scholarly journals Chloride Transport of High Alumina Cement Mortar Exposed to a Saline Solution

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Hee Jun Yang ◽  
Sung Ho Jin ◽  
Ki Yong Ann
Keyword(s):  
Chloride Transport ◽  
Setting Time ◽  
High Alumina ◽  
Cement Matrix ◽  
X Ray Diffraction ◽  
Exposure Test ◽  
Aluminum Oxides ◽  
Alumina Cement ◽  
High Alumina Cement ◽  
Chloride Profile

Chloride transport in different types of high alumina cement (HAC) mortar was investigated in this study. Three HAC cement types were used, ranging from 52.0 to 81.1% of aluminum oxides in clinker. For the development of the strength, the setting time of fresh mortar was measured immediately after mixing and the mortar compressive strength was cured in a wet chamber at 25 ± 2°C and then measured at 1–91 days. Simultaneously, to assess the rate of chloride transport in terms of diffusivity, the chloride profile was performed by an exposure test in this study, which was supported by further experimentation including an examination of the pore structure, chloride binding, and chemical composition (X-ray diffraction) analysis. As a result, it was found that an increase in the Al2O3 content in the HAC clinker resulted in an increase in the diffusion coefficient and concentration of surface chloride due to increased binding of chloride. However, types of HAC did not affect the pore distribution in the cement matrix, except for macro pores.

Hydration of sodium phosphate-modified high alumina cement

1994 ◽  
Vol 9 (5) ◽  
pp. 1291-1298 ◽  
Author(s):  
Weiping Ma ◽  
Paul W. Brown
Keyword(s):  
Isothermal Calorimetry ◽  
High Strength ◽  
High Alumina ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Alumina Cement ◽  
X Ray ◽  
Morphological Variations ◽  
High Alumina Cement ◽  
Sodium Phosphates

High strength can be achieved in high alumina cement (HAC) through the incorporation of phosphate-based additions at levels of 10 and 20 wt. %. In order to establish the mechanism that results in higher strength, the effects of a variety of condensed sodium phosphates (NaPO3)n, (NaPO3)n · Na2O, Na5P3O10, and (NaPO3)3 were studied. The influence of these additions on the kinetics of hydration was studied using isothermal calorimetry. The phosphatic additions enhanced reactivity, but x-ray diffraction analyses did not reveal evidence of new crystalline phosphate-containing hydration products. Microstructural evolution was examined in real time using environmental SEM, and hydration products exhibiting distinct morphologies were observed. The features exhibited ranged from amorphic to polygonal shapes, plates, and fibers. These frequently formed between crystalline calcium aluminate hydrate grains and by doing so appear to provide a means to enhance the strengths of these cements. In spite of the morphological variations, companion energy dispersive x-ray analysis showed that the compositions of these products did not vary widely. Their ranges of compositions are 52-60 wt. % Al2O3, 20-26 wt. % P2O5, and 20-24 wt. % CaO.

The influence of NaCl on the reactivity of high alumina cement in water: Pore-solution and solid phase characterization

1994 ◽  
Vol 9 (6) ◽  
pp. 1533-1539 ◽  
Author(s):  
S. Goñi ◽  
M.T. Gaztañaga ◽  
J.L. Sagrera ◽  
M.S. Hernández
Keyword(s):  
Pore Solution ◽  
Solid Phase ◽  
High Alumina ◽  
Sodium Ions ◽  
X Ray Diffraction ◽  
Mechanical Pressure ◽  
Alumina Cement ◽  
X Ray ◽  
High Alumina Cement ◽  
Phase Characterization

The influence of NaCl (3% of Cl−by weight of cement) on the reactivity of High Alumina Cement (HAC) in water has been studied over a period of one month. The changes in microstructure were monitored by x-ray diffraction and scanning electron microscopy. The pore-solution, extracted by the application of high mechanical pressure (500 MPa), was studied for the chemical composition and changes caused by chloride and sodium ions.

