What Does a Cinder Block Weigh?

Block Weights

• Concrete is a mixture of cement -- a limestone powder -- sand, aggregate and water. The usual size of a standard concrete block or lighter-weight cinder block used in constructing walls is approximately 8 inches high by 8 inches wide and 16 inches long. Standard concrete blocks of this size weigh from 38 to 43 pounds each, whereas cinder blocks weigh from 26 to 33 pounds. Lighter blocks weighing 22 to 28 pounds contain an aggregate of pumice or of crushed clay, shale and slate that is heated to puff it up and reduce density. The weights of all these blocks vary depending on their size and style. In particular, some types of concrete block are solid, whereas traditional cinder block contains large interior holes.

Terminology

• The terms "concrete block" and "cinder block" are often used interchangeably, even by workers in the construction industry. However, coal bottom ash was the kind of cinder used in blocks during the heyday of cinder block construction in the first half of the 20th century. As the use of coal for heating and producing electricity decreased, so did the supply of bottom ash as well as the fine, silica-like fly ash that helps cement concrete together while also lightening its density. Another term used for both concrete and cinder block is CMU, which is short for "concrete masonry unit."

Cinder Block Uses

• Building construction in the United States increasingly relies on poured concrete walls. However, in cases where construction involves concrete block, it is typical to use heavier-weight standard concrete block instead of cinder block for foundation walls beneath ground level. The Atlas Block website says that lighter-weight kinds of concrete block are best for residential and commercial interior walls and fire-rated walls, such as the ones constructed between garages and living quarters to protect against the ignition of flammable materials, including gasoline.

Benefits for Workers

• Do-it-yourselfers -- who usually don't have the skills, equipment or helpers to pour concrete walls -- often build using concrete and cinder blocks. Due to its lighter weight, cinder block causes less physical stress during construction work. The Construction Solutions website notes that the lighter weight particularly decreases back injuries and fatigue.

Potential Problem

• Concrete manufacturers often include fly ash in their products, which is good for the environment as it recycles coal waste material. But the Minnesota Independent newspaper reports that coal ash contains toxins including arsenic, lead and mercury. Commenting at the Green Home Guide website of the U.S. Green Building Council, architect Anthony Addesso notes that it is unclear whether fly ash in concrete building materials releases -- offgasses -- these toxins into buildings. If it does, this may cause health problems.