Everything about refractory mixtures: characteristics, properties, prices

Recommendation points

• Raw materials for refractory compositions
• Masonry mix
• Refractory plaster
• Tile adhesive and mastic
• Refractory cement

In this article, you will learn what makes common mortars fireproof. We will give examples of making heat-resistant mixtures with your own hands from ordinary ingredients, indicating the proportions of ingredients. The article contains prices for raw materials and ready-made compositions of various domestic manufacturers..

Why can’t ordinary cement withstand high temperatures? The answer is simple – it uses combustible raw materials. More precisely, substances that decompose when heated. To create compositions with heat-resistant properties, scientists had to solve only one problem – to replace combustible raw materials with non-combustible ones with similar properties..

Raw materials for refractory compositions

Clay. For the manufacture of 80% of refractory materials, widely used in private construction, use ordinary clay. Even in the form of raw materials extracted from the subsoil, it has refractory properties that are several times superior to those of industrially produced Portland cement. At the same time, raw clay does not have the ability to reliably bond surfaces. Our ancestors perfectly studied the properties of clay and used it for laying Russian stoves and coating the walls of the house..

Fireclay, expanded clay. This is heat-treated clay. When baked in the oven, clay evaporates moisture and loses the ability to accumulate it again. Fireclay is used to make refractory bricks, blocks and rings for laying fireplaces, chimneys, stoves. When ground, both of these materials form the basis of most refractory plant mixes..

Prices for refractory and auxiliary raw materials

Name	Manufacturer	Packing, kg	Packing price, rub.	Price 1 kg, rub.
Chamotte clay	“VOLMA”, Volgograd	20	240	12
Fireproof polyurethane foam	FOME Pro, Germany	680 ml balloon	480	–
Liquid glass	“MITSAR”, St. Petersburg	15	390	26
Liquid glass	Bitumast, Belgorod	12	720	60
Mortar	“TERRACOT”, Kurgan	20	350	17.5
Base for mastic ZVMKV (prom)	“Termostroy”, Perm	50	34,500	690

Masonry mix

As mentioned above, raw clay can be used for laying refractory bricks, but the wall thickness must be at least one brick (250 mm). Such masonry has weak stability, the wall does not crumble due to the static nature of the brick, the clay only distributes the load. This is quite acceptable for stoves and fireplaces inside the house, since the seams do not shrink and the walls do not deform.

Another problem with clay is that it falls out of the seam over time. To give such masonry strength, you can use a cement-clay mortar. Its proportions:

1. Clay – 2 parts.
2. Sand – 1 part.
3. Cement – 0.3 parts or 10% of the volume of the mixture.

A small amount of cement will help hold the clay in the joints. Such a solution can be conditionally called heat-resistant, since there is still a combustible material in its composition. Cement-clay mortar will withstand temperatures no more than 80-90 ° С.

Of course, the best solution for refractory masonry with your own hands will be factory mixes. Up to 90% of their composition are mortars – ready-made refractory powders, which are incorporated in different proportions into the cement-sand mixture. The amount of mortar is calculated depending on the temperature – the higher it is, the greater the percentage of powder. Joint thickness – from 3 to 12 mm.

Refractory masonry mixes

Name	Manufacturer	Packing, kg	Packing price, rub.	Price 1 kg, rub.
OgneuporSnabService	Novgorod	25	190	7.6
Termix	Borovichi	25	215	8.6
BROZEX	Yekaterinburg	18	210	11.6
“Hercules”	Novosibirsk	20	255	12.75
“TERRACOT” Masonry	Omsk	20	620	31

Refractory plaster

As in mixtures for general construction purposes, mortars for masonry and plaster differ little in terms of ingredients. The functional difference between the masonry mortar and the plaster mortar is that the plaster layer is protective, perceives the “blows” of the external environment, and therefore must be more hardy (stable).

The easiest and most affordable way to give the plaster refractory properties is silicatization. In practice, this means the addition of silicon glue, colloquially “liquid glass”. To achieve properties sufficient for use on the inner surface of a stove or fireplace, you need 20% liquid glass by volume of the solution. For 1 cubic meter m (1000 l) solution needs 200 l of liquid glass.

Factory refractory plasters and putties are made from kaolin clay, fireclay dust (waste from the production of fireclay products) and a heat-resistant binder. They are guaranteed to withstand temperatures of 200 ° C.

Factory refractory plasters

Name of plaster	Manufacturer	Packing, kg	Packing price, rub.	Price 1 kg, rub.
“Pechnik”	Permian	20	370	18.5
“PLITONIT-SuperFireplace”	Kirovsk LO	20	850	42.5
“Stroyzashita” “Nerteks-U”	Moscow	15	265	17.6
Ekabud	St. Petersburg	25	420	16.8
Bergauf BauTermo	Yekaterinburg	25	450	18
“Dune” SHT-60	Chelyabinsk	25	210	8.4

Tile adhesive and mastic

For the manufacture of glue and mastic, mortar and liquid glass are also used. In essence, such a mastic is two of these components mixed together. The glue can withstand up to 1100 ° C, it is used for facing visible fireplaces with heat-resistant ceramic tiles. Mastic is used to fill (grout) the joints of masonry exposed to high temperatures, since the masonry mortar has a much lower heat resistance (up to 200 ° C).

Mortar can be of two types – hydraulic and thermal hardening. Hydraulic cures like conventional cement mortar. Thermally hardens during firing to form a continuous ceramic surface (like pottery).

Factory heat-resistant adhesives and mastics

Name of mastic, glue	Manufacturer	Packing, kg	Packing price, rub.	Price 1 kg, rub.
KDP-50 (UNIVERSAL)	Yekaterinburg	25	240	9.6
NEOMID Supercontact	St. Petersburg	4	330	82.5
HT-7200	Samara	75	1400	18.5
Nullifire F0100	St. Petersburg	3	180	58.8
Triumf	Novosibirsk	15	675	45

Refractory cement

This type of mineral binder uses calcium aluminate, which retains the strength characteristics of concrete and mortars. Distinctive features of mortars and concretes based on heat-resistant cement (in addition to refractory ones):

1. Corrosion resistance. This property is achieved through the use of inorganic raw materials – calcium aluminate – which is not subject to rapid natural decomposition (unlike marl and lime in ordinary cement).
2. Early hardening time due to the displacement of moisture from the solution.
3. Manufacturability of application. The method of use and proportions does not differ from Portland cement.
4. Dielectric properties due to lack of moisture.

It is impossible to make refractory cement on your own, but it is easy to find it on the free market. It allows you to prepare refractory concrete, which helps to move away from the canons of masonry fireplaces and embody the most daring design ideas..

Refractory cement prices

Product name	Manufacturer	Packing, kg	Packing price, rub.	Price 1 kg, rub.
Kerneos SECAR 38R	France	25	500	20
GC-40	Novosibirsk	40	900	22.5
ISIDAS 40	Turkey	25	625	25
Lakka Tulenkestava	Finland	25	1300	52
VHC-I-35, VHC-50	Novosibirsk	20	1800	90

In addition to kaolin clay, special additives based on silicon, asbestos, barium or other alumina materials give refractory properties to dry mixes. Reacting with water or a catalyst solution, the mass acquires the necessary properties. One more property should be noted, which is “attached as a bonus” to the heat resistance. This is hydrophobization or waterproofing. This is especially true for solutions using liquid glass, which in smaller proportions (10-15%) provides the waterproofing properties of a conventional solution.