Many transportation structures are built using steel-reinforced concrete. The integrity of these structures, especially those that are exposed to salt water, depends on the concrete's resistance to ion migration through its pores. There have been concerns on whether the current surface resistivity test adequately predicts durability. Kyle A Riding, University of Florida researcher from the department of civil and coastal engineering, served as the principal investigator of this project. He tested a variety of concrete mixtures using the surface resistivity test and several other tests to determine how well surface resistivity measures concrete resistance to water and ion penetration. The preliminary testing conducted in this project indicated a good correlation between surface resistivity and other measures of concrete’s susceptibility to ion penetration. A second phase of testing will re-examine the samples to determine any change in concrete properties over a longer time period.