Synthesis of calcium sulfate whiskers via acidification exploiting FGD gypsum for improved binder properties

Abstract

This research focuses on the synthesis of calcium sulfate whiskers using FGD (Flue Gas Desulfurization) gypsum as raw material through the acidification method and their utilization in gypsum binders. The acidification method using H2SO4 (1.5 mol/L) is distinguished by its sustainability and resource efficiency. The addition of Calcium Sulfate Whisker as an activator enhances the binder's properties by increasing its strength, durability, resistance to environmental factors, and overall structural integrity. The effects of different reaction parameters on the properties and microstructure of CSW have been studied. This research has the potential to bring about significant improvements in various applications, from construction materials to industrial products. Calcium Sulfate Whiskers act as pore fillers within the binder matrix which reduces the porosity and helps to decrease water absorption up to 12%. CSW is characterized by its needle-like structure, which provides an intricate network within the binder matrix. SEM images showed the strong interfacial bonding between the whiskers and the binder matrix, enhanced by the rough surface of the whiskers, which improves mechanical interlocking and adhesion. CSW demonstrates its potential as a highly active component in the binder. The whiskers facilitate efficient nucleation sites, accelerating the hydration reactions within the binder and enhancing the overall performance of the binder. CSW incorporation in the binder increases the compressive strength by up to 21.6% and flexural strength by 37%. The exceptional mechanical strength and efficient nucleation sites provided by CSW contribute to an increase in the workability of the binder and make it suitable for interior as well as exterior applications. These interconnected facets collectively position the project as a valuable and highly pertinent contribution, where sustainable innovation and improved material properties are of paramount importance. It potentially reduces the need for traditional additives with higher environmental impacts, making the binder formulation more eco-friendly.