard Test Methods for Sampling and Testing Fly Ash or Natural
Pozzolans for Use in Portland-Cement Concrete
The terms used in this specification arc defined in ASTM C 125.
3.1 .2. fly ash—finely divided residue that results from the combustion of ground or powdered coal and that is transported by flue gasses.
Note 2—This definition of fly ash does not include, among other things, the residue resulting from: (1) the burning of municipal garbage or any other refuse with coal; (2) the injection of lime
class N—Raw or calcined natural pozzolans that comply with the applicable requirements for the class as given herein, such as some diatornaccous earths; opalinc cherts and shales; tuffs and volcanic ashes or pumicites, calcined or uncalcined; and various materials requiring calcination to induce satisfactory properties, such as some clays and shales.
4.2. Class F—Fly ash that meets the applicable requirements for this class as given herein. This class fly ash has pozzolanic properties.
4.3. Class C—Fly ash that meets the applicable requirements for this class as given herein. This class of fly ash, in addition to having pozzolanic properties, also has some cementitious properties.
Note 3 —Class F fly ash is typically produced from burning anthracite or bituminous coal but may also be produced from sub-bituminous coal and from lignite. Class C fly ash is typically produced from burning lignite or sub-bituminous coal and may also be produced by anthracite or bituminous coal.AASHTO M 295 pdf download.