Engineering and Geologic Investigation of Potential Sources of Aggregate, Fort Irwin, California.

Abstract : Planned construction at Fort Irwin for the National Training Center consists of a number of buildings, roads, parking areas, and other structures in the cantonment area, an airfield with structures and aprons, and a railroad spur. The total amount of bituminous and concrete aggregates required for the construction ranges between 200,000 and 300,000 tons. This investigation was conducted to determine if adequate quantities of good quality fine aggregate and coarse aggregate could be excavated at a reasonable cost from two designated locations. This report describes the geology of the aggregate sources and presents the results of the field explorations and laboratory testing program. The sites investigated were found to contain adequate quantities of good quality fine and coarse aggregates suitable for use in the planned construction activities at Fort Irwin. Select borrow material from both sites is suitable for use as subgrade and subbase course. Crushed material from the coarse aggregate site is suitable for use as a stabilized aggregate base with a design CBR 80. The crushed coarse aggregate material is suitable for use in bituminous concrete; however, stripping is a problem and an antistripping agent will be required. Good quality portland cement concrete can be produced using aggregates from the two sites. However, since the aggregates are potentially reactive in the alkali-silica reaction, it is recommended that low-alkali portland cement be required in the concrete.