Refractory cement is a trade name, not one product: it covers calcium aluminate cement, cement-bonded castables, air-setting jointing mortars and sodium-silicate furnace cements, and the job decides which one is needed. Each of the four answers to a different standard. Calcium aluminate cement with 35 to 58 % Al2O3 falls under EN 14647:2005 + AC:2006, while the 70 and 80 % refractory grades are assessed under EAD 150002-00-0301. Castables carry ASTM C401-12(2022) classes that end at class G, 1760 °C (3200 °F) as printed in the standard, so a label claiming 4,000 °F (2204 °C) has no class to be checked against.
Refractory itself has two definitions. ASTM C71-12(2024) sets the US boundary at 538 °C (1,000 °F), while ISO 836:2001 (term 107) defines a refractory by its usability in a high temperature environment and sets no threshold. Refractory cement in all four senses is therefore one route into the wider family of refractory materials; the overview of refractory materials places it among bricks, insulation, raw materials and binders.
Every value names its standard and edition, the product data sheet or the dated source it comes from; see our methodology and fact-checking process.
The four products sold as refractory cement differ in what they are, how they bond and where ISO 1927-1:2012 places them, as the table below compares.
| Sense | What it is | Bond | ISO 1927-1:2012 type | Page |
|---|---|---|---|---|
| Calcium aluminate cement | Hydraulic binder, main phase CA (CaO·Al2O3) | Hydraulic | Binder, outside the product scheme | calcium aluminate cement for refractories |
| Castable sold as refractory cement | Cement-bonded dry mix cast in place | Hydraulic | Castable (4.1) | castable refractory cement |
| Jointing mortar sold as refractory or fire brick cement | Fine mix for brick joints | Air-setting silicate, heat-setting clay or phosphate | Jointing material (4.4) | refractory mortar |
| Furnace cement | Sodium-silicate paste for sealing joints | Air-setting silicate | Jointing material (4.4) | sodium and potassium silicate binders |
| Not sold as refractory cement | Rammed, ready-to-install products | Clay or phosphate | Ramming material (4.3) | plastic refractories |
What Is Refractory Cement? Four Products Under One Name#
Refractory cement is a buyer's word that ISO 1927-1:2012 does not use: the standard sorts unshaped products into castables, gunning, ramming, jointing and other materials, and each product sold as refractory cement falls into one group or is a binder. A castable sold under the name belongs to clause 4.1, while mortars and furnace cements belong to jointing materials under clause 4.4. Calcium aluminate cement sits outside the product scheme because it is an ingredient, not a lining product. Retail tubs sold for stoves, fireplaces and pizza ovens are not covered here.
The binder sense is the oldest. Ciment Fondu, the first commercial calcium aluminate cement, was patented by J. Bied of Lafarge in 1908, according to a producer statement. The word cement later travelled from that binder to the castables, mortars and pastes that the family of monolithic refractories now groups by placement method.
Trade, Regional and Customs Names#
Five names reach the same four products, and the name alone does not tell which one is in the bag. The five names are listed below.
- Furnace cement or stove cement: US retail name for the sodium-silicate paste.
- castable refractory cement: US retail name for a cement-bonded castable.
- Fire brick cement, and fire cement in the UK: names for a jointing mortar, the refractory mortar sense.
- High alumina cement or aluminous cement: formulator usage for calcium aluminate cement.
- HS heading 3816, "Refractory cements, mortars, concretes and similar compositions, including dolomite ramming mix, other than products of heading 3801": the customs name, with US subheading 3816.00.20 for everything except dolomite ramming mix (US HTS, checked 2026-10-27).
What Each Refractory Cement Is Made Of#
What a refractory cement is made of depends on its sense: a calcium aluminate cement is built on monocalcium aluminate (CaO·Al2O3), a castable is graded aggregate held by that cement, a mortar is fine refractory filler with a bond matched to the brick, and a furnace cement is a silicate paste. The cement content of a castable is a formulation figure, not a class limit: patent WO1996001700A1 describes conventional castables with 10 to 30 % cement by weight, and class membership under ASTM C401-12(2022) follows CaO content, not cement content.
