Claims
- 1. A process for synthesizing a hydraulic binder from natural calcium sulfate or synthesized calcium sulfate, consisting in treating said calcium sulfate to form:a hydraulic binder comprising anhydrite III or α anhydrite comprising: a heating the calcium sulfate from ambient temperature to a temperature in the range 220° C. to 350° C. depending on the characteristics of the calcium sulfate in the treating step; rapidly quenching the product obtained by reducing its temperature from 220° C.-350° C. to less than 80° C. in less than two minutes, for stabilizing the α anhydrite by crystallographic blocking and fixing; and obtaining an hydraulic binder that contains more than 70% of stable, soluble anhydrite III or α anhydrite.
- 2. A process according to claim 1, characterized in that the heating temperature is in the range of 300° C.-310° C.
- 3. A process according to claim 1, characterized in that the quenching temperature is in the range 40° C. to 50° C.
- 4. A process according to claim 1, characterized in that the temperature is raised in a period of 10 to 40 minutes depending on the nature and grain size of the calcium sulfate.
- 5. A process according to claim 4, characterized in that prior to treatment, the treated calcium sulfate comprises 0 to 20% of water, and its grain size is in the range 0 to 30 millimeters (mm).
- 6. A process according to claim 5, characterized in that the treated calcium sulfate comprises 5% to 15% of water and its grain size is in the range 0 to 10 mm.
- 7. A hydraulic binder that can be used as a cement comprising anhydrite III or α anhydrite obtained by the process according to any one of claims 1 to 6.
- 8. A hydraulic binder that can be used as a cement comprising anhydrite III or α anhydrite obtained by the process according to any one of claims 1 to 6, characterized in that it contains more than 90% of stable or soluble anhydrite III or α anhydrite.
- 9. A hydraulic binder that can be used as a cement comprising anhydrite III or α anhydrite obtained by the process according to any one of claims 1 to 6, characterized in that the mechanical strength is: 22 Mpa at 24 hours; 30 Mpa at 8 days; more than 40 Mpa at 14 days.
PRIORITY CLAIM
This is a U.S. national stage application of international application No. PCT/FR99/00312, filed on Feb. 12, 1999. Priority is claimed from that application.
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/FR99/00312 |
|
WO |
00 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO00/47531 |
8/17/2000 |
WO |
A |
US Referenced Citations (3)
Foreign Referenced Citations (1)
Number |
Date |
Country |
9008111 |
Jul 1990 |
WO |
Non-Patent Literature Citations (1)
Entry |
Gerhartz W. et al., “The CAS04-H20 System” Ullmann's Encyclopedia of Industrial Chemistry, Benzyl Alcohol to Calcium Sultate, vol. A4, pp. 556-569. |