Concrete – Effects of Deicers

The two most recognized organizations pertaining to the working technical knowledge of concrete are The American Concrete Institute (ACI) and the Portland Cement Association (PCA). Practicing civil engineers and those in the construction industry belong to these organizations and rely on their research findings for the latest information on concrete.

Both of these organizations have published their research findings on deicers and their effect on concrete, and they both agree that sodium and calcium chloride when used as a deicer will not harm concrete when it is properly made, placed, and cured according to their recommendations. The ACI gives their specific recommendations in ACI 201.2R-01, and the PCA in their RD124 Bulletin.

The ACI Guide to Durable Concrete shows the attack rates of commonly used chemicals on concrete. The part of the table that pertains to the use of deicers on concrete is shown below. It is from the ACI 201.2R-01 Guide to Durable Concrete, reported by committee 201, Copyright 2001.

Table 2.1 Rates of attack for common deicers on concrete
DeicerRate of Attack on Concrete
Sodium ChlorideNegligible
Calcium ChlorideNegligible
Magnesium ChlorideSlow
Ammonuim SulfateModerate
Table 2.1 shows sodium and calcium chloride have a negligible chemical rate of attack on concrete. Magnesium chloride has a slow rate of attack and ammonium sulfate (a fertilizer) has moderate rate of attack.

Magnesium chloride often said to be “safe on concrete”. However, there is plenty of research evidence showing magnesium chloride (MgCl2) is harmful to concrete as referenced below:

Magnesium Chloride as a Road Deicer: A Critical Review
Peter G. Snow, FACI
Burns Concrete, Inc.
Idaho Falls, Idaho

American Concrete Institute Tech Paper 105-M70
Effects of Deicers on Concrete Deterioration
ACI Materials Journal, V. 105, No. 6, November-December 2008

The Role of Magnesium in Concrete Deterioration
Iowa DOT HR-355, Final Report
The Iowa Highway Research Board
Department of Geological and Atmospheric Sciences, Iowa State University

Effects of Various Deicing Chemicals on Pavement Concrete Deterioration
Mid-Continent Transportation Symposium
Hyomin Lee, Robert D. Cody, Anita M. Cody, and Paul G. Spry
Department of Geological and Atmospheric Sciences, Iowa State University

Supply Warehouse, Inc. has concluded from the above evidence not to recommend deicers with magnesium chloride. We have also concluded that deicers should be applied per manufacturer’s instructions and NOT be over applied. Over application leaves excess chemical on the pavement when the ice is cleared. The excess deicer puts the concrete through additional, unnecessary freeze/thaw cycles which can cause concrete of questionable quality to scale. We recommend using deicers with a coverage Indicator (coloring) which significantly helps control the product application rate.