Different Grades of Solid Bricks - ASTM Standard C62-99

Bricks can be classified into different grades as per ASTM C 62-99, Standard Specification for Building Brick for Solid Masonry Units Made From Clay or Shale. It is graded based on the resistance of the brick to damage by freezing wet (saturated). It is a condition of the brick that has absorbed water to an amount equal to that resulting from the submersion in room temperature water for 24 hours).

This article explains the different grades of solid bricks made of clay and shale that are used in masonry construction. 

Based on ASTM C62-99, bricks can be classified into:

1. Grade SW
2. Grade MW
3. Grade NW

1. Grade SW - Severe Weathering

This grade of brick is highly and uniformly resistant to damage that is caused by cyclic freezing. These are site conditions, where the bricks may be frozen when saturated with water.

2. Grade MW - Moderate Weathering

These bricks have moderate resistance to cyclic freezing damage. These are site conditions, where the bricks may be damp when saturated with water.

3. Grade NW - Negligible Weathering

Brick with little resistance to cyclic freezing damage but which are acceptable for applications protected from water absorption and freezing.

Physical Requirements of Different Grades of Solid Bricks - ASTM C 62-99

Design Features- ASTM C 62-99

1. When Grade is not specified, the requirements for Grade SW shall govern. Unless otherwise specified by the purchaser, a brick of Grade SW or MW shall be accepted instead of Grade NW; and Grade SW instead of Grade MW.
2. Figure -1 shows the weathering index of The United States. Table-2 gives the correlation between the grade of building brick, weathering index, and exposure. The specifier can use these recommendations or use the grade descriptions and physical requirements along with use exposure and local climatological conditions to select grades.
   

Fig.1. Weathering Index United States

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