International Journal of Minerals, Metallurgy and Materials
Volume 17, Number 1, February 2010, Page 108
DOI: 10.1007/s12613-010-0119-9
Corresponding author: Xiao-ming Liu E-mail: xliu35@wisc.edu
© University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg 2010
Relationship between the microstructure and reaction performance
of aluminosilicate
Xiao-ming Liu
1,4)
, Heng-hu Sun
2)
, Xiang-peng Feng
3)
, and Na Zhang
4)
1) School of Resource and Safety Engineering, China University of Mining & Technology, Beijing 100083, China
2) School of Engineering and Computer Science, University of the Pacific, Stockton CA 95211, USA
3) Shougang Environmental Protection Industry Department, Beijing 100041, China
4) Department of Civil and Environmental Engineering, University of Wisconsin, Madison WI 53706, USA
(Received: 29 December 2008; revised: 5 February 2009; accepted: 23 February 2009)
Abstract: A systematic study was conducted to comprehend the mechanism of thermal activation of silica-alumina materials by using
29
Si
and
27
Al magnetic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. The reaction performance of silica-alumina-based
materials with different molar ratios of Si/Al, which were thermally activated, was also investigated. With the increase in calcining tempera-
ture, the coordination of Al in metakaolin becomes four, five, and six firstly, and then transforms completely to four and six. It is indicated by
identical coupled plasma optical emission spectroscopy (ICP) and NMR that, the reaction performance of monomeric silicate anions is better
than that of polymeric silicate anions which are primarily cross-linked in the alkali solution. Moreover, it also shows that the thermal activa-
tion temperature, cooling method, and the molar ratio of Na/Ca have remarkable effects on the reaction performance.
Keywords: calcination; aluminosilicate; reaction performance; microstructure, nuclear magnetic resonance
[This work was financially supported by the National Key Technologies R&D Program of China (No.2006BAC21B03) and the National
Natural Science Foundation of China (No.50674062).]
1. Introduction
It is significant to investigate how to use silica-alumina
minerals to produce silica-alumina-based cementitious ma-
terials, because more than 65% of the earth crust consists of
silica-alumina materials. Silica-alumina-based cementitious
materials are environment-friendly products which have
lower energy consumption in the process of production. It
has been demonstrated that a wide range of waste sil-
ica-alumina materials can be used to produce sil-
ica-alumina-based cementitious materials with excellent
properties [1-5]. The hydration of the cementitious material
is engendered by the copolymerization of individual silicate
and aluminate generated from the dissolution of silicon and
aluminum in raw materials. The basis of this process is that
the solution induces a certain amount of Si and Al atoms to
dissolve or hydrolyze from the feedstock such as alumi-
nosilicate. These atoms form geomonomers in the solution
and then polycondense to form rigid networks under the
“trigger” of applied heat [6-9].
The hydration process and hydrates of silica-alumina-
based cementitious materials, which have been studied in
recent years, are different from those of the ordinary Port-
land cement [10-12]. However, up to now, there is no inte-
grated conclusion which has been established on exact rela-
tionships between the distortion degree of silica-alumina-
based raw materials and the reaction performance. To be
further considered, silicon is always four-coordinate, while
aluminum ions can be four-coordinate or six-coordinate in
aluminosilicate structures. Therefore, it is possible that the
coordination number of aluminum in raw materials plays a
significant role in its eventual bonding in hydrates [13].
Moreover, a detailed knowledge about the relationship be-