TRL | Trials of higher brine share pre-wetted treatments

Sensor measurements and records of road conditions were used to assess the conditions under which effective treatments were carried out using pre-wetted salt with a 50:50 ratio of dry salt:brine and to provide a comparison with standard pre-wetted treatments. The measurements indicated that comparable freezing point temperatures were achieved by the FS 30 and FS 50 pre-wetted salt, with a minimum freezing point around -20⁰C achieved on damp roads (<0.05mm) and -15⁰C on wet roads (<0.1mm). The amount of salt that can be spread by FS100 provides effective treatments to -5⁰C on wet roads, and much lower on dry and damp roads. FS 70 provides effective treatments down to around -7⁰C on wet roads. As road wetness increases, all treatment types show reduced freezing points of the road surface moisture, tending towards very low suppression at around 0.5mm water thickness and 2mm of precipitation (water equivalent). For all treatment methods, the freezing point behaviour tends to show a much flatter response as compared to the residual salt. The initial dissolution of salt will decrease the freezing point. This depression appears to be maintained over the duration of the treatment for damp and wet roads. Salt may be lost as solution, resulting in the reduction in salt amount shown by the sensors, however the freezing point of the solution remaining is maintained, except on very wet roads where precipitation or heavy dew formation will dilute and/or wash away the salt solution.

Trials of higher brine share pre-wetted treatments

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