ASTM C67 Standard Test Methods for Sampling and Testing Brick and Structural Clay Tile

 Get Certified ASTM C67 Testing for Reliable Brick and Structural Clay Tile Quality 

The quality of brick and structural clay tile products is critical to the strength, durability, and appearance of masonry construction over decades of service. Prior to delivery, a production lot is tested to verify that it conforms to its specified modulus of rupture, compressive strength, absorption, and dimensional requirements by means of a Certified ASTM C67 test. As such, manufacturers and specifiers feel assured in the units’ performance in the finished building. In addition, recorded test results provide an architect and/or contractor with a concrete benchmark to compare brick and tile from various suppliers. 

The scope of ASTM C67 includes:

• Material type: Brick, structural clay tile, and solid masonry units. 
• Purpose: Applies to brick and structural clay tile of all shapes and depths. 
• Elements analyzed: Modulus of rupture, Compressive strength, Absorption, Saturation coefficient, Freeze-thaw resistance, Efflorescence, Initial rate of absorption, Weight, Size, Warpage, Length change, and Void area. 
• Method: The method involves selecting typical samples, preparing them according to the specified standard, and testing them using appropriate tests for each property, including flexural loading for the modulus of rupture, oven-drying for absorption, etc. 
• Result: The value of each property is reported in the appropriate unit, e.g., compressive strength per unit area, absorption percentage of dry mass. 
• Test Limitations: The number of bricks sampled is dependent on the size of the lot, and is a minimum of 10 for lots of 1,000,000 or less, and 5 for lots of 250 tons (226.8 Mg) or a portion thereof. 
• Environmental conditions: Oven drying for a minimum of 24 hours at 110 °C to 115 °C and weighing every 2 hours until constant weight is required for absorption testing. 
• Applications: Masonry construction quality control, material specification compliance, and structural clay tile and brick manufacturing. 

What are the Uses of ASTM C67  Testing?

ASTM C67 testing helps brick and structural clay tile manufacturers verify their specified mechanical and physical properties before bricks and tiles are introduced to the marketplace. Besides, uniform sample amounts allow for uniform comparison of results between production lots and laboratories. This standard –

• Supports production quality control in brick and Structural Clay Tile production.
• Verifies compressive strength and Modulus of Rupture within specification requirements.
• Checks valid values of absorption and saturation coefficient for durability class.
• Aids in the determination of freeze-thaw durability and efflorescence resistance for exterior use.
• Defines and documents brick and tile specifications for construction. 

What Materials Can Be Tested Under ASTM C67? 

ASTM C67 is applicable to full-size bricks, structural clay tile, and solid masonry units from a production lot that span the gamut of color, texture, and size. Laboratories brush or clean a specimen to get rid of dirt, mud, mortar, or other material that may be interfering with the test. Manufacturers commonly use this standard to characterize facing brick, common brick, and structural clay tile intended for load-bearing and non-load-bearing masonry construction.

Why is ASTM C67  Important? 

ASTM C67 provides manufacturers and specifiers with an accepted method to assure brick and structural clay tile possess the strength, absorption, and durability properties needed for masonry construction. These units are the backbone of many buildings as well as their look, so regular testing ensures that they last for many weathering cycles and structural loads. ASTM C67 establishes quantities and testing procedures for properties from modulus of rupture to freeze-thaw resistance, ensuring the masonry industry’s quality and durability standards are met among manufacturers. 

ASTM C67  Testing Process and Data Collection

The first step, which is key in the analysis, is to take representative brick or tile samples using a representative lot size and to clean the samples to remove foreign material. This is followed by mechanical tests, namely flexural tests (modulus of rupture) and compressive tests (until failure). Technicians used ventilated ovens, cooling them at each step, to dry specimens, and then weighed them over and over until they reached a constant weight for the absorption testing. After that, the saturation coefficient, freeze-thaw resistance, and efflorescence are measured to test durability when exposed to weathering. Last but not least, mechanical test results, absorption test results, and weight, size, warpage, and change-in-length data are all recorded. 

Common Challenges and Troubleshooting

The ASTM C67 requirements for specimen selection are not always met, which leads to inconsistent averages, as the specimens don’t cover the full range of colors, textures, and sizes of a lot. There may also be effects on absorption and strength readings if the dirt, mortar, or other residues are not completely removed. Inconsistent oven temperature during the drying process also means variable drying and weight measurement. The solution is to ensure a good selection of samples covering the entire range of the lot, a thorough cleaning of each unit prior to drying, and to ensure the temperature of the oven is within the stated 110°C to 115°C drying range. 

• Compressive strength and modulus of rupture validate the mechanical load-bearing capacity of the unit.
• Absorption and saturation coefficient values are used to grade for durability in outdoor and load-bearing uses.
• Weight, size, warpage, and length change measurements ensure dimensional stability within the production lot.
• The prediction of the long-term weathering performance for exterior applications is supported by freeze-thaw and efflorescence observations. 

Link to ASTM C67