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Reasons and solutions of affecting bricks quality

2026-03-16

1, Malformed adobe, appears large cracks. In more serious cases, the whole adobe will split.

Reasons: the plasticity index of pug is too low, almost no plasticity.

Solution: to increase the plasticity index of raw materials, such as clay, coal slime or clay agent, etc.

For raw materials of low plasticity index, it can also be improved after aging, watering, stirring, rolling, extruding and other methods.

2, The body of adobe is not smooth, the obvious particles, more sand pits, and horns or flutes are missing.

Reasons: The shatter of raw materials does not meet the requirements of making bricks because there is much large particles.

Solutions: Install fine grinding equipment, as required for crushing the raw materials to make particles 3 mm or less.

Some kiln owners are not willing to spend money in equipping the machinery of raw material pre-treatment, such as roller crusher,double shaftmixers. Some kilns are only equipped with a pair of rollers, some only with mixers, some even neither of them. How can we get good bricks if there are bricks, tile, stone and other debris in the mud raw materials? Even if it is hard to send someone to pick them out clean. The fundamental way to solve the problem is equipped with auxiliary equipment.

3, The quality of adobe is unstable, sometimes good and sometimes poor.

Reasons: uneven mixing of raw materials

Solutions: Increase the mixer and feeder

Some brick factories are not equipped with rollers and mixers, even without the feeders, all by artificially feeding into the brick machine with shovel, which inevitably occurs two major drawbacks.①, raw material soil cannot be stirred and mixed well. The plasticity of raw soil is not exactly the same, and sometimes the disparity is very great, the Yellow River sludge is like that.②, the inside fuels such as coal, coal gangue, slime and others cannot be stirred evenly. The two heterogeneous, will inevitably lead to the instability of adobes’ quality.

4, malformed adobe and mud column, will spread immediately after cutting.

Reasons: Failure of the vacuum chamber

Solutions: a, improve the maintenance, service, repair technology of brick machine to ensure the normal function of brick machines’ properties. b, make the necessary technical transformation

b, Another reason for resulting in failure of the vacuum chamber, is the sand-based raw material, so the closed mud layer of the upper auger is too thin, easy to be drawn through, causing the vacuum failure, so the adobe could not be molded. The best way to solve this problem is to change the ratio of raw materials, to increase the plasticity index of raw materials. The other way is to cut the front end of the superiors auger to 2-10 centimeters according to the material properties of soil (must be conducted under the guidance of skilled technical personnel, don’t do it by yourself).

5, Many brick cracks on adobes or broke into two sections, more wastes after sintering.

Reasons: There are too many viscous ingredients in raw materials, so the plasticity index is too high.

Solutions: change the ratio of raw materials, reduce the plasticity index. The plasticity index of clay can be up to 25, can be properly incorporated into the coal ash, slag, fly ash or waste of brick powder to make it thin.

6, Soft adobe, easy to form, or crack after cutting.

Reason: the improper control of moisture in the mud.

Solution: soft adobe, easy to be deformed, showing that the water of sludge is too much, should reduce water. If the mud column quickly occurs crack or split of mud column after molding, which is caused by too little water in mud, it can be solved by increasing appropriate water.

7. Brick production capacity not stable

Reason: Not equip with box feeder

Solution : Some brick factory owners in order to save money, they refuse to use box feeder but some labors to feed soil manually .Therefore, soil feeding amount is not stable,sometimes more than what the extruder need, some times, less what extruder need, thus greatly influencing production capacity.

All in all, there are all kinds of raw materials to make bricks, in addition to the different climate, some abnormal situations inevitably occur in the production and it is really hard to avoid. If there are problems, knowing the following two points will be easy. One isto havea team with a strong sense of responsibility and a technical team ofprofessional mechanics. Two is to timely communicate high and difficult technical problems with industry colleagues.

How to produce hollow clay blocks ?

