When concrete is under pressure,but a very strong performance,subject to performance at a very weak.It is the tensile strength only its compression strength of 8 % to 14 % .As a result,low-tensile capacity in its loading early will form a curved cracks.
Concrete compression performance is strong, but performance is weak when tension, its tensile strength is only 8% road cent of its compressive strength, tensile capacity due to low, it load earlier would form bending crack
The concrete is strong under pressure but week when pulled,It's tensile strength is only 8% to 14% to it's comprssive strength.Because of this kind of compressive strength,bending cracks will be formed in the early time.