PROPERTIES OF HIGH-STRENGTH CONCRETE USING A FINE FLY-ASH

A Class F fine fly ash (FFA) with a fineness of 99% passing a 45 mu m sieve was used to produce workable high-strength concrete. Six mixture s were cast with total cementitious contents of 400 and 500 kg/m(3). T he replacement of cement by FFA, on equal mass basis, was 0, 10, and 1 5%. The mixtures were tested for workability and strength. Drying shri nkage and water absorption characteristics were determined as indicati ve of durability. The slump varied between 45 to 110 mm and fluid/ceme ntitious ratio varied between 0.25 to 0.38. The optimum cement replace ment for both 400 and 500 kg total cementitious material mixtures was 10%. The 28-day maximum strength for the two optimum mixtures was 94 a nd 111 MPa with a slump of 45 and 85 mm, respectively. The indirect te nsile strength of the two concretes was only 5 and 6% of their compres sive strength, respectively. The 2 h water penetration of the two conc retes was comparatively low, II and 13mm, respectively. The drying shr inkage of all the six concretes were very similar with a maximum value of 470 microstrain after 56 days of standard exposure. The 28-day mod ulus of elasticity of all the concretes varied between 40-46 GPa. (C) 1998 Elsevier Science Ltd.