What Is the Difference Between a Hollow & Solid Concrete Block?

Hollow Blocks

• 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.

Solid Blocks

• Contrary to what their name indicates, solid concrete blocks are not necessarily solid. They are merely less hollow than the blocks that are normally called hollow. Solid blocks have core holes that take up less than 25 percent of the cross-sectional area of the block.

Fully Solid Blocks

• Some solid concrete blocks are in fact fully solid. Some of these blocks are called stackable stones, and some are called paving blocks. Stackable stones have two sides that are made rough and irregular to mimic the appearance of natural stone. The other four sides are perfectly flat and square to each other. They are used to easily build strong walls that look like they are made of stone. Natural stone is often irregular and difficult to fit together. Paving blocks are flat and regular, made to be put together like tiles to form paths.

Uses

• Hollow blocks are often used to build large structures like boundary fences. The reduced volume of concrete used to make each block adds up to a significant savings in cost for the materials for the whole wall. Their lighter weight also makes them easier to lift. The hollow cores also give adequate room to place reinforcing materials like steel bars if the design calls for reinforcing. Sometimes water pipes or electrical conduits are run through them. Fully solid blocks are used for paving and other projects where holes would be dangerous or inconvenient. Solid blocks can also hold more mortar between them than their hollow counterparts.