Specifications

First

Solid Content

H

Hollow

S

Solid

SS

Semi-Solid

Second

Minimum Compressive Strength Calculated on Net Area MPa

Average of 5 Units

Individual Unit

The compressive strength of
any individual unit shall not
be less than 85% of the specified
average of five units.

*

15

15

20

20

Third

Oven Dry Mass Density of
Concrete kg/m³

Maximum water
Absorption kg/m³

*

A

Over 2000

175

B

1700 - 2000

225

C

Less than 1700

300

N

no limits

no limits

Fourth

Maximum Moisture Content, Percent of Total Absorption -
Average of 5 Units

Linear Shrinkage

Moisture Content

R.H. Over 75 Percent

R.H. Under 75 Percent

Less than 0.03

45

40

*

M

0.03 to 0.045

40

35

over 0.045

35

30

O

no limits (where drying shrinkage is not of importance)

When specifying concrete masonry units under CAN3-A165, it is necessary to classify the block by their physical properties, using the four facet system in the table above.

First Facet
H defines Hollow Block
S defines Solid Block

Second Facet
Defines compressive
strength

Third Facet
Defines density
and water absorption

Fourth Facet
Defines moisture
content

Example:
Type H/15/A/M = Hollow, 15 MPa, regular weight
Type S/15/A/M = Solid, 15 MPa, regular weight

NOTE: Solid concrete masonry unit means a unit having a net area in all horizontal planes of 75 percent or more of its gross area.