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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 ...
This equation is completely empirical and is not based on theory. Note that the value of E c found is in units of psi. For normal weight concrete (defined as concrete with a w c of 150 lb/ft 3 and subtracting 5 lb/ft 3 for steel) E c is permitted to be taken as ′.
Concrete hardens as a result of the chemical reaction between cement and water (known as hydration and producing heat). For every mass (kilogram, pound, or any unit of weight) of cement (c), about 0.35 mass of water (w) is needed to fully complete the hydration reactions. [1]
As per Indian codes, compressive strength of concrete is defined as: Field cured concrete in cubic steel molds (Greece) The compressive strength of concrete is given in terms of the characteristic compressive strength of 150 mm size cubes tested after 28 days (fck). In field, compressive strength tests are also conducted at interim duration i.e ...
The law states the strength of a concrete mix is inversely related to the mass ratio of water to cement. [1] [2] As the water content increases, the strength of concrete decreases. Abrams’ law is a special case of a general rule formulated empirically by Feret: = / where S is the strength of concrete
Concrete is a composite material composed of aggregate bonded together with a fluid cement that cures to a solid over time. Concrete is the second-most-used substance in the world after water, [1] and is the most widely used building material. [2] Its usage worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminium combined. [3]
It is also known as the strength-to-weight ratio or strength/weight ratio or strength-to-mass ratio. In fiber or textile applications, tenacity is the usual measure of specific strength. The SI unit for specific strength is Pa ⋅ m 3 / kg , or N ⋅m/kg, which is dimensionally equivalent to m 2 /s 2 , though the latter form is rarely used.
For example, in designing a staircase, a dead load factor may be 1.2 times the weight of the structure, and a live load factor may be 1.6 times the maximum expected live load. These two "factored loads" are combined (added) to determine the "required strength" of the staircase.