Parx Racing in suburban Philadelphia, plagued by moisture in the base of the racing surface that alternates between freezing and thawing, expects to resume live racing on Saturday after scrapping its fifth consecutive program on Wednesday. The latest cancellation was the 10th time since Jan. 29 that Parx has either not been able to race or has run three races or fewer. During that time, seven cards have been canceled and just six total races were collectively held on three other days. Parx has not run a full card since Jan. 25. Sal Sinatra, racing secretary at the Bensalem, Pa., track in lower Bucks County, said the track has been unstable over the past two weeks as moisture embedded in the track following rain and snowstorms freezes overnight and then thaws as the mercury rises above 32 degrees during the day. For example, on Monday, the temperature in northeast Philadelphia dropped to 28 overnight, then rose to 46 in the afternoon. In an attempt to remedy the freeze-and-thaw situation, 75,000 tons of sand were added to the surface this week and the track reopened for training on Wednesday morning, although just seven horses recorded workouts. Sinatra said he is confident Parx will be able to resume racing with a 10-race card Saturday, when the advance weather forecast calls for a sunny day with a high of 36 degrees.