2D — October 10 - 23, 2014 — Northern NJ Buildings & Facility Maintenance Show — M id A tlantic www.marejournal.com NNJ B uildings & F acility M aintenance S how Real Estate Journal
By Rich Manners, Garden State Sealing Unsealed concrete is a problem waiting to happen
Steel is the most common material used as reinforce- ment in concrete. Exposure of reinforced concrete to chloride ions is the primary cause of premature corrosion of steel reinforcement. The intrusion of chloride ions, present in deicing salts and seawater, into reinforced concrete can cause steel corrosion. Often, corrosion is not detected until after substantial damage has oc- curred. Research confirms that most concrete damage is attributable to surface mois- ture and chloride intrusion.
The most common concrete damage is surface scaling from the freezing and thaw- ing of moisture. Corrosion of reinforcing steel is one of the most destructive forms of concrete deterioration. Concrete in the northeast- ern U.S is highly suscep- tible to chloride penetration specifically from road salt and other deicers. In New Jersey, chloride-laden wa- ter is carried by cars that travel roads treated for win- ter snow and ice and from exposure to coastal areas. Chlorides cause chemical changes in cement, lead- ing to loss of strength, as well as attacking the steel reinforcement present in most concrete. When steel corrodes, the resulting rust occupies a greater volume than the steel. This expan- sion creates tensile stresses in the concrete, which can eventually cause cracking, delamination, and spalling. High quality concrete seal- ers can block up to 99% of surface moisture and inhibit rebar corrosion. I see more and more de- teriorating concrete every year. It’s just a guess, but I believe that the amount of chlorides we use every year to melt snow and ice has been increasing. We are snow plow contractors in the Northeast, and I can tell you, that without exception, our clients are asking for more and more road salt and ice melt every year. The pub- lic’s tolerance for snow and ice here on the east coast is very low. I think one of our clients said it best when he said “our customers expect to open the door of their car, have a cloud appear which floats them into the store and gently sets them down.” These chlorides, whether they are sodium chloride (rock salt), magnesium chlo- ride, potassium chloride or calcium chloride all contrib- ute to the deterioration of the concrete and the associ- ated reinforcing steel. Often, concrete starts to deteriorate at the concrete joints where chloride laden water ends up. Chlorides will eventually make their way down to rein- forcing steel and accelerate the corrosion of the rebar. Yes, there is value in keep- ing moisture out of your con- continued on page 3D
s sealing Portland ce- ment concrete really worthwhile? Concrete
s e a l e r s , w h e t h e r p e n e t r a t - ing or film f o r m i n g are usually t r a n s p a r - ent, leaving little if any a e s t h e t i c
value. Concrete is porous and allows moisture to move in and out of the concrete matrix. Is there really any value in keeping the mois- ture out?
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