We, Imperial World Trade Frequently Placed In Ordinary Portland Cement Mortar, Sometimes With A Little Extra Cement Or Some Fireclay Added To Make The Mixture Fireclay Mortar. A Refractory Composition Comprising Of Heat Resistant Binding System And Low Grain Size Refractory Furnaces. Mostly Used For Joining Bricks. Two Types Of Settings: Air And Heat Setting Mortar The Mortar Hardens At A Heat Above Room Temperature. The Problem With Using Regular Mortar Is That Portland Cement Can't Take The Heat. Curiously, Cement Retains Its Energy Up To Reasonably High Temperatures But Declines As It Cools Down Through About 600�° F. Ultimately All That Is Left Of The Mortar Is The Sand And Fireclay, With No Cement Binder. The Mortar Has No Strength And Easily Falls Out Of The Joints, Especially If They Are Wide. Refractory Mortar, On The Opposite Side, Is Performed With High-Temperature Cement And Carefully Selected Aggregates That Don't Expand And Tear The Mortar Apart When Heated. The International Residential Code (IRC) And International Building Code (IBC), Which Were Recently Adopted In Approximately All States And Require That Fireboxes, Smoke Chambers, And Flue Liners Be Laid With Refractory Mortar.