scholarly journals STUDY OF THE EFFECT OF PARTICULATE ADDITIVES ON THE SETTING TIME AND MICROSTRUCTURE OF HIGH-ALUMINA CEMENT

2020 ◽  
pp. 30-37
Author(s):  
O. Gavshina ◽  
S. Yashkina ◽  
A. Yashkin ◽  
V. Doroganov ◽  
I. Moreva
Keyword(s):  
Setting Time ◽  
High Alumina ◽  
Grain Composition ◽  
Alumina Cement ◽  
High Alumina Cement ◽  
Chemical Phase ◽  
Ceramic Binder ◽  
Similar Chemical ◽  
Initial Setting ◽  
Microscopy Method

the paper is devoted to a full-scale study of corundum modifying dispersed additives (reactive, tabular, dispersing alumina) and artificial ceramic binder, their impact on high-alumina cement microstructure and setting time. Artificial ceramic binders are characterized by similar chemical, phase and grain composition with modifying corundum additives and characterized by the presence of particles less than 100 nm (up to 0.5%). The studied materials are finely dispersed polyfractional systems from 0.1 to 13 μm with a prevailing grading fraction of 2-10 μm. In this case, dispersing and reactive alumina are more coarse. Using the microscopy method it was established that the corundum additives increase packing density of high-alumina cement samples, especially with artificial ceramic binder addition. Studies of dispersed additives effect on the setting time of cement was conducted. It is established that the adding of artificial ceramic binder or dispersing alumina at 0.5% is speeding up the initial setting, but a further increasing of the additive content does not affect this indicator. The maximum reduction of setting time is caused by the introduction of 5% tabular alumina.

scholarly journals The Hydration of Heavy Metal Salts Admixtured High Alumina Cement – A X-Ray Diffraction Study

2009 ◽  
Vol 1 (2) ◽  
Author(s):  
R. Nithya ◽  
S. Barathan ◽  
M. Gopalakrishan ◽  
G. Sivakumar ◽  
B. Gobinath
Keyword(s):  
Heavy Metal ◽  
Diffraction Study ◽  
Metal Salts ◽  
High Alumina ◽  
X Ray Diffraction ◽  
Alumina Cement ◽  
X Ray ◽  
High Alumina Cement ◽  
Heavy Metal Salts

Study on the Properties of Ground Limestone-High Alumina Cement Gelation System

2011 ◽  
Vol 317-319 ◽  
pp. 489-497
Author(s):  
Jia Xiao ◽  
Cheng Fu Gou ◽  
Cai Yun Xu ◽  
Hao Xing ◽  
Yong Gang Jin
Keyword(s):  
Compressive Strength ◽  
Setting Time ◽  
High Alumina ◽  
Alumina Cement ◽  
Initial Setting Time ◽  
Final Setting Time ◽  
High Alumina Cement ◽  
Binder Ratio ◽  
Initial Setting ◽  
Ground Limestone

Effects of various amounts of ground limestone on the setting time, fluidity and compressive strength of high alumina cement were described in this paper. Microstructure analyses were performed by SEM. The results indicate that the initial setting time, the final setting time, the fluidity and the compressive strength of the pastes increase first and decrease later with the ground limestone content increasing, all of which reach the maximum when the ground limestone content is 3%. Meanwhile, an increase of the fineness of the ground limestone produces a shorter setting time, the fluidity of the pastes increases when the content of the ground limestone increases, and the compressive strength of the hardened pastes increases with the ground limestone content increasing and decreases with water-binder ratio increasing. The 28d strength of the pure high alumina cement paste is lower than the 3d strength, appearing the strength shrinkage, which can be improved by a proper addition of the ground limestone.

The conversion of high alumina cement

1975 ◽  
Vol 27 (91) ◽  
pp. 59-77 ◽  
Author(s):  
H. G. Midgley ◽  
Ann Midgley
Keyword(s):  
High Alumina ◽  
Alumina Cement ◽  
High Alumina Cement
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