This standard (Part 1) specifies the requirements for solid and hollow concrete masonry units used in load-bearing and non-load-bearing walls. It outlines standard dimensions, materials, physical criteria such as compressive strength, drying shrinkage, and water absorption, as well as sampling and testing procedures.
Covers the requirements for lightweight aggregate concrete blocks used in masonry construction.
Quick Reference Values
Length tolerance± 5 mm
Height and width tolerance± 3 mm
Maximum water absorption10% by mass
Maximum drying shrinkage (load-bearing)0.06%
Minimum compressive strength (Grade A hollow load-bearing)3.5 N/mm²
Minimum compressive strength (Grade C solid load-bearing)4.0 N/mm²
Practical Notes
Ensure concrete blocks are adequately cured and allowed to dry for at least 28 days before use to minimize drying shrinkage cracking in walls.
Water absorption should be strictly checked; high water absorption can suck moisture from the mortar, weakening the masonry joints.
Check for uniform shape, squareness, and straight edges upon delivery to ensure thin and consistent mortar joints.