Named make-ups show how far apart the senses lie. The conventional reference concept in an Almatis technical paper holds 20 % calcium aluminate cement and reaches 84 % Al2O3 with 5.0 % CaO (typical data). The HWI SAIRSET safety data sheet (2024) lists 6.49 % sodium silicate as the bond of an air-setting mortar.
The table below compares the main constituents of each sense with a named example and its basis.
| Sense | Main constituents | Named example and basis |
|---|---|---|
| Calcium aluminate cement | CA (CaO·Al2O3) with other aluminates and some C2S | Phase make-up per producer explainer; identity CAS 65997-16-2 |
| Conventional castable | Refractory aggregate plus 10 to 30 % cement by weight (formulation figure, not a class limit) | Patent WO1996001700A1; Almatis reference concept 20 % CAC, 84 % Al2O3, 5.0 % CaO (typical data) |
| Castable product | Mullite 50 to 70 %, amorphous silica 10 to 30 %, CAC 2.5 to 10 %, cristobalite 2.5 to 10 %, silica fume 2.5 to 10 %, quartz 0.1 to 1 % | Typical product value of Mizzou Castable Plus, HWI SDS 2019 |
| Air-setting mortar | Mullite 30 to 50 %, cristobalite 10 to 25 %, quartz 13.31 %, kaolin 7.95 %, sodium silicate 6.49 % | Typical product value of SAIRSET, HWI SDS 2024 |
| Furnace cement | Sodium-silicate paste | n/a |
| Lower cement levels | CaO-classed castables with less cement | low-cement castables |
Binders and Additives Behind Each Product#
The binder separates the four senses more clearly than any name: hydraulic calcium aluminate cement in castables, sodium silicate in air-setting mortars and furnace cements, a ceramic clay bond in heat-setting mortars and phosphoric acid or monoaluminum phosphate in phosphate-bonded grades. Excess calcium aluminate cement lowers high-temperature performance, so microsilica replaces part of it in castables, a producer view given in a refractory maker's explainer.
The table below links each binder or additive to the sense that uses it and its role.
| Binder or additive | Sense | Role | Page |
|---|---|---|---|
| Calcium aluminate cement (CAS 65997-16-2) | Castable, gunning mix, hydraulic mortar, insulating concrete | Hydraulic set | calcium aluminate cement for refractories |
| Sodium silicate (CAS 1344-09-8) | Furnace cement, air-setting mortar | Air set | sodium and potassium silicate binders |
| Phosphoric acid or monoaluminum phosphate | Phosphate-bonded mortar | Heat set | phosphate binders |
| Microsilica (CAS 69012-64-2) | Castable | Replaces part of the cement | microsilica in refractory castables |
| Dispersants | Deflocculated castable | Water reduction; STPP 0.15 % in patent WO2005021434A2 example A (formulation figure) | dispersants and deflocculants for castables |
| All binder families | All senses | n/a | refractory additives and binders |
Calcium Aluminate Cement: The Binder Sense#
Calcium aluminate cement (CAS 65997-16-2, EC 266-045-5) is sold in grades named by alumina content, from about 40 % to about 80 % Al2O3. Named grades span ISTRA 40 at 38 to 42 % Al2O3 (Calucem data sheet, May 2024), Secar 71 at 68.6 to 70.6 % and Secar 80 at 79.5 to 82.5 % (Imerys, UNITECR 2025 conference paper), and Almatis CA-14 at 71 to 72 % (typical product values).
The grade also decides the standard. EN 14647:2005 + AC:2006 covers only calcium aluminate cement with 35 to 58 % Al2O3, so the 70 and 80 % refractory grades are assessed as calcium aluminate based refractory cement (CABRC) under EAD 150002-00-0301 (July 2015, published in the OJEU 2017), which requires at least 70 % cement clinker, up to 30 % alumina-rich material and up to 0.2 % additives. Grades, hydration and first heat of the binder are covered on the page on calcium aluminate cement for refractories.
Silicate and Air-Setting Bonds in Furnace Cement and Mortar#
Sodium silicate (water glass, CAS 1344-09-8) hardens an air-setting mortar or furnace cement through its full thickness at room temperature, before any ceramic bond exists.