The Advantages Of The New Energy-Saving Mobile Rotary Tunnel Kiln

Core Climate Characteristics of Southeast Asia for Brick Production

First, the region maintains an annual average air humidity of 75% to 90%, causing raw materials such as river sand, fly ash, and concrete aggregate to absorb moisture quickly and clump easily. Second, the local rainy season lasts 4 to 6 months per year with frequent torrential rains, which easily cause factory waterlogging and disrupt production schedules. Third, the perennial high ambient temperature ranging from 25℃ to 35℃ increases operating heat load on brick machine mechanical structures and electrical systems, raising equipment failure risks.

Key Factory Construction & Production Line Adaptation Measures

1. Factory Site Selection and Layout Optimization. Select high-elevation, well-drained terrain to prevent rainwater from flooding production areas and raw material yards. Build fully enclosed waterproof and moisture-proof raw material warehouses to avoid material caking caused by high humidity, which severely reduces brick forming quality and qualification rate. Arrange standardized drainage ditches around production lines and brick curing areas to ensure rapid water discharge during heavy rainfall.

2. Professional Production Line Equipment Upgrades. All electrical components of the automatic brick production line must reach IP54 or higher dustproof, waterproof and moisture-proof grades. Equip hydraulic systems and driving motors with enhanced heat dissipation devices to prevent overheating shutdown under long-term high-temperature working conditions. Upgrade conveyor belts, mixing shafts and mixing tank inner walls with anti-corrosion treatment to adapt to humid and sultry tropical working environments.

3. Adaptive Brick Curing Process Adjustment. The natural curing speed of non-fired bricks drops significantly during high-humidity rainy seasons. Prolong controlled curing time appropriately or install simple greenhouse constant-humidity curing facilities to guarantee finished brick compressive strength and stability. Avoid long-term open-air stacking of finished bricks to prevent surface peeling, strength attenuation and rainwater erosion damage.

Conclusion

The core requirements for building a qualified brick plant in Southeast Asia are moisture proofing, waterproofing and equipment heat dissipation optimization. Scientific climate-adaptive factory layout and targeted production line configuration support 365-day continuous stable production, greatly reduce equipment failure rates, and effectively improve the qualification rate of finished concrete bricks and clay bricks.

What Additives Optimize Production Processes of Fired Bricks?

Fired brick production relies heavily on raw material processability, and professional functional additives are core to optimizing production workflows, stabilizing molding quality, and reducing production costs. All additives applied in formal brick production must pass strict pre-production trial tests to adapt to different raw material characteristics and production line parameters, avoiding quality fluctuations and production losses.

Plasticizers are essential process additives for low-plasticity raw materials. They effectively improve the plasticity, bonding force and fluidity of brick raw materials, solving the problems of difficult molding and easy cracking of lean raw materials with poor cohesion. High-plasticity clay is the most commonly used traditional plasticizer, with stable modification effects and wide adaptability. The only limitation is the increased transportation cost, which raises overall production expenses.

Contrary to plasticizers, lean additives (deplasticizers) are designed to adjust excessive mud plasticity. By coarsening the particle gradation of raw material mixtures, they harden overly soft mud, significantly reduce the drying shrinkage rate of brick bodies, and eliminate common production defects such as drying deformation and cracking. In addition to conventional granular lean materials, sodium sulfite salts and surfactants are efficient auxiliary materials that can further reduce the drying shrinkage of fired bricks.

Fluxing agents and anti-firing deformation additives focus on high-temperature firing process optimization. Fluxing agents lower the melting point of brick raw materials, promote the formation of uniform glass phases in the brick body at high temperatures, and improve the compactness and firing maturity of products. Anti-firing deformation additives enhance the fire resistance stability of green bricks, enabling the bricks to withstand high-temperature firing and heavy load pressure without shape distortion, ensuring stable product dimensional accuracy in mass production.

fired Black core elimination additives resolve the common firing defect of reductive black cores. These defects typically occur in internal-fired brick production due to insufficient firing temperature, rapid heating speed, and inadequate holding time, which leave residual carbon unburned inside the brick core. Industrial materials such as calcined clay, clinker, waste brick powder, low-carbon fly ash, and ammonium compounds promote full oxidation of internal residual carbon, effectively reducing or eliminating black core defects and improving the finished brick yield.

