The Effects of De-Icing Salts on Concrete Pavements

Lorella Angelini
Author: Lorella Angelini, Angelini Consulting Services, LLC

“…If you can meet with Triumph and Disaster
And treat those two impostors just the same…”

                                   From “If” by Rudyard Kipling

Can de-icing salts be regarded as “impostors”? On one end they keep bridge and road traffic surfaces clean from ice during the winter, while on the other they generally create serious deterioration of steel reinforced concrete.

Not all the de-icing salts perform the same. Between Sodium Chloride (NaCl), Calcium Chloride (CaCl2) and Magnesium Chloride (MgCl2), the last two are much more effective against ice than NaCl, but at the same time significantly more aggressive against concrete.

CaCl2 can decompose the Portland cement binder due to its reaction with calcium hydroxide (Ca(OH)2), which is generated by the reaction between water and cement.

MgCl2 can decompose the Portland cement binder at an even deeper level than CaCl2 because of its reactions with calcium silicate hydrates (C-S-H), which are the backbone of concrete giving it its structural framework.

Deicers containing ammonium nitrate and ammonium sulfate can also rapidly attack and disintegrate concrete.

Here are a few studies on the effect of different de-icing salts on concrete.

Spotlight – “Bridge Notes” Initiative by Oregon DOT

Lorella Angelini
Author: Lorella Angelini, Angelini Consulting Services, LLC

A new communication initiative comes from Oregon DOT (ODOT). It is the “Bridge Notes” released on the ODOT web site under the Spotlight banner. It started on January 2016.

ODOT Bridge Notes are stand-alone articles. They are part of a series addressing technical issues of great interest for bridge preservation. The first two articles focus on steel painting and bridge deck rehabilitation. Upcoming articles will provide information about cathodic protection and strengthening low capacity bridges.

While technical publications about bridge preservation are widely available, Bridge Notes stand out for their colloquial tone, relevant but accessible information. Their aim is to get the attention of the Oregon general public, as well as the Legislators and Transportation Commission, with the ultimate goal to help increase funding for preservation actions for State bridges.

Congratulations to ODOT and Bridge Notes editor Liz Hunt, for the initiative and the bold resolution to take a step outside the boundaries of our bridge preservation community.