Concrete block
A concrete block, also known as a cinder block in
Concrete blocks may be produced with hollow centers (cores) to reduce weight, improve insulation and provide an interconnected void into which concrete can be poured to solidify the entire wall after it is built.
Concrete blocks are some of the most versatile building products available because of the wide variety of appearances that can be achieved using them.[1]
Naming
Those that use cinders (
In Australia, they are often known as besser blocks (because the Besser Company was a major supplier of machines that made concrete blocks), and also as grey blocks or concrete masonry units (CMUs).[5]
Clinker blocks use clinker (ash created as a waste product from impurities in minerals such as coal, limestone and iron-ore), also called slag.[2]
Composition
Concrete blocks are made from
Lightweight blocks can also be produced using autoclaved aerated concrete; these are widely used for construction in Finland and other Scandinavian countries, as well as in central Europe, for the material's inherent thermal insulation characteristics, as are expanded clay aggregate blocks.
Sizes and structure
Blocks come in modular sizes, with the most popular typically referred to (by their thickness) as "4-inch", "6-inch", "8-inch", and "12-inch". In the US, concrete blocks are nominally 16 in (410 mm) long and 8 in (200 mm) wide. Their actual dimensions are 3⁄8 inch (9.5 mm) less than the nominal dimensions (to allow for 3⁄8-inch mortar joints between blocks in any orientation).[10] In Ireland and the UK, blocks are usually 440 mm × 215 mm × 100 mm (17.3 in × 8.5 in × 3.9 in) excluding mortar joints. In Australia, New Zealand and Canada, blocks are usually 390 mm × 190 mm × 190 mm (15.4 in × 7.5 in × 7.5 in) excluding mortar joints.
Block cores are typically tapered so that their top surface (as laid) has a greater surface on which to spread a mortar bed and for easier handling. Most concrete blocks have two cores, but three- and four-core units are also produced. A core also allows for the insertion of
A variety of specialized shapes exist to allow special construction features. U-shaped blocks, or knockout blocks, have notches to allow the construction of bond beams or lintel assemblies, using horizontal reinforcing grouted into place in the cavity. Blocks with a channel on the end, known as "jamb blocks", allow doors to be secured to wall assemblies. Blocks with grooved ends permit the construction of control joints, allowing a filler material to be anchored between the un-mortared block ends. Other features, such as radiused corners known as "bullnoses", may be incorporated. A wide variety of decorative profiles also exist.[13]
Concrete blocks may be formulated with special aggregates to produce specific colors or textures for finish use. Special textures may be produced by splitting a ribbed or solid two-block unit; such factory-produced units are called "split-rib" or "split-face" blocks.[14] Blocks may be scored by grooves the width of a mortar joint to simulate different block modules. For example, an 8-by-16-inch (200 mm × 410 mm) block may be scored in the middle to simulate 8-by-8-inch (200 mm × 200 mm) masonry, with the grooves filled with mortar and struck to match the true joints.[15]
Uses
Concrete block, when built with integral
Properties
Concrete masonry walls may be ungrouted, partially grouted, or fully grouted, the latter two enhancing their structural strength. Additionally, steel reinforcement bars (rebar) can be used both vertically and horizontally inside a concrete block wall to maximize its structural performance. The cells in which the rebar is placed must be grouted for the bars to bond to the wall. For this reason, high-seismic zones typically allow only fully grouted walls in their building codes. The American design code that guides design engineers in using concrete blocks as a structural system is the Masonry Standards Joint Committee's Building Code Requirements & Specification for Masonry Structures (TMS 402/ACI 530/ASCE 5).[citation needed]
The compressive strength of concrete blocks and masonry walls varies from approximately 3.4 to 34.5 MPa (500–5,000 psi) based on the type of concrete used to manufacture the unit, stacking orientation, the type of mortar used to build the wall, and whether it is a load-bearing partition or not, among other factors. [16][17][18][19]
See also
References
- ^ "Concrete Masonry". ncma.org. Retrieved 31 January 2023.
- ^ a b "breeze-block". Encyclopedia.com. 26 July 2023. Retrieved 3 August 2023.
- ^ "breeze, n.3". breeze (2nd ed.). Oxford University Press. 1989. Archived from the original on May 24, 2011. Retrieved 2007-11-30.
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ignored (help) - ^ Henderson, Rabekah (24 September 2019). "All about breeze blocks". Atomic Ranch. Retrieved 3 August 2023.
- ^ "The Who, What, When & Why of Besser Blocks". Apex Masonry. 15 August 2019. Retrieved 3 August 2023.
- ^ "A new invention by two female engineers could be the solution to Gaza's rebuilding problems - The Independent". 28 February 2018. Archived from the original on 28 February 2018. Retrieved 20 October 2018.
- ^ "Rebuilding Gaza: 'Green Cake' could be the phoenix rising from Gaza's ashes - Middle East Eye". 17 April 2017. Archived from the original on 17 April 2017. Retrieved 20 October 2018.
- ^ "Block Making Machine aggregate example". Web Editor.
- ^ "Masonry & LEED v4: Continuing Education from Echelon Masonry". www.echelonmasonry.com. Retrieved 2019-02-12.
- ^ "Concrete Block (CMU) Sizes, Shapes, and Finishes". Archtoolbox.com.
- ^ Beall 1987, pp. 61–63.
- ^ "EPS Insulation | Geofoam, Styrofoam, EPS & Polystyrene | Universal Foam Products". universalconstructionfoam.com. Retrieved 2020-10-26.
- ^ Beall 1987, pp. 66–68.
- ^ Beall 1987, pp. 68–70.
- ISBN 978-0-470-64885-8.
- ^ "ASTM Specifications for concrete masonry units".
- ^ "Compressive Strength of Masonry" (PDF). Portland Cement Organization. Retrieved June 5, 2016.
- ^ "Comprehensive Strength of Hollow Concrete Blockwork" (PDF). Government of Canada. 4 June 1986. Archived from the original (PDF) on 2012-09-16.
- ^ "Properties of Concrete Blocks — Strength".
Sources
- Beall, Christine (1987). Masonry Design and Detailing for Architects, Engineers and Builders (2nd ed.). New York: ISBN 0-07-004223-3.