What Does Capillary Rise Method Mean?
The capillary rise method is a test conducted to determine the surface tension of a liquid or the contact angle of liquid with soil or pipe material. Capillary rise is the rise in a liquid above zero pressure level caused by net upward force that is produced by the attraction of water molecules to a solid surface.
Capillary rise takes place due to the combined effect of cohesive and adhesive forces that cause liquids to rise up in tubes of very small diameter.
Trenchlesspedia Explains Capillary Rise Method
The capillary rise method consists of dipping a thin circular capillary into the liquid to be tested. If the adhesion forces (the interaction between the liquid and the capillary wall) are stronger than the cohesive forces (that between the liquid molecules) the liquid will wet the wall and rise in the capillary tube to a certain level with the meniscus having a concave shape.
If the adhesion forces between liquid and the capillary wall are weaker than the cohesive forces between the liquid molecules, the liquid level decreases in the capillary tube making the meniscus convex.