Bond beam units used in concrete masonry have open cells in them like any other units. Unlike with lintel blocks that are closed on the bottom, the grout poured into a bond beam will flow into the cells of the units below. When bond beams are used, does the entire wall have to be solid grouted? How can you have partially grouted cells in a reinforced masonry wall that uses bond beams?
Most concrete masonry walls that use bond beams are not fully grouted. Grout is prevented from flowing into ungrouted cells by using metal lath or plastic mesh in the bed joint below the bond beam. The lath or mesh is fine enough to prevent most of the grout from flowing into the cell below. Obviously, this material is not extended over cells to be grouted. Materials for this purpose are manufactured by several companies that sell wall ties and masonry accessories.