What is capillary action and why is it important for concrete? Think back to when you experienced a rainstorm in your area. Particularly remember the plants before the storm and then a few days after. Before they may have been just beginning to sprout. After the storm, the plants are standing upwards and have grown much more. Capillary action plays a hand in why this occurs. During the storm, the water becomes absorbed by the soil and since plants have small capillaries, roots, the water will be pulled up into the plant. While there are many other factors at play, capillary action is an important factor in getting water into the plant. Not only does this concept apply to plants, but any environment where water can interact with an object that has a small pore size. Well, how does this relate to concrete? Capillary action must be considered when putting a floor covering on top of concrete. Water can also be pulled up the small capillary pores found in concrete. Therefore, if the floor covering is put on too soon, the water can pool at the top and debonding can occur which can cause the floor covering to not properly adhere.