Reasons for Cracks in Concrete Basement Walls

[crk]

Cracks are developed in concrete basement walls constructed @ six months ago. The length of wall is @ 47ft. There are several cracks developed on interior side from top to bottom. Also, there are cracks developed on exterior side from top to midheight of basement walls.
1.What may be the reasons for these cracks?Is it due to temperature changes, or is there any limitations on length of basement wall beyond which we have to provide expansion or control joints?
2. What are the reinforcement requirements to resist thermal stresses?

 

[sbp]

If the load on the wall is less than design load then the cracks could be because of temp variation. If taken the temperature difference as 40 deg celsius, the expansion legth for 47 feet comes out to be 6.7 mm. Assuming the width of visible cracks as 0.1 mm, yoy may find around 65 visble cracks for unreinforced section. You should investigate the cracks. See the depth of cracks by making 'V' cuts on both sides of the wall. Temperature cracks are not deep. Typically such crack depth would not exceed 5 mm.
Knowing the expansion length, u can find out the strain produced and thereby the thermal stress by multiplying the strain by modulus of elasticity of concrete.
The reinforcement required can then be easily found out for this stress.
Minimum temperature reinforcement depends upon the thickness of wall. Reynolds Handbook can give the details.

 

[sbp]

sorry, while finding the thermal stress, it will not be just multiplication of strain by elastic modulus of concrete. Stress-strain relationship for cocrete being non-linear, you will have to find out the stress corresponding to that strain from graph. Once stress known, find out the reinforcement.

 

[Zulak]

Cracks that are vertical in basement walls are usually the effects of expansion and contraction (from thermal or shrinkage). The wall is restrained by the basement slab and the first floor framing, so if it were overloaded, it would bow, and probably crack, horizontally (which is not the case.)

 

[LPPE]

Shrinkage cracks, settlement problems, backfilling before floor framing in place, backfilling before concrete has had time to cure, the list goes on and on. There are many reasons why there are cracks in your wall.

Was the wall reinforced?