Fresh and hardened properties of ultra-high performance concrete incorporating coal bottom ash and slag powder

Abstract

This experimental research addresses the physical properties of eco-friendly Ultra High Performance Concrete (UHPC) incorporating industrial by-products including coal bottom ash, fly ash and two types of slag powder. Slump flow, compressive strength development, porosity, setting time, autogenous shrinkage and thermogravimetric analysis of UHPC are characterized. The experimental results indicate that coal bottom ash and fly ash are promising industrial by-products by effectively replacing silica powder in UHPC without significant losses in workability and strength development. It is revealed that normal-sized and finer-sized ground granulated blast furnace slag can be effectively used without additional activator to partially substitute cement and silica fume, respectively, which results in enhanced workability and comparable compressive strength, albeit relatively slow strength development. Furthermore, it is found that the adoption of various forms of industrial by-products in UHPC does not play a significant role in affecting autogenous shrinkage, porosity and capillary water absorption of UHPC.