Effects of Deicing Salt Solutions on Physical Properties of Pavement Concretes

摘要

Salt solutions are used on pavement surfaces during wintry weather events to guarantee safedriving conditions. In addition to sodium chloride (NaCl) which continues to be traditionallyused as deicer, the usage of solutions of calcium chloride (CaCl_2) and magnesium chloride(MgCl_2) is on the increase due to need provide a more consistent ice and snow control and thusensure safety of the travelling public. This paper assesses the effects of three different saltsolutions (NaCl, CaCl_2, and MgCl_2) on several physical and mechanical properties of pavementconcretes. These deicing solutions were used under simulated wetting-drying (WD) and freezing9thawing (FT) exposure regimes with total ion concentration of the deicers was 10.5 molal forWD exposure and 5.5 molal for FT exposure.Two types of concretes were used in the study; the ordinary portland cement concrete andthe fly ash concrete (20% of cement replacement by mass). The prismatic and cylindricalspecimens were used to monitor physical changes due to these exposure regimes. The physicalchanges of cylindrical specimens subjected to the WD regime were monitored by takingultrasonic pulse velocity (UPV) measurements after every 2 weeks of exposure and crushingthese cylinders at the end to obtain the compressive strength. The effects on prismatic specimenswere monitored by measuring mass and resonant frequencies after every 2 weeks of exposureand using these data to calculate changes in the relative dynamic modulus of elasticity (RDME).The test results obtained from the RDME and UPV measurements, combined with visualobservations were used to assess the effects of deicers on concretes. It was observed that CaCl_2solution is more harmful as compared to MgCl_2 solution for both plain and fly ash modifiedconcretes.