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.

http://www2.udot.utah.gov/main/uconowner.gf?n=8081525197623431

http://www.ctre.iastate.edu/pubs/midcon/lee.pdf

http://www2.ku.edu/~iri/publications/SLR073.pdf

Modern Trends for Concrete Repair – My Top Three

International Concrete Repair Institute Convention

Author: Lorella Angelini, Angelini Consulting Services, LLC

The upcoming International Concrete Repair Institute (ICRI) Convention in Fort Worth, TX, from October 14 to 16, is titled “Modern Trends in the Repair Industry”. The Convention will gather consulting engineers, contractors, owners and manufacturers, who are experts in the field of concrete repair and restoration. Here is the link to the program of the Convention.

http://www.icri.org/Events/2015_Fall/conv_home.asp

According to ICRI, the way we do business in the repair industry is changing from strategies to materials and from techniques to technology. Based on my education as a civil engineer specialized in construction materials, my top three trends for the repair industry are as follows.

  1. Use of materials that fully integrate with the structure to be restored, providing strength and durability but also the capacity to respond to stress and deformation consistently with the original structure.
  2. Give preference to materials that can be applied easily and successfully, even by unspecialized crews.
  3. Choice of materials that are safe for applicators, users and the environment.

Do you agree with my opinion?

 

Let’s Start Our Conversation…

ed lorellaThe purpose of this blog, “A Conversation about Bridge Preservation”, is to speak about bridge preservation in an open and informal way, thus reaching the general public in addition to the specialists. TSP2 believes in the value of exchanging opinions, ideas and experiences between people who have a stake in bridge preservation or simply are passionate about it.

The writers, Ed Welch and Lorella Angelini, are two civil engineers who share a strong commitment to increasing awareness of bridge preservation within and beyond the construction industry.

Ed is from the Northeast and after a long career as the New Hampshire DOT Bridge Maintenance Engineer, is now the Bridge Preservation Engineer for the AASHTO-TSP2 Program facilitated @ MSU. Lorella is an independent consultant who lives in Minneapolis. She has decades of experience with manufacturers of specialty products in the area of concrete repair and protection..

During the next months, we will be covering two topics; the value of NTPEP (National Transportation Product Evaluation Program) for bridge preservation and the importance of Communicating the Value of Bridge Preservation.  Feel free to suggest any other topics you would like to explore!

Stay tuned for an interview with Drew Storey and Jeremy Hunter of Indiana DOT.