Introduction to the physical indicators of clay bricks

 
Clay bricks are clay products made of aluminum silicates with an Al203 content of 30%-40%. Clay bricks are made of 50% soft clay and 50% hard clay clinker. They are compounded according to a certain particle size requirement. After being shaped and dried, they are fired at a high temperature of 1300-1400C. The mineral composition of clay bricks is mainly kaolinite and 6% -7% impurities (potassium, sodium, calcium, iron, iron oxides). The firing process of clay bricks is mainly a process in which kaolinite is continuously dehydrated and decomposed to form mullite crystals. SiO2 and A1203 in clay bricks form eutectic low melting point silicates with impurities during firing, and are surrounded by mullite crystals. Clay bricks are weakly acidic refractory products, which can resist the erosion of acidic slag and acidic gases, and have a slightly lower resistance to alkaline substances. Clay bricks have good thermal properties and are resistant to rapid cold and heat. The fire resistance of clay bricks is comparable to that of silicon bricks, up to 1690-1730 ° C, but the softening temperature under load is more than 200 ° C lower than that of silicon bricks. Because in addition to the high refractory mullite crystals, clay bricks also contain nearly half of the low-melting amorphous glass phase. In the temperature range of 0-1000 ° C, the volume of clay bricks expands uniformly as the temperature rises, the linear expansion curve is approximately a straight line, and the linear expansion rate is 0.6% -0.7%, only for silicon bricks. About half. When the temperature
When the temperature continues to rise after reaching 1200 ° C, its volume will shrink from the maximum expansion. Residual harvest of clay bricks
Shrinkage causes loosening of gray joints in masonry, which is a major disadvantage of clay bricks.
 
When the temperature exceeds 1200 ° C, the low-melting substances in the clay bricks gradually melt, and the particles are held close to each other due to the surface tension, thereby causing volume shrinkage.