Hollow Concrete Block, 12" W X 8" H X 12" L

Concrete blocks, also called cinder blocks and cement blocks, come in a wide variety of shapes and sizes. They are made out of a mixture of Portland cement, sand, gravel and water. When the mixture is wet it is paste-like and can be cast into the form of the block. When it dries, it hardens until it becomes like stone.

Hollow concrete blocks have one or more hollow cores. These cores reduce the total cross-sectional area of the block by at least 25 percent. In general, a hollow-core concrete block is more than 50 percent solid. Standard hollow concrete blocks come in full and half sizes. Full-size blocks are rectangular and have two cores. Half size blocks are cubical and have one core.

• 12" wide x 8" high x 12" long hollow block
• Sold individually
• 72 blocks per cube
• Available in other sizes
• Meets ASTM C-90 Standards