CHLORIDES the CORROSION CHALLENGE Charles F. Lawrence, P.E.
CHLORIDES the CORROSION CHALLENGE Charles F. Lawrence, P.E. NACE International Cathodic Protection Specialist Why Does Corrosion Occur? The Corrosion Cell Me n+ - Me + ne Corrosion Battery ANODE Closure Circuit - e
CATHODE H+ H+ H+ H+ Real World Corrosion + e- The Chloride Difference Insoluble Fe +3 Fe +3 + O = Fe2O3 = + Cl = FeCl3 -
Very Soluble Corrodible Things Infrastructure Roads Pipelines Bridges Equipment Automobiles Trucks/ Plows Loaders Infrastructure Cl- Cl- Cl- Cl- Cl- Cl- ClCl- Cl- Cl- ClCl- Cl- ClCl- Cl- Cl- Cl- Cl- Possible? Solutions No salt Less salt Construction practices Coated rebar Fiberglass rebar
Denser concrete / cover Overlays Maintain coating Metalizing Equipment Possible? Solutions Remove salt residue frequently Non-metallic components Metalized components Better coatings Maintain coatings Scrupulously maintain lubrication Add corrosion inhibitors Salt Sodium Chloride (NaCl) PROS CONS CHEAP Readily available Works to 20F
Stable in storage Easily applied Corrodes metals Only works to 20F Damaging to vegetation Pollutes waterways Contaminates soils Salt (NaCl) Alternatives PROS PROS 1. Sand / Cinders Works to -2F Essentially non-corrosive -25F Essentially Works Works Works non-corrosive to to
to to-25F -75F 0F 0F Can beWorks used with or instead May Cheap be free 21F 2. Calcium Chloride (CaCl2) Environment and animal Wont harm vegetation Environmentally friendly? Provides Safer
Non-corrosive Exothermic Exothermic for good animals traction and of brine Somewhat Lowers Acts the better as fertilizer temperature than regular friendly Biodegradable Less chlorides /#by (10%)
Temperature Quickly More vegetables hygroscopic biodegradable independent melt temp 10F Safer than limits brine salt of for brine animals 3. Magnesium Chloride (MgCl2) Lowers Timed release Less Less Doesnt harmful
Minimal harmful leave to to toxicity avegetation vegetation powdery Sugars are less corrosive 4. Potassium Chloride (KCl) Prevents iceresidue from sticking to Relatively inexpensive surfaces Helps stick to pavement 5. Beet Juice Safe for pavement 6. Cheese Brine
CONS CONS 7. Potato Juice CONS More expensive (20X) May beeliminate expensive More Does More expensive not expensive than (3X) (2X) (8X) ice Urea Bloody mess Similar Yuck
corrosion factor issues to expensive (8X) Only works to more 25F Slower melter Still StillMore corrosive corrosive Can Impact cause damage (14% (3% slickness more to Cl Cl))
Sticks to vehicles More regular Beet expensive Juice brine (5X) 8. Urea Not readily in bulk Subject towindshields refreezing Very Leaves vehicles hygroscopic, Low aload /available white oxygen
keeps Nutrient on residue streams Acts as fertilizer 9. CMA Calcium Magnesium Acetate In large amounts can Plugs surfaces storm wet Ineffective whensewers veryreduce cold waterways Oto levels Forms Silts greyish waterways
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