THE MECHANICAL PROPERTIES OF THE DIFFERENT COOLING REQUIREMENTS OF HIGH-TEMPERATURE PLASTER

This experimental research investigates changes in the mechanical properties of plaster under the influence of high temperature. To achieve this objective, four types of plaster cement, lime, gypsum, and hybrid mortar (cement + lime) were manufactured. Prism samples with dimensions of 40x40x160 mm were kept in a laboratory from 28 to 90 days. Mortar samples were exposed to 20, 125, 250, 500, 600, and 900 degrees C. Half of the samples were air-cooled (under laboratory conditions), while the other half were cooled through the sprinkler (spray water) method. After cooling the samples, the bending, tensile, and compressive strength tests were performed. Test results were examined statistically to determine the influence of high temperature on the mortar, which revealed that at a temperature of 125 degrees C, an increase was observed in bending strength and pressure resistance of all air-cooled mortar types; meanwhile, a decrease in bending strength and pressure resistance was found under the other temperatures. For the water-cooled mortar types, bending strength and pressure resistance values could not be identified because of the occurrence of fusion in all the mortar samples.