IS 4139 : 1989calcium silicate bricks

≠IS 4139 classifies bricks by compressive strength into fixed classes (e.g., Class 150), whereas ASTM C73 uses weathering grades (SW/MW) tied to strength and absorption, and EN 771-2 uses a performance-based approach where manufacturers declare properties.

≠The water absorption test method and limits differ significantly. IS 4139 specifies a maximum of 20% by weight after 24-hour cold water immersion, while ASTM C73 uses a 5-hour boiling test with stricter limits (e.g., max 10% for Grade SW).

≠IS 4139 does not have an explicit requirement or test for frost resistance, only noting suitability for areas where frost is not severe. In contrast, EN 771-2 and GOST 379 have mandatory frost resistance classifications (e.g., F1/F2 in EN, F15-F100 in GOST) for bricks used in exposed conditions.

≠The minimum required compressive strength for the highest grades/classes varies. The highest IS 4139 class (200) requires ~19.6 MPa, whereas the highest ASTM C73 grade (SW) requires a minimum average of 31.0 MPa.

≈All standards define the fundamental material composition as a mixture of sand (siliceous aggregate) and lime, which is molded and cured under high-pressure steam in an autoclave.

≈Compressive strength, water absorption, and dimensional tolerances are universally recognized as the primary properties for specifying and controlling the quality of calcium silicate bricks.

≈All standards include clauses for visual inspection, requiring bricks to be sound, free from major cracks, chips, or other defects that would impair their structural integrity or appearance.

≈The basic principle of determining compressive strength by applying a uniaxial compressive load to the brick until failure is consistent across all standards, even if test procedures have minor variations.