A BASIC STUDY ON ACTIVITY INDEX IN JAPANESE INDUSTRIAL STANDARD OF FLY ASH FOR USE IN CONCRETE

Abstract

Previous report said that it is quite difficult to satisfy the value of standard in the 28 day activity index of JIS of fly ash for use in concrete. First, in consideration of the fluid improvement effect, a compressive strength ratio examination which is based on the old JIS method is carried out. It was found from the test results that a compressive strength ratio is more practicable to show a concept of mechanical aspect of fly ash in comparison with the activity index of the present JIS method. Second, if activity index can presume at an early stage before 28 days, it will be thought that it is very useful on quality control of fly ash. This paper also reports the result of developing a simple prediction method of 28 day activity index.