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Changes of pore water content due to drying or wetting processes cause significant volume changes of concrete in load-free specimens. They are called the shrinkage (typically causing strains between 0.0002 and 0.0005, and in low strength concretes even 0.0012) or swelling (< 0.00005 in normal concretes, < 0.00020 in high strength concretes).
The specific weight, also known as the unit weight (symbol γ, the Greek letter gamma), is a volume-specific quantity defined as the weight W divided by the volume V of a material: = / Equivalently, it may also be formulated as the product of density, ρ, and gravity acceleration, g: = Its unit of measurement in the International System of Units (SI) is newton per cubic metre (N/m 3), with ...
Concrete has a very low coefficient of thermal expansion, and as it matures concrete shrinks. All concrete structures will crack to some extent, due to shrinkage and tension. Concrete which is subjected to long-duration forces is prone to creep. The density of concrete varies, but is around 2,400 kilograms per cubic metre (150 lb/cu ft). [1]
Permeable interlocking concrete pavements are concrete units with open, permeable spaces between the units. [ 28 ] : 2 More recently manufacturers have introduced styles with smaller joint allowing for better ADA compliance and still capturing a significant amount of stormwater.
The amount of fibers added to a concrete mix is expressed as a percentage of the total volume of the composite (concrete and fibers), termed "volume fraction" (V f). V f typically ranges from 0.1 to 3%. The aspect ratio (l/d) is calculated by dividing fiber length (l) by its diameter (d).
[citation needed] Another major benefit of the system is its reduction in slab weight compared with regular solid decks. Up to 50% of the slab volume may be removed in voids, resulting in less load on structural members. [1] This also allows increased weight and/or span, since the self-weight of the slab contributes less to the overall load.
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A percentage is typically added to neat volume to estimate loose (i.e. uncompacted) volumes for procurement purposes. With concrete work, neat volume is calculated assuming there is no bowing in the formwork , or, for cast-in-place concrete, that the surfaces in contact with the concrete have no voids or imperfections that would require a ...