The silicate bond passes a strength trough at intermediate temperature. In NBS Research Paper RP1461 (Heindl and Pendergast, National Bureau of Standards, 1942), 11 of 17 neat air-setting mortars were weaker after 750 °C (1,382 °F) than after 1000 or 1350 °C (1,832 or 2,462 °F). The same 17 mortars carried 0 to 1.90 % soluble alkali as Na2O, and that alkali acts as a flux in the joint at service temperature.
Refractory Cement Properties: Standard Requirements and Typical Values#
Refractory cement data come in two kinds: requirements a standard sets for a product class, and typical values one named product reached in its maker's test. The table below keeps the two apart for each property, with the ASTM and ISO or EN method side by side.
| Property | Standard requirement (standard, edition) | Typical value (named product, basis) | Method ASTM / ISO or EN |
|---|---|---|---|
| Dense castable, dried bulk density | Above 1.68 g/cm³ (105 lb/ft³), ASTM C401-12(2022) | n/a | C134-95(2023) / n/a |
| Permanent linear change at class temperature | 1.5 % or less after 5 h, ASTM C401-12(2022) classes A to G | n/a | C113-14(2025) / ISO 1927-6:2012 |
| Service rating, castable | none | 1204 °C (2,200 °F), Rutland Castable Refractory Cement; 1649 °C (3,000 °F), Mizzou Castable Plus (HWI) | maker rating |
| CAC compressive strength, EN 14647 grades | 6 h at least 18 MPa (2,611 psi); 24 h at least 40 MPa (5,802 psi), EN 14647:2005 + AC:2006 | ISTRA 40 above 30 MPa (4,351 psi) at 6 h, above 50 MPa (7,252 psi) at 1 d (Calucem data sheet) | EN 196-1 mortar |
| CAC initial set | At least 90 min, EN 14647:2005 + AC:2006 | ISTRA 40 1 to 4 h (Calucem data sheet) | EN 196-3 |
| CAC refractoriness, refractoriness and pyrometric cone equivalent | Reported under EAD 150002-00-0301 (EN 993-12) | ISTRA 40 about 1270 °C (2,318 °F); EL-61 1460 °C (2,660 °F) (USEM data sheet) | producer method |
| CAC cold crushing strength after firing at 1000 °C (1,832 °F) | none | 25 to 44 MPa (3,626 to 6,382 psi), Almatis CA-14 and CA-270 data sheet | C133-24 / ISO 10059-1:2025 |
A requirement exists only per sense: ASTM C401-12(2022) for castables and EN 14647:2005 + AC:2006 for calcium aluminate cement in its alumina window, while a retail temperature rating is a maker claim with no standard behind it. Strength, density and refractoriness are explained method by method under properties of refractory materials.
Temperature Ratings: Reading 2,200, 3,000 and 4,000 °F Claims#
A refractory cement label temperature is a maker's service rating, not a class; ASTM C401-12(2022) classes A 1095 °C (2000 °F) to G 1760 °C (3200 °F), °C as printed in the standard, are the ladder to check it against. Each class requires a permanent linear change of 1.5 % or less after 5 h at its temperature. Rutland Castable Refractory Cement is rated 1204 °C (2,200 °F) and Mizzou Castable Plus 1649 °C (3,000 °F) by HWI, two ratings that fall between classes B and C and between classes E and F.
A 4,000 °F claim equals 2204 °C, which lies above class G, so no C401 class exists to confirm it. A buyer asks for the class claimed and its test temperature. "High temperature" itself starts at 538 °C (1,000 °F) under ASTM C71-12(2024), which makes the phrase a minimum, not a rating.
Which Standards Cover Refractory Cement?#
No standard defines refractory cement as such, so each sense is specified by its own standard: ASTM C401-12(2022) and ISO 1927-1:2012 for castables, ASTM C1655-06(2022) and the ISO 13765 series for mortars, and EN 14647:2005 + AC:2006 or EAD 150002-00-0301 for the binder. The table below sets the ASTM and ISO or EN documents side by side for each sense and purpose.
