Table of Contents
International Scholarly Research Notices
Volume 2014, Article ID 873215, 10 pages
http://dx.doi.org/10.1155/2014/873215
Research Article

Low Temperature Synthesis of Belite Cement Based on Silica Fume and Lime

1Chemistry Department, Faculty of Science, Minia University, Minia 61111, Egypt
2Chemistry Department, Faculty of Science, Al-Azhar University, Assiut 71524, Egypt

Received 17 May 2014; Revised 3 July 2014; Accepted 4 July 2014; Published 29 October 2014

Academic Editor: Tomasz Czujko

Copyright © 2014 M. A. Tantawy et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper describes the low temperature synthesis of belite (β-C2S) from silica fume. Mixtures of lime, BaCl2, and silica fume with the ratio of (Ca + Ba)/Si = 2 were hydrothermally treated in stainless steel capsule at 110–150°C for 2–5 hours, calcined at 600–700°C for 3 hours, and analyzed by FTIR, XRD, TGA/DTA, and SEM techniques. Dicalcium silicate hydrate (hillebrandite) was prepared by hydrothermal treatment of lime/silica fume mixtures with (Ca + Ba)/Si = 2 at 110°C for 5 hours. Hillebrandite partially dehydrates in two steps at 422 and 508°C and transforms to γ-C2S at 734°C which in turn transforms to α′-C2S at 955°C which in turn transforms to β-C2S when cooled. In presence of Ba2+ ions, β-C2S could be stabilized with minor transformation to γ-C2S. Mixture of silica fume, lime, and BaCl2 with the ratio of (Ca + Ba)/Si = 2 was successfully utilized for synthesis of β-C2S by hydrothermal treatment at 110°C for 5 hours followed by calcination of the product at 700°C for 3 hours.