FiberWallâ„¢ is an alkali-resistant, fiberglass-reinforced, Portland cement-base surface bonding cement with sand, used for construction of concrete block walls by dry-stack (without mortar). It is also ideal to waterproof, strengthen, rehabilitate, reinforce, restore and beautify various existing deteriorating surfaces, including chimneys, retaining walls and other concrete, brick, stone, tile or stucco areas above and below grade, on the interior and exterior.