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Concrete cover, in reinforced concrete, is the least distance between the surface of embedded reinforcement and the outer surface of the concrete (ACI 130). The concrete cover depth can be measured with a cover meter. The purpose of concrete cover is to protect the reinforcement from corrosion, fire, and other potential damage.
The minimum concrete cover is normally regulated by design or building codes. If the reinforcement is too close to the surface, early failure due to corrosion may occur. The concrete cover depth can be measured with a cover meter. However, carbonated concrete incurs a durability problem only when there is also sufficient moisture and oxygen to ...
The engineering study of every reinforced concrete construction, whether it is a building, a bridge, a bearing wall, or another structure, dictates the positioning of steel rebars at specific positions in the volume of concrete (predicted concrete cover of steel reinforcement bars). This cover varies between 10 mm and 100 mm.
Reinforcement is generally placed in areas of the concrete that are likely to be subject to tension, such as the lower portion of beams. Usually, there is a minimum of 50 mm cover, both above and below the steel reinforcement, to resist spalling and corrosion which can lead to structural instability. [122]
ASTM A706 Gr. 60 is an example of a controlled property range material specification which has a minimum yield strength of 60 ksi (420 MPa), maximum yield strength of 78 ksi (540 MPa), minimum tensile strength of 80 ksi (550 MPa) and not less than 1.25 times the actual yield strength, and minimum elongation requirements that vary by bar size.
The initiation time is related to the rate at which carbonation propagates in the concrete cover thickness.Once that carbonation reaches the steel surface, altering the local pH value of the environment, the protective thin film of oxides on the steel surface becomes instable, and corrosion initiates involving an extended portion of the steel surface.
Double tees are connected during the construction without topping with concrete to create the parking structure floor surface. [6] A benefit of pre-topped double tees is a higher quality concrete for more durable surface to reduce traffic wears. Factories can produce the topping with minimum concrete strength of 5,000 psi. In some areas, the ...
Unlike an I-beam, a T-beam lacks a bottom flange, which carries savings in terms of materials, but at the loss of resistance to tensile forces. [5] T- beam designs come in many sizes, lengths and widths to suit where they are to be used (eg highway bridge, underground parking garage) and how they have to resist the tension, compression and shear stresses associated with beam bending in their ...