Effects of fly ash fineness on the mechanical properties of concrete

摘要

The present study reviews the effects of fly ash fineness on the compressive and splitting tensile strength of the concretes. A fly ash of lignite origin with Blaine fineness of 2351 cm~2/g was ground in a ball mill. As a consequence of the grinding process, fly ashes with fineness of 3849 cm~2/g and 5239 cm~2/g were obtained. Fly ashes with three different fineness were used instead of cement of 0%, 5%, 10%, and 15% and ten different types of concrete mixture were produced. In the concrete mixtures, the dosage of binder and water/cement ratio were fixed at 350 kg/m~3 and 0.50, respectively. Slump values for the concretes were adjusted to be 100 ± 20 mm. Cubic samples were cast with edges of 100 mm. The specimens were cured in water at 20℃. At the end of curing process, compressive and splitting tensile strengths of the concrete samples were determined at 7, 28, 56, 90, 120 and 180 days. It was observed that compressive and splitting tensile strength of the concretes was affected by fineness of fly ash in short- and long-terms. It was found that compressive and tensile strength of the concretes increased as fly ash fineness increased. It was concluded that Blaine fineness value should be above 3849 cm~2/g fineness of fly ash to have positive impact on mechanical properties of concrete. The effects of fly ash fineness on the compressive and splitting tensile strength of the concretes were remarkably seen in the fly ash with FAC code with fineness of 5235 cm~2/g.