Normalised compressive strength of clay and calcium silicate masonry blocks

Table 4C.7 Normalised compressive strength (N/mm²) of masonry units of clay and calcium silicate blocks complying with BS EN 771-1 and 2 Standard Condition Group 1 masonry units Group 2 masonry units A 5.0 8.0 B 7.5 11.0 C 15.0 21.0 Notes: 1. Values in this Table are normalised compressive strengths (N/mm²). Compressive strengths of masonry units should be derived according to BS EN 772-1. 2. The Table applies to clay and calcium silicate block masonry units where the work size exceeds 337.5 mm in length or 112.5 mm in height. 3. Group 1 masonry units have not more than 25% formed voids (20% for frogged bricks). Group 2 masonry units have formed voids greater than 25%, but not more than 55%.