QUALITY AND PERFORMANCE EVALUATION OF CONCRETE USING COAL ASH CLASSIFIED AS TYPE Ⅳ FLY ASH

Abstract

In this study, we evaluated the quality and performance of fly ash concrete in which 20％ mass of fly ash was used with regard to cement. In the mix proportion, mass of cement was stayed and fly ash was externally used as an admixture by replacing from aggregates. Fly ash used in this study was the coal ash which was classified as type Ⅳ fly ash, however a part of them has as good quality as type Ⅱ fly ash. As a result, it was confirmed that this fly ash can ensure the air entrainment of fly ash concrete without impairing fly ash concrete workability as a powder interpolating cement and fine aggregate. Based on this result, the quality range of fly ash controlled by type Ⅳ fly ash to be used was proposed for the practical application of ready-mixed concrete in the future. Furthermore, the applicability to actual cast-in-place prestressed concrete road bridge deck slab was examined. It was shown that the fly ash concrete having sufficient fresh concrete properties such as slump, air contents and bleeding ratio, and hardened properties such as design strength and required early stage compressive strength for introducing pre-stressing and having sufficient anti-chloride ingress performance and alkali silica reaction resistance can be produced.