Cement Prefabricated Flue in Old Houses

In old houses, flues from the 1980s were mostly made of brick-and-concrete structures, while modern cement-prefabricated flues have significantly improved in terms of materials, craftsmanship, and performance.

I. Material and Structural Differences

Flues in prefabricated buildings from the 1980s were primarily brick-and-concrete structures and served as load-bearing components. Their production was mostly manual, resulting in thin pipe walls and low material strength. Some flues suffered from insufficient durability due to the use of inferior cement or fiberglass mesh, leading to aging and cracking issues after long-term use. In contrast, modern cement-prefabricated flues use 32.5# Portland cement as the main raw material, reinforced with 22# - 26# galvanized steel wire mesh, and are manufactured through mechanical forming processes, falling under the category of building prefabricated components. Their material strength is significantly enhanced, and the addition of steel wire mesh improves crack resistance.

II. Production Process Comparison

Traditional flues relied on manual production, leading to significant human errors, uneven pipe wall thickness, insufficient compactness, and rough inner walls prone to blockage. Modern cement-prefabricated flues adopt vibration casting forming processes combined with steam curing technology, resulting in uniform pipe wall thickness and smooth inner walls. Mechanical production reduces human intervention, greatly improving the compactness and stability of the finished products, with a vertical load-bearing capacity of ≥90KN, far exceeding that of manually produced flues.

III. Performance Characteristics and Specifications

Modern cement-prefabricated flues possess characteristics such as lightweight, corrosion resistance, excellent sound insulation, high-temperature resistance, and flame retardancy. Their compressive strength can reach 10MPa, with some brands offering even higher specifications like 30MPa, 50MPa, and 180MPa. Their specifications cover commonly used market sizes such as 250×300, 300×350, 350×400, 400×500, and 450×500, with adjustable wall thickness to meet different architectural requirements. In contrast, traditional flues are prone to air leakage and odor transmission issues due to material aging and are more difficult to repair.

IV. Application Scenarios and Advantages

Modern cement-prefabricated flues are widely used in new residential buildings, commercial structures, and old house renovations. Their standardized production ensures quality stability, with smooth inner walls that are less prone to blockage, reducing long-term maintenance costs. Additionally, their high-strength materials allow them to replace some traditional load-bearing structures, meeting the higher safety and functionality requirements of modern architecture. For old houses with brick-and-concrete flues requiring renovation, it is recommended to assess structural safety and consider replacing them with modern prefabricated flues to enhance the user experience.