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The water-cement ratio of the fresh concrete mix is one of the main, if not the most important, factors determining the quality and properties of hardened concrete, as it directly affects the concrete porosity, and a good concrete is always a concrete as compact and as dense as possible.
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 ′.
Abrams' law (also called Abrams' water-cement ratio law) [1] is a concept in civil engineering. 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 ...
Saturated unit weight The unit weight of a soil when all void spaces of the soil are completely filled with water, with no air. The formula for saturated unit weight is: = (+) + where γ s is the saturated unit weight of the material; γ w is the unit weight of water; G s is the specific gravity of the solid; e is the void ratio [3] Submerged ...
In biology, the unit "%" is sometimes (incorrectly) used to denote mass concentration, also called mass/volume percentage. A solution with 1 g of solute dissolved in a final volume of 100 mL of solution would be labeled as "1%" or "1% m/v" (mass/volume). This is incorrect because the unit "%" can only be used for dimensionless quantities.
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 test hammer hits the concrete at a defined energy. Its rebound is dependent on the hardness of the concrete and is measured by the test equipment. By reference to a conversion chart, the rebound value can be used to determine the concrete's compressive strength. When conducting the test, the hammer should be held at right angles to the ...
γ′ is the effective unit weight when saturated or the total unit weight when not fully saturated. B is the width or the diameter of the foundation. φ′ is the effective internal angle of friction. K pγ is obtained graphically. Simplifications have been made to eliminate the need for K pγ. One such was done by Coduto, given below, and it ...