5Thomas M D A, Shehata M, Shashippakash S G. The use of fly ash in concrete: classification by composition [J]. Cem Concr Ag gregates, 1999,12(2) : 105- 110.
6Kecek R H, Riggs E H. Specifying fly ash for drabble concrete [J]. Concrete International Journal, 1993, (12) : 586- 593.
