Brick/mortar joint behavior

Figure 25 describes the thermal expansion of the silica KD brick-only and the silica KD brick/mortar composite samples. The mortar-only sample was also tested. The brick-only and the brick/mortar composite samples are similar except for temperatures above about 1100°F. The mortar softens considerably, as reflected in the mortar-only sample. Due to the confinement of the mortar within the mortar joint in the brick/mortar composite sample, the mortar maintains reasonable strength. This confirms that the true compressive stress-strain behavior of mortar must be tested with the mortar contained in the mortar joint (2). Containment of the mortar is an important and necessary parameter in testing the thermomechanical behavior of mortar. 

Figures 30, 31, and 32 show the creep behavior of the brick-only, mortar-only, and brick/mortar composite samples at 816°C (1500°F), 1094°C (2000°F), and 1372°C (2500°F), respectively. At all three temperatures the brick-only and brick/mortar composite samples exhibit insignificant creep. The mortar-only samples (no confinement) exhibit relatively considerable creep response. The creep tests also confirm that unconfined mortar tests do not replicate the true confined behavior of the mortar in the mortar joint.

Figures 33 and 34 show the temperature dependent thermal expansion of the silica KN brick-only, mortar-only, and brick/mortar composite samples. The interpretive results are quite similar to the interpretive results of the silica KD tests. These results also show that the mortar-only (unconfined mortar) tests do not reflect the true confined thermomechanical behavior of mortar in mortar joints. Strength patterns as a function of temperature are also similar to the silica KD brick.

Schacht CA. The effect of mortar joints on the thermomechanical behavior of refractory brick lining systems in cylindrical vessels. AISE Spring Conference, Birmingham, AL, March 1985. 

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