What is the difference between fireclay mortar, high alumina mortar and basic mortar?

Chemistry. Fireclay mortar is 30–42% Al₂O₃ with the rest silica and binder, rated to about 1400°C — used with fireclay bricks. High alumina mortar (HA-50 to HA-80) carries 50–82% Al₂O₃ to match the brick course it lays, rated up to 1750°C. Basic mortar is 85–92% MgO, used with magnesia and dolomite bricks in steel converters and cement kiln burning zones. Using the wrong chemistry creates a chemically incompatible joint that cracks, spalls or melts at temperature.

What is the difference between air-setting, heat-setting and hydraulic-setting mortars?

Air-setting mortars develop strength on drying at room temperature — convenient for repairs that cannot be heated. Heat-setting (ceramic-bonded) mortars are weak when laid but develop high refractoriness at 800–1000°C — used for the strongest hot-face joints. Hydraulic mortars contain calcium aluminate cement and set wet, like a fast-curing castable. We help match the setting type to your installation schedule and dry-out plan.

How thick should a refractory brick joint be?

Generally 1–3 mm for dense fireclay and high alumina brick courses, 1–2 mm for basic and MgO-C brick courses (where thinner is always better for slag resistance), and 3–6 mm for insulating fire bricks and acid-proof tiles. Thicker joints lower the overall lining strength and become the first failure point. Apply mortar to BOTH the bed and the brick face (buttered joint) for full contact.

Do you supply acid-proof mortars for chemical plant applications?

Yes. We stock furan resin mortar (best resistance to most strong acids except HF), phenolic resin mortar, and potassium silicate mortar for milder duty and high-temperature acid environments up to 1000°C. These are paired with Crown Ceramics acid-proof bricks and tiles to form the complete acid-resistant lining system, including grout and primer.

Which brands of refractory mortar do you supply?

We are an authorised dealer for Mahakoshal Refractories — covering their full mortar range from fireclay to HA-80, basic, and insulating grades. We also stock CUMI Super Refractories and Calderys mortars for matching their proprietary brick chemistries, plus Crown Ceramics acid-proof mortars. Same-day dispatch from Delhi for standard grades.

Refractory Mortars: Fireclay, High Alumina, Basic & Acid-Proof | Mahakoshal

PRODUCT OVERVIEW

Refractory mortars are fine-grained bonding materials used to lay refractory bricks, fill expansion joints, and repair small areas of furnace lining. The right mortar matches the brick chemistry — fireclay mortars for fireclay bricks, high alumina mortars for high alumina linings, basic mortars for magnesia and dolomite zones — so the joint chemistry stays consistent with the surrounding refractory mass. Available in air-setting, heat-setting (ceramic-bonded) and hydraulic-setting variants depending on the application.

$Refractory Mortars$

KEY PROPERTIES

Al₂O₃ Range

30 – 95% (grade-dependent)

Setting Type

Air-setting / Heat-setting / Hydraulic

Joint Thickness

1 – 4 mm typical

Service Temp

Up to 1750°C (HA-80 grade)

Form

Wet ready-to-use OR dry powder + water

Shelf Life

6 months sealed (wet); 12 months (dry)

APPLICATIONS

Brick jointing and bedding for refractory linings

Surface finishing of cast or rammed refractory shapes

Expansion joint filling in long brick courses

Hot-face patching of small eroded areas

Anchor pocket filling around stainless steel anchors

Boiler refractory brick laying — water wall + roof

Acid plant tile and brick lining (acid-proof grades)

TECHNICAL SPECIFICATIONS

Grade	Al₂O₃	Bulk Density	Application	Max Temp
Fireclay Mortar	30-42%	1.85 g/cc	Fireclay brick jointing	1400°C
50% Al₂O₃ Mortar	50-55%	2.20 g/cc	Mid-range alumina bricks	1600°C
70% Al₂O₃ Mortar	68-72%	2.45 g/cc	High alumina 70% bricks	1700°C
80% Al₂O₃ Mortar	78-82%	2.60 g/cc	High alumina 80/90% bricks	1750°C
Magnesia Mortar	—	2.70 g/cc	Magnesia / MgO-C brick zones	1700°C
Insulating Mortar	40-50%	1.10 g/cc	IFB jointing	1400°C
Acid-Proof Mortar	—	1.95 g/cc	Acid-proof bricks / tiles	500°C

* Test conditions: IS 1528 (India) / ASTM C-133 / EN 1402. Values are typical — exact data sheets available on request.

AVAILABLE GRADES

Fireclay Mortar50% Al₂O₃ Mortar70% Al₂O₃ Mortar80% Al₂O₃ MortarMagnesia MortarInsulating MortarAcid-Proof Mortar (Furan / Potassium Silicate)

INSTALLATION NOTES

1
Match the mortar chemistry to the brick — never use fireclay mortar with high alumina bricks above HA-70
2
Mix dry powder with measured potable water (typically 22–30% by weight) until smooth
3
Apply joint thickness of 1.5–3 mm using a steel trowel on bedding surface AND brick face
4
Lay bricks within 10 minutes of mortar application before initial set
5
Hammer-tap each brick into final position — never adjust after the mortar has stiffened
6
Allow 24 hours air-set before any heat-up; first heat-up at 25°C/hour to 200°C with a 4-hour soak
7
For acid-proof furan mortar: 7-day cure at 25°C before any chemical exposure

WHY BUY FROM SHANKER AGENCIES

Shanker Agencies stocks the full Mahakoshal Refractories mortar range — fireclay, high alumina (HA-50 to HA-80), basic and insulating grades — alongside Crown Ceramics acid-proof furan and potassium silicate mortars. Our engineers will match the mortar chemistry to your brick spec so the joint never becomes the weakest link in the lining.

PARTNER BRANDS

Mahakoshal Refractories CUMI Super Refractories Calderys India

FREQUENTLY ASKED QUESTIONS

A refractory mortar is a fine-grained bonding material used to lay refractory bricks and fill the joints between them. It is supplied as a wet ready-to-use paste or a dry powder mixed with water on site. Beyond brick laying, mortars are also used for surface finishing of cast linings, expansion joint filling, and small hot-face patch repairs. The mortar must be chemistry-matched to the brick — fireclay mortar with fireclay bricks, high alumina mortar with HA-70/80, basic mortar with magnesia bricks.

QUICK INFORMATION

Max Temperature

1750°C

MORE IN UNSHAPED REFRACTORIES

Low Cement Castables (LCC)

High-strength castables with 3–5% cement — the industry standard for steel ladles

Ultra Low Cement Castables (ULCC)

Premium monolithics with <1.5% cement for the most demanding high-wear zones

Ramming Masses

Dense dry/moist masses for jointless induction furnace linings

Gunning Materials

Pneumatically applied repair mixes — minimise downtime with in-situ hot repairs

READY TO ORDER OR NEED A SAMPLE?

Our engineers can recommend the exact grade for your application. Sample kits available for trials. No minimum order on standard grades.

Get a Quote Call +91 98999 57888

REFRACTORY MORTARS