The use of road salts and chemicals for deicing concrete bridge decks is an effective method for ice removal but causes damage to concrete and corrosion of reinforcing steel. The use of insulation materials for ice control and electric or thermal heating for deicing have been attempted and have met limited success. Conductive concrete may be defined as a cementitious composite that contains a certain amount of electronically conductive components to attain stable and relatively high electrical conductivity. When connected to a power source, heat is generated because of the electrical resistance in the cement admixture with metallic particles and steel fibers. Based on the results of a transient heat transfer analysis, a thin conductive concrete overlay on a bridge deck has the potential to become a cost-effective deicing method. Small-scale slab heating experiments have shown that an average power of approximately 520 W/sq m (48 W/sq ft) was generated by the conductive concrete to raise the slab temperature from -1.1 deg C (30 deg F) to 15.6 deg C (60 deg F) in 30 min. This power level is consistent with the successful deicing applications using electical heating cited in the literature. The work described in this paper is part of an ongoing research project being conducted for the Nebraska Department of Roads. Two large slabs are under construction for a bridge deck deicing experiment in the natural environment to monitor power consumption and deicing performance. The construction costs and experimental data will be used to evaluate the cost effectiveness of using a conductive concrete overlay for bridge deck deicing or anti-icing.

Conductive concrete overlay for bridge deck deicing

This report provides an overview of roadway snow and ice control practices, the types of road weather information currently available, the means for communicating road weather information, and the uses for such information in roadway snow and ice control. The report presents the results of field tests conducted to answer questions on the location of road weather information systems (RWIS), and to discuss a methodology used to determine possible cost-reduction ranges for RWIS implementation in support of roadway snow and ice by state and local highway maintenance agencies in support of snow and ice control activities.

Road weather information systems volume 1: research report

Correlating lab and field tests for evaluation of deicing and anti-icing chemicals: A review of potential approaches

Numerous laboratory and field studies have been conducted to evaluate the performance of deicing and anti-icing products and their resulting friction coefficient of treated pavement. However, laboratory results often do not translate to the field performance due to varying temperatures, wind, traffic, etc. in actual field conditions. Also, the existing laboratory tests fail to address all the significant issues in the actual field environment or to provide actual performance of deicers to guide practitioners. This study sheds light on the challenges of developing a laboratory test that correlates the field test based on literature reviews and interviews from various agencies and practitioners. Recommendations for laboratory testing include the use of environmental chamber that can control and monitor air temperature, humidity, air speed and solar radiation. In addition, it is recommended to incorporate a plowing mechanism into the laboratory test to better simulate the field operations. Two friction-measuring devices were recommended that can be used both in laboratory and in field. In addition, it may be preferable to use a friction trailer if the necessary laboratory space can be obtained. For field testing, it is preferable to conduct the research in a controlled field environment. Recommendations from this study may assist in developing a test method that would closely mimic the actual performance.

Correlating Lab and Field Tests for Evaluation of Deicing and Anti-icing Chemicals: A Renewed Perspective

Concrete bridge decks are prone to ice accumulation. The use of road salts and chemicals for deicing is cost effective but causes damage to concrete and corrosion of reinforcing steel in concrete bridge decks. This problem is a major concern to transportation officials and public works due to rapid degradation of existing concrete pavements and bridge decks. The use of insulation materials for ice control and electric or thermal heating for deicing have been attempted and met limited success. Conductive concrete may be defined as a cementitious composite, which contains a certain amount of electronically conductive components to attain stable and relatively high electrical conductivity. When connected to a power source, heat is generated due to the electrical resistance in the cement admixture with metallic particles and steel fibers. Based on the results of a transient heat transfer analysis, a thin conductive concrete overlay on a bridge deck has the potential to become a cost effective deicing method. Small-scale slab heating experiments have shown that an average power of about W/m2 was generated by the conductive concrete to raise the slab temperature from -1.1 degrees C (30 degrees F) to 15.6 degrees C (60 degrees F) in 30 minutes. This power level is consistent with the successful deicing applications using electrical heating cited in the literature. The work described in this paper is part of an on-going research project being conducted for Nebraska Department of Roads. Two large slabs are under construction for a bridge deck deicing experiment in a natural environment to monitor power consumption and deicing performance. The construction costs and experimental data will be used to evaluate the cost effectiveness of using a conductive concrete overlay for bridge deck deicing or anti-icing.

