For ecological as well as economic optimization of highway deicing operations, one must know the relative efficiencies of the two agents most commonly used--calcium chloride and rock salt. Because data on this subject are in conflict, new measurements have been made of the extent to which anhydrous calcium chloride pellets and typical Michigan rock salt undercut a sheet of 0.3175-cm-thick (1/8-in.-thick) ice bonded to a concrete block. The extent to which undercutting (the breaking of the bond between ice and concrete) occurred as a function of time and temperature was followed by adding a dye to the chemical, which caused the brine formed by melting ice to flouresce under ultraviolet light. Commercial anhydrous calcium chloride pellets have a relatively narrow particle size distribution and are very uniform in action; reproducible data could be obtained. However, the action of rock salt was found to be strongly affected by wide variability in size and purity of individual particles. After the action of two particle sizes of pure fused sodium chloride was measured, a reasonable estimate could be made of the average action of a typical commercial Michigan rock salt. The results are presented as a table of the quantity of chemical per unit area required to completely undercut the ice sheet as a function of time and temperature. Rock salt is about equal to calcium chloride above -3.89 deg C (25 deg F) for 1 h. As temperatures are lowered and times are shortened, increasingly larger relative quantities of rock salt are required. This must be considered an ecological concern.

Media Info

  • Media Type: Print
  • Features: Figures; Photos; References; Tables;
  • Pagination: pp 54-57
  • Monograph Title: Maintenance management, the federal role, unionization, pavement maintenance, and ice control
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00153150
  • Record Type: Publication
  • ISBN: 0309025672
  • Files: TRIS, TRB
  • Created Date: May 31 1977 12:00AM