Criteria for evaluating the potential performance of industrial waste products as pavements materials are outlined. It is shown that a net energy saving is realized over a selected analysis period whenever the energy saved in the production of raw materials for a pavement that contains waste products (in comparision with a conventional pavement design) is equal to or greater than a function of the energy cost of resurfacing and the times required for both the conventional and waste-product pavements to reach a present serviceability index of 2.5. The" marginal waste product" is (a) in energy terms, that material for which the energy cost of resurfacing over the analysis period, and (b) in economic terms, that product for which the cost per unit of energy saved is equal to the current unit price of energy. Potentially useful industrial waste products can be ranked according to these criteria. A performance criterion for waste materials requires that data be available on which to base reasonable estimates of serviceability history. Several examples of waste products that are currently used as paving materials are discussed, and a statistical study of the compressive strength of pozzolanic concrete correlated with available data on pavement performance is examined.(Author)