Bleeding in concrete, as seen from the photo above, is a physical migration of water on the surface of concrete after compaction of concrete and before the concrete set. Bleeding water carries more amount of cement particles which makes a layer of water on the concrete surface.

Bleeding in concrete affects concrete’s properties. Bleeding can be decreased by increasing the fineness of cement because finer particles hydrate earlier and their rate of sedimentation is lower.

Increasing fineness of cement for an ordinary user is not within your control. You may think of it while buying next lot of cement. However, from practical prospective, we advise to control other’s factor such as higher water-cement ratio, over vibration, etc…
The properties of cement are not the only sole factor influencing the bleeding of concrete. The presence of fine aggregates and higher water-cement ratio also lead to bleeding.

Bleeding in Concrete: Disadvantages
• Concrete becomes porous. This is one the reasons for leakages in buildings.
• It loses the homogeneity of concrete.
• It decreases strength and wear resistance of concrete.
• It makes the poor bond between two layers of concrete as well as the bond between concrete and reinforcement.
• In the construction of concrete pavement, if water accumulates on the surface of pavement slab, the bleeding water flows over the unsupported side which causes collapsing of sides!
• Bleeding water on concrete surface delay the surface finishing for the concrete finishers and the overall application of curing.
• If concrete is poured by a pump truck, Bleeding water reduces the pumping ability of concrete.