Cinder block

In the United States, a concrete masonry unit (CMU) – also called concrete block, cement block, and foundation block – is a large rectangular brick
A brick is a block of ceramic material used in masonry construction, usually laid using various kinds of mortar. It has been regarded as one of the longest lasting and strongest building materials used throughout history.-History:...

 used in construction
In the fields of architecture and civil engineering, construction is a process that consists of the building or assembling of infrastructure. Far from being a single activity, large scale construction is a feat of human multitasking...

. Concrete blocks are made from cast
In metalworking, casting involves pouring liquid metal into a mold, which contains a hollow cavity of the desired shape, and then allowing it to cool and solidify. The solidified part is also known as a casting, which is ejected or broken out of the mold to complete the process...

Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

, i.e. Portland cement
Portland cement
Portland cement is the most common type of cement in general use around the world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout...

 and aggregate
Construction Aggregate
Construction aggregate, or simply "aggregate", is a broad category of coarse particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregates are the most mined material in the world...

, usually sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...

 and fine gravel
Gravel is composed of unconsolidated rock fragments that have a general particle size range and include size classes from granule- to boulder-sized fragments. Gravel can be sub-categorized into granule and cobble...

 for high-density blocks. Lower density blocks may use industrial wastes as an aggregate. Those that use cinders (fly ash
Fly ash
Fly ash is one of the residues generated in combustion, and comprises the fine particles that rise with the flue gases. Ash which does not rise is termed bottom ash. In an industrial context, fly ash usually refers to ash produced during combustion of coal...

 or bottom ash
Bottom ash
Bottom ash refers to part of the non-combustible residues of combustion. In an industrial context, it usually refers to coal combustion and comprises traces of combustibles embedded in forming clinkers and sticking to hot side walls of a coal-burning furnace during its operation. The portion of...

) are called cinder blocks in the US, breeze blocks (breeze is a synonym of ash) in the UK and are also known as besser blocks or bricks in Australia. Clinker blocks use clinker
Clinker (waste)
Clinker is a general name given to waste from industrial processes — particularly those that involve smelting metals, burning fossil fuels and using a blacksmith's forge which will usually result in a large buildup of clinker around the tuyère...

 as aggregate. In non-technical usage, the terms cinder block and breeze block are often generalized to cover all of these varieties. Lightweight blocks can also be produced using aerated concrete
Aerated autoclaved concrete
Autoclaved aerated concrete , also known as autoclaved cellular concrete or autoclaved lightweight concrete , was invented in the mid-1920s by the Swedish architect and inventor Johan Axel Eriksson. It is a lightweight, precast building material that simultaneously provides structure, insulation,...


Sizes and structure

Concrete blocks may be produced with hollow centres to reduce weight or improve insulation. The use of blockwork allows structures to be built in the traditional masonry
Masonry is the building of structures from individual units laid in and bound together by mortar; the term masonry can also refer to the units themselves. The common materials of masonry construction are brick, stone, marble, granite, travertine, limestone; concrete block, glass block, stucco, and...

 style with layers (or courses) of staggered blocks. Blocks come in many sizes. In the US, with an R-Value of 1.11 the most common nominal size
Nominal size
In manufacturing, a nominal size or trade size is a size "in name only" used for identification. The nominal size may not match any dimension of the product, but within the domain of that product the nominal size may correspond to a large number of highly standardized dimensions and tolerances.For...

 is 8 x; the actual size is usually about 3/8 in smaller to allow for mortar joints. In Ireland and the UK, blocks are usually 440 x excluding mortar joints.
In New Zealand, blocks are usually 390 × 190 × 190 mm excluding mortar joints.


Concrete block, when reinforced with concrete columns and tie beams
Beam (structure)
A beam is a horizontal structural element that is capable of withstanding load primarily by resisting bending. The bending force induced into the material of the beam as a result of the external loads, own weight, span and external reactions to these loads is called a bending moment.- Overview...

, is a very common building material for the load-bearing walls of buildings, in what is termed "concrete block structure" (CBS) construction. American suburban houses typically employ a concrete foundation
Foundation (architecture)
A foundation is the lowest and supporting layer of a structure. Foundations are generally divided into two categories: shallow foundations and deep foundations.-Shallow foundations:...

 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 -beams
-beams, also known as H-beams, W-beams , rolled steel joist , or double-T are beams with an - or H-shaped cross-section. The horizontal elements of the "" are flanges, while the vertical element is the web...

. Tilt-wall
Tilt slab
Tilt-up, tilt-slab or tilt-wall is a type of building and a construction technique using concrete. It is a cost-effective building technique and efficient construction method.In this method concrete elements Tilt-up, tilt-slab or tilt-wall is a type of building and a construction technique using...

 construction, however, is replacing CBS for some large structures.

Structural properties

The compressive strength of concrete masonry units and masonry walls varies from approximately 1000 psi (7 MPa) to 5000 psi (34 MPa) based on the type of concrete used to manufacture the unit, stacking orientation, the type of mortar used to build the wall, reinforcement, and other factors.


This gallery shows images of 200 series (190 x 190 x 390 full blocks) modular concrete blockwork used in residential construction in a cyclonic region of Northern Australia. Typically there is a vertical reinforced (N12 [1/2" or #4 U.S.] or N16 [5/8" or #5 U.S.] rebar
A rebar , also known as reinforcing steel, reinforcement steel, rerod, or a deformed bar, is a common steel bar, and is commonly used as a tensioning device in reinforced concrete and reinforced masonry structures holding the concrete in compression...

) concrete core at every corner, alongside each opening and at 600 mm (23.6 in) centers elsewhere. Bond beams (typically 2/N12 [1/2" or #4 U.S.] rebar) occur continuously around perimeter and over all openings and under windows. Corefill concrete is typically 15 MPa (2,175.6 psi) compressive strength. For more photos of similar construction see hurricane-proof building
Hurricane-proof building
Tornadoes, cyclones, and other strong winds damage or destroy many buildings. However, with proper design and construction, the damage to buildings by these forces can be greatly reduced. A variety of methods can help a building survive strong winds and storm surge....


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.