Fire Clay Bricks and Regular Clay Bricks Whats the DifferenceFire Clay Bricks and Regular Clay Bricks, What's the Difference?
Loka Refractories - What is the difference between fire clay bricks and regular clay bricks?

In terms of appearance, both of them look similar. But actually, they are very different!

Fire clay bricks and regular clay bricks have very different uses and compositions. The differences will be outlined in the following explanation.

Differences between fire clay bricks and regular clay bricks

First, let's discuss the difference in composition.

Fire clay bricks have a main composition of alumina derived from bauxite and silica derived from quartz sand.

These raw materials have refractory properties that make them resistant to very high temperatures.

In addition to alumina and silica, refractory bricks also have other raw materials such as magnesia, carbon, silica carbide, and so on according to their needs and applications.

Meanwhile, regular clay bricks are made from clay with additives such as sand, lime, ash, and so on. Therefore, they do not have refractory properties.

Second, let's compare their uses. Regular clay bricks are commonly used to build walls of houses, buildings, and many more.

Whereas fire clay bricks are used to build lining in furnaces, ovens, boilers, ladles, reformers that involve heat energy and high pressure.

The thing is, regular clay bricks are resistant to fire. However, it does not have resistance to temperatures up to 1800 C as well as pressure and abrasion.

Another difference is that regular clay brick has a much cheaper price than fire clay bricks.

If you need clay bricks, you can find them easily at the nearest building store.

Finding refractory bricks is no less easy. Contact Loka Refractories at:
Phone : (031) 7663307/0821-4280-8500
E-mail :

We supply refractory bricks with standard sizes (230x114x65mm) and custom sizes according to your industry needs!
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Refractory Failure SpallingRefractory Failure: Spalling
Did you know about refractory failure?

Refractory materials installed in a furnace will be in contact with extreme environments such as high temperatures and high pressure. Therefore, refractory failure can happen if the right material is not used.

There are many types of refractory failure caused by various factors. One of the most common things that occurs is spalling. What is spalling and what causes it? Check out the explanation below!

What is Spalling?

Spalling is the release of part of the material from its parent due to internal pressure (stress) of the material in response to changes in environmental conditions. Usually, spalling starts from the appearance of cracks or splitting of the installed material.

There are three types of spalling with different causes, namely thermal spalling, structural spalling, and mechanical spalling.

Types of Spalling

Thermal spalling is material damage by temperature shock which results in temperature differences that cause stress.
Damage occurs through the formation of initial cracks due to stress caused by temperature shock which is greater than the strength of the material and is followed by crack propagation.

Structural Spalling is spalling caused by changes in phase (mineralogy, form), so that differences in the properties of the changed and original parts cause internal stress.

Structural spalling is caused by overheating and chemical reactions/penetration.

Structural spalling caused by overheating can be prevented by:
- Temperature control
- Control of intake air or furnace atmosphere
- Selection of appropriate refractory

Meanwhile, those caused by chemical reactions and penetration are prevented by:
- Selection of refractory materials according to the nature of the environment in the furnace (acid, neutral, alkaline)
- Arrangement of porosity, pore size distribution, wettability, etc.

Mechanical Spalling is a failure that is often caused by concentrated loads due to unequal distribution of mechanical forces.

One of them is the lining design on the refractory and metal connections such as steel anchors, and on the masonry in the furnace arc. Another cause is the use of inappropriate materials.

Spalling or other refractory failures can be prevented by selecting refractory materials with the right specifications and good quality.

Get the best quality refractory materials from Loka Refractories! Contact us for our best offer!

Phone : 0821-4280-8500

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Corrosion  What It Is and How To Control ItCorrosion : What It Is and How To Control It
Hi everyone! We are back again with another article about one of refractory failures.

Previously, our article is about refractory failure by spalling, which you can read here.

This time, we will discuss about corrosion which is the loss of mass of refractory material lining.

What caused it? How to prevent it? Scroll down and find out more!

What is corrosion?

Corrosion is the loss of refractory mass caused by chemical reactions between contacting materials.

Materials that come into contact with refractories can be solids, liquids or gases.

Corrosion can occur through four processes, namely dissolution, reaction, and penetration of chemical substances into the pores.

How to control corrosion process?

In general, the corrosion process can be prevented with the following steps:

- Reduces chemical reactivity and increases specific area. Because the finer the granules, the more reactive they are, so the substance dissolves more quickly into the melt.

- Set the composition of the filer and matrix.

- Reducing the dissolution rate by reducing the interface and melt concentration difference, avoiding stirring, and
lower the temperature.

- Regulate the suitability of the acidity level between the refractory and the slag.

- Controlling porosity and texture by:
1. Using wide range particle distribution to reduce interconnection between pores.

2. Improved mixing and molding techniques during production.

3. Adding ingredients that allow pore closure.

- Controling the penetration process with
increases viscosity and covers pores.

- Controlling dissolution by regulating chemical reactivity and specific area, and lowering temperature.

- Controlling oxidation - reduction reactions by adjusting the composition/addition of oxidation preventers.

That was a brief explanation about corrosion of refractory linings and how to control it.

Get the best refractory solutions for your industry now by contacting:
Telephone: 0821-4280-8500/031-7665507
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Refractory Failure AbrasionRefractory Failure: Abrasion
Are you familiar with the word Abrasion?

Generally, abrasion is known as the process of coastal erosion due to pressure from sea waves.

Then, did you know that abrasion can also occur on refractory materials?

Refractory failure can occur due to abrasion so that it experiences erosion or wear due to mechanical work such as grinding, friction, rubbing, etc.
Each refractory material has a different abrasion resistance.

