Refractory Materials

Refractory Mortar

Service Temp Up to 3,400°F

Forms Air-Set & Heat-Set

Application Trowel · Brush · Dip

Bond Types Chemical & Ceramic

Packaging 5-gal pails & 50-lb bags

What we supply

The bond that holds your furnace together.

Refractory mortar is not a commodity. Joint thickness, brick composition, thermal cycling frequency, and chemical atmosphere all determine the correct formulation. We stock and source the full spectrum — from dense fireclay mortars for coke ovens to high-alumina and silica bonds for specialty kilns and boilers.

Fireclay Mortar

The industry workhorse. Dense, plastic consistency bonds fireclay and super-duty brick in furnaces, boilers, incinerators, and fireplaces. Rated 2,600–2,800°F. Available air-set and heat-set.

High-Alumina Mortar

Alumina from 50% to 90%+ for extreme-duty applications. Resists slag, iron, and aggressive fluxes. Matched to high-alumina brick in petrochemical, steel, and non-ferrous installations up to 3,200°F.

Silica & Magnesia Mortar

Purpose-built for silica brick coke ovens and magnesia-chrome linings. Chemical compatibility is critical — we match mortar chemistry to brick chemistry precisely.

Air-Set Mortar

Chemical bond activated at room temperature. Ideal for cold repairs and installations where early strength before heat-up is required. Full ceramic bond develops in service.

Heat-Set (Ceramic Bond)

Develops full strength only after firing. Used where maximum joint density and thermal shock resistance are required. The ceramic glass phase formed during cure provides superior bond permanence.

Phosphate & Specialty

Phosphate-bonded, colloidal silica-bonded, and ultra-low-cement formulations for severe cycling, reducing atmospheres, and alkali exposure.

Matching mortar to brick: why it matters

The mortar joint is the weakest point in any brick system — unless the mortar is correctly specified. Mismatched thermal expansion coefficients cause joint failure even when the brick itself survives. Our team can review your brick specs and recommend the correct mortar chemistry, bond type, and consistency for your operating conditions.

Product specifications

Grade	Alumina %	Max Temp	Bond Type	Best For
Standard Fireclay	30–35%	2,600°F	Air-Set / Heat-Set	Fireplaces, boilers, general furnace work
Super-Duty Fireclay	38–45%	2,800°F	Air-Set / Heat-Set	Industrial furnaces, kilns, incinerators
High-Alumina 50	50%	2,900°F	Chemical / Ceramic	Reheat furnaces, glass tanks
High-Alumina 70	70%	3,100°F	Ceramic Bond	Petrochemical, specialty kilns
High-Alumina 90+	90–99%	3,200°F+	Ceramic Bond	Extreme-duty, reducing atmospheres
Silica Mortar	<1%	3,000°F	Ceramic Bond	Coke ovens, silica brick systems
Magnesia Mortar	—	3,400°F	Ceramic Bond	Basic oxygen furnaces, EAF roofs

Application guidelines

Proper application is as important as product selection. Joints should be buttered on all bonding faces at the correct consistency — peanut butter for trowel work, thinner for dipping or brushing.

Trowel: standard brick and block work, 1/16"–3/16" joints
Dip: thin, consistent coating for close-tolerance joints
Brush or spray: large surfaces, sprung arches, thin sections
Always follow the manufacturer's dry-out schedule before high-temp operation

Storage & shelf life

Refractory mortar is moisture-sensitive. Bagged material should be stored off the ground on pallets in a dry location. Premixed pail mortars must not freeze.

Bagged mortars: 12-month shelf life in dry storage
Premixed pails: 6–12 months sealed; use within 30 days of opening
Do not over-dilute with water — weakens the bond
Seal partially used pails; keep away from temperature extremes

Ready to move forward?

Refractory Mortar — sourced, specified, delivered.

Request a Mortar Quote