How Can Daily Operation and Routine Maintenance Extend Your Clay Brick Making Machine’s Service Life?

1. Pre-Start Inspection: Eliminate Hidden Dangers Before Production

A complete pre-shift inspection can avoid 70% of daily mechanical faults. Before starting the clay brick making machine every day, operators must conduct a comprehensive visual and manual check. First, fasten all loose bolts, fixing screws and connecting parts, especially the vibration motor base, mold fixing frame and extrusion barrel connection positions, which are prone to loosening under long-term vibration. Second, check the tightness of transmission belts and chains; overly loose belts will cause slipping and power loss, while over-tight belts will accelerate bearing wear. Third, confirm no metal debris, hard stones or foreign materials remain in the mixing bin and extrusion cavity, as hard impurities will scratch the screw propeller and mold lining, causing permanent equipment damage.

2. Standard Operation: Strictly Avoid Overload & Wrong Operation

Overload operation is the biggest killer of clay brick making machines. Many factories pursue output blindly and feed excessive clay materials continuously, leading to long-term overload operation of the extrusion system, reducer and motor. This will not only cause motor overheating and accelerated aging of internal coils but also increase the pressure of the hydraulic system, resulting in oil leakage and component deformation. Operators must strictly follow the equipment rated feeding capacity, prohibit long-time overload operation, and stop feeding immediately once abnormal noise, vibration or pressure fluctuation occurs. In addition, avoid frequent cold start and sudden shutdown; preheat the machine for 3-5 minutes in low-load state before formal production to ensure all moving parts run smoothly.

3. Post-Shift Cleaning & Basic Lubrication

Clay materials contain fine sediment and moisture, which will harden and adhere to machine surfaces after air drying. If not cleaned in time, accumulated clay residues will block operating gaps, increase friction of moving parts, and even cause local corrosion. After each shift, workers must thoroughly clean the mixing shaft, extrusion screw, mold cavity and cutting mechanism to remove all residual clay. Meanwhile, complete daily lubrication work: fill standard lithium-based grease into bearings, chain gears and rotating parts, and check the lubricating oil level of the reducer to ensure sufficient lubrication. Scientific lubrication can reduce metal friction loss by more than 60% and effectively delay component aging.

4. Regular Daily Inspection of Electrical & Hydraulic System

The electrical control system and hydraulic system are the core control parts of the brick machine. Daily inspection should focus on checking whether the wiring is loose or damp, whether the control panel displays normally, and whether the heat dissipation fan works efficiently to avoid circuit burnout caused by overheating. For the hydraulic system, check for oil leakage at pipe joints and cylinder rods every day, and ensure the hydraulic oil is clean without turbidity. Tiny impurities in hydraulic oil will wear the hydraulic valve core and reduce system stability, leading to gradual decline of machine performance.

Conclusion: Daily standardized operation and meticulous routine maintenance are the most fundamental guarantee for the long-term operation of clay brick making machines. Adhering to daily inspection, standard operation, thorough cleaning and timely lubrication can effectively avoid most minor faults, greatly reduce equipment wear, and lay a solid foundation for extending the overall service life of the machine.

How to Reduce Brick Breakage Rate During Drying and Firing Process?

High brick breakage and cracking rate is one of the biggest profit killers for overseas brick factories. Many new brick plants suffer from 8%–20% brick loss rate due to improper drying and firing control, which directly raises production costs and cuts down net profit.

This professional guide shares practical, factory-tested methods to reduce brick breakage in drying and firing stages. All solutions fit fully automatic and semi-automatic tunnel kiln brick production lines

1. Main Causes of Brick Cracking and Breakage

Most brick defects happen in two critical stages: uneven drying shrinkage and excessive temperature difference during firing. Common reasons include unreasonable raw material moisture, wrong brick stacking method, rapid temperature rise, poor kiln airflow and immature aging process.

