In the past, substantial quantities of natural aggregates and crushed stone sources located throughout the country have been discarded or rejected because of restrictive specifications or other reasons. Much of this material could be used in concrete structural elements if proper attention were given to developing mix designs to meet the structural requirements and environmental conditions to which it will be exposed. Utilization of local materials should also reduce transportation requirements and thereby contribute significantly to energy conservation. Paving contractors have now adopted the term "econocrete" to identify concrete mixes designed to use local aggregates that do no necessarily conform to conventional standards. And they have gained the support of the Federal Highway Administration and local governmental agencies in moving the econocrete concept from the laboratories into the field. Econocrete mixes are based on laboratory tests and are designed for specific strength and durability levels in accordance with their intended use. They are being designed for use in the lower course of monolithic concrete slabs for high-traffic highways, full depth pavement for low-volume residential streets and concrete highway shoulders, and as subbases for conventional concrete pavements. If local sources of fine aggregate for concrete pavement fail to meet new skid-resistance requirements but produce satisfactory concrete strength and durability, why import material from a hundred miles or more away to be incorporated into the full slab depth? Only the pavement surface requires aggregate providing maximum skid resistance? Similarly, if local coarse aggregates containing particles that pop out under normal exposure are confined to the lower course of a pavement that is covered by a relatively thin surface layer of concrete made with quality aggregate, the coarse material will remain in place below and contribute to the strength of the pavement.