How Porosity Destroys Concrete and Basements

The "Inside Story" – Concrete Is Porous

Most people do not realize that concrete is porous – more porous than Swiss cheese! The pores constitute 12 – 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. As this surplus water pushes to the surface, it leaves behind a network of capillary pores in the concrete.

Concrete Porosity in Damp Basements

The pores are orders of magnitude larger than a water molecule. Water vapor and soil gases, including radon gas, flow easily right through, drawn in by the lower pressure inside buildings. But liquid water is initially held back by its surface tension inside the dry microscopic pores as the globs of water get stuck. However, once the pores get wet, the liquid water breaks through. Moreover, the wet pores start actively pulling in water from the ground by capillary action.

Did you know concrete blocks and cinder blocks are much more porous than poured concrete?

Cement paste, which holds concrete together, contains platelets of calcium. Since this calcium is soluble in water, the pores in concrete get gradually larger and larger in the presence of water. A previously perfectly dry basement will start smelling musty, feeling humid, and eventually will start seeping water.

Even if your basement or concrete slab looks perfectly dry, deep-seal it now with RadonSeal® Penetrating Concrete Sealer against invisible water vapor and gases, and protect it against water infiltration, efflorescence, and deterioration.

Water Slowly Destroys Porous Concrete and Bricks

Problems with Basements and Concrete Slabs

concrete porosity to water and radon gas
  • wet basement - water seeping through concrete walls or floor
  • cracks in basement walls
  • cracks in concrete floors
  • leaking floor-to-wall joints or saw-cut control joints
  • leaking form ties or pipe penetrations
  • efflorescence - the sign of beginning water seepage
  • radon gas seeping through concrete and openings
  • damp basement - water vapor infiltration
  • molds and mildew, musty odors
  • condensation - in basements or on garage floors
  • concrete dusting - harmful to the lungs and machinery
  • sump pump failure - backup sump pump needed
  • leaky crawlspace or storm shelter

Problems with Outdoor Concrete, Bricks, and Masonry

  • spalling or pitting of driveways and outdoor concrete due to freeze/thaw cycle and road salts
  • cracks in driveways, pool decks, and patios
  • leaking brick walls and chimneys due to wind-driven rain
  • crumbling bricks
  • efflorescence on concrete or brick walls, and pavers
  • deteriorating stone or masonry walls
  • pool decks - cracks, pit marks, deterioration
  • cracks in swimming pools
  • leaking fish ponds
  • deterioration of concrete in marinas due to wind-carried salts
  • algae growth on outdoor concrete or bricks
  • concrete needs staining