Why do bricks have pores?
Im by no means Authoritative, but Ill have a go at answering this. Bricks are basicaly baked mud/clay. When the wet brick is placed in the giant kiln, the water in the clay boils, forming bubbles in the clay that has not yet dried out. The steam also forces its way out of the brick, due to the pressure created from boiling within the brick. Bubbles + steam + often grainy, sandy clay composiiton = Porous texture. Someone can hop in with a better answer if they like, But I hope this helped.