Qualitative Comparison of Sampling Methods for Determining Chloride Concentrations of Concrete

The objective of this research was to compare the method of removing concrete cylinders using a coring machine with the method of removing concrete powder using a rotary hammer for chloride concentration determination; a special focus was given to these methods as they relate to sampling of concrete bridges, where chloride concentration test results commonly inform bridge management decisions. Criteria for comparing the two sampling methods were subdivided into the categories of feasibility and accuracy, where feasibility was evaluated based on location, depth, concrete quality, and speed and accuracy was evaluated based on contamination, spatial resolution, and distortion. This qualitative comparison indicates that the powder drilling method is preferred over the coring method with respect to every criterion except spatial resolution, for which a preferred method was not apparent. Additional research is recommended to quantitatively compare the accuracy of the two methods.