I ordered solid concrete block. It came with cores in it. The manufacturer claims this is OK. Is it?
Solid load-bearing concrete masonry units as defined by ASTM C 145, Specification for Solid Load-bearing Concrete Masonry Units, may contain cores making up to 25% of the cross-sectional area of the unit. If units with no cores are required, they should be specified as 100%-solid units in the specification or on the drawings in the appropriate locations. In most cases, looking at how the units are to be used in the building should make it clear whether or not they must be 100% solid. Usually block don't have to be 100% solid. They should be 100% solid, though, if the cores would be exposed to weather.