Properties that require consideration when buying or specifying clay brick are:
- Compressive strength (varies from 7MPa to 50MPa)
- Water absorption (face brick up to 10%, NFP up to 16%)
- Modulus of rupture - strength in bending
- Moisture expansion - important when detailing longer structures
Irreversible moisture expansion takes place with all clay products predominently during the first 24 months after manufacture. This expansion is dependent on the clay minerals present in the product and the firing temperature of the process. The movement takes place in both the vertical and horizontal directions.
- Initial rate of absorption.
This affects the bond between the mortar and the brick. Bricks with high rates of absorption may require pre-wetting well before laying to prevent absorbing excessive water from the mortar mix. Trial and error experiments when bricks arrive on site will determine the need to pre-wet bricks.
- Buying Bricks