The Impact of Variable Curing Conditions on the Properties and Microstructures of Mixtures of Ground Granulated Blast Furnace Slag and Circulating Fluidized Bed Combustion Ash

Abstract

The use of Portland cement, an important construction material, is encountering growing challenges because of its adverse environmental impacts. In this study, a new hydration system without Portland cement, which blends ground granulated blast furnace slag (GGBFS) and circulating fluidized bed combustion (CFBC) ash, was developed and tested. The variables included the effect of different types of CFBC ash, the mass ratios between CFBC ash and GGBFS, and different curing temperatures. The mortar properties were determined through the compressive strength test, absorption test, shrinkage test, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The main results were as follows: (1) The compressive strength of mortar specimens made with this ecologically friendly hydration system reached at least 40 MPa under a 35 degrees C curing temperature. (2) Mortar with finer CFBC ash as an activator had higher compressive strength and lower absorption. (3) A proper mass ratio of GGBFS to CFBC ash is necessary for engineering applications. The present findings indicate that to maximize compressive strength, the particle size and the mass ratio of CFBC ash to GGBFS must be considered. According to the result, the type A ash with 3:7 mass ratio of CFBC ash to GGBFS is recommended.