Effect of Heat-Treatment on the Constitution and Mechanical Properties of Some Hydrated Aluminous Cements |
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Authors: | SAMUEL J SCHNEIDER |
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Affiliation: | National Bureau of Standards, Washington, D. C. |
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Abstract: | The compound compositions of four aluminous cements were determined on anhydrous as well as hydrated specimens which had been heat-treated at temperatures between room temperature and 1400° C. Phases were identified by X-ray diffraction and differential thermal analysis. Specimens were also tested for transverse strength, dynamic modulus of elasticity, and thermal length change. A study of the dehydration characteristics of CaO - Al2O8 - 10H2O3 3CaO.Al2O3. 6H2O, and Al2O3. 3H2O was included. The data indicated that CaO. Al2O3 10H2O was the primary crystalline hydrate formed in the cements at room temperature. At 50° C., 3 CaO Al2O3-6H2O and Al2O3. 3H2O were formed as by-products of the dehydration of CaO.Al2O3.10H2O. When heated alone in an open system, CaO.Al2O3.10H2O did not convert to 3CaO. Al2O3. 6H2O and A12O3. 3H2O. A correlation between the mechanical properties and compound compositions was noted. |
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