In today's construction, the majority of Hollow Block produced are used in two basic applications. The first is in reinforced or unreinforced single- wythe structural walls. Hollow Block units provide both the structural component and the brick finish without the need for additional materials. Hollow Block for this type of use generally range in size from 4 to 8 in. (102 to 203 mm) in nominal thickness with void areas in the 35 to 60 percent range. Cement concrete hollow blocks have an important place in modern building industry. They are cost effective and better alternative to burnt clay bricks hy virtue of their good durability, fire resistance, partial resistance to sound, thermal insulation, small dead load and high speed of construction.