Tree Sap On Concrete - Can It Be Removed? Concrete is very susceptible to stains because of its porous nature. Sap is a tough substance to remove, especially when it has been left to dry for any length of time. As it hardens, it turns dark and adheres even more strongly to whatever surface it has dripped on. The more porous the concrete, the deeper the sap goes. Dirt and grime also adhere to sap, causing further damage to the concrete. There are a variety of ways to remove tree sap, depending … [Read more...]