A-A-54115
Marking of immediate containers not as specified.
Instructions missing, incorrect, incomplete, or illegible.
Tests. Tests shall be conducted to determine compliance with specification requirements.
Preparation of test specimens. The preparation of test specimens shall be conducted at a temperature of 70 to 75oF, and 2.5 g to 1.0 ml (standard consistency).
Consistency. Procedure for consistency test shall be as described in American Dental Association (ADA) Specification No. 30 for Dental Zinc Oxide-Eugenol Type Restorative Materials, except that the 120 gram load shall be applied for 7 minutes.
Setting time. A mix of cement using 1.25 g of powder and 0.5 ml of liquid shall be loaded into a polyethylene crown for cap with approximate internal dimensions of 9.5 mm diameter by 7 mm deep. Type A durometer hardness shall be determined as described in ASTM Designation D2240. Readings shall be taken at 0.5 minute intervals. Hardness shall be plotted against time, and the setting time in minutes shall be interpolated value of time when durometer reading equals 50. Setting time shall be reported to the nearest 0.5 minute.
Compressive strength. Procedure for compressive strength test shall be as described in ADA specification No.30, except that the specimens shall be stored for one week in water at 37oC before crushing. The equipment used for determining compressive strength shall be the Instron Corporation’s Test Machine, or other suitable equipment, provided prior approval is received from the contracting officer. Testing conditions on the Instron test machine shall be as follows:
a. Crosshead speed of 0.2 inch per minute.
b. Force range of 1000 pounds.
c. Chart speed of 10 inches per minute.
The value for compressive strength shall be reported as the average of three or more from a group of five specimens and shall be rounded off to the nearest 50 pounds. If the values for individual specimens fall more than 15 percent below the average of the five, they shall be discarded and the average of the remaining specimens shall be reported. In case more than two of the specimens are eliminated, the test shall be repeated.
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