Mineral Waste Coupled with Boron Oxide for Producing Active Belite Cement Clinker: Fid-Bau Portal

Mineral Waste Coupled with Boron Oxide for Producing Active Belite Cement Clinker

Liu, Yan-jun / Zheng, Yong-Chao

This paper presents a laboratory study on active belite cement clinker using boron oxide as dopant to stabilize high temperature phases of Dicalcium silicate (C₂S), and mineral waste as siliceous materials in complete replacement of clay. The clinker samples were soaked in Muffle Furnace at different burning temperatures and for various time durations, and then, cooled down to room temperature using air blower. Quantitative X-ray Diffraction analysis (QXRD) by Rietveld method indicates that major mineral components are Dicalcium Silicate (C₂S), Ferrite (C₂ (A_0.48F_1.52) O₅) and trace amount of Tricalcium Silicate (C₃S) in the cement clinkers. Among them, Dicalcium silicate is over 85 percent, Ferrite around 10 percent and Tricalcium silicate less than 10 percent. Thermogravimetric and Differential Scanning Calorimetric (TGA-DSC) spectrum shows that there is no significant phase change while cement clinker was cooling down, which means significant amount of high temperature polymorphic C₂S was stabilized during cooling process. It is agreeable with the results from QXRD analysis. Specifically, among polymorphic belite phases, α_H-C₂S accounts for around 66% of cement clinker, and α_L-C₂S for about 22% of cement clinker. In addition, massive belite phase was identified by Scanning Electronic Microscope (SEM) analysis and Light Microscopy analysis. At last, the mechanical tests on active belite cement show that active belite cement clinker has a slow strength development at early ages, but rapid strength gain at 28 days in comparison with belite clinker without adding boron oxide. Thus, this active belite cement clinker demonstrates very promising prospect in sustainable cement industry development.