Processes that Control Development of Quantity of Salt on Road Surfaces after Salt Application

Abstract

This paper is part of a larger project to study how the quantity of salt on road surfaces develops after salt application. The goal of the work presented in this paper was to identify the physical processes that control the development of salt quantities on road surfaces. Field observations were made to study the quantity of salt after application. The results suggest that the development of salt quantity after salt application is controlled by three processes: initial loss, dissolution of salt, and loss of salt. A theoretical approach was taken to investigate the process of salt dissolution. The paper presents a principal, physically based model of the measured salt quantity on road surfaces as a function of traffic. It is proposed that the dissolution of salt be expressed by an exponential equation and that the rate of dissolution depends mainly on the quantity of water on the road. The loss of salt caused by blow-off and spray-off is considered to follow an exponential curve. The resultant equation that incorporated the dissolution and the loss was compared with field observations of moist and wet road surfaces.