| Sense or purpose | ASTM (edition) | ISO / EN (edition) | Note |
|---|---|---|---|
| Terminology | C71-12(2024), ASTM C71 refractory terminology | ISO 836:2001 | US boundary 538 °C (1,000 °F) in C71 only |
| Castable classification | C401-12(2022), ASTM C401 classification of castables | ISO 1927-1:2012, EN ISO 1927-1:2012 | Dense classes A to G, insulating classes N to V |
| Castable consistency | C1445-13(2025) | ISO 1927-4:2012 | Flow table |
| Mortar classification and specification | C1655-06(2022); F1097-17(2022) | ISO 13765-1 to -4:2004, -6:2004, -7:2021 (methods) | Fireclay and high-alumina mortars; air-setting mortar |
| Mortar pier test and bond | C199-22; C198-09(2025) | see the ISO 13765 row | C199-84(2016) withdrawn 2022-03-03 |
| CAC binder, 35 to 58 % Al2O3 | n/a | EN 14647:2005 + AC:2006 | Cement standard |
| CAC binder, 70 and 80 % Al2O3 | n/a | EAD 150002-00-0301 (July 2015, OJEU 2017) | CABRC |
| Refinery castable linings | API Std 936, 5th ed. (March 2024) | n/a | Installation quality control |
| Customs | n/a | HS 3816; US 3816.00.20 | Tariff heading |
Methods in one row measure the same property; results are not interchangeable.
Furnace cement has no product standard of its own. Its nearest test is the ASTM C199-22 pier test, which checks whether a mortar flows out of the joints of a heated brick pier, and refinery castable linings add API Std 936, 5th edition (March 2024), as an installation quality-control layer. The product types, chemical types and classification temperatures behind the castable sense are set out on the page on ISO 1927 monolithic refractory products.
Where Refractory Cement Is Used in Industrial Linings#
Industrial linings use refractory cement in all four senses: castables for doors, burner sections and complex shapes, mortar for every brick joint, silicate paste for sealing, and calcium aluminate cement inside castables, gunning mixes and insulating concretes.
The table below maps industries to the lining job and the sense each job takes.
| Industry | Lining job | Sense used | Page |
|---|---|---|---|
| Iron and steel | Reheating and heat-treatment furnace doors, piers, lintels, car tops | Castable | refractories for iron and steel |
| Refining and petrochemical | Heaters, ducts, FCC units under API Std 936, 5th ed. | Castable | refinery and petrochemical refractories |
| Power and boilers | Brick joints and cast sections | Mortar and castable | boiler refractory |
| Cement and lime kilns | Cast sections | Castable | refractories for cement and lime kilns |
| Any brick lining | Bed and head joints | Mortar | n/a |
| Castable and gunning mix manufacture | Hydraulic binder | Calcium aluminate cement | n/a |
Conventional dense castables line steel reheating and heat-treatment furnaces at doors, piers, lintels and car tops, and refinery heaters and ducts. Mortar fills the bed and head joints of every brick lining, so a brick-lined boiler or kiln uses the mortar sense even where no castable is installed.
How Each Product Is Placed and Brought Into Service#
How to use refractory cement depends on the sense: a castable is mixed with the stated water and cast within its working time, a mortar is laid in thin joints, a furnace cement is troweled into joints, and a calcium aluminate cement is proportioned into a mix.
Castable placement starts from the maker's water figure. Rutland states 0.946 L (1 US qt) of water per 5.67 kg (12.5 lb) of dry mix and a working time of 20 to 30 min for its castable. Industrial castables check consistency with the ASTM C1445-13(2025) flow table or ISO 1927-4:2012.
Mortar goes into thin joints by rub-and-tap or by dipping the brick, with mortar chemistry matched to the brick. Mixing ratios, tools and placement steps for each product sit under refractory installation methods.
Furnace cement is troweled into joints as a paste. Air-setting products stay covered during work and in airtight storage, since their strength deteriorates in containers that are not airtight (NBS RP1461, 1942).
The binder sense follows the EAD 150002-00-0301 common mix design by volume: aggregate to cement 2.0 to 4.0 (max 6.0) for mortar, 3.0 to 5.5 (max 9.0) for concrete, and water to cement 0.3 to 0.6 (max 1.0).
Cement-bonded products hold chemically combined water after setting, so the first heat is slow, and producer heat-up schedules are guidance, not a standard. Holds, rates and cure conditions per product class are set out under refractory dry-out and heat-up schedules.
