Effects of Fly Ash and Silica Fume on High Performance Concrete

Abstract

These days, large and complicated concrete structures are mushrooming. Performance requirements include not only functionality and strength but also aesthetics. From a material viewpoint, it can be said that the requirements for high performance concrete include: adequate flowability, strength and durability. This study shows that combining fly ash and silica fume as mineral admixture is an effective way to improve the properties of concrete. The influence of fly ash and silica fume on fluidity and strength of mortar and concrete was experimentally investigated. Five fly ashes, classified into 3 types obtaining from each hopper of precipitator, were used and constituted 60, 70, 80 and 100% by weight of the total amount of mineral admixture. In this study, flowability was investigated by measuring the flow/slump flow while keeping the chemical admixture-binder ratio within a pre-determined range. Strength was evaluated by compressive strength tests at 14,28 and 91 days. The relationship between mineral admixture properties and mortar/concrete properties were studied. As a result of the tests, higher strength and adequate flowability were obtained by combining fly ash and silica fume.