(gÉrÄ­l`É) [Span.,=little war], fighting by groups of irregular troops (guerrillas) within areas occupied by the enemy. When guerrillas obey the laws of conventional warfare they are entitled, if captured, to be treated as ordinary prisoners of war; however, they are often executed by their captors.
The Inside Story â Concrete Is Porous. Most people do not realize that concrete is porous â more porous than Swiss cheese! The pores constitute 12 â 18% or more of the concrete but they are invisible, much smaller than the diameter of human hair. After new concrete is poured, almost half of the water has to evaporate.
So to Answer the Questionâ¦. No, concrete tiles do not need to be re-sealed, the process is entirely optional. I have seen concrete porous tiles on very old roofs and not one drop of water has entered the property. The pitch of the roof and the way tiles overlap means water cannot seep through them directly. Most salesmen who sell roof coatings wonât tell you that though.