Inhibitor Longevity and Deicer Performance Study

Primary Investigator Contact Information

Xianming Shi
Western Transportation Institute
PO Box 174250
Bozeman, Montana 59717
406-994-6486
xianming_s@coe.montana.edu

External Project Contact(s)

Kim Willoughby
Washington Department of Transportation, Research Office
310 Maple Park Avenue Southeast
Olympia, Washington 98504-7372
willouk@wsdot.wa.gov

Report(s)

Investigating Longevity of Corrosion Inhibitors and Performance of Deicer Products Under Storage or After Pavement Application
1. Xianming Shi, Laura Fay, Keith Fortune, Robert Smithlin, Matthew Johnson, Marijean M. Peterson, Andrew Creighton, Xhengxian Yang, Doug Cross
2. 4W1978_Final_Report.pdf
Investigating Longevity of Corrosion Inhibitors and Performance of Deicer Products Under Storage or After Pavement Application Executive Summary
1. Xianming Shi, Laura Fay, Keith Fortune, Robert Smithlin, Matthew Johnson, Marijean M. Peterson, Andrew Creighton,Zhengxian Yang, Doug Cross
2. 4W1978_Executive_Summary.pdf

Project Objective

The objective of this research is to evaluate the cost effectiveness of corrosion inhibitors in deicing chemicals, and their longevity when in storage or on the road. The project also aims to establish a reliable measure to quantify the performance of anti-icing and deicing chemicals.

Project Abstract

In the northern United States and Canada, snow- and ice-control operations are essential to ensure the safety, mobility and productivity of winter highways. These maintenance activities offer direct benefits to the public, such as fewer accidents, improved mobility and reduced travel costs. They also offer indirect benefits such as sustained economic productivity, reduction in accident claims and continued emergency services. Depending on weather, available resources and local practice, maintenance agencies use a combination of tools for winter road maintenance including anti-icing, deicing, sanding and snowplowing. In recent years, transportation agencies have been shifting from reactive strategies, such as sanding, to proactive strategies, such as anti-icing. Anti-icing can lead to decreased use of chemicals and abrasives, decreased maintenance costs, improved level of service, and lower accident rates. Reliable weather forecasts are key to a successful anti-icing program, as the pavement surface temperature dictates the application rate and timing. When conducted properly, anti-icing can reduce plowing, decrease the quantity of chemicals required and, in many cases, eliminate the need for abrasives . The growing use of deicers has raised concerns about their effects on motor vehicles, transportation infrastructure, and the environment. The types of deicers applied onto highways often contain chlorides because of their cost-effectiveness. Acetate-based deicers (potassium acetate, sodium acetate, and calcium magnesium acetate [CMA]) have been used as non-corrosive alternatives. Electrochemical and weight loss tests have indicated that bridge structural metals corroded considerably less in CMA solutions than in NaCl solutions. Formates (sodium formate and potassium formate) and bio-based products have also emerged as potential alternative deicers, however these have not been widely used mainly due to their high cost, potential impact on concrete and toxicity to aquatic resources. The costs due to corrosion induced by winter maintenance practices have led to the addition of corrosion inhibitors to chloride-based deicers. The inhibitors are often organic and significantly increase the cost. Uncertainties regarding their longevity and performance need to be resolved before decisions can be made regarding the cost-effectiveness of their use. The objectives of the proposed research are to evaluate the longevity of corrosion inhibitors in storage and on the road and their cost-effectiveness, and to establish a reliable measure to quantify the performance of anti-icing and deicing products. Specifically, this Transportation Pooled-Fund study will use laboratory investigation and field tests to answer the following important questions: 1) What is the longevity of the corrosion inhibitors, when in storage or on the road? 2) How long do the inhibitors remain with the deicers when applied onto the road? 3) What are the effects of storage (temperature, UV intensity, exposure time, and type of deicer) on inhibitor longevity and effectiveness? 4) Do the inhibitors contribute to freezing-point suppression or improve the effectiveness of deicers? 5) How does the laboratory test protocol correlate with deicer performance in the field? 6) What is the most effective product to use and its optimal application rate to combat ice formation under various typical road weather scenarios? By answering the first four questions, this research will allow the transportation agency to determine whether the inclusion of inhibitors into liquid or solid deicers is cost-effective, taking into account: the acceptable deicer corrosivity and reasonable duration of protection expected of inhibitors.

Task Descriptions

Field Investigation
1. Preliminary testing and development of rapid test methods for processing the quantity of samples to be collected in the field and development of a general understanding of the factors that affect inhibitor longevity, field testing and sampling will be investigated. Field experiments will be conducted under realistic storage and road weather conditions at WTI’s Lewistown Cold Regions Test Bed and Research Facility. Field data, in conjunction with laboratory data, will ensure that the research results are applicable to actual situations governing the storage and use of corrosion inhibited deicers. Liquid deicers will be stored in six 3,000 gallon poly tanks. Three of the tanks will be agitated weekly and three will not. Samples will be collected regularly and tested for chloride, cation, and inhibitor concentrations following methods determined in laboratory tests. Solid chemicals will be stored and tested using two methods—in two 25- to 30-ton piles stored outside with full exposure to the elements, and two similar piles within an enclosure of three walls and a roof. All will be on sloping concrete pads so that leachate from each pile can be collected and tested. Random samples will be gathered regularly from each pile and tested for inhibitor concentration. Deicer performance will be evaluated by application of selected deicer products at various application rates onto pavement test sections at the Lewistown facility. Snowmaking equipment will be used to simulate winter storm events, and chemical performance and concentrations will then be evaluated using sample collection, photography, friction measurements, etc.
Project Reporting
1. The research team will provide quarterly progress reports through the course of the project, and a final report when the research is completed. The budget for this task also includes funding for the Principal Investigator to travel to one to-be-determined conference (e.g., TRB Annual Meeting in Washington, D.C.) to give a presentation on the results of this research.
Project Management
1. Dr. Xianming Shi at the Western Transportation Institute (WTI) at Montana State University (MSU) will serve as the Principal Investigator. Laura Fay, M.Sc. at WTI/MSU will serve as the co-Principal Investigator. A Technical Advisory Committee (TAC) consisting of representatives from the Pacific Northwest Snowfighters, contributing agencies, and invited participants will provide technical input/guidance throughout the duration of the research.
Laboratory Investigation
1. This task involves establishing methods to rapidly quantify chloride and inhibitor concentrations to allow the tracking of the chloride and inhibitors in field samples once applied onto the roadway or to monitor the presence and concentration of the corrosion inhibitors subjected to various storage conditions. Under this task, researchers will also establish a method to rapidly quantify corrosivity of deicers by immersing multiple steel coupons in various deicer solutions. It will also involve establishing a method to rapidly quantify deicer performance by testing to see if inhibitors contribute to freezing-point suppression. Field investigations for inhibitor longevity, both in storage and on the road, will be conducted as much as is practicable. Many of the parameters in the field, however, can only be documented rather than controlled. It is nearly impossible to reproduce the field results, or to conduct field tests of different products in similar environmental conditions. As such, it is important to investigate in the laboratory setting the effect of parameters such as dilution, temperature, UV intensity and duration on inhibitor longevity and performance.
Experiment Design and Planning
1. This task covers planning activities for the laboratory investigation and field investigation components of this project.