Category Construction Glossary
Concrete Block
A concrete masonry unit (CMU) , concrete block, cement block or foundation block
is a large rectangular brick used in construction. Concrete blocks are made from
cast concrete, i.e. Portland cement and aggregate, usually sand and fine gravel
for high-density blocks. Lower density blocks may use industrial wastes as an
aggregate. Those that use cinders (fly ash or bottom ash) are called cinder blocks
in the US. Clinker blocks use clinker as aggregate. Concrete blocks that do not
contain cinders are often mistakenly called cinder or breeze blocks in everyday
speech. Lightweight blocks can also be produced using aerated concrete.
Concrete blocks may be produced with hollow centres to reduce weight or improve
insulation. The use of block work allows structures to be built in the traditional
masonry style with layers (or courses) of overlapping blocks. Blocks come in many
sizes. In the US, the most common size is 8 in × 8 in × 16 in.. The actual size is
usually about 3/8 in smaller to allow for mortar joints.
Concrete block, when reinforced with concrete columns and tie beams, is a very
common building material for the load-bearing walls of buildings, in what is termed
CBS construction for Concrete Block Structure. US suburban houses typically
employ a concrete foundation and slab with a concrete block wall on the perimeter.
Large buildings typically use copious amounts of concrete block; for even larger
buildings, concrete block supplements steel I-beams. Tilt-wall construction,
however is replacing CBS for some large structures. The holes inside concrete
block allow rebar and concrete (creating reinforced concrete) to run vertically
through the block to compensate for the lack of tensile strength. Because most
people find the appearance of concrete block to be drab and unattractive,
exposed surfaces are generally given a decorative finish of stucco, brick, paint or
siding.
When the rebar running vertically through a concrete block wall is anchored, as is
usually the case, into the foundation or floor slab before the wall is built, it presents
a potential problem in assembling the wall, since every block might need to be
lowered from the rebar tops to its resting place in the wall. This problem is solved
by using a style of open-ended block whose plan form resembles the letter "H",
commonly known as a mortarless head joint or speed block. Speed blocks can be
maneuvered between the reinforcing bars and tilted into place; the vertical spaces
are then filled with concrete as with ordinary concrete blocks.
Glazing such as that used for pottery can also be applied to concrete masonry
units, resulting in a hard, glossy finish on this construction material. This finish
often can be made virtually any color and, with integral water repellents, can be
made water-resistant.
This makes glazed masonry an ideal fit for areas in which special attention must be
paid to moisture issues and sanitation codes. This includes car washes, pools,
locker rooms, shower stalls and dining areas such as cafeterias and commercial
kitchens.
In the United States, concrete masonry standards are maintained by the National
Concrete Masonry Association
is a large rectangular brick used in construction. Concrete blocks are made from
cast concrete, i.e. Portland cement and aggregate, usually sand and fine gravel
for high-density blocks. Lower density blocks may use industrial wastes as an
aggregate. Those that use cinders (fly ash or bottom ash) are called cinder blocks
in the US. Clinker blocks use clinker as aggregate. Concrete blocks that do not
contain cinders are often mistakenly called cinder or breeze blocks in everyday
speech. Lightweight blocks can also be produced using aerated concrete.
Concrete blocks may be produced with hollow centres to reduce weight or improve
insulation. The use of block work allows structures to be built in the traditional
masonry style with layers (or courses) of overlapping blocks. Blocks come in many
sizes. In the US, the most common size is 8 in × 8 in × 16 in.. The actual size is
usually about 3/8 in smaller to allow for mortar joints.
Concrete block, when reinforced with concrete columns and tie beams, is a very
common building material for the load-bearing walls of buildings, in what is termed
CBS construction for Concrete Block Structure. US suburban houses typically
employ a concrete foundation and slab with a concrete block wall on the perimeter.
Large buildings typically use copious amounts of concrete block; for even larger
buildings, concrete block supplements steel I-beams. Tilt-wall construction,
however is replacing CBS for some large structures. The holes inside concrete
block allow rebar and concrete (creating reinforced concrete) to run vertically
through the block to compensate for the lack of tensile strength. Because most
people find the appearance of concrete block to be drab and unattractive,
exposed surfaces are generally given a decorative finish of stucco, brick, paint or
siding.
When the rebar running vertically through a concrete block wall is anchored, as is
usually the case, into the foundation or floor slab before the wall is built, it presents
a potential problem in assembling the wall, since every block might need to be
lowered from the rebar tops to its resting place in the wall. This problem is solved
by using a style of open-ended block whose plan form resembles the letter "H",
commonly known as a mortarless head joint or speed block. Speed blocks can be
maneuvered between the reinforcing bars and tilted into place; the vertical spaces
are then filled with concrete as with ordinary concrete blocks.
Glazing such as that used for pottery can also be applied to concrete masonry
units, resulting in a hard, glossy finish on this construction material. This finish
often can be made virtually any color and, with integral water repellents, can be
made water-resistant.
This makes glazed masonry an ideal fit for areas in which special attention must be
paid to moisture issues and sanitation codes. This includes car washes, pools,
locker rooms, shower stalls and dining areas such as cafeterias and commercial
kitchens.
In the United States, concrete masonry standards are maintained by the National
Concrete Masonry Association