Effect of Different Kinds of Zinc (II) on Early Hydration of Calcium Aluminate Cement
- PDF / 871,319 Bytes
- 5 Pages / 595.276 x 841.89 pts (A4) Page_size
- 13 Downloads / 225 Views
925
https: //doi. org/10.1007/s11595-020-2338-x
Effect of Different Kinds of Zinc (II) on Early Hydration of Calcium Aluminate Cement WANG Jingran1, ZHANG Jinhua1, TAN Hongbo2, MA Baoguo2
(1. The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081,China; 2. State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China)
Abstract: The early hydration of calcium aluminate cement (CAC) with different kinds of zinc (II), such as ZnSO4•7H2O, ZnO, Zn(NO3)2•6H2O and ZnCl2, was analyzed. Changes in consistency, setting time, hydration heat flow, hydration heat amount, ion concentration in solution, and hydration products were found upon the addition of different Zn2+. The water consumption of standard consistency of CAC is decreased with different Zn2+. Zn2+ can delay the initial hydration of CAC. The induction period of cement with Zn2+ is longer than that of CAC, especially the reaction time of the acceleration period is extended. Zn2+ can promote hydration hydrate of CAC at 24 h. The characteristic diffraction peaks of CA and CA2 in CAC with different Zn2+ are significantly reduced. It can inhibit the formation of CAH10 and promote the formation C3AH6 and AH3 in hydration products at 24 h. Key words: zinc; calcium aluminate cement; ion concentration; hydration
1 Introduction With development of human civilization and progress of science and technology, heavy metal pollution has drawn considerable attention. Heavy metal zinc pollution exists widely in zinc manufacturing, packaging, painting, coating and other industries[1-3]. Generally, zinc salt is a collaborative inorganic retarder, which can reduce the hydration heat, delay the setting time of cement, so that the cement paste has good plasticity. As the retarder of ordinary Portland cement, zinc salt is usually deemed to form an insoluble film on the surface of cement particles[4-6]. Studies have also shown that the hydration generated during the hydration of Zn2+ or other heavy metal and ordinary Portland cement generates insoluble hydration products, which cover the surface of cement particles and hinder further hydration of cement[7-10].
© Wuhan University of Technology and Springer-Verlag GmbH Germany, Part of Springer Nature 2020 (Received: Oct.29, 2019; Accepted: June 18, 2020) WANG Jingran(王景然): Ph D; E-mail: [email protected] Funded by National Natural Science Foundation of China (No.51802235), and State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology (No. SYSJJ2015-07)
Compared with high alkalinity ordinary Portland cement, calcium aluminate cement (CAC) has low alkalinity and does not form OH- during hydration[11]. Hydration products of CAC are composed of stable Ca 3 Al 2 O 6 ·6H 2 O (C 3 AH 6 ), Al 2 O 3 ·3H 2 O (AH 3 ) and metastable compounds CaAl 2 O 4 ·10H 2 O (CAH 10 ), Ca 2Al 2O 5·8H 2O (C 2AH 8) and Ca 4Al 2O 7·xH 2O (x=7, 11, 13, 19), which are similar to metastable hydration products CaAl-LDHs[12].
Data Loading...
