Concrete paving contractors often sublet the construction of the stabilized subbase. This often creates problems with scheduling and grade control. It is also likely to be expensive because of the additional equipment needed for mixing, placing, and compacting the subbase material. The paving contractor who uses econoncrete can mix and place the subbase with regular paving equipment and thus maintain complete control of the project, the scheduling and the concrete yield. The yield is determined by the elevation of the subbase. On a paving project with econoncrete subbase the normal procedure is to control the finegrading of the soil subgrade electronically from a stringline. The econoncrete subbase is then placed by a slipform paver controlling the grade from the stringline or by ski attachments sensing the prepared subbase. Pavement grade is based on the subbase surface. Thus each layer in the pavement structure becomes smoother as irregularities in the preceding layer are ironed out. As it emerges from the slipform paver econoncrete subbase has the appearance of a concrete slab. For this reason the uninitiated often expect it to meet the criteria for pavement concrete. However, the subbase is intended only to provide uniform support for the pavement and not to provide the high strengths required in the pavement itself. ACPA recommends 28 day compressive strengths in the 700-1000 psi range. This range more meets subbase requirements for strength and durability.