Why Refractory Cement Jobs Fail#
Refractory cement jobs fail first through the wrong product: portland cement used as if it were refractory dehydrates and loses strength, and a mortar used as a castable cannot carry a lining. The table below lists the failure, the sense it hits, its cause and the check that catches it.
| Failure | Sense | Cause | Check |
|---|---|---|---|
| Loss of strength on heating | Portland cement used as refractory | Dehydration | Specify a refractory class |
| Explosive spalling | Castable | Fast first heat | Dry-out record; refractory failure modes |
| Joint weakness after 750 °C (1,382 °F) | Air-setting mortar, furnace cement | Silicate strength trough | Bond type on the data sheet |
| Strength dip at 800 to 1100 °C (1,472 to 2,012 °F) | CAC-bonded castable | Hydrate loss before ceramic bond | Design check |
| Wrong product | Mortar used as castable | Sense not checked | Sense on the data sheet |
| Patch and joint damage | All senses | Wear in service | refractory repair and maintenance |
Cement-bonded castables lose their hydrates between about 800 and 1100 °C (1,472 and 2,012 °F) before a ceramic bond forms, which gives the intermediate strength dip described in an Almatis technical paper. A first heat faster than the water can escape causes steam spalling.
Health and Safety When Handling Refractory Cement#
The main hazard in refractory cements with quartz or cristobalite filler is respirable crystalline silica, limited in US workplaces to 50 µg/m³ (8-h TWA) with an action level of 25 µg/m³ under 29 CFR 1910.1053 (effective 2016-06-23). The table below gives the ECHA line for quartz verbatim; for cristobalite, see the supplier SDS. The EU binding limit for respirable crystalline silica is 0.1 mg/m³ under Directive (EU) 2017/2398 (transposition by 2020-01-17), and retail castable refractory cement from Rutland carries a Prop 65 crystalline silica warning (OEHHA listing of 1988-10-01).
Calcium aluminate cement carries "No Annex VI entry; no hazard statement in a majority of ECHA C&L notifications (H315, H318 42.5 % each; H319 38.3 %); classification is product-specific, see the product SDS" (ECHA C&L, read 2026-10-22), and it is not on the Candidate List (read 2026-10-27). Separately, the text of REACH Annex XVII entry 47, as amended by Regulation (EC) No 552/2009, limits soluble Cr(VI) in cement and cement-containing mixtures, when hydrated, to 2 mg/kg (0.0002 %) of the total dry weight of the cement; whether a given product falls under the entry is not assessed here. EAD 150002-00-0301 requires CABRC to meet entry 47 when tested by EN 196-10. Old linings under tear-out may contain asbestos, a legacy hazard of pre-ban insulation.
The table below lists each substance or rule with its classification or limit and the instrument and date.
| Topic | Rule or classification | Instrument and date |
|---|---|---|
| Quartz (crystalline silica) | No Annex VI entry; product-specific, see supplier SDS (ECHA C&L: no majority; not classified 27.5 %, H372 25.2 %, H373 18.8 %, H350 7.7 %) | CLP Annex VI and ECHA C&L, read 2026-10-27 |
| Cristobalite | see the supplier SDS | n/a |
| Respirable crystalline silica, US | PEL 50 µg/m³ (8-h TWA), action level 25 µg/m³ | 29 CFR 1910.1053 and 1926.1153, effective 2016-06-23 |
| Respirable crystalline silica, EU | 0.1 mg/m³, respirable fraction | Directive (EU) 2017/2398 Annex III, OJ L 345/87 of 2017-12-27, transposition by 2020-01-17 |
| Prop 65 | "Silica, crystalline (airborne particles of respirable size)", cancer | OEHHA list, listed 1988-10-01 (list version 2026-07-31) |
| IARC | Crystalline silica (quartz, cristobalite) Group 1 | IARC Monograph 100C (2012) |
| Calcium aluminate cement | See the line quoted above; not on the Candidate List | ECHA C&L, read 2026-10-22; Candidate List, read 2026-10-27 |
| Cr(VI) in cement (entry text) | Max 2 mg/kg (0.0002 %) soluble Cr(VI) of the total dry weight of the cement, when hydrated | REACH Annex XVII entry 47 as amended by Regulation (EC) No 552/2009 |
| CABRC Cr(VI) | Tested by EN 196-10 to meet entry 47 | EAD 150002-00-0301 (July 2015, OJEU 2017) |
| Sodium silicate (water glass) | Water glass no Annex VI entry, ECHA C&L notified H315, H318; see the supplier SDS | ECHA C&L, read 2026-10-27 |
Two related hazards have their own pages, listed below.
