Salvaged materials can provide suitable aggregate for lean mix concrete for pavement subbases. But be prepared to deal with excessive air entrainment. The lean mix concrete was used under a change order that allowed it to be substituted for conventional cement-treated subbase. After extensive testing, a cement content of 8 percent was selected for the lean concrete subbase. This compares with the 5 percent usually used in cement-treated subbase in California. Use of the lean concrete increased production; 21,000 square yards per day were placed as compared to 12,200 square yards for cement-treated subbase. No hand-finishing was needed behind the paver; rolling and trimming were also eliminated and a saving in both labor and amount of material waste was effected. Two plastic-strip longitudinal joints were placed in the 50 foot width. To improve load transfer these joints were offset one foot from where longitudinal joints were planned in the concrete pavement above. State engineers have now concluded, however, that longitudinal joints are unnecessary in lean mix concrete subbase and they will not be included in future projects. At 72 hours after the start of concrete paving over the subbase concrete delivery trucks carrying 14 cubic yard loads were allowed to maneuver into position on the subbase at the paver. After 7 days, loads of 20,000 pounds per axle were allowed to travel without restriction on the subbase.