What type of failure can result from improperly installed mortared joints in firebrick?

Improperly installed mortared joints in firebrick can lead to cracking and spalling due to several factors related to the performance and integrity of the brickwork. Firebrick is specifically designed to withstand high temperatures, but when the joints are not installed correctly, it can create weak points within the structure.

Cracking may occur as thermal expansion and contraction take place with temperature fluctuations. If the mortar does not have the correct flexibility or bonding ability, the stresses from thermal cycling can lead to cracks in the mortar and the firebricks. Spalling refers to the breaking away of surface material, which can also result from the same thermal stresses or due to moisture infiltration which can expand when it freezes. Both cracking and spalling compromise the firebrick's ability to function effectively in high-temperature applications, thereby impacting the overall durability and performance of the installation.

While the other options touch on different aspects that could be of concern, they do not directly relate to the immediate structural and functional impacts caused by improperly installed mortar.