Concrete Crack direction and analysis?

[wal12345]

Can someone please provide me with a general explanation as to what the direction of a crack might mean in terms of structural integrity?

Between a vertical, horizontal and diagonal crack on a concrete building's walls, what does each mena? whic one is more aestethic and which could signify settlement or structural danger and why?

I posted a post earlier asking on where to find the infmration but got answers referring to books that I don't currently have and I can't have access to them. So i'd appreciate an answer rather than someone to tell me what book to read.

Thank you

 

[Lion06]

A crack in any direction in a RC wall could always be a shrinkage crack, and these are typically only aesthethic.
Diagonal cracks, depending on the location, are more likely to be from settlement - If a corner settles, that corner will develop a diagonal crack.

That being said, the only crack I would worry about is a wide one. As long as the cracks are small (in width) then it typically isn't a concern - concrete is supposed to crack, remember?

 

[Ron]

wal12345..I read your original post and the references given to you are excellent, particularly Neville's book.

Most cracks in concrete are caused by drying shrinkage and most of them don't have a detrimental effect on the structure, with the exception of letting water into the concrete to attack the rebar.

Cracks that are caused by a structural deficiency or settlement can take on a variety of directions. Cracks that occur at the bottom of the midspan of a beam are sometimes flexural cracks, but that is also a point where shrinkage cracks can develop as well. One can be detrimental (excess flexure) and one is innocuous (shrinkage).

Settlement cracks don't always show as diagonal cracks, but that is one common form of them. Depending on where the settlement is occurring, the crack can vary from vertical to diagonal.

StructuralEIT has given you a good rule of thumb; however, for concrete cracking in a structure, you have to look at how the structure is configured, whether the cracks are in a wall or other structural component, the orientation of the crack, and as SEIT correctly noted, the width of the crack. Cracks are generally wider at the surface than below the surface. If the crack is less than about 1/32 of an inch, don't worry about it unless you see muliple cracks that are diagonal and closely spaced near the end of a beam (could be shear deficiency, poorly placed rebar, lack of bond development, and a variety of other structural indications), or if closely spaced and vertical at the center of a beam (flexural deficiency).

A forum such as this cannot give you all the information you need about cracks in concrete. Try to get the noted references in your other post.

 

[hokie66]

In order to know what caused a crack and whether it is serious, you have to be able to think like the structural element. Depending on rules of thumb is not good enough. It takes experience and savvy.