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Freeze-thaw occurs when water absorbed within a brick expands upon freezing and contracts during thawing, causing progressive degradation. This repeated expansion and contraction cycle weakens the brick's internal structure, leading to cracking and material loss. A brick's ability to resist this damage is called durability, which is a critical factor in selecting bricks for climates with temperature fluctuations.

Bricks are graded into three durability categories based on strength and water absorption. SW-grade bricks are the most durable, offering high strength and low water absorption. MW-grade bricks provide moderate durability, while NW-grade bricks have the lowest durability. This grading system helps engineers select appropriate bricks for specific environmental conditions and structural requirements.

Brick masonry strength depends on three primary factors: the strength of the bricks themselves, the quality of the mortar used, and any reinforcement added to the structure. While individual bricks typically have compressive strength ranging from 1500 to 3000 pounds per square inch, the overall masonry performance is limited by the weakest component. Proper mortar selection and reinforcement placement are essential for achieving desired structural capacity.

Brick color is primarily determined by the type of clay used in manufacturing. Different clay sources contain varying mineral compositions and iron oxide content, which produce different natural colors ranging from red and brown to yellow and tan. The specific clay selection during production is the main factor controlling the final brick color.

Brick surface texture and overall appearance are shaped by the dies, molds, and attachments used during the manufacturing process. These tools imprint patterns, textures, and finishes onto the brick surface, creating visual variety. The manufacturing method directly influences aesthetic qualities, allowing producers to create smooth, textured, or decorative brick surfaces for different architectural applications.

Brick appearance is influenced by changes in size and shape, visible damage such as chips on the face or corners, and the degree of chippage present. For facing bricks used in visible applications, the extent of surface damage and defects significantly impacts aesthetic appeal. Size consistency, shape uniformity, and damage-free surfaces are critical for bricks where visual presentation is a priority.

Water absorption directly affects a brick's susceptibility to freeze-thaw damage and other moisture-related deterioration. Bricks with low water absorption, such as SW-grade bricks, resist moisture penetration and are more durable in harsh climates. High water absorption increases the risk of internal expansion during freezing cycles, making bricks more prone to cracking and degradation over time.