Water Absorption Test Report for Fired Clay Bricks (Compiled by Xi'an Brictec engineering Co., Ltd. )
I. Test Purpose
The water absorption test is an essential step in evaluating the physical properties of sintered clay bricks. It mainly examines the compactness, durability, and weather resistance of the finished products.
For BRICTEC’s fully automated production lines, the test serves as an important verification procedure to ensure that all fired bricks meet both national and international quality standards before leaving the factory.
Water absorption directly affects the brick’s frost resistance, long-term strength stability, and service life. If the water absorption rate is too high, the bricks tend to develop cracks, scaling, or surface peeling after repeated wet–dry and freeze–thaw cycles. Therefore, maintaining water absorption within the standard range is crucial for ensuring the reliability and durability of masonry structures.
II. Testing Method and Procedure
The experiment follows the national standard GB/T 32982–2016, Performance Requirements for Load-bearing and Non-load-bearing Sintered Bricks.
Samples were collected from BRICTEC’s automated tunnel kiln after the firing process was completed.
Testing steps were as follows:
The dry mass (M₀) of each sample was measured.
Samples were then immersed in water for 15 hours under constant temperature conditions.
After removal, surface water was wiped off, and the saturated mass (M₁) was recorded.
The water absorption rate (W) was calculated using the following formula:
W=M1−M0M0×100%Where: M0: Dry weight of the brick (g)；M1: Weight after 15 hours of water absorption (g)
III. Test Results
No.
Dry Weight (g)
Weight After 15h Soaking (g)
Water Absorption (%)
1
2785.7
3117.1
11.90
2
2845.4
3193.0
12.22
3
2835.7
3171.7
11.85
4
2819.9
3137.2
11.25
Average Water Absorption: 11.81%
According to GB/T 32982–2016, the 5-hour boiling water absorption rate for load-bearing sintered bricks should have an average value ≤18% and a single value ≤17%.
The BRICTEC samples show a significantly lower absorption rate, demonstrating excellent density, low porosity, and outstanding overall performance.
IV. Analysis and Discussion
The low water absorption rate reflects the technological precision and optimized control of BRICTEC’s manufacturing process.
The uniform temperature distribution within the tunnel kiln ensures complete sintering and dense internal structure formation.
The precise control of moisture and combustion air minimizes internal pores and enhances compactness.
The advanced mixing and extrusion systems increase green brick density, improving impermeability and frost resistance.
These factors together indicate that BRICTEC’s production technology guarantees consistent, high-density, and high-performance fired bricks, suitable for load-bearing structures and harsh environmental conditions.
V. Conclusion
Based on the test results and analysis, the average water absorption rate of fired clay bricks produced by BRICTEC’s fully automated line is 11.81%, which is well below the limit specified in GB/T 32982–2016.
This confirms that:
The bricks achieve excellent vitrification and densification during firing.
The finished products exhibit superior resistance to moisture, frost, and weathering.
The overall production process is technologically advanced, stable, and reliable.
BRICTEC will continue to implement systematic quality monitoring and standardized testing procedures, ensuring that every fired brick produced meets international standards for durability, structural integrity, and environmental performance.
VI. Further Testing Recommendations (Extended Quality Verification Items)
To comprehensively evaluate the overall performance of the product, it is recommended to conduct the following supplementary tests based on the water absorption test results and establish corresponding benchmark indices:
Open Porosity / Apparent Density / Bulk Density – for direct correlation between water absorption and mechanical properties.
Compressive Strength / Flexural Strength – to assess mechanical load-bearing performance.
5-Hour Boiling Water Absorption Test – verification method required by Table 4 of GB/T 32982-2016.
Freeze–Thaw Cycle Test – recommended for projects in cold regions.
Salt Crystallization Resistance Test – for bricks used in coastal areas or road pavements.
Microporous Structure Analysis (BET surface area, pore-size distribution, microscopic observation) – to identify structural causes and guide process optimization.
Permeability and Pore Connectivity Analysis – for simulating long-term durability in engineering applications.
These extended tests help establish a complete quality profile and ensure that the sintered bricks meet performance requirements under different environmental and structural conditions.
VII. Key Elements of the Water Absorption Test Report (for Project Documentation)
When issuing the official water absorption test report, BRICTEC recommends including the following elements to ensure traceability and technical completeness:
Project title, sample ID, sampling date, and test date;
Testing standard and reference (e.g., GB/T 32982–2016, including specific clauses);
Model and calibration record of all instruments used;
Drying conditions, immersion procedure/time, and weighing method (including scale precision);
Detailed raw measurement data (m_d, m_s, and full calculation process), along with statistical values (mean, max, min, and standard deviation);
Compliance assessment (whether the sample meets the relevant standards and project specifications, and if further freeze–thaw testing is required);
Technical recommendations and proposed follow-up tests;
Signatures of testing personnel and authorized quality supervisors.
This standardized format ensures that the test documentation is suitable for international project submissions, EPC acceptance reports, and long-term traceability audits.
VIII. Conclusion (BRICTEC Technical Evaluation Summary)
Based on the 15-hour water absorption test of the four provided samples, the average absorption rate is approximately 11.8%, which is significantly below the limit value (≤15%) specified in Table 4 of GB/T 32982–2016 for load-bearing decorative bricks. From this single performance indicator, it can be concluded that the finished bricks exhibit good compactness and material quality.
The results confirm that the current raw material formulation, forming density, and firing regime have achieved excellent densification. Under these conditions, freeze–thaw pre-screening is not required based solely on water absorption data (provided the testing method and standard comparison are consistent).
However, for projects operating under more demanding environmental conditions or where long-term durability is a key design concern, BRICTEC recommends performing additional evaluations including:
The 5-hour boiling water absorption test,
Freeze–thaw cycle testing, and
Other durability assessments as specified in relevant national or international standards.
Based on the results, targeted optimization of the raw materials and firing process can be implemented to further enhance the product’s durability and reliability.
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