A FIELD METHOD FOR MEASURING THE CHLORIDE CONTENT OF CONCRETE

A previous laboratory study demonstrated that based on accuracy, cost, speed, and level of expertise, the specific ion electrode was the bes t method for field measurements of the chloride content of reinforced concrete. This study addresses the development of a field procedure fo r measuring the chloride content of concrete using the specific ion el ectrode. The procedure requires a method to extract powdered samples, weigh 3.0 grams of extracted powder and calibration of the specific io n probe. The sampling method uses a vacuum collection, carbide drill s ampling unit. Calibrated vials, a low cost scale and a triple beam bal ance were evaluated as sample weighing devices. The calibrated vials a re too laborious and slow and the low cost scale too inaccurate. The c alibration method was shown to be quick and consistent with a very sma ll variance independent of number of measurements per specimens and ca libration run. Samples taken from three bridges in Florida, Virginia, Pennsylvania and Wisconsin demonstrated that aggregate type has no eff ect on the chloride measurements. Finally, the variance associated wit h the instrument and the operational procedures of the test method was determined.