- crystalline silica and cristobalite in refractories: exposure control during mixing and tear-out.
- asbestos in old refractories: legacy linings and their removal.
Refractory Cement Grades, Packaging and Sourcing#
Industrial refractory cement ships as bagged dry mix, premixed paste or bulk binder, and a buyer compares offers only after naming the sense, the class or grade and the service temperature. Named examples show the spread: Mizzou Castable ships in 24.9 kg (55 lb) bags (US retail listing), ISTRA 40 keeps about 6 months and Almatis CA grades keep 24 months. In one trial reported by Imerys at UNITECR 2025, a 68 % CAC bauxite low-cement castable stored 6 weeks in paper bags at 20 °C (68 °F) set more than 20 h later than fresh mix, so the manufacture date belongs on every order.
A data sheet answers seven questions before any brand comparison, listed below.
- Sense: binder, castable, mortar or furnace cement.
- Standard and class with edition, for example ASTM C401-12(2022) class or EN 14647:2005 + AC:2006.
- Temperature rating and its basis: class temperature or maker rating.
- Chemistry with its basis: Al2O3 and CaO in mass %.
- Water or liquid demand and working time.
- Manufacture date and shelf life.
- SDS sections 2 and 3: classification and composition.
Imports clear under HS heading 3816. Buying routes, regional producers and distributors are listed under refractory manufacturers and suppliers.
What Refractory Cement Costs: Quote Factors and Price Trend#
Industrial refractory cement is priced per quote, and the sense decides the price driver: binder grade for calcium aluminate cement, class and aggregate for castables, chemistry for mortars. The table below lists the factors a quote depends on and what the buyer states for each.
| Price factor | What the buyer states |
|---|---|
| Sense and grade | CAC Al2O3 grade, ASTM C401-12(2022) class or mortar bond |
| Raw-material origin | Aggregate and binder source, where specified |
| Quantity and packaging | Tonnes, bags or pails |
| Manufacture date and shelf life | Latest acceptable manufacture date |
| Freight | Delivery country and Incoterms |
| Installation and dry-out | Supply only or installed |
| Price trend | US BLS PPI, clay refractories (WPU1352): 405.818 (1982 = 100), September 2026, a trend, not a price |
The US BLS producer price index for clay refractories (WPU1352, 1982 = 100) stood at 405.818 in September 2026, a trend, not a price.
Refractory Cement Next to Portland Cement, Mortar and Castable#
Refractory cement differs from portland cement in its binder: portland cement dehydrates and loses strength when heated, while calcium aluminate cement and the silicate and phosphate bonds keep or develop a bond at service temperature. No additive turns portland cement into a refractory product, because refractory products are factory mixes with a declared class or grade.
A refractory mortar bonds brick, while refractory cement in the binder sense is the calcium aluminate cement that binds castable aggregate, a distinction drawn in a producer explainer. Bags labeled refractory cement can hold either, and the choice between the three products is set out in refractory mortar vs refractory cement vs castable.
Refractory Cement FAQs#
Is Furnace Cement the Same as Refractory Cement?#
Furnace cement is one of the four senses: a sodium-silicate paste for sealing joints, not a castable or a cement binder. It sets by air drying, carries no ASTM C401-12(2022) class and has no product standard of its own.
How Is Refractory Cement Made?#
Refractory cements are factory products: a CABRC under EAD 150002-00-0301 is at least 70 % calcium aluminate cement clinker, and EN 14647:2005 + AC:2006 cement is at least 99.8 % clinker. Castables and mortars are dry mixes whose binder level and water demand the maker sets and states on the data sheet.
Which Refractory Cement Suits a Boiler?#
A boiler takes two of the senses: refractory mortar for brick joints and a castable for cast sections and repairs. Boiler zones and the materials for each are covered under boiler refractory.