1. 1) ASTM C457-98: Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete, American Society for Testing and Materials, 1998.
2. 2) Powers, T.C.: The air requirement of frost-resistant concrete, Proceedings, Highway Research Board, Vol.29, pp.184-202, 1949.
3. 3) Powers, T.C.: Void spacing as a basis for producing air-entrained concrete, Journal of American Concrete Institute, No.50, pp.741-60, 1954.
4. 4) British Standard: Admixtures for concrete, mortar and grout- Test methods- Part 11: Determination of air void characteristics in hardened concrete, BS-EN 480-11: 2005.
5. 5) Mindess, S. and Young, J.F.: Concrete, Prentice-Hall, 1981.