2. Reduce Breakage in the Drying Process (Key Pre-Firing Stage)

More than 60% of brick cracks are formed in the drying stage, not during firing. Controlling drying speed and uniformity is the most cost-effective way to lower brick scrap rate.

2.1 Control Raw Material Moisture and Aging Time

Unbalanced moisture inside brick blanks causes inconsistent shrinkage. For standard clay, shale and mixed raw materials, keep the forming moisture between 18%–24%. Extend material aging time to 24–48 hours to ensure even water distribution and plasticity stability.

Effect: Effectively eliminate irregular surface cracks and blank breakage before entering the dryer.

2.2 Adopt Gradient Slow Drying Mode

Many new factories make the mistake of fast high-temperature drying. Rapid surface water loss leads to surface hardening while the inner layer remains wet, causing burst cracks.

Set staged drying parameters: low temperature and high humidity at the initial stage, gradual temperature rise and dehumidification in the middle stage, and thorough drying in the final stage.

2.3 Standardize Automatic Brick Stacking Method

Disordered stacking blocks hot air circulation, resulting in partial under-drying and over-drying. Keep uniform gaps between brick layers to ensure 360° hot air flow. Avoid dense stacking at the edge of the drying car.

3. Reduce Brick Breakage in the Tunnel Kiln Firing Process

Firing breakage mainly comes from temperature shock, uneven kiln temperature and unreasonable fuel combustion. Stable temperature curve management can control the firing scrap rate below 3%.

3.1 Avoid Rapid Temperature Rising and Cooling

Brick blanks are fragile before sintering. Sharp temperature increase will produce huge internal thermal stress and cause layered cracking. Strictly follow the standard heating curve: slow heating, constant temperature sintering and slow cooling.

3.2 Balance Kiln Internal Airflow and Temperature

Local overheating or cold zones inside the tunnel kiln are common causes of deformed and broken bricks. Optimize the hot air circulation system and waste heat recovery system to ensure consistent temperature in all kiln zones.

3.3 Optimize Fuel Combustion Efficiency

Incomplete combustion leads to unstable fire power and temperature fluctuation. No matter using coal, natural gas or heavy oil, keep sufficient oxygen supply and uniform combustion to avoid local temperature deviation.

4. Raw Material Formula Optimization to Lower Breakage Rate

Single pure clay material has large shrinkage coefficient after high-temperature firing. Proper material mixing can greatly improve brick stability.
Mix 20%–40% shale into clay to reduce overall shrinkage rate
Add 10%–30% coal gangue or fly ash to balance internal stress
Remove large stone and hard impurities to prevent local stress concentration

5. Daily Operation Management Standards

Regularly check dryer and tunnel kiln sealing to avoid cold air intrusion
Keep stable production speed and avoid frequent line start-stop
Train workers on standardized stacking and parameter adjustment
Record daily breakage data to track abnormal fluctuations

What Automation Level Should I Choose for My Brick Plant? Semi‑Auto vs Full‑Auto Complete Decision Guide

Choosing the right automation level is the foundation of profitable brick plant operation. For new investors and factory upgraders, the biggest confusion is choosing between semi-automatic and fully automatic brick production lines. Many factory owners make blind investments, resulting in either high labor waste or excessive equipment investment and slow capital recovery. To solve this pain point, this article evaluates the two mainstream brick production models from four core dimensions: labor demand, initial investment, daily maintenance cost, and payback period, and provides targeted regional suggestions for Africa and the Middle East with distinct labor cost characteristics.

1. Labor Demand Comparison

A standard semi-automatic brick production line is equipment-assisted and labor-dependent. Key links including raw material feeding, mold cleaning, brick palletizing, finished product transportation require manual operation. Normally, a complete semi-auto line needs 6–10 workers per shift to ensure continuous production. Its advantage lies in flexible operation, suitable for frequent product specification adjustments and small-batch production.