Bridge deck deicing

The use of liquid calcium chloride on unpaved roads as a dust control agent and as a base stabilization material is examined. In the first section, a description is provided of how calcium chloride controls dust and the benefits it produces. The performance of calcium chloride is compared with that of other commonly used dust control agents. Recommended guidelines and application rates for controlling dust on unpaved roads with calcium chloride are then given. The second section provides a description of how calcium chloride stabilizes unpaved road bases and lists the seven ways the chemical helps build stronger roads. Recommended guidelines and application rates for stabilizing road bases with calcium chloride are provided.

Liquid calcium chloride for dust control and base stabilization of unpaved road systems

The ice-penetration and ice-melting characteristics of seven commercially available chemical deicers that were tested at temperatures ranging from 0 deg F to 25 deg F are examined in this paper. The materials tested included four discrete deicing chemicals and three blends: sodium chloride, calcium chloride, potassium chloride, urea, sodium chloride with traces of carboxymethylcellulose, a sodium chloride/potassium blend, and a sodium chloride/urea blend. The ice penetration tests were conducted using a Plexiglas (trademark) dish containing a 1/8-in.-thick layer of ice. Deicers were placed on the ice surface at a selected rate. Melt brine was collected, measured, and reintroduced periodically with a syringe. The extensive data base resulting from the tests was used to compare the several classes of deicers with regard to their ability to melt and penetrate ice as a function of time and temperature, to establish lower temperature limits for deicer use, and to relate observed behavior to chemical and thermochemical properties of deicers.

Comparative study of chemical deicers

A laboratory study was conducted to determine the undercutting and disbondment characteristic of 10 chemical deicers. The materials included six discrete deicing chemicals and four blends: calcium chloride pellets, calcium chloride flakes, two sodium chloride products, potassium chloride, pelletized urea, sodium chloride with a small amount of carboxymethocellulose, a blend of sodium chloride and potassium chloride sprayed with urea, a blend of sodium chloride and urea, and calcium magnesium acetate. In the undercutting tests, deicer particles were distributed on 6- x 9- x 2-in. concrete slabs covered with a 1/8-in. layer of ice. Tests were conducted at temperatures ranging from 0 deg F to 25 deg F in 5 deg F increments. Results were photographed and subsequently measured with a computerized stylus. The disbondment test apparatus measured and recorded the horizontal and vertical forces required to remove ice from a concrete specimen as it was drawn beneath a stationary blade. Each deicer was applied to the 1/8-in. ice samples and allowed to undercut for 30 min before disbondment forces were recorded. The tests showed that at least a 95% complete undercutting is necessary for ice removal by mechanical disbondment forces of 2.8 lb per inch of blade width.

Comparative study of undercutting and disbondment characteristics of chemical deicers

Highway and city maintenance departments began wetting rock salt and abrasives with liquid calcium chloride more than 20 years ago to enhance the deicing performance of these materials on highways and streets. The newest method for combining rock salt or abrasives with liquid calcium chloride is called stockpile wetting. Stockpile wetting of rock salt consists of the injection of solutions of calcium chloride into the upper sections of piles of rock salt stored for use in highway ice and snow control. In this study, stockpile wetting was simulated by injection of calcium chloride solutions into 6-in.-diameter by 9-ft-tall columns of salt at temperatures of 50 deg F, 45 deg F, 40 deg F, 35 deg F, and 30 deg F. Concentrations of calcium chloride in the injected solutions ranged from 32 to 42 percent. The following characteristics of stockpile wetting were determined: (a) the extent and rate of movement of liquid downward through the simulated stockpile; (b) the quantity of liquid exiting the bottom of the stockpile as a function of temperature, solution concentration, and time; (c) the distribution of calcium chloride within the stockpile and quantities of calcium chloride in leachates; and (d) the ice melting capacity of stockpile-wetted rock salt compared to that of unwetted rock salt. Test results at temperatures 50 deg F or lower indicate that the preferred wetting parameters consist of injecting 42 percent CaCl2 at a rate of 8 gal per ton. At 50 deg F and lower, wetting with 32 percent, 35 percent, and 38 percent CaCl2 yielded leachates. Quantity of leachates is primarily a function of CaCl2 concentrations. Wetted salt that remains in storage during hot summer months may produce leachate based upon test temperature rise to 85 deg F. Stockpile wetted rock salt out-performed dry rock salt in total ice melt at all temperatures and almost all time intervals.

Henry W Kirchner

Papers

Liquid calcium chloride for dust control and base stabilization of unpaved road systems

Comparative study of chemical deicers

Comparative study of undercutting and disbondment characteristics of chemical deicers

Study on wetting salt and sand stockpiles with liquid calcium chloride