Masonry Magazine December 1989 Page. 28
Facing Brick
Facing brick are intended for use in both structural and non-structural masonry where appearance is a requirement.
Hollow Brick
Hollow brick are identical to facing brick but have a larger core area. Most hollow brick are used in the same application as facing brick. Hollow brick with very large cores are used in walls that are reinforced with steel and grouted solid. Larger cores or cells in hollow brick allow reinforcing steel and grout to be placed in these units whereas it would be difficult to do so with building brick, facing brick or some hollow brick.
Paving Brick
Paving brick are intended for use as a paving material to support pedestrian and light vehicular traffic.
Ceramic Glazed Brick
Ceramic glazed brick are units with a ceramic glaze fused to the body and used as facing brick. The body may be either facing brick or other solid masonry units.
Thin Brick
Thin brick veneer units are fired clay units with normal face dimensions, but a reduced thickness. They are used in adhered veneer applications.
Sewer and Manhole Brick
Sewer and manhole brick are intended for use in drainage structures for the conveyance of sewage, industrial wastes, and storm water; and related structures, such as manholes and catch basins.
GENERAL REQUIREMENTS
There are several terms in each standard used for classification which may include exposure, appearance, physical properties, efflorescence, dimensional tolerances, distortion, chippage, cores and frogs. Brick can be classified by use, grade, type and/or class in most specifications. All options should be specified, as each ASTM brick standard has requirements for grade and type which apply automatically if an option is omitted. By not specifying the desired requirements, a delivery may contain brick not suitable for the intended use.
Exposure
Because of the varying climates throughout the country, and the different applications of brick, specific grades of brick are required. Brick must meet a grade of SW, MW, or NW based on the weathering index and the exposure of the brick. The weathering index is the product of the average annual number of freezing cycle days and the average annual winter rainfall in inches (see Figure 1). The exposure is related to either a vertical or horizontal surface and whether the unit will be in contact with the earth (see Table 1). A higher weathering index or a more severe exposure will require a face brick to meet the SW requirements. The grade is typically based on physical properties of the brick. See Technical Notes 9B for selection of grades. The grades for each specification are listed in Table 2, and the physical requirements are listed in Table 4.
TABLE 1
Grade Requirements for Face Exposures
| Exposure | Weathering Index |
|---|---|---|
| | Less Than 50 | 50 to 500 | 500 and Greater |
| In vertical surfaces: | | | |
| In contact with earth | MW | SW | SW |
| Not in contact with earth | MW | SW | SW |
| In other than vertical surfaces: | | | |
| In contact with earth | SW | SW | SW |
| Not in contact with earth | MW | SW | SW |
TABLE 2
Exposure
| ASTM Standard | More Severe Exposure | Less Severe Exposure |
|---|---|---|
| C 62 Grade | SW | MW | NW |
| C 216 Grade | SW | MW | - |
| C 652 Grade | SW | MW | - |
| C 902 Class | SX | MX | NX |
| C 1261 | - | Exterior | Interior |
| C 1088 Grade | - | - | - |
| C 32 Sewer2 Grade | SS | SM | - |
| Manhole | MS | MM | - |
No requirements for durability
Based on durability and abrasion
Appearance
Brick types are related to the appearance of the unit, and specifically to limits on dimensional tolerances, distortion tolerances and chippage of the units. The brick type can be selected depending upon whether: a high degree of precision is necessary; a wider range of color or size is permitted; or a characteristic architectural effect is desired. The types of brick for each specification are listed in Table 3, and requirements for size variation, distortion, and chippage are listed in Tables 5, 6 and 7, respectively.
Physical Property Requirements
The physical property requirements in most specifications are compressive strength, water absorption and saturation coefficient. These properties must be determined in accordance with ASTM C 67, Standard Methods of Sampling and Testing Brick and Structural Clay Tile. The minimum compressive strength, maximum water absorption and maximum saturation coefficient are used in combination to predict the durability of the units in use. The saturation coefficient, also referred to as the C/B ratio, is the ratio of 24 hour cold water absorption to the 5 hour boiling absorption. The physical property requirements for each standard are listed in Table 4.