Shrinkage in Concrete
Shrinkage in Concrete
(OP)
Hi all
i ask a question ,i am afarid that it is a simple question and from basics of Concrete Design,(but anyway)
what is meant by shrinkage of concrete?
and when it happend?
i ask a question ,i am afarid that it is a simple question and from basics of Concrete Design,(but anyway)
what is meant by shrinkage of concrete?
and when it happend?






RE: Shrinkage in Concrete
RE: Shrinkage in Concrete
RE: Shrinkage in Concrete
try the Portland Cemen Association's website for additional technical information about concrete
http://www.cement.org/
RE: Shrinkage in Concrete
am i right in what i said?
RE: Shrinkage in Concrete
RE: Shrinkage in Concrete
—
For relatively deep flexural members,some reinforcement should be placed near the vertical faces of the tension zone to control cracking in the web.
Without such auxiliary steel,the width of the cracks in the
web may exceed the crack widths at the level of the flexural tension reinforcement.
Where the provisions for deep beams, walls,or precast panels require more steel,those provisions(along with their spacing requirements) will govern.
they have not mentionated shrinkage or temp. effect in this article.(but i think they mean this reinforcement is for shrinkage and Tempreature)
Does this article also apply to MAT Foundations and Other Footings?!
Does Shrinkage have big effect in Mat and Footings as in beams and slabs?
RE: Shrinkage in Concrete
RE: Shrinkage in Concrete
Linear Shrinkage of concrete does not induce any stresses or cracking in concrete.
Restraint to the shrinkage of concrete induces stresses in the concrete. This restraint can be caused by connection to other elements which will not allow the concrete member to shorten due to shrinkage or is may be induced by the presence of reinforcement in the concrete which in itself does not shrink when the concrete does thus causing tensile stresses in the concrete.
The reinforcement in a normal concrete slab can easily induce 1MPa (145psi) or more tensile stress depending on the percentage of reinforcement provided and its placement. Designers should take this into account for their cracking and deflection calculations.
RE: Shrinkage in Concrete
but i do not understand a point.
How can Reinforcement make cracks in the concrete?!
Does shrinkage occur on the sides of thick Footings and thick Mats?
RE: Shrinkage in Concrete
When the concrete shrinks the reinforcement that is bonded to it goes into compression because it does not shrink itself. The two materials are bonded together so if the concrete shortens due to shrinkage then the reinforcement must shorten by the same amount. To shorten the reinfrocement must experience a compressive stress. This compression induces an equal and opposite tension stress in the concrete. If the reinforcement is not arranged symmetrically in the section, it will also induce bending stress due to the eccentricity of the compression stresses.
While this tensile stress itself would not normally be sufficient to crack the concrete unless the reinforcement ratio is very large, when combined with other tensile stresses from loading or other effects it could be sufficient to cause a supposedly uncracked concrete section to crack.
RE: Shrinkage in Concrete