A fully automatic brick production line realizes unmanned operation for the whole process from batching, mixing, molding, curing to stacking. Only 1–2 workers per shift are required for equipment monitoring, parameter adjustment and emergency troubleshooting. It greatly reduces labor dependence, avoids product quality instability caused by human error, and supports long-term continuous high-volume production.

2. Initial Equipment Investment

Semi-automatic brick lines have simple structure and low supporting facility requirements. The total investment is between $18,000 and $35,000, which is 35%–50% lower than full-auto lines. It features low entry threshold, flexible site requirements, and is very suitable for small-scale brick plants, startup investors and projects with limited budget.

Fully automatic brick lines adopt integrated intelligent equipment with complete automated supporting systems. The total investment ranges from $50,000 to $120,000, depending on output and configuration. Although the upfront cost is high, it supports standardized large-scale production and is oriented to medium and large-scale brick factories with long-term development plans.

3. Maintenance Cost & Failure Rate

Semi-automatic equipment has simple mechanical structure, fewer precision parts, and low failure rate. The daily maintenance is convenient and low-cost, mainly including regular lubrication, component cleaning and simple wearing part replacement. The annual maintenance cost is only 3%–5% of the total equipment investment, and ordinary workers can complete daily maintenance training in a short time.

Fully automatic lines are composed of intelligent control systems, servo motors, automated palletizing and conveying systems, with complex internal structures. The failure rate is low in formal operation, but once precision parts or control systems fail, maintenance is difficult and costly. The annual maintenance cost accounts for 8%–12% of the total investment, and professional technicians are required for regular inspection and maintenance.

4. Payback Period Analysis

Thanks to low upfront investment and low operating cost, semi-automatic brick lines have a fast capital return speed. Under normal market sales conditions, the payback period is 8–12 months. It has low operational risk and strong ability to resist market fluctuations, which is friendly for new factories.

Full-automatic lines rely on high output and stable quality to create profits. Although the initial investment is high, the unit labor cost and defective rate are extremely low. For stable large-order production, the payback period is 15–20 months. After the payback stage, the profit margin is far higher than that of semi-automatic lines.

5. Regional Targeted Suggestions: Africa vs Middle East

Africa Market Recommendation: Priority to Semi-Automatic Brick Lines

Most African countries have abundant labor resources and extremely low labor costs. Local brick plant labor expenditure is far lower than equipment operation and maintenance costs. Choosing semi-automatic lines can save a large amount of upfront equipment investment, make full use of local cheap labor, and avoid unnecessary capital waste. It is the most cost-effective solution for African brick plant investors. For large factories with annual output exceeding 10 million bricks, a low-match full-automatic line can be considered.

Middle East Market Recommendation: Priority to Fully Automatic Brick Lines

Labor resources in Middle East countries are scarce and labor costs are extremely expensive. Manual employment, management and training costs form the main operating expenditure of local brick plants. Fully automatic lines can greatly reduce labor staffing, cut long-term labor costs, and offset high initial equipment investment. For almost all medium and large brick plants in the Middle East, full-automatic lines are the best choice for long-term profit growth. Small factories with limited funds can choose semi-automatic lines for transitional operation.

Which Raw Materials Can Be Used for Clay Brick Production? Can I Use Coal Gangue, Fly Ash and Soil?

Many overseas brick factory investors encounter a critical problem before starting construction and production: whether local soil, coal gangue, and fly ash can produce standard and qualified fired clay bricks. Improper raw material selection will directly cause low brick compressive strength, high cracking and breakage rates, unstable firing quality, and even severe economic losses for the entire production line.

This article comprehensively introduces the applicability, scientific mixing ratio, production requirements, advantages and disadvantages of common brick-making raw materials, including natural clay, coal gangue, fly ash and shale. It helps overseas brick plant investors quickly verify local raw material availability and match the most suitable brick production line configuration.

