الفهرس 
COVEROnly 14 pages are availabe for public view
 |  | from | 182 |  |  |
| | | from | 182 | | |
Abstract
The hydration behavior of tricalcium aluminate has been studied in water and in different alkali sulphate solutions, namely 1%Na2SO4, 1%K2SO4 and 1%MgSO4.
Also, the effect of gypsum and gypsum + lime on the hydration reaction of tricalcium aluminate at room temperature has been investigated in water and in the above mentioned sulphate solutions.
The hydration process was carried out in an excess amount of alkali sulphate solutions and followed for various time intervals from 2 minutes up to 7 days.
The results obtained from XRD analysis and SEM have revealed that the only phase found in all the systems was the ettringite phase except in the following two cases:-
1-In case of the hydration of tricalcium aluminate in water,the phase obtained was hydrogarente due to the absence of sulphate ions.
2- In the presence of 1%MgSO4 solution, the existing phases were tetracalcium aluminate hydrate and gypsum as a result of decreasing the alkalinity of the medium which retards the hydration reaction and prevents the ettringite formation.
In all cases, the results obtained from the X-ray diffraction analysis and SEM are in the good agreement with those appeared from the solution composition.