The most common type of brick we use for building houses is ordinary red brick, while refractory bricks are mainly used in the construction of high-temperature furnaces, aluminum smelting furnaces, and other high-temperature environments. Although both are bricks, they are fundamentally different.

1.Differences in shape and color

In terms of appearance, apart from irregularly shaped bricks, the shape of most refractory bricks, especially right-angled bricks, is not much different from that of ordinary bricks; they are all rectangular. However, the shapes of irregularly shaped refractory bricks vary, such as arch bricks and anchor bricks, and are selected according to different applications.
Ordinary bricks are mostly reddish-brown or gray, and the color varies depending on the type of soil used in production. Natural refractory bricks are white, but due to differences in the metal content of the raw materials, the fired colors also vary, including coffee, moss green, red, and jet black.

2.Different occasions of use

Refractory bricks are generally used in the construction of high-temperature kilns and firewalls, where extremely high temperatures are required for the bricks to withstand.
Ordinary bricks are more commonly used in the construction of houses.

3.Different material compositions

There are many types of refractory bricks, mainly including aluminosilicate refractory bricks, basic refractory bricks, carbon-containing refractory bricks, zirconium-containing refractory bricks, and insulating refractory bricks. Today, we will mainly introduce aluminosilicate refractory bricks, where silica bricks refer to refractory bricks with a silica content of 93% or more. Clay bricks are mainly composed of mullite (25%–50%), a glassy phase (25%–60%), and cristobalite and quartz (up to 30%). The mineral composition of high-alumina refractory bricks consists of corundum, mullite, and a glassy phase. Their content depends on the Al₂O₃/SiO₂ ratio and the type and quantity of impurities. Refractory bricks can be graded according to their Al₂O₃ content. Corundum refractory bricks refer to refractory bricks with an Al₂O₃ content of not less than 90% and corundum as the main phase.

4.Different refractory temperatures

Refractory bricks have high refractoriness, with a temperature range of 1580℃-1770℃, and some high-quality refractory bricks can reach around 1800℃.
Ordinary bricks can withstand temperatures of around 1200℃; if the temperature is too high, they are prone to decomposition.

5.Difference in thermal conductivity

Refractory bricks contain ceramic and iron oxide chemical additives that absorb high temperatures but do not transfer them. Therefore, refractory bricks are heat-resistant, have low thermal conductivity, and offer higher energy efficiency and insulation value. Ordinary bricks, because they are not used in very specific environments, have higher thermal conductivity.

Refractory bricks are primarily composed of high alumina content, have low thermal conductivity, and are mostly pale yellow or beige in color. Ordinary bricks are primarily composed of silicon dioxide and iron oxide, have high thermal conductivity, and are reddish in color.

6.Heat resistance and thermal properties

One of the most significant differences between refractory bricks and common bricks is their heat resistance.

Refractory bricks:

Can withstand temperatures of 1,200°C–1,800°C without losing strength.

Low thermal conductivity – this helps retain heat in furnaces or ovens.

Can be dense (for load-bearing furnaces) or insulating (lightweight to reduce heat loss).

Common bricks:

Temperature resistance is generally limited to 600°C–800°C.

Higher thermal conductivity results in faster heat dissipation.

Not suitable for prolonged direct contact with flames.

7.Ingredients and manufacturing process

Refractory Bricks

Raw Materials: High-alumina clay, silica, magnesia, and other refractory minerals.

Additives: May include clinker (pre-fired crushed refractory material) to improve thermal shock resistance.

Firing Temperature: Extremely high – typically exceeding 1,400°C – to ensure heat resistance.

Texture: Depending on the application, dense or porous; low iron content to avoid lowering the melting point.

Common Bricks

Raw Materials: Natural clay, shale, and sometimes sand.

Additives: May contain lime or fly ash to improve strength.

Firing Temperature: Lower – generally between 900°C and 1,100°C.

Texture: More porous than refractory bricks; higher iron content, typically reddish.

Key Difference: Refractory bricks are made from specially selected heat-resistant materials and fired at higher temperatures, exhibiting excellent thermal stability.

8.Mechanical strength and durability

Refractory bricks: Designed to maintain high-temperature strength. Dense refractory bricks possess extremely high compressive strength (up to 60 MPa or higher), making them ideal for lining industrial kilns and furnaces.

Common bricks: Offer good structural strength (approximately 20-40 MPa), but lose most of their strength at high temperatures.

Durability under thermal cycling: Refractory bricks are designed to resist thermal shock—the expansion and contraction caused by rapid temperature changes. Common bricks are more prone to cracking under these conditions.

9.Application areas

Uses of Firebricks:

Industrial furnaces, kilns, and boilers
Fireplace linings
Wood-fired pizza ovens and bread ovens
Smelting and glass production furnaces
Incinerators

Uses of Standard Bricks:

Walls in residential and commercial buildings
Sidewalks and garden landscaping
Partition walls
Structural foundations
Decorative facades

10.Service life and maintenance

Firebricks: When installed correctly, they can last for decades in high-temperature environments. Maintenance typically involves only replacing damaged bricks.

Ordinary bricks: They can last for over a century under normal weather conditions, but they degrade rapidly when used in high-temperature environments.

11.Cost comparison

Refractory bricks: Due to the use of special raw materials and high-temperature firing processes, they are relatively expensive. Prices vary by grade—insulating refractory bricks are typically less expensive than dense high-alumina refractory bricks.

Standard bricks: More affordable and widely used, they are an ideal choice for large-scale construction projects.