Current studies of the engineering properties of bottom ash havejustified its use in many kinds of highway construction, such as backfill, embankment, subbase, and even base courses. However, the electrochemical characteristics of bottom ash are still not well known, and neither is its corrosivity to the metal structures that are commonly included in highway construction. A simple corrosivity test and corrosivity evaluation results are presented for Indiana bottom ashes to clarify the extent of this problem. Four corrosivity parameters were used to estimate the corrosivity of bottom ash: minimum electrical resistivity (r), pH, soluble chloride content, and soluble sulfate content. The corresponding noncorrosive limits are proposed tobe a minimum resistivity of 1, 500 ohm-cm, a minimum pH of 5.5, a maximum soluble chloride of 200 ppm, and a maximum soluble sulfate of 1, 000 ppm. Eleven bottom ashes collected from 10 power plants in Indiana, were tested. If the same holds true for bottom ashes produced in other states, the following actions are recommended before use inthe vicinity of the metal structure in highway construction: a) thoroughly examine the corrosion potential of the bottom ashes proposedfor use; (b) pretreat the potentially corrosive bottom ashes, either at the power plant source or on the site of use; and c) use corrosion-resistant metal members or plastic substitutes
Samenvatting