Permeability relates to the rate at which water can pass through the concrete.
Important in hydraulic structures to reduce seepage.
Important in chemically active environment, reduces ingress of chemicals which may lead to degradation of concrete(especially sulphate attacks).
Generally reflected in concrete strength, because the factors which leads to higher strength lead to decreased permeability.
- Increase w/c ratio is directly proportional to it.
- Fine cement is inversely proportional to it.
- Well graded aggregates tends to decrease permeability.
- Increased curing time results in the formation of C-S-H gel in pores which decreases permeability.
- If samples are allowed to dry during curing, significant increase in permeability may occur, possibly due to the formation of shrinkage cracks.
- Improper compaction can lead to large voids if poor compaction, or segregation if excessive compaction, both which can increase permeability.
- Excessive bleeding can develop channels through which water can later flow.
It plays an important role in the strength of the concrete, as the permeability of the material is high, as it lower the strength of the material, because more the permeability means the amount of porous in the material. It depends on the homogeneously of the material, as the material is more homogeneous the amount of porous automatically decreases, The amount of water affects the material in so many ways, as it reduce the strength also the strength of the product.
so that is all about the strenth.