Cement hollow blocks (CHB) and Cement grills
hollow units are known as concrete or cement block(CHB). Cement hollow blocks are specified by their nominal dimensions. The nominal dimension is greater than its specified dimension by the thickness of the mortar joint, usually 10 mm. For example A 200 x 200 x 400 block has an actual width of 190 mm, height of 190 mm, and length of 390 mm.