When considering the service life of a field concrete, the environmental conditions to which the concrete is exposed are equally as important as its transport and mechanical properties. Naturally, these conditions are highly variable thoughout the United States. For the current study, realistic environmental exposures were obtained by using the typical meteorological year weather data files available from NREL [5]. These data files provide typical hourly weather data for over 200 geographical locations within the United States, each geographical location being characterized by a five digit numerical code. For the heat transfer model described above, the following TMY2DATA parameters are utilized: ambient temperature ( Tambient ), dewpoint temperature (Tdew), ambient relative humidity, wind speed (vwind), precipitation, cloud cover (N), and incident global horizontal radiation (Qinc).
As the heat transfer model executes, two types of events are logged, namely wetting and freezing. A wetting event may be due either to a precipitation event (rain, drizzle, sleet, or hail) in the weather data file or condensation when the computed surface temperature of the concrete falls below the current dewpoint temperature (but is still above 0 ºC). It should be noted that snow is not considered a wetting event as we are assuming that the snow will be successfully removed from the pavement or bridge deck before substantial melting/wetting occurs. A freezing event is defined by the concrete surface temperature falling below 0 ºC. This value was chosen as a conservative estimate, since the freezing point of pore water in concrete is typically depressed by the presence of ionic species and the small sizes of the capillary and gel pores in the concrete. When a wetting event occurs, the following values are logged to a file: the initiation time (hours since the beginning of the year), the duration of the event in hours, the average of the concrete surface temperatures at the initiation and the termination of the event, and the ambient relative humidity at the initiation of the event. For a freezing event, only the initiation time, duration, and minimum achieved surface temperature are logged to a freezing event data file.