Common Quality Defects and Professional Solutions in fired brick and block Production
Fired bricks and fired blocks are indispensable traditional building materials widely used in industrial and civil construction projects worldwide. The overall quality of clay fired building bricks directly determines the safety, durability and service life of construction projects, closely related to public property and personal safety. With the continuous upgrading of brick-making technology, modern brick factories mainly adopt tunnel kiln firing technology to produce perforated fired bricks and hollow bricks, replacing the traditional soil kiln and wheel kiln production modes.
After years of wall renovation and production practice, the industry has summarized a core principle for high-quality brick manufacturing: raw material optimization is the key, professional technology is the condition, and standardized management is the guarantee. The ancient brick-making industry emphasized raw material processing, with the classic industry saying “30% depends on firing technology, 70% depends on raw material treatment”. Modern quality sampling inspections of fired brick products show that most production quality defects are caused by unreasonable raw material processing and insufficient aging treatment.
This article systematically analyzes six typical quality problems in fired brick production and puts forward targeted industrial solutions for B2B brick manufacturers and construction material suppliers.
1. Dimensional Deviation of Finished Bricks
Causes: Unreasonable raw material particle gradation and insufficient raw material aging time are the core causes of brick size deviation. Unprocessed raw materials with uneven particle sizes will lead to unstable extrusion molding effects.
Solutions: First, conduct professional sieve analysis to adjust and optimize raw material particle gradation to ensure uniform raw material fineness. Second, extend raw material aging time strictly; the aging warehouse area must meet the production demand of at least 7 days to improve the raw material plasticity index. Third, optimize the extrusion outlet size of the brick making machine, adjust the mud strip extrusion specification according to the actual plasticity data of raw materials, and control size deviation within the standard range.
2. Edge and Corner Cracks
Causes: Excess coarse particles in raw materials and low molding water content increase the extrusion resistance of mud strips, resulting in edge and corner cracks of fired bricks after molding and firing.
Solutions: Improve raw material crushing fineness and reduce sieve hole diameter to optimize particle matching. Adjust the gap of high-speed roller press to a standard 3mm to ensure thorough raw material crushing. Reasonably increase raw material moisture content to reduce mud strip extrusion resistance and avoid corner crack defects.
3. Horizontal Cracks on Ribs and Walls
Causes: This defect commonly occurs in fired perforated bricks and hollow blocks. Excessive coarse raw material particles cause inconsistent shrinkage of thick and thin particles. In addition, excessive drying temperature and ultra-fast drying speed of the drying kiln will also trigger horizontal shrinkage cracks on brick ribs and walls.
Solutions: Optimize raw material particle gradation to balance particle shrinkage. Strictly control drying kiln temperature: the temperature of green bricks entering the drying kiln is controlled at about 40℃, and the outlet temperature is stably maintained at about 110℃. Adjust the drying time and fan operating speed according to the real-time temperature and humidity in the kiln to achieve uniform and slow drying.
4. Under-fired Bricks
Causes: Under-fired bricks with pale color and low compressive strength often appear at the bottom and both sides of tunnel kiln cars, leading to high crushing rate of finished products. The main reasons include loose kiln car sealing leading to cold air inflow, unbalanced temperature and pressure in the tunnel kiln, insufficient internal heat of raw materials, and shortened firing and heat preservation time for excessive production output.
Solutions: Regularly inspect and repair the sand seal and sealing groove of kiln cars to prevent cold air from entering the kiln bottom. Adjust the positive pressure, zero pressure and negative pressure balance in the tunnel kiln to reduce the upper and lower temperature difference of brick stacks. Detect raw material heat value in real time and appropriately increase firing temperature. Implement strict “fixed zone, fixed temperature, fixed time” firing standards, and never sacrifice product quality for production volume.
5. Over-fired & Burst Bricks
Causes: Brick deformation, bubbling and bursting often occur in the middle and upper parts of brick stacks, which is caused by excessive heat proportion of raw materials, unreasonable brick stacking methods, and forward movement of the firing zone leading to prolonged firing and heat preservation time.
Solutions: Scientifically proportion raw material heat value to avoid excessive internal heat. Optimize the green brick stacking process and reserve reasonable gaps between brick bodies for uniform heat circulation. Precisely control the firing cycle and heat preservation time to eliminate over-fired defects.
6. Poor Weathering Resistance
Causes: Most enterprises ignore raw material homogenization and aging treatment, and directly crush and use raw materials. Under fixed firing temperature, the solid-liquid phase reaction of raw material particles is incomplete, resulting in uneven firing and poor weathering resistance of finished bricks.
Solutions: Mandatorily implement raw material homogenization and long-term aging treatment. Appropriately increase the tunnel kiln firing temperature. Improve the crushing fineness of low-quality raw materials to ensure complete firing reaction.
FAQ
Q1: What is the most critical factor affecting fired brick quality?
A1: Raw material treatment is the core factor. Reasonable particle gradation, sufficient aging time and scientific heat proportion determine 70% of fired brick quality, while firing process and management guarantee the final finished effect.
Q2: How to solve under-fired brick problems in tunnel kiln production?
A2: Focus on kiln car sealing maintenance, balance kiln internal pressure and temperature, optimize raw material heat value, and strictly implement standardized firing time management to avoid insufficient firing.
Q3: Why do fired hollow bricks have rib and wall cracks?
A3: It is mainly caused by uneven raw material particles and unreasonable drying process. Optimizing particle matching and controlling constant-temperature slow drying can effectively solve this problem.
Q4: How to improve the weathering resistance of fired bricks?
A4: Complete raw material homogenization and aging treatment, improve raw material crushing fineness, and properly adjust firing temperature to ensure full firing of brick bodies.