1. Natural Soil / Clay — The Most Universal Base Raw Material

Pure natural clay is the most traditional and widely applicable raw material for fired clay bricks, suitable for brick factories in Africa, Southeast Asia, Central Asia, and the Middle East. It provides essential plasticity for extrusion molding and ensures finished brick density and structural stability.

Qualification Standards for Brick-Making Clay

Plasticity index: 7–15 is the most suitable range for vacuum extrusion molding
Impurity control: Avoid excessive large stones, organic residues, and high-salinity soil
Moisture content: 18%–24% for standard brick blank forming

Pros: Easy mining, low cost, stable molding effect, no complex pretreatment required.

Cons: Pure clay consumes arable land; single clay material may cause slight shrinkage and cracking during high-temperature firing.

Suggestion: Mix 10%–20% shale or industrial waste ash to optimize firing stability and reduce production costs.

2. Coal Gangue — High-Cost-Effective Industrial Waste Raw Material

Coal gangue is a common solid waste from coal mining and coal washing. It is 100% usable for fired brick production and has become a mainstream raw material for modern environmentally friendly brick plants worldwide. It contains residual carbon, which can self-supply heat during firing and greatly reduce coal or gas consumption.

Key Usage Requirements

Must be crushed and screened into fine particles before batching
Best mixing ratio: 30%–60% coal gangue + 40%–70% clay/shale
Low sulfur content is required to avoid brick surface peeling and environmental emission problems

Core Advantages: Low raw material cost, waste recycling, 30%–40% lower fuel cost than pure clay bricks, compliant with international green building and waste reuse standards.

Applicable regions: Areas with coal resources, such as Central Asia, Eastern Europe, and parts of Africa.

3. Fly Ash — Eco-Friendly Auxiliary Raw Material for High-Quality Bricks

Fly ash is a fine powder waste from coal-fired power plants. It cannot be used alone for fired bricks but is an excellent auxiliary material to replace part of clay. It is widely used in energy-saving brick production lines and effectively solves the problems of clay resource shortage and brick blank shrinkage cracking.

Scientific Mixing Ratio & Rules

Safe and optimal proportion: 20%–40% fly ash mixed with main clay/shale materials
High fineness fly ash improves brick surface smoothness and compressive strength
Strict moisture control is required to prevent fly ash agglomeration and uneven batching

Production Benefits: Reduces clay consumption, lowers brick body shrinkage rate, improves finished brick durability, and meets global environmental protection policies for solid waste utilization.

Note: Excessive fly ash (more than 50%) will reduce plasticity, cause difficult molding and low brick blank hardness.

4. Other Common Alternative Raw Materials (For Reference)

Shale has stable texture and uniform components. It can be mixed with clay or used as the main material. It effectively reduces firing shrinkage and cracking, greatly improving the finished brick yield rate. It is the most ideal complementary raw material for clay brick production.

River Silt / Lake Silt

After drying, impurity removal and aging treatment, silt can replace part of clay. It is low-cost and environmentally friendly, suitable for brick factories near water areas.

5. Raw Material Matching Quick Reference Table

Raw Material	Usability	Recommended Mix Ratio	Core Advantage
Natural Clay	Fully usable (main material)	60%–100%	Good plasticity, easy molding, low pretreatment cost
Coal Gangue	Fully usable (main/auxiliary)	30%–60%	Self-heating, save fuel cost, waste recycling
Fly Ash	Auxiliary only	20%–40%	Improve brick quality, protect clay resources
Shale	Fully usable	20%–50%	Reduce cracking, high finished product rate

6. Professional Tips for Overseas Brick Plant Investors

Most overseas production failures are caused by unmatched raw materials and production line configuration. Before purchasing brick-making equipment, you must complete raw material testing first.

Send local soil, coal gangue or fly ash samples for plasticity and component testing
Determine the optimal mixing ratio according to local raw material characteristics
Configure targeted crushing, aging and vacuum extrusion equipment
Adjust tunnel kiln firing temperature curve according to raw material heat resistance

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