The abrasion resistance of refractory materials is influenced by the Modulus of Rupture, impact particle size and spray pressure, as well as impact angle and impact particle size.

Want to know more? Check out the explanation below!

Modulus of Rupture (MOR) is a measure of the strength of refractory material before it cracks and breaks. Abrasion resistance is inversely proportional to MOR. The higher the volume lost due to abrasion, the lower the MOR of the material.

The crusher particle size and spray pressure also affect abrasion resistance. The greater the size/mass and pressure, the greater the kinetic energy and the volume lost by abrasion increases.

Apart from that, the size of the impact particles and the impact angle have an influence on abrasion resistance which is explained as follows:

• The larger the size of the impact particle and the angle of collision, the greater the kinetic energy

• If the particle size of the crusher is smaller than the particle size of the aggregate, it will affect the matrix. Improve strength by decreasing matrix quantity.

• If the crusher particle size is smaller than the aggregate particle size, then choose aggregates with high abrasion resistance such as SiC and Al2O3.

Thus the article about refractory failure caused by abrasion. Get abrasion resistant refractory materials by contacting:

Phone: 0821-4280-8500
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Refractory Bricks Classification Based On Quality StandardRefractory Bricks Classification Based On Quality Standard

There are many classifications of refractory materials. These include based on shape, properties, composition, and so on.

In this article, we will discuss the classification of refractory bricks based on quality standards.

The quality standards for refractory bricks refer to the standards issued by American Standard Testing and Materials or ASTM International.

So, what are the classifications based on ASTM International quality standards? Check out the explanation below!

Silica Brick (C 416-97 ASTM)

The composition of Silica Brick is as follows:
a)    AI₂O₃    < 1.5 %
b)    TiO₂    < 0.2 %
c)    Fe₂O₃    < 2.5%
d)    CaO    < 4.0 %

The presence of contaminants in silica bricks tends to reduce refractoriness and their use is limited.

The amount of alkali and alumina can be used to estimate refractoriness properties.

Silica Bricks are classified based on impurities and usually called flux factor.

Alumina Silicate (fire clay) and high alumina bricks (C 27-98 ASTM)

Alumina-silica Refractory Bricks are produced from various combinations of alumina and silica grades.

The variation in chemical composition is quite wide, ranging from almost 100% alumina with a little silica, to almost 100% silica with a little alumina.

Classification based on chemical composition and physical properties consists of:

1. Fire clay bricks are classified based on physical properties, which can be an overlap between alumina and silica content:
Super-duty, High-duty, Semi-silica, Medium-duty, and Low-duty.

2. High alumina bricks are classified based on alumina content: 50, 60, 70, 80, 85, 90, and 99%.

Schamotte Insulating Brick (Insulating Fire Brick)

The classification of heat insulating materials is known as samot insulating brick (insulating fire brick). This insulating material is suitable for lining certain types of industrial furnaces.

AI₂O₃ - SiO₂ Insulation Brick (fire brick) ASTM C 155 - 97 is classified as follows:


Shrinkage max 2%

on Temp°C

Bulk Density max

Lb/ft3 (g/cm3)

























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Monolithic Refractory Inspection MethodsMonolithic Refractory Inspection Methods
Every time you install refractory material, an inspection needs to be carried out afterwards. The aim is to ensure that the installed materials comply with the specified conditions and comply with the design that has been made.

Refractory inspection methods vary according to type. In this article we will explain inspection methods for monolithic or unformed refractories such as castables, mortars and so on.

Monolithic refractories are inspected using two methods, namely visual inspection and lining inspection for pressure vessels. Check out the explanation below!

Visual Inspection

Some visual inspection methods include the following:
1) Cover Joint Inspection
Check that the mortar or seal between the packings has been packed between the joints properly.

2) Dimensional Inspection
Check dimensions carefully, especially locations where dimensional accuracy must be maintained (e.g. joints with accessories).

3) Repair
If the inspection finds repairs, follow-up with repairs is required after removing the damaged refractory from the repair location. Remove the castable properly to allow the anchor to support the installation of the new refractory.

Some things to pay attention to include:

1. Make sure that the removal does not affect the surrounding normal lining. Also ensure that there are backup materials in case any are damaged by demolition.

2. Clean the area after dismantling the refractory. Replace with only castable of the same type. Also before reinstalling the castable, use fresh water to wet the area ready to be installed that contacts the new castable.

3. To fix the lining, generally the same installation method is used for large areas in the same way as when the initial refractory was installed.

Layer Inspection for Pressure Vessels

Lining inspection for pressure vessels can be carried out using visual or sound waves, and hammer tests.

This inspection is carried out after natural drying and dryout. If necessary, x-rays or other non-destructive tests may be performed for particularly important areas.

Lining inspection methods for pressure vessels include:

1. Inspection after natural drying (24 hours after installation)
a) Ensure that the lining workmanship is satisfactory.
b) Check if there is any reflective material still attached to the gunning surface.
c) Check for cracks.
d) Check dimensions.

2. Hammer Test
The hammer test refers to striking the lining with a hammer, at approximately 300mm intervals to ensure from sound that the lining is installed satisfactorily.

The hammer test is aimed primarily at determining that there is no reflective material attached to the lining being gunned, there are no laminations on the lining that cause peeling, the refractory castable is in contact with the cells and there is empty space in the refractory.

If your company needs a monolithic refractory for applications in furnaces, boilers and kilns, contact us at:

Phone: 0821-4280-8500
E-mail :

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