Effects of Deicing Salt Solutions on Physical Properties of Pavement Concretes

Abstract

Salt solutions are used on pavement surfaces during wintry weather events to ensure safe driving conditions. In addition to sodium chloride (NaCl), which continues to be traditionally used as a deicer, solutions of calcium chloride (CaCl₂) and magnesium chloride (MgCl₂) are being increasingly used to provide a more consistent ice and snow control and thus ensure safe driving. This paper assesses the effects of three salt solutions (NaCl, CaCl₂, and MgCl₂) on several physical and mechanical properties of pavement concretes. These deicing solutions were used under simulated wetting–drying (W-D) and freezing–thawing (F-T) exposure regimes with total ion concentration of the deicers of 10.5 molal for W-D exposure and 5.5 molal for F-T exposure. Two types of concretes were used in the study: ordinary portland cement concrete and fly ash concrete, in which 20% (by mass) of cement was replaced by Class C fly ash. The physical changes of cylindrical specimens subjected to the W-D regime were monitored by ultrasonic pulse velocity measurements after every 2 weeks of exposure until the end of the test. At the end of the W-D exposure period, the same test cylinders were used to obtain the compressive strength of the concrete. The results of all measurements, combined with visual observations of the overall condition of the specimen, were used to assess the relative effect of deicers (and the exposure conditions) on both types of concretes. The overall findings from this research indicated that exposure to the CaCl₂ deicer resulted, in general, in more severe changes in the physical and mechanical properties of both types of concrete used in this study.