Refractory Mortar

Refractory mortar is a jointing material laid between refractory bricks to bond them together and seal the joints against hot gas and flame penetration. It is used when building or repairing furnace, kiln and boiler brickwork with Fire Clay Bricks, High Alumina Bricks and similar shapes, and for sealing furnace joints.

Refractory mortar is available for maximum service temperatures of 1300°C to 1700°C, depending on the grade. Fire clay mortars sit toward the lower end and high alumina mortars toward the upper end. The mortar should be rated at least as high as the bricks it joins, so it does not become the weak point in the lining.

Air-setting refractory mortar forms a chemical bond and gains handling strength as it dries, while heat-setting mortar develops its full strength through a ceramic bond when the lining is fired. Air-setting grades are useful where joints must hold before first firing; heat-setting grades suit linings that will reach high temperature across the whole joint.

Choose a refractory mortar whose chemistry matches the brick: fire clay mortar for Fire Clay Bricks and high alumina mortar for High Alumina Bricks. Grades range from 35% to 80% Al2O3, and matching the alumina level keeps thermal expansion and chemical behavior compatible between brick and joint. Tell us the brick type and grade in your enquiry.

Refractory mortar joints of 1 to 3 mm are recommended. Thin joints reduce the amount of weaker jointing material in the hot face and limit paths for gas and flame penetration. Bricks should be dipped or buttered so the joint is fully filled, with excess mortar removed before it sets.

Refractory mortar is supplied either as a ready-mix paste or as a dry powder that is mixed with water on site. Ready-mix paste is convenient for smaller jobs and repairs, while dry powder is practical for large brickwork and longer storage. Mix powder to a consistency that allows thin 1 to 3 mm joints.

Refractory mortar in this catalogue is referenced to IS 6 and ASTM C199. Grades are selected by service temperature and alumina content to suit the brick type. If you need particular test documentation for your order, mention it in your enquiry and we will confirm what is available.

Refractory mortar is classified under HS code 38160000, the heading for refractory cements, mortars, concretes and similar compositions. It shares this code with Castable Refractory and Ramming Mass, while refractory bricks are classified separately, which is worth noting when preparing documents for a mixed refractory shipment.

Refractory mortar is packed in 20 kg or 25 kg bags, or in buckets for ready-mix paste. It can be loaded in the same container as Fire Clay Bricks, High Alumina Bricks or other refractory and insulation products, shipped FCL or LCL from Nhava Sheva (JNPT) or Mumbai. Quantities are usually estimated from the number of bricks and the joint thickness.