Pavement bricks, also known as clay bricks, typically have a technical grade ranging from 75 to 100. The standard dimensions of ordinary pavement bricks are 240 mm × 115 mm × 53 mm, with a vibrant red color, though they may occasionally appear in deep black hues. Beyond their inherent strength and durability, these bricks possess notable thermal insulation and soundproofing properties due to their porous structure. Consequently, they are widely used not only as wall materials but also for constructing architectural elements such as columns, arches, chimneys, flooring, and foundations. Historically, this type of brick has been a favored material in traditional building practices, having been first introduced by the ancient Romans. Today, many surviving classical structures across Europe still bear the unmistakable imprint of red bricks—whether on their roofs or walls.

　　When producing square bricks, it is common practice to use high heat to thoroughly fire the bricks both inside and out. Afterward, the kiln is allowed to cool naturally while the fire is extinguished. During this cooling process, air circulation within the kiln remains active, ensuring ample oxygen supply and creating an ideal oxidizing atmosphere. This allows the iron elements in the bricks to oxidize into iron oxides, which impart a reddish hue to the final product. However, if water is introduced into the kiln after the bricks have already been fully fired, the high temperature inside will rapidly convert the water into steam. This steam effectively blocks air circulation, leading to a localized oxygen-deficient environment within the kiln. As a result, the iron oxides present in the bricks undergo reduction, transforming into ferrous oxide instead. Since ferrous oxide has a bluish-gray color, the finished bricks will exhibit a distinctive blue-gray tone.

　　How is the raw material for paving bricks supplied and processed? Here's an introduction: After being extracted, the raw materials are stockpiled and aged. They are then loaded into a chain-plate feeder using a loader and transported via belt conveyor to a roller mill for crushing. Meanwhile, internal coal-fired fly ash is also fed into the roller mill through a belt-type coal mixer, where it is mixed with the slurry before being crushed. The crushed material is subsequently screened using a rotary screen; any coarse particles remaining on the screen are returned to the process via belt conveyor for repeated crushing. Finally, the screened raw materials are conveyed by belt conveyor to storage warehouses for future use.

　　How are the paving bricks formed and fired? Let me introduce the process: The processed raw materials are conveyed via a belt conveyor to the upper section of a vacuum extruder. This machine generates an extrusion pressure as high as 3.5 MPa, ensuring that the materials are squeezed under significant pressure. As a result, the moisture content of the green body is significantly reduced, which helps maintain precise dimensions and enhances the strength of the wet green body. Consequently, the green body remains stable during mechanical stacking without deforming. Next, the material undergoes further twisting, compression, and cutting processes, making the granules denser and ensuring more uniform moisture distribution throughout the material. Additionally, within the vacuum chamber, a vacuum pump extracts air from the spaces between the material particles, further increasing the extrusion density. This step not only boosts the product's compressive and flexural strength but also smooths the surface finish, thereby improving the overall yield rate. Finally, the material is fed into the lower section of the vacuum extruder, where it is once again compressed by a spiral auger. The extruded strip is then automatically cut into various desired shapes by the strip-cutting system. These shaped strips are subsequently transferred onto kiln cars by a hydraulic automatic coding system, which marks each strip with specific production information before they are moved by electric carts into the firing kiln. Inside the kiln, the bricks are pushed in according to a predetermined firing schedule, undergoing a single-step firing process until they are fully baked.