Masonry Systems

Masonry Systems

Masonry is the building of structures from individual units, which are often laid in and bound together by mortar.

Concrete Hollow Blocks (CHB)

CHB are the most common masonry units in the Philippines.

• Nominal Dimensions: Typically 400 mm long x 200 mm high. Thickness varies (100mm, 150mm, 200mm).
• Face Shell: The outer wall of the block.
• Web: The partitions connecting the face shells.
• Cell: The hollow space within the block.

Mortar and Grout

Mortar (ASTM C270)

Used to bond masonry units together.

• Type M: High compressive strength (17.2 MPa). Used for foundations and retaining walls.
• Type S: Moderate to high strength (12.4 MPa). Used for reinforced masonry.
• Type N: Medium strength (5.2 MPa). General purpose for above grade.
• Type O: Low strength (2.4 MPa). Non-load bearing interior walls.

Grout (ASTM C476)

Used to fill cells in hollow masonry units to bond the masonry to the reinforcement. High slump (200-250 mm) to flow into small spaces.

Structural Design

Testing of Masonry

• Prism Test (ASTM C1314): Determines the compressive strength of masonry ($f'_m$).
• Mortar Cube Test (ASTM C109): Compressive strength of 50mm mortar cubes.
• Grout Prism Test (ASTM C1019): Compressive strength of grout molded in masonry units.