Sustainable clinker-free solid waste binder produced from wet-ground granulated blast-furnace slag, phosphogypsum and carbide slag

Abstract

Reducing or replacing cement clinker is one of the most important ways for the sustainable development of the cement industry. In the present work, three types of industrial solid wastes, wet ground granulated blast-furnace slag (WGGBS), phosphogypsum (PG) and carbide slag (CS), were designed as clinker-free, high-performance ternary binders for applications such as construction and underground filling. The results show that the wet grinding process with PG and CS can synergistically excite the GGBS and make the compressive strength of the sample surpass that of the cement, reaching 45.6 MPa. However, its cost and carbon emissions are only 51% and 12% of cement, which is expected to completely replace cement as a low carbon cementitious material. In addition, with the increase of PG content and the decrease of CS content, the ettringite content increased significantly and its microstructure changed from long and thin to short and thick, and the porosity gradually decreased, which was beneficial to the development of compressive strength. The type and morphology of hydration products and the amount of crystalline hydrates are closely related to the ratio of PG/CS, and explain the development of compressive strength and microstructure of the clinker-free ternary binder.