Compressive strength and hydration process of ground granulated blast furnace slag-waste gypsum system managed by wet grinding

摘要

Replacement of Portland cement by industrial wastes has been accepted as a potential way to reduce carbon emissions. Ground granulated blast furnace slag (GGBS), desulphurization gypsum (DG), and phosphogypsum (PG), known as the common industrial wastes, were used in this study. Binders comprised of GGBS and waste gypsum were designed to develop a novel low carbon material; in order to promote the reactivity raw materials were processed by wet grinding. Compressive strength was examined and hydration process was researched by XRD, TG, NMR, SEM, and MIP. Results showed that wet grinded PG (WGPG) and wet grinded DG (WGDG) were able to greatly augment compressive strength of wet grinded GGBS (WGS) system. The reasons were attributed to the accelerated formation of ettringite and the reduced porosity. On the one hand, the presence of ettringite could construct the crystal skeleton resulted in the hardening of system accelerated. On the other hand, the constantly produced C-S-H gel densified the microstructure and decreased the porosity significantly. Moreover, in comparison with WGDG-WGS system, the early strength of WGPG-WGS system was lower caused by the retardation effect of phosphorus in PG. Results was expected to be used for the design of low carbon materials. (C) 2019 Elsevier Ltd. All rights reserved.