The base course in a pavement structure serves multiple functions, but the primary function is to supply foundational support and capacity to the pavement structure; to provide a stable course to minimize flexural tensile stresses in surface layers; and to dissipate stresses induced by traffic loading to subbases and weaker underlying subgrades. The selection of an appropriate base material for a pavement structure is dependent on the overall interaction of the base course with the entire pavement structure.

The “

Flexible Base Selection Guide

¹ may be used to assist department personnel with the selection of appropriate base grades. The descriptions that follow are contained in this guide; these bases are also most frequently prescribed by the standard specification Item 247. Other information, such as a background for establishing the current specification, structural notes, base selection factors, and base selection example, is also included.