According to the action mechanism of polycarboxylate superplasticizer, polar molecules are adsorbed around the cement particles, so that the particles repel each other, reduce the flocculation effect, release the water wrapped by the cement particles, and make the adsorption water layer on the surface of the cement particles become thin, and the wetting water amount required is greatly reduced. By this mechanism, the water reducer will increase the amount of free bleeding water in the fresh concrete and increase the bleeding. But on the other hand, due to the effect of polycarboxylate superplasticizer, the same slump of concrete required mixing water greatly reduced water, so that the concrete can be bleeding free water reduction. The final bleeding condition depends on which action is dominant.
The adaptability of admixtures and cement also affects the bleeding of concrete. There is no recognized research results on the mechanism of adaptability.
